draft-ietf-lake-edhoc-06.txt   draft-ietf-lake-edhoc-07.txt 
Network Working Group G. Selander Network Working Group G. Selander
Internet-Draft J. Mattsson Internet-Draft J. Mattsson
Intended status: Standards Track F. Palombini Intended status: Standards Track F. Palombini
Expires: 23 October 2021 Ericsson AB Expires: 25 November 2021 Ericsson AB
21 April 2021 24 May 2021
Ephemeral Diffie-Hellman Over COSE (EDHOC) Ephemeral Diffie-Hellman Over COSE (EDHOC)
draft-ietf-lake-edhoc-06 draft-ietf-lake-edhoc-07
Abstract Abstract
This document specifies Ephemeral Diffie-Hellman Over COSE (EDHOC), a This document specifies Ephemeral Diffie-Hellman Over COSE (EDHOC), a
very compact and lightweight authenticated Diffie-Hellman key very compact and lightweight authenticated Diffie-Hellman key
exchange with ephemeral keys. EDHOC provides mutual authentication, exchange with ephemeral keys. EDHOC provides mutual authentication,
perfect forward secrecy, and identity protection. EDHOC is intended perfect forward secrecy, and identity protection. EDHOC is intended
for usage in constrained scenarios and a main use case is to for usage in constrained scenarios and a main use case is to
establish an OSCORE security context. By reusing COSE for establish an OSCORE security context. By reusing COSE for
cryptography, CBOR for encoding, and CoAP for transport, the cryptography, CBOR for encoding, and CoAP for transport, the
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This Internet-Draft will expire on 23 October 2021. This Internet-Draft will expire on 25 November 2021.
Copyright Notice Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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1.5. Terminology and Requirements Language . . . . . . . . . . 6 1.5. Terminology and Requirements Language . . . . . . . . . . 6
2. EDHOC Outline . . . . . . . . . . . . . . . . . . . . . . . . 7 2. EDHOC Outline . . . . . . . . . . . . . . . . . . . . . . . . 7
3. Protocol Elements . . . . . . . . . . . . . . . . . . . . . . 9 3. Protocol Elements . . . . . . . . . . . . . . . . . . . . . . 9
3.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 9 3.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 9
3.2. Method and Correlation . . . . . . . . . . . . . . . . . 10 3.2. Method and Correlation . . . . . . . . . . . . . . . . . 10
3.2.1. Method . . . . . . . . . . . . . . . . . . . . . . . 10 3.2.1. Method . . . . . . . . . . . . . . . . . . . . . . . 10
3.2.2. Connection Identifiers . . . . . . . . . . . . . . . 10 3.2.2. Connection Identifiers . . . . . . . . . . . . . . . 10
3.2.3. Transport . . . . . . . . . . . . . . . . . . . . . . 11 3.2.3. Transport . . . . . . . . . . . . . . . . . . . . . . 11
3.2.4. Message Correlation . . . . . . . . . . . . . . . . . 11 3.2.4. Message Correlation . . . . . . . . . . . . . . . . . 11
3.3. Authentication Parameters . . . . . . . . . . . . . . . . 11 3.3. Authentication Parameters . . . . . . . . . . . . . . . . 11
3.3.1. Authentication Keys . . . . . . . . . . . . . . . . . 12 3.3.1. Authentication Keys . . . . . . . . . . . . . . . . . 11
3.3.2. Identities . . . . . . . . . . . . . . . . . . . . . 12 3.3.2. Identities . . . . . . . . . . . . . . . . . . . . . 12
3.3.3. Authentication Credentials . . . . . . . . . . . . . 13 3.3.3. Authentication Credentials . . . . . . . . . . . . . 13
3.3.4. Identification of Credentials . . . . . . . . . . . . 14 3.3.4. Identification of Credentials . . . . . . . . . . . . 15
3.4. Cipher Suites . . . . . . . . . . . . . . . . . . . . . . 16 3.4. Cipher Suites . . . . . . . . . . . . . . . . . . . . . . 16
3.5. Ephemeral Public Keys . . . . . . . . . . . . . . . . . . 17 3.5. Ephemeral Public Keys . . . . . . . . . . . . . . . . . . 18
3.6. Auxiliary Data . . . . . . . . . . . . . . . . . . . . . 18 3.6. External Authorization Data . . . . . . . . . . . . . . . 18
3.7. Applicability Statement . . . . . . . . . . . . . . . . . 18 3.7. Applicability Statement . . . . . . . . . . . . . . . . . 19
4. Key Derivation . . . . . . . . . . . . . . . . . . . . . . . 20 4. Key Derivation . . . . . . . . . . . . . . . . . . . . . . . 20
4.1. EDHOC-Exporter Interface . . . . . . . . . . . . . . . . 22 4.1. EDHOC-Exporter Interface . . . . . . . . . . . . . . . . 23
5. Message Formatting and Processing . . . . . . . . . . . . . . 22 5. Message Formatting and Processing . . . . . . . . . . . . . . 23
5.1. Encoding of bstr_identifier . . . . . . . . . . . . . . . 23 5.1. Encoding of bstr_identifier . . . . . . . . . . . . . . . 24
5.2. Message Processing Outline . . . . . . . . . . . . . . . 23 5.2. Message Processing Outline . . . . . . . . . . . . . . . 24
5.3. EDHOC Message 1 . . . . . . . . . . . . . . . . . . . . . 24 5.3. EDHOC Message 1 . . . . . . . . . . . . . . . . . . . . . 25
5.3.1. Formatting of Message 1 . . . . . . . . . . . . . . . 24 5.3.1. Formatting of Message 1 . . . . . . . . . . . . . . . 25
5.3.2. Initiator Processing of Message 1 . . . . . . . . . . 25 5.3.2. Initiator Processing of Message 1 . . . . . . . . . . 26
5.3.3. Responder Processing of Message 1 . . . . . . . . . . 26 5.3.3. Responder Processing of Message 1 . . . . . . . . . . 27
5.4. EDHOC Message 2 . . . . . . . . . . . . . . . . . . . . . 26 5.4. EDHOC Message 2 . . . . . . . . . . . . . . . . . . . . . 28
5.4.1. Formatting of Message 2 . . . . . . . . . . . . . . . 27 5.4.1. Formatting of Message 2 . . . . . . . . . . . . . . . 28
5.4.2. Responder Processing of Message 2 . . . . . . . . . . 27 5.4.2. Responder Processing of Message 2 . . . . . . . . . . 28
5.4.3. Initiator Processing of Message 2 . . . . . . . . . . 29 5.4.3. Initiator Processing of Message 2 . . . . . . . . . . 30
5.5. EDHOC Message 3 . . . . . . . . . . . . . . . . . . . . . 29 5.5. EDHOC Message 3 . . . . . . . . . . . . . . . . . . . . . 31
5.5.1. Formatting of Message 3 . . . . . . . . . . . . . . . 30 5.5.1. Formatting of Message 3 . . . . . . . . . . . . . . . 31
5.5.2. Initiator Processing of Message 3 . . . . . . . . . . 30 5.5.2. Initiator Processing of Message 3 . . . . . . . . . . 31
5.5.3. Responder Processing of Message 3 . . . . . . . . . . 32 5.5.3. Responder Processing of Message 3 . . . . . . . . . . 34
6. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 33 6. Error Handling . . . . . . . . . . . . . . . . . . . . . . . 34
6.1. Success . . . . . . . . . . . . . . . . . . . . . . . . . 34 6.1. Success . . . . . . . . . . . . . . . . . . . . . . . . . 36
6.2. Unspecified . . . . . . . . . . . . . . . . . . . . . . . 34 6.2. Unspecified . . . . . . . . . . . . . . . . . . . . . . . 36
6.3. Wrong Selected Cipher Suite . . . . . . . . . . . . . . . 35 6.3. Wrong Selected Cipher Suite . . . . . . . . . . . . . . . 36
6.3.1. Cipher Suite Negotiation . . . . . . . . . . . . . . 35 6.3.1. Cipher Suite Negotiation . . . . . . . . . . . . . . 37
6.3.2. Examples . . . . . . . . . . . . . . . . . . . . . . 35 6.3.2. Examples . . . . . . . . . . . . . . . . . . . . . . 37
7. Transferring EDHOC and Deriving an OSCORE Context . . . . . . 37 7. Transferring EDHOC and Deriving an OSCORE Context . . . . . . 38
7.1. EDHOC Message 4 . . . . . . . . . . . . . . . . . . . . . 37 7.1. EDHOC Message 4 . . . . . . . . . . . . . . . . . . . . . 38
7.1.1. Formatting of Message 4 . . . . . . . . . . . . . . . 37 7.1.1. Formatting of Message 4 . . . . . . . . . . . . . . . 39
7.1.2. Responder Processing of Message 4 . . . . . . . . . . 38 7.1.2. Responder Processing of Message 4 . . . . . . . . . . 39
7.1.3. Initiator Processing of Message 4 . . . . . . . . . . 38 7.1.3. Initiator Processing of Message 4 . . . . . . . . . . 40
7.2. Transferring EDHOC in CoAP . . . . . . . . . . . . . . . 39 7.2. Transferring EDHOC in CoAP . . . . . . . . . . . . . . . 40
7.2.1. Deriving an OSCORE Context from EDHOC . . . . . . . . 41
7.2.2. Error Messages with CoAP Transport . . . . . . . . . 42
8. Security Considerations . . . . . . . . . . . . . . . . . . . 42 8. Security Considerations . . . . . . . . . . . . . . . . . . . 42
8.1. Security Properties . . . . . . . . . . . . . . . . . . . 42 8.1. Security Properties . . . . . . . . . . . . . . . . . . . 42
8.2. Cryptographic Considerations . . . . . . . . . . . . . . 44 8.2. Cryptographic Considerations . . . . . . . . . . . . . . 45
8.3. Cipher Suites and Cryptographic Algorithms . . . . . . . 45 8.3. Cipher Suites and Cryptographic Algorithms . . . . . . . 46
8.4. Unprotected Data . . . . . . . . . . . . . . . . . . . . 46 8.4. Unprotected Data . . . . . . . . . . . . . . . . . . . . 46
8.5. Denial-of-Service . . . . . . . . . . . . . . . . . . . . 46 8.5. Denial-of-Service . . . . . . . . . . . . . . . . . . . . 47
8.6. Implementation Considerations . . . . . . . . . . . . . . 46 8.6. Implementation Considerations . . . . . . . . . . . . . . 47
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 48 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 49
9.1. EDHOC Cipher Suites Registry . . . . . . . . . . . . . . 48 9.1. EDHOC Exporter Label . . . . . . . . . . . . . . . . . . 49
9.2. EDHOC Method Type Registry . . . . . . . . . . . . . . . 49 9.2. EDHOC Cipher Suites Registry . . . . . . . . . . . . . . 49
9.3. EDHOC Error Codes Registry . . . . . . . . . . . . . . . 50 9.3. EDHOC Method Type Registry . . . . . . . . . . . . . . . 50
9.4. The Well-Known URI Registry . . . . . . . . . . . . . . . 50 9.4. EDHOC Error Codes Registry . . . . . . . . . . . . . . . 51
9.5. Media Types Registry . . . . . . . . . . . . . . . . . . 50 9.5. The Well-Known URI Registry . . . . . . . . . . . . . . . 51
9.6. CoAP Content-Formats Registry . . . . . . . . . . . . . . 51 9.6. Media Types Registry . . . . . . . . . . . . . . . . . . 51
9.7. Expert Review Instructions . . . . . . . . . . . . . . . 51 9.7. CoAP Content-Formats Registry . . . . . . . . . . . . . . 52
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 52 9.8. Expert Review Instructions . . . . . . . . . . . . . . . 52
10.1. Normative References . . . . . . . . . . . . . . . . . . 52 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 53
10.2. Informative References . . . . . . . . . . . . . . . . . 54 10.1. Normative References . . . . . . . . . . . . . . . . . . 53
Appendix A. Use of CBOR, CDDL and COSE in EDHOC . . . . . . . . 56 10.2. Informative References . . . . . . . . . . . . . . . . . 55
A.1. CBOR and CDDL . . . . . . . . . . . . . . . . . . . . . . 57 Appendix A. Compact Representation . . . . . . . . . . . . . . . 58
A.2. CDDL Definitions . . . . . . . . . . . . . . . . . . . . 57 Appendix B. Use of CBOR, CDDL and COSE in EDHOC . . . . . . . . 58
A.3. COSE . . . . . . . . . . . . . . . . . . . . . . . . . . 59 B.1. CBOR and CDDL . . . . . . . . . . . . . . . . . . . . . . 59
Appendix B. Test Vectors . . . . . . . . . . . . . . . . . . . . 59 B.2. CDDL Definitions . . . . . . . . . . . . . . . . . . . . 59
B.1. Test Vectors for EDHOC Authenticated with Signature Keys B.3. COSE . . . . . . . . . . . . . . . . . . . . . . . . . . 61
(x5t) . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Appendix C. Test Vectors . . . . . . . . . . . . . . . . . . . . 61
B.1.1. Message_1 . . . . . . . . . . . . . . . . . . . . . . 60 C.1. Test Vectors for EDHOC Authenticated with Signature Keys
B.1.2. Message_2 . . . . . . . . . . . . . . . . . . . . . . 61 (x5t) . . . . . . . . . . . . . . . . . . . . . . . . . . 62
B.1.3. Message_3 . . . . . . . . . . . . . . . . . . . . . . 69 C.1.1. Message_1 . . . . . . . . . . . . . . . . . . . . . . 62
B.1.4. OSCORE Security Context Derivation . . . . . . . . . 75 C.1.2. Message_2 . . . . . . . . . . . . . . . . . . . . . . 63
B.2. Test Vectors for EDHOC Authenticated with Static C.1.3. Message_3 . . . . . . . . . . . . . . . . . . . . . . 71
Diffie-Hellman Keys . . . . . . . . . . . . . . . . . . . 77 C.1.4. OSCORE Security Context Derivation . . . . . . . . . 77
B.2.1. Message_1 . . . . . . . . . . . . . . . . . . . . . . 78 C.2. Test Vectors for EDHOC Authenticated with Static
B.2.2. Message_2 . . . . . . . . . . . . . . . . . . . . . . 79 Diffie-Hellman Keys . . . . . . . . . . . . . . . . . . . 79
B.2.3. Message_3 . . . . . . . . . . . . . . . . . . . . . . 85 C.2.1. Message_1 . . . . . . . . . . . . . . . . . . . . . . 80
B.2.4. OSCORE Security Context Derivation . . . . . . . . . 90 C.2.2. Message_2 . . . . . . . . . . . . . . . . . . . . . . 81
Appendix C. Applicability Template . . . . . . . . . . . . . . . 92 C.2.3. Message_3 . . . . . . . . . . . . . . . . . . . . . . 87
Appendix D. EDHOC Message Deduplication . . . . . . . . . . . . 93 C.2.4. OSCORE Security Context Derivation . . . . . . . . . 92
Appendix E. Change Log . . . . . . . . . . . . . . . . . . . . . 94 Appendix D. Applicability Template . . . . . . . . . . . . . . . 94
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 96 Appendix E. EDHOC Message Deduplication . . . . . . . . . . . . 95
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 97 Appendix F. Change Log . . . . . . . . . . . . . . . . . . . . . 96
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 99
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 99
1. Introduction 1. Introduction
1.1. Motivation 1.1. Motivation
Many Internet of Things (IoT) deployments require technologies which Many Internet of Things (IoT) deployments require technologies which
are highly performant in constrained environments [RFC7228]. IoT are highly performant in constrained environments [RFC7228]. IoT
devices may be constrained in various ways, including memory, devices may be constrained in various ways, including memory,
storage, processing capacity, and power. The connectivity for these storage, processing capacity, and power. The connectivity for these
settings may also exhibit constraints such as unreliable and lossy settings may also exhibit constraints such as unreliable and lossy
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"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
Readers are expected to be familiar with the terms and concepts Readers are expected to be familiar with the terms and concepts
described in CBOR [RFC8949], CBOR Sequences [RFC8742], COSE described in CBOR [RFC8949], CBOR Sequences [RFC8742], COSE
structures and process [I-D.ietf-cose-rfc8152bis-struct], COSE structures and process [I-D.ietf-cose-rfc8152bis-struct], COSE
algorithms [I-D.ietf-cose-rfc8152bis-algs], and CDDL [RFC8610]. The algorithms [I-D.ietf-cose-rfc8152bis-algs], and CDDL [RFC8610]. The
Concise Data Definition Language (CDDL) is used to express CBOR data Concise Data Definition Language (CDDL) is used to express CBOR data
structures [RFC8949]. Examples of CBOR and CDDL are provided in structures [RFC8949]. Examples of CBOR and CDDL are provided in
Appendix A.1. When referring to CBOR, this specification always Appendix B.1. When referring to CBOR, this specification always
refer to Deterministically Encoded CBOR as specified in Sections refer to Deterministically Encoded CBOR as specified in Sections
4.2.1 and 4.2.2 of [RFC8949]. 4.2.1 and 4.2.2 of [RFC8949].
The single output from authenticated encryption (including the The single output from authenticated encryption (including the
authentication tag) is called 'ciphertext', following [RFC5116]. authentication tag) is called 'ciphertext', following [RFC5116].
2. EDHOC Outline 2. EDHOC Outline
EDHOC specifies different authentication methods of the Diffie- EDHOC specifies different authentication methods of the Diffie-
Hellman key exchange: digital signatures and static Diffie-Hellman Hellman key exchange: digital signatures and static Diffie-Hellman
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- The Initiator lists supported cipher suites in order of - The Initiator lists supported cipher suites in order of
preference preference
- The Responder verifies that the selected cipher suite is the - The Responder verifies that the selected cipher suite is the
first supported cipher suite (or else rejects and states first supported cipher suite (or else rejects and states
supported cipher suites). supported cipher suites).
* Method types and error handling. * Method types and error handling.
* Transport of opaque auxiliary data. * Transport of external authorization data.
EDHOC is designed to encrypt and integrity protect as much EDHOC is designed to encrypt and integrity protect as much
information as possible, and all symmetric keys are derived using as information as possible, and all symmetric keys are derived using as
much previous information as possible. EDHOC is furthermore designed much previous information as possible. EDHOC is furthermore designed
to be as compact and lightweight as possible, in terms of message to be as compact and lightweight as possible, in terms of message
sizes, processing, and the ability to reuse already existing CBOR, sizes, processing, and the ability to reuse already existing CBOR,
COSE, and CoAP libraries. COSE, and CoAP libraries.
To simplify for implementors, the use of CBOR and COSE in EDHOC is To simplify for implementors, the use of CBOR and COSE in EDHOC is
summarized in Appendix A and test vectors including CBOR diagnostic summarized in Appendix B and test vectors including CBOR diagnostic
notation are given in Appendix B. notation are given in Appendix C.
3. Protocol Elements 3. Protocol Elements
3.1. General 3.1. General
An EDHOC message flow consists of three mandatory messages An EDHOC message flow consists of three mandatory messages
(message_1, message_2, message_3) between Initiator and Responder, an (message_1, message_2, message_3) between Initiator and Responder, an
optional fourth message (message_4), plus an EDHOC error message. optional fourth message (message_4), plus an EDHOC error message.
EDHOC messages are CBOR Sequences [RFC8742], see Figure 3. The EDHOC messages are CBOR Sequences [RFC8742], see Figure 3. The
protocol elements in the figure are introduced in the following protocol elements in the figure are introduced in the following
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(AEAD, hash) in the selected cipher suite (see Section 3.4) and the (AEAD, hash) in the selected cipher suite (see Section 3.4) and the
application can make use of the established connection identifiers application can make use of the established connection identifiers
C_1, C_I, and C_R (see Section 3.2.4). EDHOC may be used with the C_1, C_I, and C_R (see Section 3.2.4). EDHOC may be used with the
media type application/edhoc defined in Section 9. media type application/edhoc defined in Section 9.
The Initiator can derive symmetric application keys after creating The Initiator can derive symmetric application keys after creating
EDHOC message_3, see Section 4.1. Application protected data can EDHOC message_3, see Section 4.1. Application protected data can
therefore be sent in parallel or together with EDHOC message_3. therefore be sent in parallel or together with EDHOC message_3.
Initiator Responder Initiator Responder
| C_1, METHOD_CORR, SUITES_I, G_X, C_I, AD_1 | | C_1, METHOD_CORR, SUITES_I, G_X, C_I, EAD_1 |
+------------------------------------------------------------------>| +------------------------------------------------------------------>|
| message_1 | | message_1 |
| | | |
| C_I, G_Y, C_R, Enc(ID_CRED_R, Signature_or_MAC_2, AD_2) | | C_I, G_Y, C_R, Enc(ID_CRED_R, Signature_or_MAC_2, EAD_2) |
|<------------------------------------------------------------------+ |<------------------------------------------------------------------+
| message_2 | | message_2 |
| | | |
| C_R, AEAD(K_3ae; ID_CRED_I, Signature_or_MAC_3, AD_3) | | C_R, AEAD(K_3ae; ID_CRED_I, Signature_or_MAC_3, EAD_3) |
+------------------------------------------------------------------>| +------------------------------------------------------------------>|
| message_3 | | message_3 |
Figure 3: EDHOC Message Flow Figure 3: EDHOC Message Flow
3.2. Method and Correlation 3.2. Method and Correlation
The data item METHOD_CORR in message_1 (see Section 5.3.1), is an The data item METHOD_CORR in message_1 (see Section 5.3.1), is an
integer specifying the method and the correlation properties of the integer specifying the method and the correlation properties of the
transport, which are described in this section. transport, which are described in this section.
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connection identifiers SHALL adhere to the requirements for that connection identifiers SHALL adhere to the requirements for that
protocol. Each party choses a connection identifier it desires the protocol. Each party choses a connection identifier it desires the
other party to use in outgoing messages. (For OSCORE this results in other party to use in outgoing messages. (For OSCORE this results in
the endpoint selecting its Recipient ID, see Section 3.1 of the endpoint selecting its Recipient ID, see Section 3.1 of
[RFC8613]). [RFC8613]).
3.2.3. Transport 3.2.3. Transport
Cryptographically, EDHOC does not put requirements on the lower Cryptographically, EDHOC does not put requirements on the lower
layers. EDHOC is not bound to a particular transport layer, and can layers. EDHOC is not bound to a particular transport layer, and can
be used in environments without IP. The transport is responsible to be used in environments without IP. The application using EDHOC is
handle message loss, reordering, message duplication, fragmentation, responsible to handle message loss, reordering, message duplication,
and denial of service protection, where necessary. fragmentation, demultiplex EDHOC messages from other types of
messages, and denial of service protection, where necessary.
The Initiator and the Responder need to have agreed on a transport to The Initiator and the Responder need to have agreed on a transport to
be used for EDHOC, see Section 3.7. It is recommended to transport be used for EDHOC, see Section 3.7. It is recommended to transport
EDHOC in CoAP payloads, see Section 7. EDHOC in CoAP payloads, see Section 7.
3.2.4. Message Correlation 3.2.4. Message Correlation
If the whole transport path provides a mechanism for correlating If the whole transport path provides a mechanism for correlating
messages received with messages previously sent, then some of the messages received with messages previously sent, then some of the
connection identifiers may be omitted. There are four cases: connection identifiers may be omitted. There are four cases:
skipping to change at page 12, line 17 skipping to change at page 12, line 5
Hellman key. The Initiator and the Responder MAY use different types Hellman key. The Initiator and the Responder MAY use different types
of authentication keys, e.g. one uses a signature key and the other of authentication keys, e.g. one uses a signature key and the other
uses a static Diffie-Hellman key. When using a signature key, the uses a static Diffie-Hellman key. When using a signature key, the
authentication is provided by a signature. When using a static authentication is provided by a signature. When using a static
Diffie-Hellman key the authentication is provided by a Message Diffie-Hellman key the authentication is provided by a Message
Authentication Code (MAC) computed from an ephemeral-static ECDH Authentication Code (MAC) computed from an ephemeral-static ECDH
shared secret which enables significant reductions in message sizes. shared secret which enables significant reductions in message sizes.
The MAC is implemented with an AEAD algorithm. When using static The MAC is implemented with an AEAD algorithm. When using static
Diffie-Hellman keys the Initiator's and Responder's private Diffie-Hellman keys the Initiator's and Responder's private
authentication keys are called I and R, respectively, and the public authentication keys are called I and R, respectively, and the public
authentication keys are called G_I and G_R, respectively. authentication keys are called G_I and G_R, respectively. The
authentication key algorithm needs to specified with enough
parameters to make it completely determined. Note that for most
signature algorithms, the signature is determined by the signature
algorithm and the authentication key algorithm together. For
example, the curve used in the signature is typically determined by
the authentication key parameters.
* Only the Responder SHALL have access to the Responder's private * Only the Responder SHALL have access to the Responder's private
authentication key. authentication key.
* Only the Initiator SHALL have access to the Initiator's private * Only the Initiator SHALL have access to the Initiator's private
authentication key. authentication key.
3.3.2. Identities 3.3.2. Identities
EDHOC assumes the existence of mechanisms (certification authority, EDHOC assumes the existence of mechanisms (certification authority,
trusted third party, manual distribution, etc.) for specifying and trusted third party, manual distribution, etc.) for specifying and
distributing authentication keys and identities. Policies are set distributing authentication keys and identities. Policies are set
based on the identity of the other party, and parties typically only based on the identity of the other party, and parties typically only
allow connections from a specific identity or a small restricted set allow connections from a specific identity or a small restricted set
of identities. For example, in the case of a device connecting to a of identities. For example, in the case of a device connecting to a
network, the network may only allow connections from devices which network, the network may only allow connections from devices which
authenticate with certificates having a particular range of serial authenticate with certificates having a particular range of serial
numbers in the subject field and signed by a particular CA. On the numbers in the subject field and signed by a particular CA. On the
other side, the device may only be allowed to connect to a network other side, the device may only be allowed to connect to a network
which authenticates with a particular public key (information of which authenticates with a particular public key (information of
which may be provisioned, e.g., out of band or in the Auxiliary Data, which may be provisioned, e.g., out of band or in the external
see Section 3.6). authorization data, see Section 3.6).
The EDHOC implementation must be able to receive and enforce The EDHOC implementation must be able to receive and enforce
information from the application about what is the intended endpoint, information from the application about what is the intended endpoint,
and in particular whether it is a specific identity or a set of and in particular whether it is a specific identity or a set of
identities. identities.
* When a Public Key Infrastructure (PKI) is used, the trust anchor * When a Public Key Infrastructure (PKI) is used, the trust anchor
is a Certification Authority (CA) certificate, and the identity is is a Certification Authority (CA) certificate, and the identity is
the subject whose unique name (e.g. a domain name, NAI, or EUI) is the subject whose unique name (e.g. a domain name, NAI, or EUI) is
included in the endpoint's certificate. Before running EDHOC each included in the endpoint's certificate. Before running EDHOC each
skipping to change at page 14, line 44 skipping to change at page 15, line 7
CRED_x = { CRED_x = {
1: 1, 1: 1,
-1: 4, -1: 4,
-2: h'b1a3e89460e88d3a8d54211dc95f0b90 -2: h'b1a3e89460e88d3a8d54211dc95f0b90
3ff205eb71912d6db8f4af980d2db83a', 3ff205eb71912d6db8f4af980d2db83a',
"subject name" : "42-50-31-FF-EF-37-32-39" "subject name" : "42-50-31-FF-EF-37-32-39"
} }
3.3.4. Identification of Credentials 3.3.4. Identification of Credentials
ID_CRED_I and ID_CRED_R are identifiers of the public authentication ID_CRED_I and ID_CRED_R are used to identify and optionally transport
keys of the Initiator and the Responder, respectively. ID_CRED_I and the public authentication keys of the Initiator and the Responder,
ID_CRED_R do not have any cryptographic purpose in EDHOC. respectively. ID_CRED_I and ID_CRED_R do not have any cryptographic
purpose in EDHOC.
* ID_CRED_R is intended to facilitate for the Initiator to retrieve * ID_CRED_R is intended to facilitate for the Initiator to retrieve
the Responder's public authentication key. the Responder's public authentication key.
* ID_CRED_I is intended to facilitate for the Responder to retrieve * ID_CRED_I is intended to facilitate for the Responder to retrieve
the Initiator's public authentication key. the Initiator's public authentication key.
The identifiers ID_CRED_I and ID_CRED_R are COSE header_maps, i.e. The identifiers ID_CRED_I and ID_CRED_R are COSE header_maps, i.e.
CBOR maps containing Common COSE Header Parameters, see Section 3.1 CBOR maps containing Common COSE Header Parameters, see Section 3.1
of [I-D.ietf-cose-rfc8152bis-struct]). In the following we give some of [I-D.ietf-cose-rfc8152bis-struct]). In the following we give some
examples of COSE header_maps. examples of COSE header_maps.
Raw public keys are most optimally stored as COSE_Key objects and Raw public keys are most optimally stored as COSE_Key objects and
identified with a 'kid' parameter: identified with a 'kid' parameter:
* ID_CRED_x = { 4 : kid_x }, where kid_x : bstr, for x = I or R. * ID_CRED_x = { 4 : kid_x }, where kid_x : bstr, for x = I or R.
Public key certificates can be identified in different ways. Header Public key certificates can be identified in different ways. Header
parameters for identifying C509 certificates and X.509 certificates parameters for identifying C509 certificates and X.509 certificates
are defined in [I-D.mattsson-cose-cbor-cert-compress] and are defined in [I-D.ietf-cose-cbor-encoded-cert] and
[I-D.ietf-cose-x509], for example: [I-D.ietf-cose-x509], for example:
* by a hash value with the 'c5t' or 'x5t' parameters; * by a hash value with the 'c5t' or 'x5t' parameters;
- ID_CRED_x = { 34 : COSE_CertHash }, for x = I or R, - ID_CRED_x = { 34 : COSE_CertHash }, for x = I or R,
- ID_CRED_x = { TDB3 : COSE_CertHash }, for x = I or R, - ID_CRED_x = { TDB3 : COSE_CertHash }, for x = I or R,
* by a URI with the 'c5u' or 'x5u' parameters; * by a URI with the 'c5u' or 'x5u' parameters;
- ID_CRED_x = { 35 : uri }, for x = I or R, - ID_CRED_x = { 35 : uri }, for x = I or R,
- ID_CRED_x = { TBD4 : uri }, for x = I or R, - ID_CRED_x = { TBD4 : uri }, for x = I or R,
* ID_CRED_x MAY contain the actual credential used for * ID_CRED_x MAY contain the actual credential used for
authentication, CRED_x. For example, a certificate chain can be authentication, CRED_x. For example, a certificate chain can be
transported in ID_CRED_x with COSE header parameter c5c or transported in ID_CRED_x with COSE header parameter c5c or
x5chain, defined in [I-D.mattsson-cose-cbor-cert-compress] and x5chain, defined in [I-D.ietf-cose-cbor-encoded-cert] and
[I-D.ietf-cose-x509]. [I-D.ietf-cose-x509].
It is RECOMMENDED that ID_CRED_x uniquely identify the public It is RECOMMENDED that ID_CRED_x uniquely identify the public
authentication key as the recipient may otherwise have to try several authentication key as the recipient may otherwise have to try several
keys. ID_CRED_I and ID_CRED_R are transported in the 'ciphertext', keys. ID_CRED_I and ID_CRED_R are transported in the 'ciphertext',
see Section 5.5 and Section 5.4. see Section 5.5 and Section 5.4.
When ID_CRED_x does not contain the actual credential it may be very When ID_CRED_x does not contain the actual credential it may be very
short. One byte credential identifiers are realistic in many short. One byte credential identifiers are realistic in many
scenarios as most constrained devices only have a few keys. In cases scenarios as most constrained devices only have a few keys. In cases
where a node only has one key, the identifier may even be the empty where a node only has one key, the identifier may even be the empty
byte string. byte string.
3.4. Cipher Suites 3.4. Cipher Suites
An EDHOC cipher suite consists of an ordered set of COSE code points An EDHOC cipher suite consists of an ordered set of algorithms from
from the "COSE Algorithms" and "COSE Elliptic Curves" registries: the "COSE Algorithms" and "COSE Elliptic Curves" registries.
Algorithms need to be specified with enough parameters to make them
completely determined. Currently, none of the algorithms require
parameters. EDHOC is only specified for use with key exchange
algorithms of type ECDH curves. Use with other types of key exchange
algorithms would likely require a specification updating EDHOC. Note
that for most signature algorithms, the signature is determined by
the signature algorithm and the authentication key algorithm
together, see Section 3.3.1.
* EDHOC AEAD algorithm * EDHOC AEAD algorithm
* EDHOC hash algorithm * EDHOC hash algorithm
* EDHOC ECDH curve * EDHOC key exchange algorithm (ECDH curve)
* EDHOC signature algorithm * EDHOC signature algorithm
* EDHOC signature algorithm curve
* Application AEAD algorithm * Application AEAD algorithm
* Application hash algorithm * Application hash algorithm
Each cipher suite is identified with a pre-defined int label. Each cipher suite is identified with a pre-defined int label.
EDHOC can be used with all algorithms and curves defined for COSE. EDHOC can be used with all algorithms and curves defined for COSE.
Implementation can either use one of the pre-defined cipher suites Implementation can either use one of the pre-defined cipher suites
(Section 9.1) or use any combination of COSE algorithms to define (Section 9.2) or use any combination of COSE algorithms and
their own private cipher suite. Private cipher suites can be parameters to define their own private cipher suite. Private cipher
identified with any of the four values -24, -23, -22, -21. suites can be identified with any of the four values -24, -23, -22,
-21.
The following cipher suites are for constrained IoT where message The following cipher suites are for constrained IoT where message
overhead is a very important factor: overhead is a very important factor:
0. ( 10, -16, 4, -8, 6, 10, -16 ) 0. ( 10, -16, 4, -8, 10, -16 )
(AES-CCM-16-64-128, SHA-256, X25519, EdDSA, Ed25519, (AES-CCM-16-64-128, SHA-256, X25519, EdDSA,
AES-CCM-16-64-128, SHA-256) AES-CCM-16-64-128, SHA-256)
1. ( 30, -16, 4, -8, 6, 10, -16 ) 1. ( 30, -16, 4, -8, 10, -16 )
(AES-CCM-16-128-128, SHA-256, X25519, EdDSA, Ed25519, (AES-CCM-16-128-128, SHA-256, X25519, EdDSA,
AES-CCM-16-64-128, SHA-256) AES-CCM-16-64-128, SHA-256)
2. ( 10, -16, 1, -7, 1, 10, -16 ) 2. ( 10, -16, 1, -7, 10, -16 )
(AES-CCM-16-64-128, SHA-256, P-256, ES256, P-256, (AES-CCM-16-64-128, SHA-256, P-256, ES256,
AES-CCM-16-64-128, SHA-256) AES-CCM-16-64-128, SHA-256)
3. ( 30, -16, 1, -7, 1, 10, -16 ) 3. ( 30, -16, 1, -7, 10, -16 )
(AES-CCM-16-128-128, SHA-256, P-256, ES256, P-256, (AES-CCM-16-128-128, SHA-256, P-256, ES256,
AES-CCM-16-64-128, SHA-256) AES-CCM-16-64-128, SHA-256)
The following cipher suite is for general non-constrained The following cipher suite is for general non-constrained
applications. It uses very high performance algorithms that also are applications. It uses very high performance algorithms that also are
widely supported: widely supported:
4. ( 1, -16, 4, -7, 1, 1, -16 ) 4. ( 1, -16, 4, -7, 1, -16 )
(A128GCM, SHA-256, X25519, ES256, P-256, (A128GCM, SHA-256, X25519, ES256,
A128GCM, SHA-256) A128GCM, SHA-256)
The following cipher suite is for high security application such as The following cipher suite is for high security application such as
government use and financial applications. It is compatible with the government use and financial applications. It is compatible with the
CNSA suite [CNSA]. CNSA suite [CNSA].
5. ( 3, -43, 2, -35, 2, 3, -43 ) 5. ( 3, -43, 2, -35, 3, -43 )
(A256GCM, SHA-384, P-384, ES384, P-384, (A256GCM, SHA-384, P-384, ES384,
A256GCM, SHA-384) A256GCM, SHA-384)
The different methods use the same cipher suites, but some algorithms The different methods use the same cipher suites, but some algorithms
are not used in some methods. The EDHOC signature algorithm and the are not used in some methods. The EDHOC signature algorithm is not
EDHOC signature algorithm curve are not used in methods without used in methods without signature authentication.
signature authentication.
The Initiator needs to have a list of cipher suites it supports in The Initiator needs to have a list of cipher suites it supports in
order of preference. The Responder needs to have a list of cipher order of preference. The Responder needs to have a list of cipher
suites it supports. SUITES_I is a CBOR array containing cipher suites it supports. SUITES_I is a CBOR array containing cipher
suites that the Initiator supports. SUITES_I is formatted and suites that the Initiator supports. SUITES_I is formatted and
processed as detailed in Section 5.3.1 to secure the cipher suite processed as detailed in Section 5.3.1 to secure the cipher suite
negotiation. Examples of cipher suite negotiation are given in negotiation. Examples of cipher suite negotiation are given in
Section 6.3.2. Section 6.3.2.
3.5. Ephemeral Public Keys 3.5. Ephemeral Public Keys
The ECDH ephemeral public keys are formatted as a COSE_Key of type EDHOC always uses compact representation of elliptic curve points,
EC2 or OKP according to Sections 7.1 and 7.2 of see Appendix A. In COSE compact representation is achieved by
[I-D.ietf-cose-rfc8152bis-algs], but only the 'x' parameter is formatting the ECDH ephemeral public keys as COSE_Keys of type EC2 or
included G_X and G_Y. For Elliptic Curve Keys of type EC2, compact OKP according to Sections 7.1 and 7.2 of
representation as per [RFC6090] MAY be used also in the COSE_Key. If [I-D.ietf-cose-rfc8152bis-algs], but only including the 'x' parameter
the COSE implementation requires an 'y' parameter, any of the in G_X and G_Y. For Elliptic Curve Keys of type EC2, compact
possible values of the y-coordinate can be used, see Appendix C of representation MAY be used also in the COSE_Key. If the COSE
[RFC6090]. COSE always use compact output for Elliptic Curve Keys of implementation requires an 'y' parameter, the value y = false SHALL
be used. COSE always use compact output for Elliptic Curve Keys of
type EC2. type EC2.
3.6. Auxiliary Data 3.6. External Authorization Data
In order to reduce round trips and number of messages, and in some In order to reduce round trips and number of messages or to simplify
cases also streamline processing, certain security applications may processing, external security applications may be integrated into
be integrated into EDHOC by transporting auxiliary data together with EDHOC by transporting authorization related data together with the
the messages. One example is the transport of third-party messages. One example is the transport third-party identity and
authorization information protected outside of EDHOC authorization information protected out of scope of EDHOC
[I-D.selander-ace-ake-authz]. Another example is the embedding of a [I-D.selander-ace-ake-authz]. Another example is the embedding of a
certificate enrolment request or a newly issued certificate. certificate enrolment request or a newly issued certificate.
EDHOC allows opaque auxiliary data (AD) to be sent in the EDHOC EDHOC allows opaque external authorization data (EAD) to be sent in
messages. Unprotected Auxiliary Data (AD_1, AD_2) may be sent in the EDHOC messages. External authorization data sent in message_1
message_1 and message_2, respectively. Protected Auxiliary Data (EAD_1) or message_2 (EAD_2) must be considered unprotected by EDHOC,
(AD_3) may be sent in message_3. see Section 8.4. External authorization data sent in message_3
(EAD_3) or message_4 (EAD_4) is protected between Initiator and
Responder.
Since data carried in AD_1 and AD_2 may not be protected, and the External authorization data is a CBOR sequence (see Appendix B.1) as
content of AD_3 is available to both the Initiator and the Responder, defined below:
special considerations need to be made such that the availability of
the data a) does not violate security and privacy requirements of the EAD = (
service which uses this data, and b) does not violate the security type : int,
properties of EDHOC. 1* ext_authz_data : any,
)
where type is an int and is followed by one or more ext_authz_data
depending on type as defined in a separate specification.
The EAD fields of EDHOC are not intended for generic application
data. Since data carried in EAD_1 and EAD_2 fields may not be
protected, special considerations need to be made such that a) it
does not violate security, privacy etc. requirements of the service
which uses this data, and b) it does not violate the security
properties of EDHOC. Security applications making use of the EAD
fields must perform the necessary security analysis.
3.7. Applicability Statement 3.7. Applicability Statement
EDHOC requires certain parameters to be agreed upon between Initiator EDHOC requires certain parameters to be agreed upon between Initiator
and Responder. Some parameters can be agreed through the protocol and Responder. Some parameters can be agreed through the protocol
execution (specifically cipher suite negotiation, see Section 3.4) execution (specifically cipher suite negotiation, see Section 3.4)
but other parameters may need to be known out-of-band (e.g., which but other parameters may need to be known out-of-band (e.g., which
authentication method is used, see Section 3.2.1). authentication method is used, see Section 3.2.1).
The purpose of the applicability statement is describe the intended The purpose of the applicability statement is describe the intended
skipping to change at page 18, line 51 skipping to change at page 19, line 29
payload of a CoAP message with a certain Uri-Path or Content- payload of a CoAP message with a certain Uri-Path or Content-
Format; see Section 7.2. Format; see Section 7.2.
2. Method and correlation of underlying transport messages 2. Method and correlation of underlying transport messages
(METHOD_CORR; see Section 3.2.1 and Section 3.2.4). This gives (METHOD_CORR; see Section 3.2.1 and Section 3.2.4). This gives
information about the optional connection identifier fields. information about the optional connection identifier fields.
3. How message_1 is identified, in particular if the optional 3. How message_1 is identified, in particular if the optional
initial C_1 = "null" of message_1 is present; see Section 5.3.1 initial C_1 = "null" of message_1 is present; see Section 5.3.1
4. Authentication credentials (CRED_I, CRED_R; see Section 3.3.3). 4. Profile for authentication credentials (CRED_I, CRED_R; see
Section 3.3.3), e.g., profile for certificate or COSE_key,
including supported authentication key algorithms (subject public
key algorithm in X.509 certificate).
5. Type used to identify authentication credentials (ID_CRED_I, 5. Type used to identify authentication credentials (ID_CRED_I,
ID_CRED_R; see Section 3.3.4). ID_CRED_R; see Section 3.3.4).
6. Use and type of Auxiliary Data (AD_1, AD_2, AD_3; see 6. Use and type of external authorization data (EAD_1, EAD_2, EAD_3,
Section 3.6). EAD_4; see Section 3.6).
7. Identifier used as identity of endpoint; see Section 3.3.2. 7. Identifier used as identity of endpoint; see Section 3.3.2.
8. If message_4 shall be sent/expected, and if not, how to ensure a 8. If message_4 shall be sent/expected, and if not, how to ensure a
protected application message is sent from the Responder to the protected application message is sent from the Responder to the
Initiator; see Section 7.1. Initiator; see Section 7.1.
The applicability statement may also contain information about The applicability statement may also contain information about
supported cipher suites. The procedure for selecting and verifying supported cipher suites. The procedure for selecting and verifying
cipher suite is still performed as specified by the protocol, but it cipher suite is still performed as specified by the protocol, but it
may become simplified by this knowledge. may become simplified by this knowledge.
An example of an applicability statement is shown in Appendix C. An example of an applicability statement is shown in Appendix D.
For some parameters, like METHOD_CORR, ID_CRED_x, type of AD_x, the For some parameters, like METHOD_CORR, ID_CRED_x, type of EAD, the
receiver is able to verify compliance with applicability statement, receiver is able to verify compliance with applicability statement,
and if it needs to fail because of incompliance, to infer the reason and if it needs to fail because of incompliance, to infer the reason
why the protocol failed. why the protocol failed.
For other parameters, like CRED_x in the case that it is not For other parameters, like CRED_x in the case that it is not
transported, it may not be possible to verify that incompliance with transported, it may not be possible to verify that incompliance with
applicability statement was the reason for failure: Integrity applicability statement was the reason for failure: Integrity
verification in message_2 or message_3 may fail not only because of verification in message_2 or message_3 may fail not only because of
wrong authentication credential. For example, in case the Initiator wrong authentication credential. For example, in case the Initiator
uses public key certificate by reference (i.e. not transported within uses public key certificate by reference (i.e. not transported within
skipping to change at page 20, line 5 skipping to change at page 20, line 35
other endpoint, but this applies only to the later phases of the other endpoint, but this applies only to the later phases of the
protocol when identities are known. (Initiator does not know protocol when identities are known. (Initiator does not know
identity of Responder before having verified message_2, and Responder identity of Responder before having verified message_2, and Responder
does not know identity of Initiator before having verified does not know identity of Initiator before having verified
message_3.) message_3.)
Other conditions may be part of the applicability statement, such as Other conditions may be part of the applicability statement, such as
target application or use (if there is more than one application/use) target application or use (if there is more than one application/use)
to the extent that EDHOC can distinguish between them. In case to the extent that EDHOC can distinguish between them. In case
multiple applicability statements are used, the receiver needs to be multiple applicability statements are used, the receiver needs to be
able to determine which is applicable for a given protocol instance, able to determine which is applicable for a given session, for
for example based on URI or Auxiliary Data type. example based on URI or external authorization data type.
4. Key Derivation 4. Key Derivation
EDHOC uses Extract-and-Expand [RFC5869] with the EDHOC hash algorithm EDHOC uses Extract-and-Expand [RFC5869] with the EDHOC hash algorithm
in the selected cipher suite to derive keys used in EDHOC and in the in the selected cipher suite to derive keys used in EDHOC and in the
application. Extract is used to derive fixed-length uniformly application. Extract is used to derive fixed-length uniformly
pseudorandom keys (PRK) from ECDH shared secrets. Expand is used to pseudorandom keys (PRK) from ECDH shared secrets. Expand is used to
derive additional output keying material (OKM) from the PRKs. The derive additional output keying material (OKM) from the PRKs. The
PRKs are derived using Extract. PRKs are derived using Extract.
skipping to change at page 21, line 21 skipping to change at page 22, line 5
then PRK_4x3m = Extract( PRK_3e2m, G_IY ), where G_IY is the ECDH then PRK_4x3m = Extract( PRK_3e2m, G_IY ), where G_IY is the ECDH
shared secret calculated from G_I and Y, or G_Y and I, else shared secret calculated from G_I and Y, or G_Y and I, else
PRK_4x3m = PRK_3e2m. PRK_4x3m = PRK_3e2m.
Example: Assuming the use of curve25519, the ECDH shared secrets Example: Assuming the use of curve25519, the ECDH shared secrets
G_XY, G_RX, and G_IY are the outputs of the X25519 function G_XY, G_RX, and G_IY are the outputs of the X25519 function
[RFC7748]: [RFC7748]:
G_XY = X25519( Y, G_X ) = X25519( X, G_Y ) G_XY = X25519( Y, G_X ) = X25519( X, G_Y )
The keys and IVs used in EDHOC are derived from PRK using Expand The keys and IVs used in EDHOC are derived from PRKs using Expand
[RFC5869] where the EDHOC-KDF is instantiated with the EDHOC AEAD [RFC5869] where the EDHOC-KDF is instantiated with the EDHOC AEAD
algorithm in the selected cipher suite. algorithm in the selected cipher suite.
OKM = EDHOC-KDF( PRK, transcript_hash, label, length ) OKM = EDHOC-KDF( PRK, transcript_hash, label, length )
= Expand( PRK, info, length ) = Expand( PRK, info, length )
where info is the CBOR encoding of where info is the CBOR encoding of
info = [ info = [
edhoc_aead_id : int / tstr, edhoc_aead_id : int / tstr,
skipping to change at page 22, line 26 skipping to change at page 23, line 10
IV_3ae are derived using the transcript hash TH_3 and the IV_3ae are derived using the transcript hash TH_3 and the
pseudorandom key PRK_3e2m. K_3m and IV_3m are derived using the pseudorandom key PRK_3e2m. K_3m and IV_3m are derived using the
transcript hash TH_3 and the pseudorandom key PRK_4x3m. IVs are only transcript hash TH_3 and the pseudorandom key PRK_4x3m. IVs are only
used if the EDHOC AEAD algorithm uses IVs. used if the EDHOC AEAD algorithm uses IVs.
4.1. EDHOC-Exporter Interface 4.1. EDHOC-Exporter Interface
Application keys and other application specific data can be derived Application keys and other application specific data can be derived
using the EDHOC-Exporter interface defined as: using the EDHOC-Exporter interface defined as:
EDHOC-Exporter(label, length) EDHOC-Exporter(label, context, length)
= EDHOC-KDF(PRK_4x3m, TH_4, label, length) = EDHOC-KDF(PRK_4x3m, TH_4, label_context, length)
where label is a tstr defined by the application and length is a uint label_context is a CBOR sequence:
defined by the application. The label SHALL be different for each
different exporter value. The transcript hash TH_4 is a CBOR encoded label_context = (
bstr and the input to the hash function is a CBOR Sequence. label : tstr,
context : bstr,
)
where label is a registered tstr from the EDHOC Exporter Label
registry (Section 9.1), context is a bstr defined by the application,
and length is a uint defined by the application. The (label,
context) pair must be unique, i.e. a (label, context) MUST NOT be
used for two different purposes. However an application can re-
derive the same key several times as long as it is done in a secure
way. For example, in most encryption algorithms the same (key,
nonce) pair must not be reused.
The transcript hash TH_4 is a CBOR encoded bstr and the input to the
hash function is a CBOR Sequence.
TH_4 = H( TH_3, CIPHERTEXT_3 ) TH_4 = H( TH_3, CIPHERTEXT_3 )
where H() is the hash function in the selected cipher suite. Example where H() is the hash function in the selected cipher suite.
use of the EDHOC-Exporter is given in Sections 7.2.1. Examples of use of the EDHOC-Exporter are given in Section 7.1.2 and
[I-D.ietf-core-oscore-edhoc].
To provide forward secrecy in an even more efficient way than re- To provide forward secrecy in an even more efficient way than re-
running EDHOC, EDHOC provides the function EDHOC-KeyUpdate. When running EDHOC, EDHOC provides the function EDHOC-KeyUpdate. When
EDHOC-KeyUpdate is called the old PRK_4x3m is deleted and the new EDHOC-KeyUpdate is called the old PRK_4x3m is deleted and the new
PRk_4x3m is calculated as a "hash" of the old key using the Extract PRK_4x3m is calculated as a "hash" of the old key using the Extract
function as illustrated by the following pseudocode: function as illustrated by the following pseudocode:
EDHOC-KeyUpdate( nonce ): EDHOC-KeyUpdate( nonce ):
PRK_4x3m = Extract( nonce, PRK_4x3m ) PRK_4x3m = Extract( nonce, PRK_4x3m )
5. Message Formatting and Processing 5. Message Formatting and Processing
This section specifies formatting of the messages and processing This section specifies formatting of the messages and processing
steps. Error messages are specified in Section 6. steps. Error messages are specified in Section 6.
skipping to change at page 23, line 44 skipping to change at page 24, line 44
bstr_identifier = bstr / int bstr_identifier = bstr / int
Note that, despite what could be interpreted by the CDDL definition Note that, despite what could be interpreted by the CDDL definition
only, bstr_identifier once decoded are always byte strings. only, bstr_identifier once decoded are always byte strings.
5.2. Message Processing Outline 5.2. Message Processing Outline
This section outlines the message processing of EDHOC. This section outlines the message processing of EDHOC.
For each protocol instance, the endpoints are assumed to keep an For each session, the endpoints are assumed to keep an associated
associated protocol state containing connection identifiers, keys, protocol state containing connection identifiers, keys, etc. used for
etc. used for subsequent processing of protocol related data. The subsequent processing of protocol related data. The protocol state
protocol state is assumed to be associated to an applicability is assumed to be associated to an applicability statement
statement (Section 3.7) which provides the context for how messages (Section 3.7) which provides the context for how messages are
are transported, identified and processed. transported, identified and processed.
EDHOC messages SHALL be processed according to the current protocol EDHOC messages SHALL be processed according to the current protocol
state. The following steps are expected to be performed at reception state. The following steps are expected to be performed at reception
of an EDHOC message: of an EDHOC message:
1. Detect that an EDHOC message has been received, for example by 1. Detect that an EDHOC message has been received, for example by
means of port number, URI, or media type (Section 3.7). means of port number, URI, or media type (Section 3.7).
2. Retrieve the protocol state, e.g. using the received connection 2. Retrieve the protocol state, e.g. using the received connection
identifier (Section 3.2.2) or with the help of message identifier (Section 3.2.2) or with the help of message
skipping to change at page 24, line 30 skipping to change at page 25, line 30
3. If the message received is an error message then process 3. If the message received is an error message then process
according to Section 6, else process as the expected next message according to Section 6, else process as the expected next message
according to the protocol state. according to the protocol state.
If the processing fails, then the protocol is discontinued, an error If the processing fails, then the protocol is discontinued, an error
message sent, and the protocol state erased. Further details are message sent, and the protocol state erased. Further details are
provided in the following subsections. provided in the following subsections.
Different instances of the same message MUST NOT be processed in one Different instances of the same message MUST NOT be processed in one
protocol instance. Note that processing will fail if the same session. Note that processing will fail if the same message appears
message appears a second time for EDHOC processing because the state a second time for EDHOC processing because the state of the protocol
of the protocol has moved on and now expects something else. This has moved on and now expects something else. This assumes that
assumes that message duplication due to re-transmissions is handled message duplication due to re-transmissions is handled by the
by the transport protocol, see Section 3.2.3. The case when the transport protocol, see Section 3.2.3. The case when the transport
transport does not support message deduplication is addressed in does not support message deduplication is addressed in Appendix E.
Appendix D.
5.3. EDHOC Message 1 5.3. EDHOC Message 1
5.3.1. Formatting of Message 1 5.3.1. Formatting of Message 1
message_1 SHALL be a CBOR Sequence (see Appendix A.1) as defined message_1 SHALL be a CBOR Sequence (see Appendix B.1) as defined
below below
message_1 = ( message_1 = (
? C_1 : null, ? C_1 : null,
METHOD_CORR : int, METHOD_CORR : int,
SUITES_I : [ selected : suite, supported : 2* suite ] / suite, SUITES_I : [ selected : suite, supported : 2* suite ] / suite,
G_X : bstr, G_X : bstr,
C_I : bstr_identifier, C_I : bstr_identifier,
? AD_1 : bstr, ? EAD ; EAD_1
) )
suite = int suite = int
where: where:
* C_1 - an initial CBOR simple value "null" (= 0xf6) MAY be used to * C_1 - an initial CBOR simple value "null" (= 0xf6) MAY be used to
distinguish message_1 from other messages. distinguish message_1 from other messages.
* METHOD_CORR = 4 * method + corr, where method = 0, 1, 2, or 3 (see * METHOD_CORR = 4 * method + corr, where method = 0, 1, 2, or 3 (see
skipping to change at page 25, line 39 skipping to change at page 26, line 39
selected. The selected suite is the first suite in the SUITES_I selected. The selected suite is the first suite in the SUITES_I
CBOR array. If a single supported cipher suite is conveyed then CBOR array. If a single supported cipher suite is conveyed then
that cipher suite is selected and SUITES_I is encoded as an int that cipher suite is selected and SUITES_I is encoded as an int
instead of an array. instead of an array.
* G_X - the ephemeral public key of the Initiator * G_X - the ephemeral public key of the Initiator
* C_I - variable length connection identifier, encoded as a * C_I - variable length connection identifier, encoded as a
bstr_identifier (see Section 5.1). bstr_identifier (see Section 5.1).
* AD_1 - bstr containing unprotected opaque auxiliary data * EAD_1 - unprotected external authorization data, see Section 3.6.
5.3.2. Initiator Processing of Message 1 5.3.2. Initiator Processing of Message 1
The Initiator SHALL compose message_1 as follows: The Initiator SHALL compose message_1 as follows:
* The supported cipher suites and the order of preference MUST NOT * The supported cipher suites and the order of preference MUST NOT
be changed based on previous error messages. However, the list be changed based on previous error messages. However, the list
SUITES_I sent to the Responder MAY be truncated such that cipher SUITES_I sent to the Responder MAY be truncated such that cipher
suites which are the least preferred are omitted. The amount of suites which are the least preferred are omitted. The amount of
truncation MAY be changed between sessions, e.g. based on previous truncation MAY be changed between sessions, e.g. based on previous
error messages (see next bullet), but all cipher suites which are error messages (see next bullet), but all cipher suites which are
more preferred than the least preferred cipher suite in the list more preferred than the least preferred cipher suite in the list
MUST be included in the list. MUST be included in the list.
* The Initiator MUST select its most preferred cipher suite, * The Initiator MUST select its most preferred cipher suite,
conditioned on what it can assume to be supported by the conditioned on what it can assume to be supported by the
Responder. If the Initiator previously received from the Responder. If the Initiator previously received from the
Responder an error message with error code 1 (see Section 6.3) Responder an error message with error code 2 (see Section 6.3)
indicating cipher suites supported by the Responder which also are indicating cipher suites supported by the Responder which also are
supported by the Initiator, then the Initiator SHOULD select the supported by the Initiator, then the Initiator SHOULD select the
most preferred cipher suite of those (note that error messages are most preferred cipher suite of those (note that error messages are
not authenticated and may be forged). not authenticated and may be forged).
* Generate an ephemeral ECDH key pair as specified in Section 5 of * Generate an ephemeral ECDH key pair using the curve in the
[SP-800-56A] using the curve in the selected cipher suite and selected cipher suite and format it as a COSE_Key. Let G_X be the
format it as a COSE_Key. Let G_X be the 'x' parameter of the 'x' parameter of the COSE_Key.
COSE_Key.
* Choose a connection identifier C_I and store it for the length of * Choose a connection identifier C_I and store it for the length of
the protocol. the protocol.
* Encode message_1 as a sequence of CBOR encoded data items as * Encode message_1 as a sequence of CBOR encoded data items as
specified in Section 5.3.1 specified in Section 5.3.1
5.3.3. Responder Processing of Message 1 5.3.3. Responder Processing of Message 1
The Responder SHALL process message_1 as follows: The Responder SHALL process message_1 as follows:
* Decode message_1 (see Appendix A.1). * Decode message_1 (see Appendix B.1).
* Verify that the selected cipher suite is supported and that no * Verify that the selected cipher suite is supported and that no
prior cipher suite in SUITES_I is supported. prior cipher suite in SUITES_I is supported.
* Pass AD_1 to the security application. * Pass EAD_1 to the security application.
If any verification step fails, the Responder MUST send an EDHOC If any processing step fails, the Responder SHOULD send an EDHOC
error message back, formatted as defined in Section 6, and the error message back, formatted as defined in Section 6, and the
protocol MUST be discontinued. session MUST be discontinued. Sending error messages is essential
for debugging but MAY e.g. be skipped due to denial of service
reasons, see Section 8.
5.4. EDHOC Message 2 5.4. EDHOC Message 2
5.4.1. Formatting of Message 2 5.4.1. Formatting of Message 2
message_2 and data_2 SHALL be CBOR Sequences (see Appendix A.1) as message_2 and data_2 SHALL be CBOR Sequences (see Appendix B.1) as
defined below defined below
message_2 = ( message_2 = (
data_2, data_2,
CIPHERTEXT_2 : bstr, CIPHERTEXT_2 : bstr,
) )
data_2 = ( data_2 = (
? C_I : bstr_identifier, ? C_I : bstr_identifier,
G_Y : bstr, G_Y : bstr,
skipping to change at page 27, line 34 skipping to change at page 28, line 37
* C_R - variable length connection identifier, encoded as a * C_R - variable length connection identifier, encoded as a
bstr_identifier (see Section 5.1). bstr_identifier (see Section 5.1).
5.4.2. Responder Processing of Message 2 5.4.2. Responder Processing of Message 2
The Responder SHALL compose message_2 as follows: The Responder SHALL compose message_2 as follows:
* If corr (METHOD_CORR mod 4) equals 1 or 3, C_I is omitted, * If corr (METHOD_CORR mod 4) equals 1 or 3, C_I is omitted,
otherwise C_I is not omitted. otherwise C_I is not omitted.
* Generate an ephemeral ECDH key pair as specified in Section 5 of * Generate an ephemeral ECDH key pair using the curve in the
[SP-800-56A] using the curve in the selected cipher suite and selected cipher suite and format it as a COSE_Key. Let G_Y be the
format it as a COSE_Key. Let G_Y be the 'x' parameter of the 'x' parameter of the COSE_Key.
COSE_Key.
* Choose a connection identifier C_R and store it for the length of * Choose a connection identifier C_R and store it for the length of
the protocol. the protocol.
* Compute the transcript hash TH_2 = H(message_1, data_2) where H() * Compute the transcript hash TH_2 = H( H(message_1), data_2 ) where
is the hash function in the selected cipher suite. The transcript H() is the hash function in the selected cipher suite. The
hash TH_2 is a CBOR encoded bstr and the input to the hash transcript hash TH_2 is a CBOR encoded bstr and the input to the
function is a CBOR Sequence. hash function is a CBOR Sequence. Note that H(message_1) can be
computed and cached already in the processing of message_1.
* Compute an inner COSE_Encrypt0 as defined in Section 5.3 of * Compute an inner COSE_Encrypt0 as defined in Section 5.3 of
[I-D.ietf-cose-rfc8152bis-struct], with the EDHOC AEAD algorithm [I-D.ietf-cose-rfc8152bis-struct], with the EDHOC AEAD algorithm
in the selected cipher suite, K_2m, IV_2m, and the following in the selected cipher suite, K_2m, IV_2m, and the following
parameters: parameters:
- protected = << ID_CRED_R >> - protected = << ID_CRED_R >>
o ID_CRED_R - identifier to facilitate retrieval of CRED_R, o ID_CRED_R - identifier to facilitate retrieval of CRED_R,
see Section 3.3.4 see Section 3.3.4
- external_aad = << TH_2, CRED_R, ? AD_2 >> - external_aad = << TH_2, CRED_R, ? EAD_2 >>
o CRED_R - bstr containing the credential of the Responder, o CRED_R - bstr containing the credential of the Responder,
see Section 3.3.4. see Section 3.3.4
o AD_2 = bstr containing opaque unprotected auxiliary data o EAD_2 = unprotected external authorization data, see
Section 3.6
- plaintext = h'' - plaintext = h''
COSE constructs the input to the AEAD [RFC5116] as follows: COSE constructs the input to the AEAD [RFC5116] as follows:
- Key K = EDHOC-KDF( PRK_3e2m, TH_2, "K_2m", length ) - Key K = EDHOC-KDF( PRK_3e2m, TH_2, "K_2m", length )
- Nonce N = EDHOC-KDF( PRK_3e2m, TH_2, "IV_2m", length ) - Nonce N = EDHOC-KDF( PRK_3e2m, TH_2, "IV_2m", length )
- Plaintext P = 0x (the empty string) - Plaintext P = 0x (the empty string)
- Associated data A = - Associated data A =
[ "Encrypt0", << ID_CRED_R >>, << TH_2, CRED_R, ? AD_2 >> ] [ "Encrypt0", << ID_CRED_R >>, << TH_2, CRED_R, ? EAD_2 >> ]
MAC_2 is the 'ciphertext' of the inner COSE_Encrypt0. MAC_2 is the 'ciphertext' of the inner COSE_Encrypt0.
* If the Responder authenticates with a static Diffie-Hellman key * If the Responder authenticates with a static Diffie-Hellman key
(method equals 1 or 3), then Signature_or_MAC_2 is MAC_2. If the (method equals 1 or 3), then Signature_or_MAC_2 is MAC_2. If the
Responder authenticates with a signature key (method equals 0 or Responder authenticates with a signature key (method equals 0 or
2), then Signature_or_MAC_2 is the 'signature' of a COSE_Sign1 2), then Signature_or_MAC_2 is the 'signature' of a COSE_Sign1
object as defined in Section 4.4 of object as defined in Section 4.4 of
[I-D.ietf-cose-rfc8152bis-struct] using the signature algorithm in [I-D.ietf-cose-rfc8152bis-struct] using the signature algorithm in
the selected cipher suite, the private authentication key of the the selected cipher suite, the private authentication key of the
Responder, and the following parameters: Responder, and the following parameters:
- protected = << ID_CRED_R >> - protected = << ID_CRED_R >>
- external_aad = << TH_2, CRED_R, ? AD_2 >> - external_aad = << TH_2, CRED_R, ? EAD_2 >>
- payload = MAC_2 - payload = MAC_2
COSE constructs the input to the Signature Algorithm as: COSE constructs the input to the Signature Algorithm as:
- The key is the private authentication key of the Responder. - The key is the private authentication key of the Responder.
- The message M to be signed = - The message M to be signed =
[ "Signature1", << ID_CRED_R >>, << TH_2, CRED_R, ? AD_2 >>, [ "Signature1", << ID_CRED_R >>, << TH_2, CRED_R, ? EAD_2 >>,
MAC_2 ] MAC_2 ]
* CIPHERTEXT_2 is encrypted by using the Expand function as a binary * CIPHERTEXT_2 is encrypted by using the Expand function as a binary
additive stream cipher. additive stream cipher.
- plaintext = ( ID_CRED_R / bstr_identifier, Signature_or_MAC_2, - plaintext = ( ID_CRED_R / bstr_identifier, Signature_or_MAC_2,
? AD_2 ) ? EAD_2 )
o Note that if ID_CRED_R contains a single 'kid' parameter, o Note that if ID_CRED_R contains a single 'kid' parameter,
i.e., ID_CRED_R = { 4 : kid_R }, only the byte string kid_R i.e., ID_CRED_R = { 4 : kid_R }, only the byte string kid_R
is conveyed in the plaintext encoded as a bstr_identifier, is conveyed in the plaintext encoded as a bstr_identifier,
see Section 3.3.4 and Section 5.1. see Section 3.3.4 and Section 5.1.
- CIPHERTEXT_2 = plaintext XOR KEYSTREAM_2 - CIPHERTEXT_2 = plaintext XOR KEYSTREAM_2
* Encode message_2 as a sequence of CBOR encoded data items as * Encode message_2 as a sequence of CBOR encoded data items as
specified in Section 5.4.1. specified in Section 5.4.1.
5.4.3. Initiator Processing of Message 2 5.4.3. Initiator Processing of Message 2
The Initiator SHALL process message_2 as follows: The Initiator SHALL process message_2 as follows:
* Decode message_2 (see Appendix A.1). * Decode message_2 (see Appendix B.1).
* Retrieve the protocol state using the connection identifier C_I * Retrieve the protocol state using the connection identifier C_I
and/or other external information such as the CoAP Token and the and/or other external information such as the CoAP Token and the
5-tuple. 5-tuple.
* Decrypt CIPHERTEXT_2, see Section 5.4.2. * Decrypt CIPHERTEXT_2, see Section 5.4.2.
* Pass EAD_2 to the security application.
* Verify that the identity of the Responder is an allowed identity * Verify that the identity of the Responder is an allowed identity
for this connection, see Section 3.3. for this connection, see Section 3.3.
* Verify Signature_or_MAC_2 using the algorithm in the selected * Verify Signature_or_MAC_2 using the algorithm in the selected
cipher suite. The verification process depends on the method, see cipher suite. The verification process depends on the method, see
Section 5.4.2. Section 5.4.2.
* Pass AD_2 to the security application. If any processing step fails, the Initiator SHOULD send an EDHOC
error message back, formatted as defined in Section 6. Sending error
If any verification step fails, the Initiator MUST send an EDHOC messages is essential for debugging but MAY e.g.be skipped if a
error message back, formatted as defined in Section 6, and the session cannot be found or due to denial of service reasons, see
protocol MUST be discontinued. Section 8. If an error message is sent, the session MUST be
discontinued.
5.5. EDHOC Message 3 5.5. EDHOC Message 3
5.5.1. Formatting of Message 3 5.5.1. Formatting of Message 3
message_3 and data_3 SHALL be CBOR Sequences (see Appendix A.1) as message_3 and data_3 SHALL be CBOR Sequences (see Appendix B.1) as
defined below defined below
message_3 = ( message_3 = (
data_3, data_3,
CIPHERTEXT_3 : bstr, CIPHERTEXT_3 : bstr,
) )
data_3 = ( data_3 = (
? C_R : bstr_identifier, ? C_R : bstr_identifier,
) )
5.5.2. Initiator Processing of Message 3 5.5.2. Initiator Processing of Message 3
The Initiator SHALL compose message_3 as follows: The Initiator SHALL compose message_3 as follows:
* If corr (METHOD_CORR mod 4) equals 2 or 3, C_R is omitted, * If corr (METHOD_CORR mod 4) equals 2 or 3, C_R is omitted,
otherwise C_R is not omitted. otherwise C_R is not omitted.
* Compute the transcript hash TH_3 = H(TH_2 , CIPHERTEXT_2, data_3) * Compute the transcript hash TH_3 = H( H(TH_2, CIPHERTEXT_2),
where H() is the hash function in the selected cipher suite. The data_3 ) where H() is the hash function in the selected cipher
transcript hash TH_3 is a CBOR encoded bstr and the input to the suite. The transcript hash TH_3 is a CBOR encoded bstr and the
hash function is a CBOR Sequence. input to the hash function is a CBOR Sequence. Note that H(TH_2,
CIPHERTEXT_2) can be computed and cached already in the processing
of message_2.
* Compute an inner COSE_Encrypt0 as defined in Section 5.3 of * Compute an inner COSE_Encrypt0 as defined in Section 5.3 of
[I-D.ietf-cose-rfc8152bis-struct], with the EDHOC AEAD algorithm [I-D.ietf-cose-rfc8152bis-struct], with the EDHOC AEAD algorithm
in the selected cipher suite, K_3m, IV_3m, and the following in the selected cipher suite, K_3m, IV_3m, and the following
parameters: parameters:
- protected = << ID_CRED_I >> - protected = << ID_CRED_I >>
o ID_CRED_I - identifier to facilitate retrieval of CRED_I, o ID_CRED_I - identifier to facilitate retrieval of CRED_I,
see Section 3.3.4 see Section 3.3.4
- external_aad = << TH_3, CRED_I, ? AD_3 >> - external_aad = << TH_3, CRED_I, ? EAD_3 >>
o CRED_I - bstr containing the credential of the Initiator, o CRED_I - bstr containing the credential of the Initiator,
see Section 3.3.4. see Section 3.3.4.
o AD_3 = bstr containing opaque protected auxiliary data o EAD_3 = protected external authorization data, see
Section 3.6
- plaintext = h'' - plaintext = h''
COSE constructs the input to the AEAD [RFC5116] as follows: COSE constructs the input to the AEAD [RFC5116] as follows:
- Key K = EDHOC-KDF( PRK_4x3m, TH_3, "K_3m", length ) - Key K = EDHOC-KDF( PRK_4x3m, TH_3, "K_3m", length )
- Nonce N = EDHOC-KDF( PRK_4x3m, TH_3, "IV_3m", length ) - Nonce N = EDHOC-KDF( PRK_4x3m, TH_3, "IV_3m", length )
- Plaintext P = 0x (the empty string) - Plaintext P = 0x (the empty string)
- Associated data A = - Associated data A =
[ "Encrypt0", << ID_CRED_I >>, << TH_3, CRED_I, ? AD_3 >> ] [ "Encrypt0", << ID_CRED_I >>, << TH_3, CRED_I, ? EAD_3 >> ]
MAC_3 is the 'ciphertext' of the inner COSE_Encrypt0. MAC_3 is the 'ciphertext' of the inner COSE_Encrypt0.
* If the Initiator authenticates with a static Diffie-Hellman key * If the Initiator authenticates with a static Diffie-Hellman key
(method equals 2 or 3), then Signature_or_MAC_3 is MAC_3. If the (method equals 2 or 3), then Signature_or_MAC_3 is MAC_3. If the
Initiator authenticates with a signature key (method equals 0 or Initiator authenticates with a signature key (method equals 0 or
1), then Signature_or_MAC_3 is the 'signature' of a COSE_Sign1 1), then Signature_or_MAC_3 is the 'signature' of a COSE_Sign1
object as defined in Section 4.4 of object as defined in Section 4.4 of
[I-D.ietf-cose-rfc8152bis-struct] using the signature algorithm in [I-D.ietf-cose-rfc8152bis-struct] using the signature algorithm in
the selected cipher suite, the private authentication key of the the selected cipher suite, the private authentication key of the
Initiator, and the following parameters: Initiator, and the following parameters:
- protected = << ID_CRED_I >> - protected = << ID_CRED_I >>
- external_aad = << TH_3, CRED_I, ? AD_3 >> - external_aad = << TH_3, CRED_I, ? EAD_3 >>
- payload = MAC_3 - payload = MAC_3
COSE constructs the input to the Signature Algorithm as: COSE constructs the input to the Signature Algorithm as:
- The key is the private authentication key of the Initiator. - The key is the private authentication key of the Initiator.
- The message M to be signed = - The message M to be signed =
[ "Signature1", << ID_CRED_I >>, << TH_3, CRED_I, ? AD_3 >>, [ "Signature1", << ID_CRED_I >>, << TH_3, CRED_I, ? EAD_3 >>,
MAC_3 ] MAC_3 ]
* Compute an outer COSE_Encrypt0 as defined in Section 5.3 of * Compute an outer COSE_Encrypt0 as defined in Section 5.3 of
[I-D.ietf-cose-rfc8152bis-struct], with the EDHOC AEAD algorithm [I-D.ietf-cose-rfc8152bis-struct], with the EDHOC AEAD algorithm
in the selected cipher suite, K_3ae, IV_3ae, and the following in the selected cipher suite, K_3ae, IV_3ae, and the following
parameters. The protected header SHALL be empty. parameters. The protected header SHALL be empty.
- external_aad = TH_3 - external_aad = TH_3
- plaintext = ( ID_CRED_I / bstr_identifier, Signature_or_MAC_3, - plaintext = ( ID_CRED_I / bstr_identifier, Signature_or_MAC_3,
? AD_3 ) ? EAD_3 )
o Note that if ID_CRED_I contains a single 'kid' parameter, o Note that if ID_CRED_I contains a single 'kid' parameter,
i.e., ID_CRED_I = { 4 : kid_I }, only the byte string kid_I i.e., ID_CRED_I = { 4 : kid_I }, only the byte string kid_I
is conveyed in the plaintext encoded as a bstr_identifier, is conveyed in the plaintext encoded as a bstr_identifier,
see Section 3.3.4 and Section 5.1. see Section 3.3.4 and Section 5.1.
COSE constructs the input to the AEAD [RFC5116] as follows: COSE constructs the input to the AEAD [RFC5116] as follows:
- Key K = EDHOC-KDF( PRK_3e2m, TH_3, "K_3ae", length ) - Key K = EDHOC-KDF( PRK_3e2m, TH_3, "K_3ae", length )
- Nonce N = EDHOC-KDF( PRK_3e2m, TH_3, "IV_3ae", length ) - Nonce N = EDHOC-KDF( PRK_3e2m, TH_3, "IV_3ae", length )
- Plaintext P = ( ID_CRED_I / bstr_identifier, - Plaintext P = ( ID_CRED_I / bstr_identifier,
Signature_or_MAC_3, ? AD_3 ) Signature_or_MAC_3, ? EAD_3 )
- Associated data A = [ "Encrypt0", h'', TH_3 ] - Associated data A = [ "Encrypt0", h'', TH_3 ]
CIPHERTEXT_3 is the 'ciphertext' of the outer COSE_Encrypt0. CIPHERTEXT_3 is the 'ciphertext' of the outer COSE_Encrypt0.
* Encode message_3 as a sequence of CBOR encoded data items as * Encode message_3 as a sequence of CBOR encoded data items as
specified in Section 5.5.1. specified in Section 5.5.1.
Pass the connection identifiers (C_I, C_R) and the application Pass the connection identifiers (C_I, C_R) and the application
algorithms in the selected cipher suite to the application. The algorithms in the selected cipher suite to the application. The
application can now derive application keys using the EDHOC-Exporter application can now derive application keys using the EDHOC-Exporter
interface. interface.
After sending message_3, the Initiator is assured that no other party After sending message_3, the Initiator is assured that no other party
than the Responder can compute the key PRK_4x3m (implicit key than the Responder can compute the key PRK_4x3m (implicit key
authentication). The Initiator does however not know that the authentication). The Initiator can securely derive application keys
Responder has actually computed the key PRK_4x3m. While the and send protected application data. However, the Initiator does not
Initiator can securely send protected application data, the Initiator know that the Responder has actually computed the key PRK_4x3m and
SHOULD NOT permanently store the keying material PRK_4x3m and TH_4 therefore the Initiator SHOULD NOT permanently store the keying
until the Initiator is assured that the Responder has actually material PRK_4x3m and TH_4, or derived application keys, until the
computed the key PRK_4x3m (explicit key confirmation). Explicit key Initiator is assured that the Responder has actually computed the key
PRK_4x3m (explicit key confirmation). This is similar to waiting for
acknowledgement (ACK) in a transport protocol. Explicit key
confirmation is e.g. assured when the Initiator has verified an confirmation is e.g. assured when the Initiator has verified an
OSCORE message or message_4 from the Responder. OSCORE message or message_4 from the Responder.
5.5.3. Responder Processing of Message 3 5.5.3. Responder Processing of Message 3
The Responder SHALL process message_3 as follows: The Responder SHALL process message_3 as follows:
* Decode message_3 (see Appendix A.1). * Decode message_3 (see Appendix B.1).
* Retrieve the protocol state using the connection identifier C_R * Retrieve the protocol state using the connection identifier C_R
and/or other external information such as the CoAP Token and the and/or other external information such as the CoAP Token and the
5-tuple. 5-tuple.
* Decrypt and verify the outer COSE_Encrypt0 as defined in * Decrypt and verify the outer COSE_Encrypt0 as defined in
Section 5.3 of [I-D.ietf-cose-rfc8152bis-struct], with the EDHOC Section 5.3 of [I-D.ietf-cose-rfc8152bis-struct], with the EDHOC
AEAD algorithm in the selected cipher suite, K_3ae, and IV_3ae. AEAD algorithm in the selected cipher suite, K_3ae, and IV_3ae.
* Pass EAD_3 to the security application.
* Verify that the identity of the Initiator is an allowed identity * Verify that the identity of the Initiator is an allowed identity
for this connection, see Section 3.3. for this connection, see Section 3.3.
* Verify Signature_or_MAC_3 using the algorithm in the selected * Verify Signature_or_MAC_3 using the algorithm in the selected
cipher suite. The verification process depends on the method, see cipher suite. The verification process depends on the method, see
Section 5.5.2. Section 5.5.2.
* Pass AD_3, the connection identifiers (C_I, C_R), and the * Pass the connection identifiers (C_I, C_R), and the application
application algorithms in the selected cipher suite to the algorithms in the selected cipher suite to the security
security application. The application can now derive application application. The application can now derive application keys
keys using the EDHOC-Exporter interface. using the EDHOC-Exporter interface.
If any verification step fails, the Responder MUST send an EDHOC If any processing step fails, the Responder SHOULD send an EDHOC
error message back, formatted as defined in Section 6, and the error message back, formatted as defined in Section 6. Sending error
protocol MUST be discontinued. messages is essential for debugging but MAY e.g.be skipped if a
session cannot be found or due to denial of service reasons, see
Section 8. If an error message is sent, the session MUST be
discontinued.
After verifying message_3, the Responder is assured that the After verifying message_3, the Responder is assured that the
Initiator has calculated the key PRK_4x3m (explicit key confirmation) Initiator has calculated the key PRK_4x3m (explicit key confirmation)
and that no other party than the Responder can compute the key. The and that no other party than the Responder can compute the key. The
Responder can securely send protected application data and store the Responder can securely send protected application data and store the
keying material PRK_4x3m and TH_4. keying material PRK_4x3m and TH_4.
6. Error Handling 6. Error Handling
This section defines the format for error messages. This section defines the format for error messages.
An EDHOC error message can be sent by either endpoint as a reply to An EDHOC error message can be sent by either endpoint as a reply to
any non-error EDHOC message. How errors at the EDHOC layer are any non-error EDHOC message. How errors at the EDHOC layer are
transported depends on lower layers, which need to enable error transported depends on lower layers, which need to enable error
messages to be sent and processed as intended. messages to be sent and processed as intended.
All error messages in EDHOC are fatal. After sending an error Errors in EDHOC are fatal. After sending an error message, the
message, the sender MUST discontinue the protocol. The receiver sender MUST discontinue the protocol. The receiver SHOULD treat an
SHOULD treat an error message as an indication that the other party error message as an indication that the other party likely has
likely has discontinued the protocol. But as the error message is discontinued the protocol. But as the error message is not
not authenticated, a received error messages might also have been authenticated, a received error message might also have been sent by
sent by an attacker and the receiver MAY therefore try to continue an attacker and the receiver MAY therefore try to continue the
the protocol. protocol.
error SHALL be a CBOR Sequence (see Appendix A.1) as defined below error SHALL be a CBOR Sequence (see Appendix B.1) as defined below
error = ( error = (
? C_x : bstr_identifier, ? C_x : bstr_identifier,
ERR_CODE : int, ERR_CODE : int,
ERR_INFO : any ERR_INFO : any
) )
Figure 5: EDHOC Error Message Figure 5: EDHOC Error Message
where: where:
* C_x - (optional) variable length connection identifier, encoded as * C_x - (optional) variable length connection identifier, encoded as
a bstr_identifier (see Section 5.1). If error is sent by the a bstr_identifier (see Section 5.1). If error is sent by the
Responder and corr (METHOD_CORR mod 4) equals 0 or 2 then C_x is Responder and corr (METHOD_CORR mod 4) equals 0 or 2 then C_x is
set to C_I, else if error is sent by the Initiator and corr set to C_I, else if error is sent by the Initiator and corr
(METHOD_CORR mod 4) equals 0 or 1 then C_x is set to C_R, else C_x (METHOD_CORR mod 4) equals 0 or 1 then C_x is set to C_R, else C_x
is omitted. is omitted.
* ERR_CODE - error code encoded as an integer. * ERR_CODE - error code encoded as an integer. The value 0 is used
for success, all other values (negative or positive) indicate
errors.
* ERR_INFO - error information. Content and encoding depend on * ERR_INFO - error information. Content and encoding depend on
error code. error code.
The remainder of this section specifies the currently defined error The remainder of this section specifies the currently defined error
codes, see Figure 6. Error codes 1, 0 and -1 MUST be supported. codes, see Figure 6. Error codes 1 and 2 MUST be supported.
Additional error codes and corresponding error information may be Additional error codes and corresponding error information may be
specified. specified.
+----------+---------------+----------------------------------------+ +----------+---------------+----------------------------------------+
| ERR_CODE | ERR_INFO Type | Description | | ERR_CODE | ERR_INFO Type | Description |
+==========+===============+========================================+ +==========+===============+========================================+
| -1 | TBD | Success | | 0 | any | Success |
+----------+---------------+----------------------------------------+ +----------+---------------+----------------------------------------+
| 0 | tstr | Unspecified | | 1 | tstr | Unspecified |
+----------+---------------+----------------------------------------+ +----------+---------------+----------------------------------------+
| 1 | SUITES_R | Wrong selected cipher suite | | 2 | SUITES_R | Wrong selected cipher suite |
+----------+---------------+----------------------------------------+ +----------+---------------+----------------------------------------+
Figure 6: Error Codes and Error Information Figure 6: Error Codes and Error Information
6.1. Success 6.1. Success
TBD Error code 0 MAY be used internally in an application to indicate
success, e.g. in log files. ERR_INFO can contain any type of CBOR
item. Error code 0 MUST NOT be used as part of the EDHOC message
exchange flow.
6.2. Unspecified 6.2. Unspecified
Error code 0 is used for unspecified errors and contain a diagnostic Error code 1 is used for errors that do not have a specific error
message. code defined. ERR_INFO MUST be a text string containing a human-
readable diagnostic message written in English. The diagnostic text
For error messages with ERR_CODE == 0, ERR_INFO MUST be a text string message is mainly intended for software engineers that during
containing a human-readable diagnostic message written in English. debugging need to interpret it in the context of the EDHOC
The diagnostic text message is mainly intended for software engineers specification. The diagnostic message SHOULD be provided to the
that during debugging need to interpret it in the context of the calling application where it SHOULD be logged.
EDHOC specification. The diagnostic message SHOULD be provided to
the calling application where it SHOULD be logged.
6.3. Wrong Selected Cipher Suite 6.3. Wrong Selected Cipher Suite
Error code 1 MUST only be used in a response to message_1 in case the Error code 2 MUST only be used in a response to message_1 in case the
cipher suite selected by the Initiator is not supported by the cipher suite selected by the Initiator is not supported by the
Responder, or if the Responder supports a cipher suite more preferred Responder, or if the Responder supports a cipher suite more preferred
by the Initiator than the selected cipher suite, see Section 5.3.3. by the Initiator than the selected cipher suite, see Section 5.3.3.
ERR_INFO is of type SUITES_R: ERR_INFO is of type SUITES_R:
SUITES_R : [ supported : 2* suite ] / suite SUITES_R : [ supported : 2* suite ] / suite
If the Responder does not support the selected cipher suite, then If the Responder does not support the selected cipher suite, then
SUITES_R MUST include one or more supported cipher suites. If the SUITES_R MUST include one or more supported cipher suites. If the
Responder does not support the selected cipher suite, but supports Responder does not support the selected cipher suite, but supports
another cipher suite in SUITES_I, then SUITES_R MUST include the another cipher suite in SUITES_I, then SUITES_R MUST include the
first supported cipher suite in SUITES_I. first supported cipher suite in SUITES_I.
skipping to change at page 36, line 6 skipping to change at page 37, line 31
Assume that the Initiator supports the five cipher suites 5, 6, 7, 8, Assume that the Initiator supports the five cipher suites 5, 6, 7, 8,
and 9 in decreasing order of preference. Figures 7 and 8 show and 9 in decreasing order of preference. Figures 7 and 8 show
examples of how the Initiator can truncate SUITES_I and how SUITES_R examples of how the Initiator can truncate SUITES_I and how SUITES_R
is used by Responders to give the Initiator information about the is used by Responders to give the Initiator information about the
cipher suites that the Responder supports. cipher suites that the Responder supports.
In the first example (Figure 7), the Responder supports cipher suite In the first example (Figure 7), the Responder supports cipher suite
6 but not the initially selected cipher suite 5. 6 but not the initially selected cipher suite 5.
Initiator Responder Initiator Responder
| METHOD_CORR, SUITES_I = 5, G_X, C_I, AD_1 | | METHOD_CORR, SUITES_I = 5, G_X, C_I, EAD_1 |
+------------------------------------------------------------------>| +------------------------------------------------------------------>|
| message_1 | | message_1 |
| | | |
| C_I, DIAG_MSG, SUITES_R = 6 | | C_I, DIAG_MSG, SUITES_R = 6 |
|<------------------------------------------------------------------+ |<------------------------------------------------------------------+
| error | | error |
| | | |
| METHOD_CORR, SUITES_I = [6, 5, 6], G_X, C_I, AD_1 | | METHOD_CORR, SUITES_I = [6, 5, 6], G_X, C_I, EAD_1 |
+------------------------------------------------------------------>| +------------------------------------------------------------------>|
| message_1 | | message_1 |
Figure 7: Example of Responder supporting suite 6 but not suite 5. Figure 7: Example of Responder supporting suite 6 but not suite 5.
In the second example (Figure 8), the Responder supports cipher In the second example (Figure 8), the Responder supports cipher
suites 8 and 9 but not the more preferred (by the Initiator) cipher suites 8 and 9 but not the more preferred (by the Initiator) cipher
suites 5, 6 or 7. To illustrate the negotiation mechanics we let the suites 5, 6 or 7. To illustrate the negotiation mechanics we let the
Initiator first make a guess that the Responder supports suite 6 but Initiator first make a guess that the Responder supports suite 6 but
not suite 5. Since the Responder supports neither 5 nor 6, it not suite 5. Since the Responder supports neither 5 nor 6, it
responds with an error and SUITES_R, after which the Initiator responds with an error and SUITES_R, after which the Initiator
selects its most preferred supported suite. The order of cipher selects its most preferred supported suite. The order of cipher
suites in SUITES_R does not matter. (If the Responder had supported suites in SUITES_R does not matter. (If the Responder had supported
suite 5, it would include it in SUITES_R of the response, and it suite 5, it would include it in SUITES_R of the response, and it
would in that case have become the selected suite in the second would in that case have become the selected suite in the second
message_1.) message_1.)
Initiator Responder Initiator Responder
| METHOD_CORR, SUITES_I = [6, 5, 6], G_X, C_I, AD_1 | | METHOD_CORR, SUITES_I = [6, 5, 6], G_X, C_I, EAD_1 |
+------------------------------------------------------------------>| +------------------------------------------------------------------>|
| message_1 | | message_1 |
| | | |
| C_I, DIAG_MSG, SUITES_R = [9, 8] | | C_I, DIAG_MSG, SUITES_R = [9, 8] |
|<------------------------------------------------------------------+ |<------------------------------------------------------------------+
| error | | error |
| | | |
| METHOD_CORR, SUITES_I = [8, 5, 6, 7, 8], G_X, C_I, AD_1 | | METHOD_CORR, SUITES_I = [8, 5, 6, 7, 8], G_X, C_I, EAD_1 |
+------------------------------------------------------------------>| +------------------------------------------------------------------>|
| message_1 | | message_1 |
Figure 8: Example of Responder supporting suites 8 and 9 but not Figure 8: Example of Responder supporting suites 8 and 9 but not
5, 6 or 7. 5, 6 or 7.
Note that the Initiator's list of supported cipher suites and order Note that the Initiator's list of supported cipher suites and order
of preference is fixed (see Section 5.3.1 and Section 5.3.2). of preference is fixed (see Section 5.3.1 and Section 5.3.2).
Furthermore, the Responder shall only accept message_1 if the Furthermore, the Responder shall only accept message_1 if the
selected cipher suite is the first cipher suite in SUITES_I that the selected cipher suite is the first cipher suite in SUITES_I that the
Responder supports (see Section 5.3.3). Following this procedure Responder supports (see Section 5.3.3). Following this procedure
ensures that the selected cipher suite is the most preferred (by the ensures that the selected cipher suite is the most preferred (by the
Initiator) cipher suite supported by both parties. Initiator) cipher suite supported by both parties.
If the selected cipher suite is not the first cipher suite which the If the selected cipher suite is not the first cipher suite which the
Responder supports in SUITES_I received in message_1, then Responder Responder supports in SUITES_I received in message_1, then Responder
MUST discontinue the protocol, see Section 5.3.3. If SUITES_I in MUST discontinue the protocol, see Section 5.3.3. If SUITES_I in
message_1 is manipulated then the integrity verification of message_2 message_1 is manipulated then the integrity verification of message_2
containing the transcript hash TH_2 = H( message_1, data_2 ) will containing the transcript hash TH_2 will fail and the Initiator will
fail and the Initiator will discontinue the protocol. discontinue the protocol.
7. Transferring EDHOC and Deriving an OSCORE Context 7. Transferring EDHOC and Deriving an OSCORE Context
7.1. EDHOC Message 4 7.1. EDHOC Message 4
This section specifies message_4 which is OPTIONAL to support. Key This section specifies message_4 which is OPTIONAL to support. Key
confirmation is normally provided by sending an application message confirmation is normally provided by sending an application message
from the Responder to the Initiator protected with a key derived with from the Responder to the Initiator protected with a key derived with
the EDHOC-Exporter, e.g., using OSCORE (see Section 7.2.1). In the EDHOC-Exporter, e.g., using OSCORE (see
deployments where no protected application message is sent from the [I-D.ietf-core-oscore-edhoc]). In deployments where no protected
Responder to the Initiator, the Responder MUST send message_4. Two application message is sent from the Responder to the Initiator, the
examples of such deployments: Responder MUST send message_4. Two examples of such deployments:
1. When EDHOC is only used for authentication and no application 1. When EDHOC is only used for authentication and no application
data is sent. data is sent.
2. When application data is only sent from the Initiator to the 2. When application data is only sent from the Initiator to the
Responder. Responder.
Further considerations are provided in Section 3.7. Further considerations are provided in Section 3.7.
7.1.1. Formatting of Message 4 7.1.1. Formatting of Message 4
message_4 and data_4 SHALL be CBOR Sequences (see Appendix A.1) as message_4 and data_4 SHALL be CBOR Sequences (see Appendix B.1) as
defined below defined below
message_4 = ( message_4 = (
data_4, data_4,
MAC_4 : bstr, CIPHERTEXT_4 : bstr,
) )
data_4 = ( data_4 = (
? C_I : bstr_identifier, ? C_I : bstr_identifier,
) )
7.1.2. Responder Processing of Message 4 7.1.2. Responder Processing of Message 4
The Responder SHALL compose message_4 as follows: The Responder SHALL compose message_4 as follows:
* If corr (METHOD_CORR mod 4) equals 1 or 3, C_I is omitted, * If corr (METHOD_CORR mod 4) equals 1 or 3, C_I is omitted,
otherwise C_I is not omitted. otherwise C_I is not omitted.
* Compute an inner COSE_Encrypt0 as defined in Section 5.3 of * Compute a COSE_Encrypt0 as defined in Section 5.3 of
[I-D.ietf-cose-rfc8152bis-struct], with the EDHOC AEAD algorithm [I-D.ietf-cose-rfc8152bis-struct], with the EDHOC AEAD algorithm
in the selected cipher suite, and the following parameters: in the selected cipher suite, and the following parameters. The
protected header SHALL be empty.
- protected = h'' - protected = h''
- external_aad = << TH_4 >> - external_aad = TH_4
- plaintext = h'' - plaintext = ( ? EAD_4 )
COSE constructs the input to the AEAD [RFC5116] as follows: where EAD_4 is protected external authorization data, see
Section 3.6. COSE constructs the input to the AEAD [RFC5116] as
follows:
- Key K = EDHOC-Exporter( "EDHOC_message_4_Key", length ) - Key K = EDHOC-Exporter( "EDHOC_message_4_Key", length )
- Nonce N = EDHOC-Exporter( "EDHOC_message_4_Nonce", length ) - Nonce N = EDHOC-Exporter( "EDHOC_message_4_Nonce", length )
- Plaintext P = ( ? EAD_4 )
- Plaintext P = 0x (the empty string) - Associated data A = [ "Encrypt0", h'', TH_4 ]
- Associated data A =
[ "Encrypt0", h'', << TH_4 >> ]
MAC_4 is the 'ciphertext' of the COSE_Encrypt0. CIPHERTEXT_4 is the 'ciphertext' of the COSE_Encrypt0.
* Encode message_4 as a sequence of CBOR encoded data items as * Encode message_4 as a sequence of CBOR encoded data items as
specified in Section 7.1.1. specified in Section 7.1.1.
7.1.3. Initiator Processing of Message 4 7.1.3. Initiator Processing of Message 4
The Initiator SHALL process message_4 as follows: The Initiator SHALL process message_4 as follows:
* Decode message_4 (see Appendix A.1). * Decode message_4 (see Appendix B.1).
* Retrieve the protocol state using the connection identifier C_I * Retrieve the protocol state using the connection identifier C_I
and/or other external information such as the CoAP Token and the and/or other external information such as the CoAP Token and the
5-tuple. 5-tuple.
* Verify MAC_4 as defined in Section 5.3 of * Decrypt and verify the outer COSE_Encrypt0 as defined in
[I-D.ietf-cose-rfc8152bis-struct], with the EDHOC AEAD algorithm Section 5.3 of [I-D.ietf-cose-rfc8152bis-struct], with the EDHOC
in the selected cipher suite, and the parameters defined in AEAD algorithm in the selected cipher suite, and the parameters
Section 7.1.2. defined in Section 7.1.2.
* Pass EAD_4 to the security application.
If any verification step fails the Initiator MUST send an EDHOC error If any verification step fails the Initiator MUST send an EDHOC error
message back, formatted as defined in Section 6, and the protocol message back, formatted as defined in Section 6, and the session MUST
MUST be discontinued. be discontinued.
7.2. Transferring EDHOC in CoAP 7.2. Transferring EDHOC in CoAP
It is recommended to transport EDHOC as an exchange of CoAP [RFC7252] It is recommended to transport EDHOC as an exchange of CoAP [RFC7252]
messages. CoAP is a reliable transport that can preserve packet messages. CoAP is a reliable transport that can preserve packet
ordering and handle message duplication. CoAP can also perform ordering and handle message duplication. CoAP can also perform
fragmentation and protect against denial of service attacks. It is fragmentation and protect against denial of service attacks. It is
recommended to carry the EDHOC messages in Confirmable messages, recommended to carry the EDHOC messages in Confirmable messages,
especially if fragmentation is used. especially if fragmentation is used.
skipping to change at page 41, line 33 skipping to change at page 42, line 33
Figure 10: Transferring EDHOC in CoAP when the Initiator is CoAP Figure 10: Transferring EDHOC in CoAP when the Initiator is CoAP
Server Server
To protect against denial-of-service attacks, the CoAP server MAY To protect against denial-of-service attacks, the CoAP server MAY
respond to the first POST request with a 4.01 (Unauthorized) respond to the first POST request with a 4.01 (Unauthorized)
containing an Echo option [I-D.ietf-core-echo-request-tag]. This containing an Echo option [I-D.ietf-core-echo-request-tag]. This
forces the initiator to demonstrate its reachability at its apparent forces the initiator to demonstrate its reachability at its apparent
network address. If message fragmentation is needed, the EDHOC network address. If message fragmentation is needed, the EDHOC
messages may be fragmented using the CoAP Block-Wise Transfer messages may be fragmented using the CoAP Block-Wise Transfer
mechanism [RFC7959]. mechanism [RFC7959]. EDHOC does not restrict how error messages are
transported with CoAP, as long as the appropriate error message can
7.2.1. Deriving an OSCORE Context from EDHOC to be transported in response to a message that failed (see
Section 6). The use of EDHOC with OSCORE is specified in
When EDHOC is used to derive parameters for OSCORE [RFC8613], the [I-D.ietf-core-oscore-edhoc].
parties make sure that the EDHOC connection identifiers are unique,
i.e. C_R MUST NOT be equal to C_I. The CoAP client and server MUST
be able to retrieve the OSCORE protocol state using its chosen
connection identifier and optionally other information such as the
5-tuple. In case that the CoAP client is the Initiator and the CoAP
server is the Responder:
* The client's OSCORE Sender ID is C_R and the server's OSCORE
Sender ID is C_I, as defined in this document
* The AEAD Algorithm and the hash algorithm are the application AEAD
and hash algorithms in the selected cipher suite.
* The Master Secret and Master Salt are derived as follows. By
default key_length is the key length (in bytes) of the application
AEAD Algorithm and salt_length is 8 bytes. The Initiator and
Responder MAY agree out-of-band on a longer key_length than the
default and a different salt_length.
Master Secret = EDHOC-Exporter( "OSCORE Master Secret", key_length )
Master Salt = EDHOC-Exporter( "OSCORE Master Salt", salt_length )
7.2.2. Error Messages with CoAP Transport
EDHOC does not restrict how error messages are transported with CoAP,
as long as the appropriate error message can to be transported in
response to a message that failed (see Section 6). In case of
combining EDHOC and OSCORE as specified in
[I-D.ietf-core-oscore-edhoc], an error message following a combined
EDHOC message_3/OSCORE request MUST be sent with a CoAP error code
and SHALL contain the ERR_INFO as payload (see Section 6).
8. Security Considerations 8. Security Considerations
8.1. Security Properties 8.1. Security Properties
EDHOC inherits its security properties from the theoretical SIGMA-I EDHOC inherits its security properties from the theoretical SIGMA-I
protocol [SIGMA]. Using the terminology from [SIGMA], EDHOC provides protocol [SIGMA]. Using the terminology from [SIGMA], EDHOC provides
perfect forward secrecy, mutual authentication with aliveness, perfect forward secrecy, mutual authentication with aliveness,
consistency, and peer awareness. As described in [SIGMA], peer consistency, and peer awareness. As described in [SIGMA], peer
awareness is provided to the Responder, but not to the Initiator. awareness is provided to the Responder, but not to the Initiator.
EDHOC protects the credential identifier of the Initiator against EDHOC protects the credential identifier of the Initiator against
active attacks and the credential identifier of the Responder against active attacks and the credential identifier of the Responder against
passive attacks. The roles should be assigned to protect the most passive attacks. The roles should be assigned to protect the most
sensitive identity/identifier, typically that which is not possible sensitive identity/identifier, typically that which is not possible
to infer from routing information in the lower layers. to infer from routing information in the lower layers.
Compared to [SIGMA], EDHOC adds an explicit method type and expands Compared to [SIGMA], EDHOC adds an explicit method type and expands
the message authentication coverage to additional elements such as the message authentication coverage to additional elements such as
algorithms, auxiliary data, and previous messages. This protects algorithms, external authorization data, and previous messages. This
against an attacker replaying messages or injecting messages from protects against an attacker replaying messages or injecting messages
another session. from another session.
EDHOC also adds negotiation of connection identifiers and downgrade EDHOC also adds negotiation of connection identifiers and downgrade
protected negotiation of cryptographic parameters, i.e. an attacker protected negotiation of cryptographic parameters, i.e. an attacker
cannot affect the negotiated parameters. A single session of EDHOC cannot affect the negotiated parameters. A single session of EDHOC
does not include negotiation of cipher suites, but it enables the does not include negotiation of cipher suites, but it enables the
Responder to verify that the selected cipher suite is the most Responder to verify that the selected cipher suite is the most
preferred cipher suite by the Initiator which is supported by both preferred cipher suite by the Initiator which is supported by both
the Initiator and the Responder. the Initiator and the Responder.
As required by [RFC7258], IETF protocols need to mitigate pervasive As required by [RFC7258], IETF protocols need to mitigate pervasive
skipping to change at page 45, line 25 skipping to change at page 45, line 42
method). method).
The data rates in many IoT deployments are very limited. Given that The data rates in many IoT deployments are very limited. Given that
the application keys are protected as well as the long-term the application keys are protected as well as the long-term
authentication keys they can often be used for years or even decades authentication keys they can often be used for years or even decades
before the cryptographic limits are reached. If the application keys before the cryptographic limits are reached. If the application keys
established through EDHOC need to be renewed, the communicating established through EDHOC need to be renewed, the communicating
parties can derive application keys with other labels or run EDHOC parties can derive application keys with other labels or run EDHOC
again. again.
Requirement for how to securely generate, validate, and process the
ephermeral public keys depend on the elliptic curve. For X25519 and
X448, the requirements are defined in [RFC7748]. For secp256r1,
secp384r1, and secp521r1, the requirements are defined in Section 5
of [SP-800-56A]. For secp256r1, secp384r1, and secp521r1, at least
partial public-key validation MUST be done.
8.3. Cipher Suites and Cryptographic Algorithms 8.3. Cipher Suites and Cryptographic Algorithms
For many constrained IoT devices it is problematic to support more For many constrained IoT devices it is problematic to support more
than one cipher suite. Existing devices can be expected to support than one cipher suite. Existing devices can be expected to support
either ECDSA or EdDSA. To enable as much interoperability as we can either ECDSA or EdDSA. To enable as much interoperability as we can
reasonably achieve, less constrained devices SHOULD implement both reasonably achieve, less constrained devices SHOULD implement both
cipher suite 0 (AES-CCM-16-64-128, SHA-256, X25519, EdDSA, Ed25519, cipher suite 0 (AES-CCM-16-64-128, SHA-256, X25519, EdDSA, AES-CCM-
AES-CCM-16-64-128, SHA-256) and cipher suite 2 (AES-CCM-16-64-128, 16-64-128, SHA-256) and cipher suite 2 (AES-CCM-16-64-128, SHA-256,
SHA-256, P-256, ES256, P-256, AES-CCM-16-64-128, SHA-256). P-256, ES256, AES-CCM-16-64-128, SHA-256). Constrained endpoints
Constrained endpoints SHOULD implement cipher suite 0 or cipher suite SHOULD implement cipher suite 0 or cipher suite 2. Implementations
2. Implementations only need to implement the algorithms needed for only need to implement the algorithms needed for their supported
their supported methods. methods.
When using private cipher suite or registering new cipher suites, the When using private cipher suite or registering new cipher suites, the
choice of key length used in the different algorithms needs to be choice of key length used in the different algorithms needs to be
harmonized, so that a sufficient security level is maintained for harmonized, so that a sufficient security level is maintained for
certificates, EDHOC, and the protection of application data. The certificates, EDHOC, and the protection of application data. The
Initiator and the Responder should enforce a minimum security level. Initiator and the Responder should enforce a minimum security level.
The hash algorithms SHA-1 and SHA-256/64 (256-bit Hash truncated to The hash algorithms SHA-1 and SHA-256/64 (256-bit Hash truncated to
64-bits) SHALL NOT be supported for use in EDHOC except for 64-bits) SHALL NOT be supported for use in EDHOC except for
certificate identification with x5u and c5u. Note that secp256k1 is certificate identification with x5u and c5u. Note that secp256k1 is
only defined for use with ECDSA and not for ECDH. only defined for use with ECDSA and not for ECDH.
8.4. Unprotected Data 8.4. Unprotected Data
The Initiator and the Responder must make sure that unprotected data The Initiator and the Responder must make sure that unprotected data
and metadata do not reveal any sensitive information. This also and metadata do not reveal any sensitive information. This also
applies for encrypted data sent to an unauthenticated party. In applies for encrypted data sent to an unauthenticated party. In
particular, it applies to AD_1, ID_CRED_R, AD_2, and ERR_MSG. Using particular, it applies to EAD_1, ID_CRED_R, EAD_2, and error
the same AD_1 in several EDHOC sessions allows passive eavesdroppers messages. Using the same EAD_1 in several EDHOC sessions allows
to correlate the different sessions. Another consideration is that passive eavesdroppers to correlate the different sessions. Another
the list of supported cipher suites may potentially be used to consideration is that the list of supported cipher suites may
identify the application. potentially be used to identify the application.
The Initiator and the Responder must also make sure that The Initiator and the Responder must also make sure that
unauthenticated data does not trigger any harmful actions. In unauthenticated data does not trigger any harmful actions. In
particular, this applies to AD_1 and ERR_MSG. particular, this applies to EAD_1 and error messages.
8.5. Denial-of-Service 8.5. Denial-of-Service
EDHOC itself does not provide countermeasures against Denial-of- EDHOC itself does not provide countermeasures against Denial-of-
Service attacks. By sending a number of new or replayed message_1 an Service attacks. By sending a number of new or replayed message_1 an
attacker may cause the Responder to allocate state, perform attacker may cause the Responder to allocate state, perform
cryptographic operations, and amplify messages. To mitigate such cryptographic operations, and amplify messages. To mitigate such
attacks, an implementation SHOULD rely on lower layer mechanisms such attacks, an implementation SHOULD rely on lower layer mechanisms such
as the Echo option in CoAP [I-D.ietf-core-echo-request-tag] that as the Echo option in CoAP [I-D.ietf-core-echo-request-tag] that
forces the initiator to demonstrate reachability at its apparent forces the initiator to demonstrate reachability at its apparent
network address. network address.
An attacker can also send faked message_2, message_3, message_4, or
error in an attempt to trick the receiving party to send an error
message and discontinue the session. EDHOC implementations MAY
evaluate if a received message is likely to have be forged by and
attacker and ignore it without sending an error message or
discontinuing the session.
8.6. Implementation Considerations 8.6. Implementation Considerations
The availability of a secure random number generator is essential for The availability of a secure random number generator is essential for
the security of EDHOC. If no true random number generator is the security of EDHOC. If no true random number generator is
available, a truly random seed MUST be provided from an external available, a truly random seed MUST be provided from an external
source and used with a cryptographically secure pseudorandom number source and used with a cryptographically secure pseudorandom number
generator. As each pseudorandom number must only be used once, an generator. As each pseudorandom number must only be used once, an
implementation need to get a new truly random seed after reboot, or implementation need to get a new truly random seed after reboot, or
continuously store state in nonvolatile memory, see ([RFC8613], continuously store state in nonvolatile memory, see ([RFC8613],
Appendix B.1.1) for issues and solution approaches for writing to Appendix B.1.1) for issues and solution approaches for writing to
skipping to change at page 47, line 13 skipping to change at page 48, line 4
unaugmented random numbers on the wire. unaugmented random numbers on the wire.
If ECDSA is supported, "deterministic ECDSA" as specified in If ECDSA is supported, "deterministic ECDSA" as specified in
[RFC6979] MAY be used. Pure deterministic elliptic-curve signatures [RFC6979] MAY be used. Pure deterministic elliptic-curve signatures
such as deterministic ECDSA and EdDSA have gained popularity over such as deterministic ECDSA and EdDSA have gained popularity over
randomized ECDSA as their security do not depend on a source of high- randomized ECDSA as their security do not depend on a source of high-
quality randomness. Recent research has however found that quality randomness. Recent research has however found that
implementations of these signature algorithms may be vulnerable to implementations of these signature algorithms may be vulnerable to
certain side-channel and fault injection attacks due to their certain side-channel and fault injection attacks due to their
determinism. See e.g. Section 1 of determinism. See e.g. Section 1 of
[I-D.mattsson-cfrg-det-sigs-with-noise] for a list of attack papers. [I-D.mattsson-cfrg-det-sigs-with-noise] for a list of attack papers.
As suggested in Section 6.1.2 of [I-D.ietf-cose-rfc8152bis-algs] this As suggested in Section 6.1.2 of [I-D.ietf-cose-rfc8152bis-algs] this
can be addressed by combining randomness and determinism. can be addressed by combining randomness and determinism.
The referenced processing instructions in [SP-800-56A] must be All private keys, symmetric keys, and IVs MUST be secret.
complied with, including deleting the intermediate computed values
along with any ephemeral ECDH secrets after the key derivation is
completed. The ECDH shared secrets, keys, and IVs MUST be secret.
Implementations should provide countermeasures to side-channel Implementations should provide countermeasures to side-channel
attacks such as timing attacks. Depending on the selected curve, the attacks such as timing attacks. Intermediate computed values such as
parties should perform various validations of each other's public ephemeral ECDH keys and ECDH shared secrets MUST be deleted after key
keys, see e.g. Section 5 of [SP-800-56A]. derivation is completed.
The Initiator and the Responder are responsible for verifying the The Initiator and the Responder are responsible for verifying the
integrity of certificates. The selection of trusted CAs should be integrity of certificates. The selection of trusted CAs should be
done very carefully and certificate revocation should be supported. done very carefully and certificate revocation should be supported.
The private authentication keys MUST be kept secret. The private authentication keys MUST be kept secret.
The Initiator and the Responder are allowed to select the connection The Initiator and the Responder are allowed to select the connection
identifiers C_I and C_R, respectively, for the other party to use in identifiers C_I and C_R, respectively, for the other party to use in
the ongoing EDHOC protocol as well as in a subsequent application the ongoing EDHOC protocol as well as in a subsequent application
protocol (e.g. OSCORE [RFC8613]). The choice of connection protocol (e.g. OSCORE [RFC8613]). The choice of connection
identifier is not security critical in EDHOC but intended to simplify identifier is not security critical in EDHOC but intended to simplify
the retrieval of the right security context in combination with using the retrieval of the right security context in combination with using
short identifiers. If the wrong connection identifier of the other short identifiers. If the wrong connection identifier of the other
party is used in a protocol message it will result in the receiving party is used in a protocol message it will result in the receiving
party not being able to retrieve a security context (which will party not being able to retrieve a security context (which will
terminate the protocol) or retrieve the wrong security context (which terminate the protocol) or retrieve the wrong security context (which
also terminates the protocol as the message cannot be verified). also terminates the protocol as the message cannot be verified).
The Responder MUST finish the verification step of message_3 before
passing AD_3 to the application.
If two nodes unintentionally initiate two simultaneous EDHOC message If two nodes unintentionally initiate two simultaneous EDHOC message
exchanges with each other even if they only want to complete a single exchanges with each other even if they only want to complete a single
EDHOC message exchange, they MAY terminate the exchange with the EDHOC message exchange, they MAY terminate the exchange with the
lexicographically smallest G_X. If the two G_X values are equal, the lexicographically smallest G_X. If the two G_X values are equal, the
received message_1 MUST be discarded to mitigate reflection attacks. received message_1 MUST be discarded to mitigate reflection attacks.
Note that in the case of two simultaneous EDHOC exchanges where the Note that in the case of two simultaneous EDHOC exchanges where the
nodes only complete one and where the nodes have different preferred nodes only complete one and where the nodes have different preferred
cipher suites, an attacker can affect which of the two nodes' cipher suites, an attacker can affect which of the two nodes'
preferred cipher suites will be used by blocking the other exchange. preferred cipher suites will be used by blocking the other exchange.
If supported by the device, it is RECOMMENDED that at least the long- If supported by the device, it is RECOMMENDED that at least the long-
term private keys is stored in a Trusted Execution Environment (TEE) term private keys are stored in a Trusted Execution Environment (TEE)
and that sensitive operations using these keys are performed inside and that sensitive operations using these keys are performed inside
the TEE. To achieve even higher security it is RECOMMENDED that the TEE. To achieve even higher security it is RECOMMENDED that in
additional operations such as ephemeral key generation, all additional operations such as ephemeral key generation, all
computations of shared secrets, and storage of the PRK keys can be computations of shared secrets, and storage of the pseudorandom keys
done inside the TEE. The TEE can also be used to protect the EDHOC (PRK) can be done inside the TEE. The use of a TEE enforces that
and application protocol (e.g. OSCORE) implementation using some code within that environment cannot be tampered with, and that any
form of "secure boot", memory protection etc. The use of a TEE data used by such code cannot be read or tampered with by code
enforces that code within that environment cannot be tampered with, outside that environment. Note that non-EDHOC code inside the TEE
and that any data used by such code cannot be read or tampered with might still be able to read EDHOC data and tamper with EDHOC code, to
by code outside that environment. protect against such attacks EDHOC needs to be in its own zone. To
provide better protection against some forms of physical attacks,
sensitive EDHOC data should be stored inside the SoC or encrypted and
integrity protected when sent on a data bus (e.g. between the CPU and
RAM or Flash). Secure boot can be used to increase the security of
code and data in the Rich Execution Environment (REE) by validating
the REE image.
9. IANA Considerations 9. IANA Considerations
9.1. EDHOC Cipher Suites Registry 9.1. EDHOC Exporter Label
IANA has created a new registry titled "EDHOC Exporter Label" under
the new heading "EDHOC". The registration procedure is "Expert
Review". The columns of the registry are Label, Description, and
Reference. All columns are text strings. The initial contents of
the registry are:
Label: EDHOC_message_4_Key
Description: Key used to protect EDHOC message_4
Reference: [[this document]]
Label: EDHOC_message_4_Nonce
Description: Nonce used to protect EDHOC message_4
Reference: [[this document]]
9.2. EDHOC Cipher Suites Registry
IANA has created a new registry titled "EDHOC Cipher Suites" under IANA has created a new registry titled "EDHOC Cipher Suites" under
the new heading "EDHOC". The registration procedure is "Expert the new heading "EDHOC". The registration procedure is "Expert
Review". The columns of the registry are Value, Array, Description, Review". The columns of the registry are Value, Array, Description,
and Reference, where Value is an integer and the other columns are and Reference, where Value is an integer and the other columns are
text strings. The initial contents of the registry are: text strings. The initial contents of the registry are:
Value: -24 Value: -24
Algorithms: N/A Algorithms: N/A
Desc: Reserved for Private Use Desc: Reserved for Private Use
skipping to change at page 49, line 10 skipping to change at page 50, line 10
Value: -22 Value: -22
Algorithms: N/A Algorithms: N/A
Desc: Reserved for Private Use Desc: Reserved for Private Use
Reference: [[this document]] Reference: [[this document]]
Value: -21 Value: -21
Algorithms: N/A Algorithms: N/A
Desc: Reserved for Private Use Desc: Reserved for Private Use
Reference: [[this document]] Reference: [[this document]]
Value: 0 Value: 0
Array: 10, 5, 4, -8, 6, 10, 5 Array: 10, -16, 4, -8, 10, -16
Desc: AES-CCM-16-64-128, SHA-256, X25519, EdDSA, Ed25519, Desc: AES-CCM-16-64-128, SHA-256, X25519, EdDSA,
AES-CCM-16-64-128, SHA-256 AES-CCM-16-64-128, SHA-256
Reference: [[this document]] Reference: [[this document]]
Value: 1 Value: 1
Array: 30, 5, 4, -8, 6, 10, 5 Array: 30, -16, 4, -8, 10, -16
Desc: AES-CCM-16-128-128, SHA-256, X25519, EdDSA, Ed25519, Desc: AES-CCM-16-128-128, SHA-256, X25519, EdDSA,
AES-CCM-16-64-128, SHA-256 AES-CCM-16-64-128, SHA-256
Reference: [[this document]] Reference: [[this document]]
Value: 2 Value: 2
Array: 10, 5, 1, -7, 1, 10, 5 Array: 10, -16, 1, -7, 10, -16
Desc: AES-CCM-16-64-128, SHA-256, P-256, ES256, P-256, Desc: AES-CCM-16-64-128, SHA-256, P-256, ES256,
AES-CCM-16-64-128, SHA-256 AES-CCM-16-64-128, SHA-256
Reference: [[this document]] Reference: [[this document]]
Value: 3 Value: 3
Array: 30, 5, 1, -7, 1, 10, 5 Array: 30, -16, 1, -7, 10, -16
Desc: AES-CCM-16-128-128, SHA-256, P-256, ES256, P-256, Desc: AES-CCM-16-128-128, SHA-256, P-256, ES256,
AES-CCM-16-64-128, SHA-256 AES-CCM-16-64-128, SHA-256
Reference: [[this document]] Reference: [[this document]]
Value: 4 Value: 4
Array: 1, -16, 4, -7, 1, 1, -16 Array: 1, -16, 4, -7, 1, -16
Desc: A128GCM, SHA-256, X25519, ES256, P-256, Desc: A128GCM, SHA-256, X25519, ES256,
A128GCM, SHA-256 A128GCM, SHA-256
Reference: [[this document]] Reference: [[this document]]
Value: 5 Value: 5
Array: 3, -43, 2, -35, 2, 3, -43 Array: 3, -43, 2, -35, 3, -43
Desc: A256GCM, SHA-384, P-384, ES384, P-384, Desc: A256GCM, SHA-384, P-384, ES384,
A256GCM, SHA-384 A256GCM, SHA-384
Reference: [[this document]] Reference: [[this document]]
9.2. EDHOC Method Type Registry 9.3. EDHOC Method Type Registry
IANA has created a new registry entitled "EDHOC Method Type" under IANA has created a new registry entitled "EDHOC Method Type" under
the new heading "EDHOC". The registration procedure is "Expert the new heading "EDHOC". The registration procedure is "Expert
Review". The columns of the registry are Value, Description, and Review". The columns of the registry are Value, Description, and
Reference, where Value is an integer and the other columns are text Reference, where Value is an integer and the other columns are text
strings. The initial contents of the registry is shown in Figure 4. strings. The initial contents of the registry is shown in Figure 4.
9.3. EDHOC Error Codes Registry 9.4. EDHOC Error Codes Registry
IANA has created a new registry entitled "EDHOC Error Codes" under IANA has created a new registry entitled "EDHOC Error Codes" under
the new heading "EDHOC". The registration procedure is the new heading "EDHOC". The registration procedure is
"Specification Required". The columns of the registry are ERR_CODE, "Specification Required". The columns of the registry are ERR_CODE,
ERR_INFO Type and Description, where ERR_CODE is an integer, ERR_INFO ERR_INFO Type and Description, where ERR_CODE is an integer, ERR_INFO
is a CDDL defined type, and Description is a text string. The is a CDDL defined type, and Description is a text string. The
initial contents of the registry is shown in Figure 6. initial contents of the registry is shown in Figure 6.
9.4. The Well-Known URI Registry 9.5. The Well-Known URI Registry
IANA has added the well-known URI 'edhoc' to the Well-Known URIs IANA has added the well-known URI 'edhoc' to the Well-Known URIs
registry. registry.
* URI suffix: edhoc * URI suffix: edhoc
* Change controller: IETF * Change controller: IETF
* Specification document(s): [[this document]] * Specification document(s): [[this document]]
* Related information: None * Related information: None
9.5. Media Types Registry 9.6. Media Types Registry
IANA has added the media type 'application/edhoc' to the Media Types IANA has added the media type 'application/edhoc' to the Media Types
registry. registry.
* Type name: application * Type name: application
* Subtype name: edhoc * Subtype name: edhoc
* Required parameters: N/A * Required parameters: N/A
skipping to change at page 51, line 22 skipping to change at page 52, line 22
"Authors' Addresses" section. "Authors' Addresses" section.
* Intended usage: COMMON * Intended usage: COMMON
* Restrictions on usage: N/A * Restrictions on usage: N/A
* Author: See "Authors' Addresses" section. * Author: See "Authors' Addresses" section.
* Change Controller: IESG * Change Controller: IESG
9.6. CoAP Content-Formats Registry 9.7. CoAP Content-Formats Registry
IANA has added the media type 'application/edhoc' to the CoAP IANA has added the media type 'application/edhoc' to the CoAP
Content-Formats registry. Content-Formats registry.
* Media Type: application/edhoc * Media Type: application/edhoc
* Encoding: * Encoding:
* ID: TBD42 * ID: TBD42
* Reference: [[this document]] * Reference: [[this document]]
9.7. Expert Review Instructions 9.8. Expert Review Instructions
The IANA Registries established in this document is defined as The IANA Registries established in this document is defined as
"Expert Review". This section gives some general guidelines for what "Expert Review". This section gives some general guidelines for what
the experts should be looking for, but they are being designated as the experts should be looking for, but they are being designated as
experts for a reason so they should be given substantial latitude. experts for a reason so they should be given substantial latitude.
Expert reviewers should take into consideration the following points: Expert reviewers should take into consideration the following points:
* Clarity and correctness of registrations. Experts are expected to * Clarity and correctness of registrations. Experts are expected to
check the clarity of purpose and use of the requested entries. check the clarity of purpose and use of the requested entries.
skipping to change at page 53, line 47 skipping to change at page 54, line 47
DOI 10.17487/RFC8724, April 2020, DOI 10.17487/RFC8724, April 2020,
<https://www.rfc-editor.org/info/rfc8724>. <https://www.rfc-editor.org/info/rfc8724>.
[RFC8742] Bormann, C., "Concise Binary Object Representation (CBOR) [RFC8742] Bormann, C., "Concise Binary Object Representation (CBOR)
Sequences", RFC 8742, DOI 10.17487/RFC8742, February 2020, Sequences", RFC 8742, DOI 10.17487/RFC8742, February 2020,
<https://www.rfc-editor.org/info/rfc8742>. <https://www.rfc-editor.org/info/rfc8742>.
[I-D.ietf-cose-rfc8152bis-struct] [I-D.ietf-cose-rfc8152bis-struct]
Schaad, J., "CBOR Object Signing and Encryption (COSE): Schaad, J., "CBOR Object Signing and Encryption (COSE):
Structures and Process", Work in Progress, Internet-Draft, Structures and Process", Work in Progress, Internet-Draft,
draft-ietf-cose-rfc8152bis-struct-14, 24 September 2020, draft-ietf-cose-rfc8152bis-struct-15, 1 February 2021,
<http://www.ietf.org/internet-drafts/draft-ietf-cose- <https://www.ietf.org/archive/id/draft-ietf-cose-
rfc8152bis-struct-14.txt>. rfc8152bis-struct-15.txt>.
[I-D.ietf-cose-rfc8152bis-algs] [I-D.ietf-cose-rfc8152bis-algs]
Schaad, J., "CBOR Object Signing and Encryption (COSE): Schaad, J., "CBOR Object Signing and Encryption (COSE):
Initial Algorithms", Work in Progress, Internet-Draft, Initial Algorithms", Work in Progress, Internet-Draft,
draft-ietf-cose-rfc8152bis-algs-12, 24 September 2020, draft-ietf-cose-rfc8152bis-algs-12, 24 September 2020,
<http://www.ietf.org/internet-drafts/draft-ietf-cose- <https://www.ietf.org/archive/id/draft-ietf-cose-
rfc8152bis-algs-12.txt>. rfc8152bis-algs-12.txt>.
[I-D.ietf-cose-x509] [I-D.ietf-cose-x509]
Schaad, J., "CBOR Object Signing and Encryption (COSE): Schaad, J., "CBOR Object Signing and Encryption (COSE):
Header parameters for carrying and referencing X.509 Header parameters for carrying and referencing X.509
certificates", Work in Progress, Internet-Draft, draft- certificates", Work in Progress, Internet-Draft, draft-
ietf-cose-x509-08, 14 December 2020, <http://www.ietf.org/ ietf-cose-x509-08, 14 December 2020,
internet-drafts/draft-ietf-cose-x509-08.txt>. <https://www.ietf.org/internet-drafts/draft-ietf-cose-
x509-08.txt>.
[I-D.ietf-core-echo-request-tag] [I-D.ietf-core-echo-request-tag]
Amsuess, C., Mattsson, J., and G. Selander, "CoAP: Echo, Amsüss, C., Mattsson, J. P., and G. Selander, "CoAP: Echo,
Request-Tag, and Token Processing", Work in Progress, Request-Tag, and Token Processing", Work in Progress,
Internet-Draft, draft-ietf-core-echo-request-tag-11, 2 Internet-Draft, draft-ietf-core-echo-request-tag-12, 1
November 2020, <http://www.ietf.org/internet-drafts/draft- February 2021, <https://www.ietf.org/archive/id/draft-
ietf-core-echo-request-tag-11.txt>. ietf-core-echo-request-tag-12.txt>.
[I-D.ietf-lake-reqs] [I-D.ietf-lake-reqs]
Vucinic, M., Selander, G., Mattsson, J., and D. Garcia- Vucinic, M., Selander, G., Mattsson, J. P., and D. Garcia-
Carillo, "Requirements for a Lightweight AKE for OSCORE", Carrillo, "Requirements for a Lightweight AKE for OSCORE",
Work in Progress, Internet-Draft, draft-ietf-lake-reqs-04, Work in Progress, Internet-Draft, draft-ietf-lake-reqs-04,
8 June 2020, <http://www.ietf.org/internet-drafts/draft- 8 June 2020, <https://www.ietf.org/archive/id/draft-ietf-
ietf-lake-reqs-04.txt>. lake-reqs-04.txt>.
10.2. Informative References 10.2. Informative References
[RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for [RFC7228] Bormann, C., Ersue, M., and A. Keranen, "Terminology for
Constrained-Node Networks", RFC 7228, Constrained-Node Networks", RFC 7228,
DOI 10.17487/RFC7228, May 2014, DOI 10.17487/RFC7228, May 2014,
<https://www.rfc-editor.org/info/rfc7228>. <https://www.rfc-editor.org/info/rfc7228>.
[RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an [RFC7258] Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an
Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May
skipping to change at page 55, line 11 skipping to change at page 56, line 11
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>. <https://www.rfc-editor.org/info/rfc8446>.
[RFC8937] Cremers, C., Garratt, L., Smyshlyaev, S., Sullivan, N., [RFC8937] Cremers, C., Garratt, L., Smyshlyaev, S., Sullivan, N.,
and C. Wood, "Randomness Improvements for Security and C. Wood, "Randomness Improvements for Security
Protocols", RFC 8937, DOI 10.17487/RFC8937, October 2020, Protocols", RFC 8937, DOI 10.17487/RFC8937, October 2020,
<https://www.rfc-editor.org/info/rfc8937>. <https://www.rfc-editor.org/info/rfc8937>.
[I-D.ietf-core-resource-directory] [I-D.ietf-core-resource-directory]
Amsuess, C., Shelby, Z., Koster, M., Bormann, C., and P. Amsüss, C., Shelby, Z., Koster, M., Bormann, C., and P. V.
Stok, "CoRE Resource Directory", Work in Progress, D. Stok, "CoRE Resource Directory", Work in Progress,
Internet-Draft, draft-ietf-core-resource-directory-26, 2 Internet-Draft, draft-ietf-core-resource-directory-28, 7
November 2020, <http://www.ietf.org/internet-drafts/draft- March 2021, <https://www.ietf.org/archive/id/draft-ietf-
ietf-core-resource-directory-26.txt>. core-resource-directory-28.txt>.
[I-D.ietf-lwig-security-protocol-comparison] [I-D.ietf-lwig-security-protocol-comparison]
Mattsson, J., Palombini, F., and M. Vucinic, "Comparison Mattsson, J. P., Palombini, F., and M. Vucinic,
of CoAP Security Protocols", Work in Progress, Internet- "Comparison of CoAP Security Protocols", Work in Progress,
Draft, draft-ietf-lwig-security-protocol-comparison-05, 2 Internet-Draft, draft-ietf-lwig-security-protocol-
November 2020, <http://www.ietf.org/internet-drafts/draft- comparison-05, 2 November 2020,
ietf-lwig-security-protocol-comparison-05.txt>. <https://www.ietf.org/archive/id/draft-ietf-lwig-security-
protocol-comparison-05.txt>.
[I-D.ietf-tls-dtls13] [I-D.ietf-tls-dtls13]
Rescorla, E., Tschofenig, H., and N. Modadugu, "The Rescorla, E., Tschofenig, H., and N. Modadugu, "The
Datagram Transport Layer Security (DTLS) Protocol Version Datagram Transport Layer Security (DTLS) Protocol Version
1.3", Work in Progress, Internet-Draft, draft-ietf-tls- 1.3", Work in Progress, Internet-Draft, draft-ietf-tls-
dtls13-40, 20 January 2021, <http://www.ietf.org/internet- dtls13-43, 30 April 2021, <https://www.ietf.org/internet-
drafts/draft-ietf-tls-dtls13-40.txt>. drafts/draft-ietf-tls-dtls13-43.txt>.
[I-D.selander-ace-ake-authz] [I-D.selander-ace-ake-authz]
Selander, G., Mattsson, J., Vucinic, M., Richardson, M., Selander, G., Mattsson, J. P., Vucinic, M., Richardson,
and A. Schellenbaum, "Lightweight Authorization for M., and A. Schellenbaum, "Lightweight Authorization for
Authenticated Key Exchange.", Work in Progress, Internet- Authenticated Key Exchange.", Work in Progress, Internet-
Draft, draft-selander-ace-ake-authz-02, 2 November 2020, Draft, draft-selander-ace-ake-authz-02, 2 November 2020,
<http://www.ietf.org/internet-drafts/draft-selander-ace- <https://www.ietf.org/archive/id/draft-selander-ace-ake-
ake-authz-02.txt>. authz-02.txt>.
[I-D.ietf-core-oscore-edhoc] [I-D.ietf-core-oscore-edhoc]
Palombini, F., Tiloca, M., Hoeglund, R., Hristozov, S., Palombini, F., Tiloca, M., Hoeglund, R., Hristozov, S.,
and G. Selander, "Combining EDHOC and OSCORE", Work in and G. Selander, "Combining EDHOC and OSCORE", Work in
Progress, Internet-Draft, draft-ietf-core-oscore-edhoc-00, Progress, Internet-Draft, draft-ietf-core-oscore-edhoc-00,
1 April 2021, <https://www.ietf.org/internet-drafts/draft- 1 April 2021, <https://www.ietf.org/internet-drafts/draft-
ietf-core-oscore-edhoc-00.txt>. ietf-core-oscore-edhoc-00.txt>.
[I-D.mattsson-cose-cbor-cert-compress] [I-D.ietf-cose-cbor-encoded-cert]
Raza, S., Hoglund, J., Selander, G., Mattsson, J., and M. Raza, S., Höglund, J., Selander, G., Mattsson, J. P., and
Furuhed, "CBOR Encoding of X.509 Certificates (CBOR M. Furuhed, "CBOR Encoded X.509 Certificates (C509
Certificates)", Work in Progress, Internet-Draft, draft- Certificates)", Work in Progress, Internet-Draft, draft-
mattsson-cose-cbor-cert-compress-06, 19 January 2021, ietf-cose-cbor-encoded-cert-00, 28 April 2021,
<http://www.ietf.org/internet-drafts/draft-mattsson-cose- <https://www.ietf.org/archive/id/draft-ietf-cose-cbor-
cbor-cert-compress-06.txt>. encoded-cert-00.txt>.
[I-D.mattsson-cfrg-det-sigs-with-noise] [I-D.mattsson-cfrg-det-sigs-with-noise]
Mattsson, J., Thormarker, E., and S. Ruohomaa, Mattsson, J. P., Thormarker, E., and S. Ruohomaa,
"Deterministic ECDSA and EdDSA Signatures with Additional "Deterministic ECDSA and EdDSA Signatures with Additional
Randomness", Work in Progress, Internet-Draft, draft- Randomness", Work in Progress, Internet-Draft, draft-
mattsson-cfrg-det-sigs-with-noise-02, 11 March 2020, mattsson-cfrg-det-sigs-with-noise-02, 11 March 2020,
<http://www.ietf.org/internet-drafts/draft-mattsson-cfrg- <https://www.ietf.org/archive/id/draft-mattsson-cfrg-det-
det-sigs-with-noise-02.txt>. sigs-with-noise-02.txt>.
[SP-800-56A] [SP-800-56A]
Barker, E., Chen, L., Roginsky, A., Vassilev, A., and R. Barker, E., Chen, L., Roginsky, A., Vassilev, A., and R.
Davis, "Recommendation for Pair-Wise Key-Establishment Davis, "Recommendation for Pair-Wise Key-Establishment
Schemes Using Discrete Logarithm Cryptography", Schemes Using Discrete Logarithm Cryptography",
NIST Special Publication 800-56A Revision 3, April 2018, NIST Special Publication 800-56A Revision 3, April 2018,
<https://doi.org/10.6028/NIST.SP.800-56Ar3>. <https://doi.org/10.6028/NIST.SP.800-56Ar3>.
[SECG] "Standards for Efficient Cryptography 1 (SEC 1)", May
2009, <https://www.secg.org/sec1-v2.pdf>.
[SIGMA] Krawczyk, H., "SIGMA - The 'SIGn-and-MAc' Approach to [SIGMA] Krawczyk, H., "SIGMA - The 'SIGn-and-MAc' Approach to
Authenticated Diffie-Hellman and Its Use in the IKE- Authenticated Diffie-Hellman and Its Use in the IKE-
Protocols (Long version)", June 2003, Protocols (Long version)", June 2003,
<http://webee.technion.ac.il/~hugo/sigma-pdf.pdf>. <http://webee.technion.ac.il/~hugo/sigma-pdf.pdf>.
[CNSA] (Placeholder), ., "Commercial National Security Algorithm [CNSA] (Placeholder), ., "Commercial National Security Algorithm
Suite", August 2015, Suite", August 2015,
<https://apps.nsa.gov/iaarchive/programs/iad-initiatives/ <https://apps.nsa.gov/iaarchive/programs/iad-initiatives/
cnsa-suite.cfm>. cnsa-suite.cfm>.
skipping to change at page 56, line 46 skipping to change at page 58, line 8
[Bruni18] Bruni, A., Sahl Jørgensen, T., Grønbech Petersen, T., and [Bruni18] Bruni, A., Sahl Jørgensen, T., Grønbech Petersen, T., and
C. Schürmann, "Formal Verification of Ephemeral Diffie- C. Schürmann, "Formal Verification of Ephemeral Diffie-
Hellman Over COSE (EDHOC)", November 2018, Hellman Over COSE (EDHOC)", November 2018,
<https://www.springerprofessional.de/en/formal- <https://www.springerprofessional.de/en/formal-
verification-of-ephemeral-diffie-hellman-over-cose- verification-of-ephemeral-diffie-hellman-over-cose-
edhoc/16284348>. edhoc/16284348>.
[CborMe] Bormann, C., "CBOR Playground", May 2018, [CborMe] Bormann, C., "CBOR Playground", May 2018,
<http://cbor.me/>. <http://cbor.me/>.
Appendix A. Use of CBOR, CDDL and COSE in EDHOC Appendix A. Compact Representation
As described in Section 4.2 of [RFC6090] the x-coordinate of an
elliptic curve public key is a suitable representative for the entire
point whenever scalar multiplication is used as a one-way function.
One example is ECDH with compact output, where only the x-coordinate
of the computed value is used as the shared secret.
This section defines a format for compact representation based on the
Elliptic-Curve-Point-to-Octet-String Conversion defined in
Section 2.3.3 of [SECG]. Using the notation from [SECG], the output
is an octet string of length ceil( (log2 q) / 8 ). See [SECG] for a
definition of q, M, X, xp, and ~yp. The steps in Section 2.3.3 of
[SECG] are replaced by:
1. Convert the field element xp to an octet string X of length ceil(
(log2 q) / 8 ) octets using the conversion routine specified in
Section 2.3.5 of [SECG].
2. Output M = X
The encoding of the point at infinity is not supported. Compact
representation does not change any requirements on validation. If a
y-coordinate is required for validation or compatibily with APIs the
value ~yp SHALL be set to zero. For such use, the compact
representation can be transformed into the SECG point compressed
format by prepending it with the single byte 0x02 (i.e. M = 0x02 ||
X).
Using compact representation have some security benefits. An
implementation does not need to check that the point is not the point
at infinity (the identity element). Similarly, as not even the sign
of the y-coordinate is encoded, compact representation trivially
avoids so called "benign malleability" attacks where an attacker
changes the sign, see [SECG].
Appendix B. Use of CBOR, CDDL and COSE in EDHOC
This Appendix is intended to simplify for implementors not familiar This Appendix is intended to simplify for implementors not familiar
with CBOR [RFC8949], CDDL [RFC8610], COSE with CBOR [RFC8949], CDDL [RFC8610], COSE
[I-D.ietf-cose-rfc8152bis-struct], and HKDF [RFC5869]. [I-D.ietf-cose-rfc8152bis-struct], and HKDF [RFC5869].
A.1. CBOR and CDDL B.1. CBOR and CDDL
The Concise Binary Object Representation (CBOR) [RFC8949] is a data The Concise Binary Object Representation (CBOR) [RFC8949] is a data
format designed for small code size and small message size. CBOR format designed for small code size and small message size. CBOR
builds on the JSON data model but extends it by e.g. encoding binary builds on the JSON data model but extends it by e.g. encoding binary
data directly without base64 conversion. In addition to the binary data directly without base64 conversion. In addition to the binary
CBOR encoding, CBOR also has a diagnostic notation that is readable CBOR encoding, CBOR also has a diagnostic notation that is readable
and editable by humans. The Concise Data Definition Language (CDDL) and editable by humans. The Concise Data Definition Language (CDDL)
[RFC8610] provides a way to express structures for protocol messages [RFC8610] provides a way to express structures for protocol messages
and APIs that use CBOR. [RFC8610] also extends the diagnostic and APIs that use CBOR. [RFC8610] also extends the diagnostic
notation. notation.
skipping to change at page 57, line 46 skipping to change at page 59, line 46
h'12cd' 0x4212cd byte string h'12cd' 0x4212cd byte string
'12cd' 0x4431326364 byte string '12cd' 0x4431326364 byte string
"12cd" 0x6431326364 text string "12cd" 0x6431326364 text string
{ 4 : h'cd' } 0xa10441cd map { 4 : h'cd' } 0xa10441cd map
<< 1, 2, null >> 0x430102f6 byte string << 1, 2, null >> 0x430102f6 byte string
[ 1, 2, null ] 0x830102f6 array [ 1, 2, null ] 0x830102f6 array
( 1, 2, null ) 0x0102f6 sequence ( 1, 2, null ) 0x0102f6 sequence
1, 2, null 0x0102f6 sequence 1, 2, null 0x0102f6 sequence
------------------------------------------------------------------ ------------------------------------------------------------------
A.2. CDDL Definitions B.2. CDDL Definitions
This sections compiles the CDDL definitions for ease of reference. This sections compiles the CDDL definitions for ease of reference.
bstr_identifier = bstr / int bstr_identifier = bstr / int
suite = int suite = int
SUITES_R : [ supported : 2* suite ] / suite SUITES_R : [ supported : 2* suite ] / suite
message_1 = ( message_1 = (
? C_1 : null, ? C_1 : null,
METHOD_CORR : int, METHOD_CORR : int,
SUITES_I : [ selected : suite, supported : 2* suite ] / suite, SUITES_I : [ selected : suite, supported : 2* suite ] / suite,
G_X : bstr, G_X : bstr,
C_I : bstr_identifier, C_I : bstr_identifier,
? AD_1 : bstr, ? EAD ; EAD_1
) )
message_2 = ( message_2 = (
data_2, data_2,
CIPHERTEXT_2 : bstr, CIPHERTEXT_2 : bstr,
) )
data_2 = ( data_2 = (
? C_I : bstr_identifier, ? C_I : bstr_identifier,
G_Y : bstr, G_Y : bstr,
skipping to change at page 58, line 42 skipping to change at page 60, line 42
data_3, data_3,
CIPHERTEXT_3 : bstr, CIPHERTEXT_3 : bstr,
) )
data_3 = ( data_3 = (
? C_R : bstr_identifier, ? C_R : bstr_identifier,
) )
message_4 = ( message_4 = (
data_4, data_4,
MAC_4 : bstr, CIPHERTEXT_4 : bstr,
) )
data_4 = ( data_4 = (
? C_I : bstr_identifier, ? C_I : bstr_identifier,
) )
error = ( error = (
? C_x : bstr_identifier, ? C_x : bstr_identifier,
ERR_CODE : int, ERR_CODE : int,
ERR_INFO : any ERR_INFO : any
) )
info = [ info = [
edhoc_aead_id : int / tstr, edhoc_aead_id : int / tstr,
transcript_hash : bstr, transcript_hash : bstr,
label : tstr, label : tstr,
length : uint length : uint
] ]
A.3. COSE B.3. COSE
CBOR Object Signing and Encryption (COSE) CBOR Object Signing and Encryption (COSE)
[I-D.ietf-cose-rfc8152bis-struct] describes how to create and process [I-D.ietf-cose-rfc8152bis-struct] describes how to create and process
signatures, message authentication codes, and encryption using CBOR. signatures, message authentication codes, and encryption using CBOR.
COSE builds on JOSE, but is adapted to allow more efficient COSE builds on JOSE, but is adapted to allow more efficient
processing in constrained devices. EDHOC makes use of COSE_Key, processing in constrained devices. EDHOC makes use of COSE_Key,
COSE_Encrypt0, and COSE_Sign1 objects. COSE_Encrypt0, and COSE_Sign1 objects.
Appendix B. Test Vectors Appendix C. Test Vectors
This appendix provides detailed test vectors compatible with versions Note: The test vectors are not updated to version -07 of the draft.
-05 and -06 of this specification, to ease implementation and ensure More changes affecting the test vectors are anticipated for -08.
interoperability. In addition to hexadecimal, all CBOR data items
and sequences are given in CBOR diagnostic notation. The test This appendix provides detailed test vectors to ease implementation
vectors use the default mapping to CoAP where the Initiator acts as and ensure interoperability. The test vectors in this version are
CoAP client (this means that corr = 1). compatible with versions -05 and -06 of the specification. In
addition to hexadecimal, all CBOR data items and sequences are given
in CBOR diagnostic notation. The test vectors use the default
mapping to CoAP where the Initiator acts as CoAP client (this means
that corr = 1).
A more extensive test vector suite covering more combinations of A more extensive test vector suite covering more combinations of
authentication method used between Initiator and Responder and authentication method used between Initiator and Responder and
related code to generate them can be found at https://github.com/ related code to generate them can be found at https://github.com/
lake-wg/edhoc/tree/master/test-vectors-05. lake-wg/edhoc/tree/master/test-vectors-05.
NOTE 1. In the previous and current test vectors the same name is NOTE 1. In the previous and current test vectors the same name is
used for certain byte strings and their CBOR bstr encodings. For used for certain byte strings and their CBOR bstr encodings. For
example the transcript hash TH_2 is used to denote both the output of example the transcript hash TH_2 is used to denote both the output of
the hash function and the input into the key derivation function, the hash function and the input into the key derivation function,
whereas the latter is a CBOR bstr encoding of the former. Some whereas the latter is a CBOR bstr encoding of the former. Some
attempts are made to clarify that in this Appendix (e.g. using "CBOR attempts are made to clarify that in this Appendix (e.g. using "CBOR
encoded"/"CBOR unencoded"). encoded"/"CBOR unencoded").
NOTE 2. If not clear from the context, remember that CBOR sequences NOTE 2. If not clear from the context, remember that CBOR sequences
and CBOR arrays assume CBOR encoded data items as elements. and CBOR arrays assume CBOR encoded data items as elements.
B.1. Test Vectors for EDHOC Authenticated with Signature Keys (x5t) C.1. Test Vectors for EDHOC Authenticated with Signature Keys (x5t)
EDHOC with signature authentication and X.509 certificates is used. EDHOC with signature authentication and X.509 certificates is used.
In this test vector, the hash value 'x5t' is used to identify the In this test vector, the hash value 'x5t' is used to identify the
certificate. The optional C_1 in message_1 is omitted. No auxiliary certificate. The optional C_1 in message_1 is omitted. No external
data is sent in the message exchange. authorization data is sent in the message exchange.
method (Signature Authentication) method (Signature Authentication)
0 0
CoAP is used as transport and the Initiator acts as CoAP client: CoAP is used as transport and the Initiator acts as CoAP client:
corr (the Initiator can correlate message_1 and message_2) corr (the Initiator can correlate message_1 and message_2)
1 1
From there, METHOD_CORR has the following value: From there, METHOD_CORR has the following value:
skipping to change at page 60, line 39 skipping to change at page 62, line 39
00 00
The Initiator selected the indicated cipher suite. The Initiator selected the indicated cipher suite.
Selected Cipher Suite (int) Selected Cipher Suite (int)
0 0
Cipher suite 0 is supported by both the Initiator and the Responder, Cipher suite 0 is supported by both the Initiator and the Responder,
see Section 3.4. see Section 3.4.
B.1.1. Message_1 C.1.1. Message_1
The Initiator generates its ephemeral key pair. The Initiator generates its ephemeral key pair.
X (Initiator's ephemeral private key) (32 bytes) X (Initiator's ephemeral private key) (32 bytes)
8f 78 1a 09 53 72 f8 5b 6d 9f 61 09 ae 42 26 11 73 4d 7d bf a0 06 9a 2d 8f 78 1a 09 53 72 f8 5b 6d 9f 61 09 ae 42 26 11 73 4d 7d bf a0 06 9a 2d
f2 93 5b b2 e0 53 bf 35 f2 93 5b b2 e0 53 bf 35
G_X (Initiator's ephemeral public key, CBOR unencoded) (32 bytes) G_X (Initiator's ephemeral public key, CBOR unencoded) (32 bytes)
89 8f f7 9a 02 06 7a 16 ea 1e cc b9 0f a5 22 46 f5 aa 4d d6 ec 07 6b ba 89 8f f7 9a 02 06 7a 16 ea 1e cc b9 0f a5 22 46 f5 aa 4d d6 ec 07 6b ba
02 59 d9 04 b7 ec 8b 0c 02 59 d9 04 b7 ec 8b 0c
skipping to change at page 61, line 16 skipping to change at page 63, line 16
09 09
Note that since C_I is a byte string in the interval h'00' to h'2f', Note that since C_I is a byte string in the interval h'00' to h'2f',
it is encoded as the corresponding integer subtracted by 24 (see it is encoded as the corresponding integer subtracted by 24 (see
bstr_identifier in Section 5.1). Thus 0x09 = 09, 9 - 24 = -15, and bstr_identifier in Section 5.1). Thus 0x09 = 09, 9 - 24 = -15, and
-15 in CBOR encoding is equal to 0x2e. -15 in CBOR encoding is equal to 0x2e.
C_I (1 byte) C_I (1 byte)
2e 2e
Since no auxiliary data is sent: Since no external authorization data is sent:
AD_1 (0 bytes) EAD_1 (0 bytes)
The list of supported cipher suites needs to contain the selected The list of supported cipher suites needs to contain the selected
cipher suite. The initiator truncates the list of supported cipher cipher suite. The initiator truncates the list of supported cipher
suites to one cipher suite only. In this case there is only one suites to one cipher suite only. In this case there is only one
supported cipher suite indicated, 00. supported cipher suite indicated, 00.
Because one single selected cipher suite is conveyed, it is encoded Because one single selected cipher suite is conveyed, it is encoded
as an int instead of an array: as an int instead of an array:
SUITES_I (int) SUITES_I (int)
skipping to change at page 61, line 48 skipping to change at page 63, line 48
h'898FF79A02067A16EA1ECCB90FA52246F5AA4DD6EC076BBA0259D904B7EC8B0C', h'898FF79A02067A16EA1ECCB90FA52246F5AA4DD6EC076BBA0259D904B7EC8B0C',
-15 -15
) )
Which as a CBOR encoded data item is: Which as a CBOR encoded data item is:
message_1 (CBOR Sequence) (37 bytes) message_1 (CBOR Sequence) (37 bytes)
01 00 58 20 89 8f f7 9a 02 06 7a 16 ea 1e cc b9 0f a5 22 46 f5 aa 4d d6 01 00 58 20 89 8f f7 9a 02 06 7a 16 ea 1e cc b9 0f a5 22 46 f5 aa 4d d6
ec 07 6b ba 02 59 d9 04 b7 ec 8b 0c 2e ec 07 6b ba 02 59 d9 04 b7 ec 8b 0c 2e
B.1.2. Message_2 C.1.2. Message_2
Since METHOD_CORR mod 4 equals 1, C_I is omitted from data_2. Since METHOD_CORR mod 4 equals 1, C_I is omitted from data_2.
The Responder generates the following ephemeral key pair. The Responder generates the following ephemeral key pair.
Y (Responder's ephemeral private key) (32 bytes) Y (Responder's ephemeral private key) (32 bytes)
fd 8c d8 77 c9 ea 38 6e 6a f3 4f f7 e6 06 c4 b6 4c a8 31 c8 ba 33 13 4f fd 8c d8 77 c9 ea 38 6e 6a f3 4f f7 e6 06 c4 b6 4c a8 31 c8 ba 33 13 4f
d4 cd 71 67 ca ba ec da d4 cd 71 67 ca ba ec da
G_Y (Responder's ephemeral public key, CBOR unencoded) (32 bytes) G_Y (Responder's ephemeral public key, CBOR unencoded) (32 bytes)
skipping to change at page 63, line 33 skipping to change at page 65, line 33
-24 -24
) )
Which as a CBOR encoded data item is: Which as a CBOR encoded data item is:
data_2 (CBOR Sequence) (35 bytes) data_2 (CBOR Sequence) (35 bytes)
58 20 71 a3 d5 99 c2 1d a1 89 02 a1 ae a8 10 b2 b6 38 2c cd 8d 5f 9b f0 58 20 71 a3 d5 99 c2 1d a1 89 02 a1 ae a8 10 b2 b6 38 2c cd 8d 5f 9b f0
19 52 81 75 4c 5e bc af 30 1e 37 19 52 81 75 4c 5e bc af 30 1e 37
From data_2 and message_1, compute the input to the transcript hash From data_2 and message_1, compute the input to the transcript hash
TH_2 = H( message_1, data_2 ), as a CBOR Sequence of these 2 data TH_2 = H( H(message_1), data_2 ), as a CBOR Sequence of these 2 data
items. items.
Input to calculate TH_2 (CBOR Sequence) (72 bytes) Input to calculate TH_2 (CBOR Sequence) (72 bytes)
01 00 58 20 89 8f f7 9a 02 06 7a 16 ea 1e cc b9 0f a5 22 46 f5 aa 4d d6 01 00 58 20 89 8f f7 9a 02 06 7a 16 ea 1e cc b9 0f a5 22 46 f5 aa 4d d6
ec 07 6b ba 02 59 d9 04 b7 ec 8b 0c 2e 58 20 71 a3 d5 99 c2 1d a1 89 02 ec 07 6b ba 02 59 d9 04 b7 ec 8b 0c 2e 58 20 71 a3 d5 99 c2 1d a1 89 02
a1 ae a8 10 b2 b6 38 2c cd 8d 5f 9b f0 19 52 81 75 4c 5e bc af 30 1e 37 a1 ae a8 10 b2 b6 38 2c cd 8d 5f 9b f0 19 52 81 75 4c 5e bc af 30 1e 37
And from there, compute the transcript hash TH_2 = SHA-256( And from there, compute the transcript hash TH_2 = SHA-256(
message_1, data_2 ) H(message_1), data_2 )
TH_2 (CBOR unencoded) (32 bytes) TH_2 (CBOR unencoded) (32 bytes)
86 4e 32 b3 6a 7b 5f 21 f1 9e 99 f0 c6 6d 91 1e 0a ce 99 72 d3 76 d2 c2 86 4e 32 b3 6a 7b 5f 21 f1 9e 99 f0 c6 6d 91 1e 0a ce 99 72 d3 76 d2 c2
c1 53 c1 7f 8e 96 29 ff c1 53 c1 7f 8e 96 29 ff
The Responder's subject name is the empty string: The Responder's subject name is the empty string:
Responder's subject name (text string) Responder's subject name (text string)
"" ""
In this version of the test vectors CRED_R is not a DER encoded X.509 In this version of the test vectors CRED_R is not a DER encoded X.509
skipping to change at page 64, line 42 skipping to change at page 66, line 42
ID_CRED_R = ID_CRED_R =
{ {
34: [-15, h'6844078A53F312F5'] 34: [-15, h'6844078A53F312F5']
} }
which when encoded as a CBOR map becomes: which when encoded as a CBOR map becomes:
ID_CRED_R (14 bytes) ID_CRED_R (14 bytes)
a1 18 22 82 2e 48 68 44 07 8a 53 f3 12 f5 a1 18 22 82 2e 48 68 44 07 8a 53 f3 12 f5
Since no auxiliary data is sent: Since no external authorization data is sent:
AD_2 (0 bytes) EAD_2 (0 bytes)
The plaintext is defined as the empty string: The plaintext is defined as the empty string:
P_2m (0 bytes) P_2m (0 bytes)
The Enc_structure is defined as follows: [ "Encrypt0", The Enc_structure is defined as follows: [ "Encrypt0",
<< ID_CRED_R >>, << TH_2, CRED_R >> ], indicating that ID_CRED_R is << ID_CRED_R >>, << TH_2, CRED_R >> ], indicating that ID_CRED_R is
encoded as a CBOR byte string, and that the concatenation of the CBOR encoded as a CBOR byte string, and that the concatenation of the CBOR
byte strings TH_2 and CRED_R is wrapped as a CBOR bstr. The CBOR byte strings TH_2 and CRED_R is wrapped as a CBOR bstr. The CBOR
diagnostic notation is the following: diagnostic notation is the following:
skipping to change at page 66, line 46 skipping to change at page 68, line 46
* external_aad = A_2m * external_aad = A_2m
* empty plaintext = P_2m * empty plaintext = P_2m
MAC_2 (CBOR unencoded) (8 bytes) MAC_2 (CBOR unencoded) (8 bytes)
fa bb a4 7e 56 71 a1 82 fa bb a4 7e 56 71 a1 82
To compute the Signature_or_MAC_2, the key is the private To compute the Signature_or_MAC_2, the key is the private
authentication key of the Responder and the message M_2 to be signed authentication key of the Responder and the message M_2 to be signed
= [ "Signature1", << ID_CRED_R >>, << TH_2, CRED_R, ? AD_2 >>, MAC_2 = [ "Signature1", << ID_CRED_R >>, << TH_2, CRED_R, ? EAD_2 >>, MAC_2
]. ID_CRED_R is encoded as a CBOR byte string, the concatenation of ]. ID_CRED_R is encoded as a CBOR byte string, the concatenation of
the CBOR byte strings TH_2 and CRED_R is wrapped as a CBOR bstr, and the CBOR byte strings TH_2 and CRED_R is wrapped as a CBOR bstr, and
MAC_2 is encoded as a CBOR bstr. MAC_2 is encoded as a CBOR bstr.
M_2 = M_2 =
[ [
"Signature1", "Signature1",
h'A11822822E486844078A53F312F5', h'A11822822E486844078A53F312F5',
h'5820864E32B36A7B5F21F19E99F0C66D911E0ACE9972D376D2C2C153C17F8E9629F h'5820864E32B36A7B5F21F19E99F0C66D911E0ACE9972D376D2C2C153C17F8E9629F
F5864C788370016B8965BDB2074BFF82E5A20E09BEC21F8406E86442B87EC3FF245B7 F5864C788370016B8965BDB2074BFF82E5A20E09BEC21F8406E86442B87EC3FF245B7
skipping to change at page 67, line 43 skipping to change at page 69, line 43
1f 17 00 6a 98 48 c9 77 cb bd ca a7 57 b6 fd 46 82 c8 17 39 e1 5c 99 37 1f 17 00 6a 98 48 c9 77 cb bd ca a7 57 b6 fd 46 82 c8 17 39 e1 5c 99 37
c2 1c f5 e9 a0 e6 03 9f 54 fd 2a 6c 3a 11 18 f2 b9 d8 eb cd 48 23 48 b9 c2 1c f5 e9 a0 e6 03 9f 54 fd 2a 6c 3a 11 18 f2 b9 d8 eb cd 48 23 48 b9
9c 3e d7 ed 1b d9 80 6c 93 c8 90 68 e8 36 b4 0f 9c 3e d7 ed 1b d9 80 6c 93 c8 90 68 e8 36 b4 0f
CIPHERTEXT_2 is the ciphertext resulting from XOR between plaintext CIPHERTEXT_2 is the ciphertext resulting from XOR between plaintext
and KEYSTREAM_2 which is derived from TH_2 and the pseudorandom key and KEYSTREAM_2 which is derived from TH_2 and the pseudorandom key
PRK_2e. PRK_2e.
* plaintext = CBOR Sequence of the items ID_CRED_R and * plaintext = CBOR Sequence of the items ID_CRED_R and
Signature_or_MAC_2 encoded as CBOR byte strings, in this order Signature_or_MAC_2 encoded as CBOR byte strings, in this order
(AD_2 is empty). (EAD_2 is empty).
The plaintext is the following: The plaintext is the following:
P_2e (CBOR Sequence) (80 bytes) P_2e (CBOR Sequence) (80 bytes)
a1 18 22 82 2e 48 68 44 07 8a 53 f3 12 f5 58 40 1f 17 00 6a 98 48 c9 77 a1 18 22 82 2e 48 68 44 07 8a 53 f3 12 f5 58 40 1f 17 00 6a 98 48 c9 77
cb bd ca a7 57 b6 fd 46 82 c8 17 39 e1 5c 99 37 c2 1c f5 e9 a0 e6 03 9f cb bd ca a7 57 b6 fd 46 82 c8 17 39 e1 5c 99 37 c2 1c f5 e9 a0 e6 03 9f
54 fd 2a 6c 3a 11 18 f2 b9 d8 eb cd 48 23 48 b9 9c 3e d7 ed 1b d9 80 6c 54 fd 2a 6c 3a 11 18 f2 b9 d8 eb cd 48 23 48 b9 9c 3e d7 ed 1b d9 80 6c
93 c8 90 68 e8 36 b4 0f 93 c8 90 68 e8 36 b4 0f
KEYSTREAM_2 = HKDF-Expand( PRK_2e, info, length ), where length is KEYSTREAM_2 = HKDF-Expand( PRK_2e, info, length ), where length is
the length of the plaintext, so 80. the length of the plaintext, so 80.
skipping to change at page 69, line 12 skipping to change at page 71, line 12
Which as a CBOR encoded data item is: Which as a CBOR encoded data item is:
message_2 (CBOR Sequence) (117 bytes) message_2 (CBOR Sequence) (117 bytes)
58 20 71 a3 d5 99 c2 1d a1 89 02 a1 ae a8 10 b2 b6 38 2c cd 8d 5f 9b f0 58 20 71 a3 d5 99 c2 1d a1 89 02 a1 ae a8 10 b2 b6 38 2c cd 8d 5f 9b f0
19 52 81 75 4c 5e bc af 30 1e 37 58 50 0f f2 ac 2d 7e 87 ae 34 0e 50 bb 19 52 81 75 4c 5e bc af 30 1e 37 58 50 0f f2 ac 2d 7e 87 ae 34 0e 50 bb
de 9f 70 e8 a7 7f 86 bf 65 9f 43 b0 24 a7 3e e9 7b 6a 2b 9c 55 92 fd 83 de 9f 70 e8 a7 7f 86 bf 65 9f 43 b0 24 a7 3e e9 7b 6a 2b 9c 55 92 fd 83
5a 15 17 8b 7c 28 af 54 74 a9 75 81 48 64 7d 3d 98 a8 73 1e 16 4c 9c 70 5a 15 17 8b 7c 28 af 54 74 a9 75 81 48 64 7d 3d 98 a8 73 1e 16 4c 9c 70
52 81 07 f4 0f 21 46 3b a8 11 bf 03 97 19 e7 cf fa a7 f2 f4 40 52 81 07 f4 0f 21 46 3b a8 11 bf 03 97 19 e7 cf fa a7 f2 f4 40
B.1.3. Message_3 C.1.3. Message_3
Since corr equals 1, C_R is not omitted from data_3. Since corr equals 1, C_R is not omitted from data_3.
The Initiator's sign/verify key pair is the following: The Initiator's sign/verify key pair is the following:
SK_I (Initiator's private authentication key) (32 bytes) SK_I (Initiator's private authentication key) (32 bytes)
2f fc e7 a0 b2 b8 25 d3 97 d0 cb 54 f7 46 e3 da 3f 27 59 6e e0 6b 53 71 2f fc e7 a0 b2 b8 25 d3 97 d0 cb 54 f7 46 e3 da 3f 27 59 6e e0 6b 53 71
48 1d c0 e0 12 bc 34 d7 48 1d c0 e0 12 bc 34 d7
PK_I (Responder's public authentication key) (32 bytes) PK_I (Responder's public authentication key) (32 bytes)
skipping to change at page 69, line 40 skipping to change at page 71, line 40
PRK_4x3m (32 bytes) PRK_4x3m (32 bytes)
ec 62 92 a0 67 f1 37 fc 7f 59 62 9d 22 6f bf c4 e0 68 89 49 f6 62 a9 7f ec 62 92 a0 67 f1 37 fc 7f 59 62 9d 22 6f bf c4 e0 68 89 49 f6 62 a9 7f
d8 2f be b7 99 71 39 4a d8 2f be b7 99 71 39 4a
data 3 is equal to C_R. data 3 is equal to C_R.
data_3 (CBOR Sequence) (1 byte) data_3 (CBOR Sequence) (1 byte)
37 37
From data_3, CIPHERTEXT_2, and TH_2, compute the input to the From data_3, CIPHERTEXT_2, and TH_2, compute the input to the
transcript hash TH_3 = H(TH_2 , CIPHERTEXT_2, data_3), as a CBOR transcript hash TH_3 = H( H(TH_2 , CIPHERTEXT_2), data_3), as a CBOR
Sequence of these 3 data items. Sequence of 2 data items.
Input to calculate TH_3 (CBOR Sequence) (117 bytes) Input to calculate TH_3 (CBOR Sequence) (117 bytes)
58 20 86 4e 32 b3 6a 7b 5f 21 f1 9e 99 f0 c6 6d 91 1e 0a ce 99 72 d3 76 58 20 86 4e 32 b3 6a 7b 5f 21 f1 9e 99 f0 c6 6d 91 1e 0a ce 99 72 d3 76
d2 c2 c1 53 c1 7f 8e 96 29 ff 58 50 0f f2 ac 2d 7e 87 ae 34 0e 50 bb de d2 c2 c1 53 c1 7f 8e 96 29 ff 58 50 0f f2 ac 2d 7e 87 ae 34 0e 50 bb de
9f 70 e8 a7 7f 86 bf 65 9f 43 b0 24 a7 3e e9 7b 6a 2b 9c 55 92 fd 83 5a 9f 70 e8 a7 7f 86 bf 65 9f 43 b0 24 a7 3e e9 7b 6a 2b 9c 55 92 fd 83 5a
15 17 8b 7c 28 af 54 74 a9 75 81 48 64 7d 3d 98 a8 73 1e 16 4c 9c 70 52 15 17 8b 7c 28 af 54 74 a9 75 81 48 64 7d 3d 98 a8 73 1e 16 4c 9c 70 52
81 07 f4 0f 21 46 3b a8 11 bf 03 97 19 e7 cf fa a7 f2 f4 40 37 81 07 f4 0f 21 46 3b a8 11 bf 03 97 19 e7 cf fa a7 f2 f4 40 37
And from there, compute the transcript hash TH_3 = SHA-256(TH_2 , And from there, compute the transcript hash TH_3 = SHA-256( H(TH_2 ,
CIPHERTEXT_2, data_3) CIPHERTEXT_2), data_3)
TH_3 (CBOR unencoded) (32 bytes) TH_3 (CBOR unencoded) (32 bytes)
f2 4d 18 ca fc e3 74 d4 e3 73 63 29 c1 52 ab 3a ea 9c 7c 0f 65 0c 30 70 f2 4d 18 ca fc e3 74 d4 e3 73 63 29 c1 52 ab 3a ea 9c 7c 0f 65 0c 30 70
b6 f5 1e 68 e2 ae bb 60 b6 f5 1e 68 e2 ae bb 60
The Initiator's subject name is the empty string: The Initiator's subject name is the empty string:
Initiator's subject name (text string) Initiator's subject name (text string)
"" ""
skipping to change at page 70, line 51 skipping to change at page 72, line 51
ID_CRED_I = ID_CRED_I =
{ {
34: [-15, h'705D5845F36FC6A6'] 34: [-15, h'705D5845F36FC6A6']
} }
which when encoded as a CBOR map becomes: which when encoded as a CBOR map becomes:
ID_CRED_I (14 bytes) ID_CRED_I (14 bytes)
a1 18 22 82 2e 48 70 5d 58 45 f3 6f c6 a6 a1 18 22 82 2e 48 70 5d 58 45 f3 6f c6 a6
Since no auxiliary data is exchanged: Since no external authorization data is exchanged:
AD_3 (0 bytes) EAD_3 (0 bytes)
The plaintext of the COSE_Encrypt is the empty string: The plaintext of the COSE_Encrypt is the empty string:
P_3m (0 bytes) P_3m (0 bytes)
The associated data is the following: [ "Encrypt0", << ID_CRED_I >>, The associated data is the following: [ "Encrypt0", << ID_CRED_I >>,
<< TH_3, CRED_I, ? AD_3 >> ]. << TH_3, CRED_I, ? EAD_3 >> ].
A_3m (CBOR-encoded) (164 bytes) A_3m (CBOR-encoded) (164 bytes)
83 68 45 6e 63 72 79 70 74 30 4e a1 18 22 82 2e 48 70 5d 58 45 f3 6f c6 83 68 45 6e 63 72 79 70 74 30 4e a1 18 22 82 2e 48 70 5d 58 45 f3 6f c6
a6 58 89 58 20 f2 4d 18 ca fc e3 74 d4 e3 73 63 29 c1 52 ab 3a ea 9c 7c a6 58 89 58 20 f2 4d 18 ca fc e3 74 d4 e3 73 63 29 c1 52 ab 3a ea 9c 7c
0f 65 0c 30 70 b6 f5 1e 68 e2 ae bb 60 58 65 54 13 20 4c 3e bc 34 28 a6 0f 65 0c 30 70 b6 f5 1e 68 e2 ae bb 60 58 65 54 13 20 4c 3e bc 34 28 a6
cf 57 e2 4c 9d ef 59 65 17 70 44 9b ce 7e c6 56 1e 52 43 3a a5 5e 71 f1 cf 57 e2 4c 9d ef 59 65 17 70 44 9b ce 7e c6 56 1e 52 43 3a a5 5e 71 f1
fa 34 b2 2a 9c a4 a1 e1 29 24 ea e1 d1 76 60 88 09 84 49 cb 84 8f fc 79 fa 34 b2 2a 9c a4 a1 e1 29 24 ea e1 d1 76 60 88 09 84 49 cb 84 8f fc 79
5f 88 af c4 9c be 8a fd d1 ba 00 9f 21 67 5e 8f 6c 77 a4 a2 c3 01 95 60 5f 88 af c4 9c be 8a fd d1 ba 00 9f 21 67 5e 8f 6c 77 a4 a2 c3 01 95 60
1f 6f 0a 08 52 97 8b d4 3d 28 20 7d 44 48 65 02 ff 7b dd a6 1f 6f 0a 08 52 97 8b d4 3d 28 20 7d 44 48 65 02 ff 7b dd a6
skipping to change at page 73, line 25 skipping to change at page 75, line 25
From there, the 64 byte signature can be computed: From there, the 64 byte signature can be computed:
Signature_or_MAC_3 (CBOR unencoded) (64 bytes) Signature_or_MAC_3 (CBOR unencoded) (64 bytes)
ab 9f 7b bd eb c4 eb f8 a3 d3 04 17 9b cc a3 9d 9c 8a 76 73 65 76 fb 3c ab 9f 7b bd eb c4 eb f8 a3 d3 04 17 9b cc a3 9d 9c 8a 76 73 65 76 fb 3c
32 d2 fa c7 e2 59 34 e5 33 dc c7 02 2e 4d 68 61 c8 f5 fe cb e9 2d 17 4e 32 d2 fa c7 e2 59 34 e5 33 dc c7 02 2e 4d 68 61 c8 f5 fe cb e9 2d 17 4e
b2 be af 0a 59 a4 15 84 37 2f 43 2e 6b f4 7b 04 b2 be af 0a 59 a4 15 84 37 2f 43 2e 6b f4 7b 04
Finally, the outer COSE_Encrypt0 is computed. Finally, the outer COSE_Encrypt0 is computed.
The plaintext is the CBOR Sequence of the items ID_CRED_I and the The plaintext is the CBOR Sequence of the items ID_CRED_I and the
CBOR encoded Signature_or_MAC_3, in this order (AD_3 is empty). CBOR encoded Signature_or_MAC_3, in this order (EAD_3 is empty).
P_3ae (CBOR Sequence) (80 bytes) P_3ae (CBOR Sequence) (80 bytes)
a1 18 22 82 2e 48 70 5d 58 45 f3 6f c6 a6 58 40 ab 9f 7b bd eb c4 eb f8 a1 18 22 82 2e 48 70 5d 58 45 f3 6f c6 a6 58 40 ab 9f 7b bd eb c4 eb f8
a3 d3 04 17 9b cc a3 9d 9c 8a 76 73 65 76 fb 3c 32 d2 fa c7 e2 59 34 e5 a3 d3 04 17 9b cc a3 9d 9c 8a 76 73 65 76 fb 3c 32 d2 fa c7 e2 59 34 e5
33 dc c7 02 2e 4d 68 61 c8 f5 fe cb e9 2d 17 4e b2 be af 0a 59 a4 15 84 33 dc c7 02 2e 4d 68 61 c8 f5 fe cb e9 2d 17 4e b2 be af 0a 59 a4 15 84
37 2f 43 2e 6b f4 7b 04 37 2f 43 2e 6b f4 7b 04
The Associated data A is the following: Associated data A = [ The Associated data A is the following: Associated data A = [
"Encrypt0", h'', TH_3 ] "Encrypt0", h'', TH_3 ]
skipping to change at page 75, line 21 skipping to change at page 77, line 21
) )
Which encodes to the following byte string: Which encodes to the following byte string:
message_3 (CBOR Sequence) (91 bytes) message_3 (CBOR Sequence) (91 bytes)
37 58 58 f5 f6 de bd 82 14 05 1c d5 83 c8 40 96 c4 80 1d eb f3 5b 15 36 37 58 58 f5 f6 de bd 82 14 05 1c d5 83 c8 40 96 c4 80 1d eb f3 5b 15 36
3d d1 6e bd 85 30 df dc fb 34 fc d2 eb 6c ad 1d ac 66 a4 79 fb 38 de aa 3d d1 6e bd 85 30 df dc fb 34 fc d2 eb 6c ad 1d ac 66 a4 79 fb 38 de aa
f1 d3 0a 7e 68 17 a2 2a b0 4f 3d 5b 1e 97 2a 0d 13 ea 86 c6 6b 60 51 4c f1 d3 0a 7e 68 17 a2 2a b0 4f 3d 5b 1e 97 2a 0d 13 ea 86 c6 6b 60 51 4c
96 57 ea 89 c5 7b 04 01 ed c5 aa 8b bc ab 81 3c c5 d6 e7 96 57 ea 89 c5 7b 04 01 ed c5 aa 8b bc ab 81 3c c5 d6 e7
B.1.4. OSCORE Security Context Derivation C.1.4. OSCORE Security Context Derivation
From here, the Initiator and the Responder can derive an OSCORE From here, the Initiator and the Responder can derive an OSCORE
Security Context, using the EDHOC-Exporter interface. Security Context, using the EDHOC-Exporter interface.
From TH_3 and CIPHERTEXT_3, compute the input to the transcript hash From TH_3 and CIPHERTEXT_3, compute the input to the transcript hash
TH_4 = H( TH_3, CIPHERTEXT_3 ), as a CBOR Sequence of these 2 data TH_4 = H( TH_3, CIPHERTEXT_3 ), as a CBOR Sequence of these 2 data
items. items.
Input to calculate TH_4 (CBOR Sequence) (124 bytes) Input to calculate TH_4 (CBOR Sequence) (124 bytes)
58 20 f2 4d 18 ca fc e3 74 d4 e3 73 63 29 c1 52 ab 3a ea 9c 7c 0f 65 0c 58 20 f2 4d 18 ca fc e3 74 d4 e3 73 63 29 c1 52 ab 3a ea 9c 7c 0f 65 0c
skipping to change at page 77, line 20 skipping to change at page 79, line 20
The AEAD Algorithm and the hash algorithm are the application AEAD The AEAD Algorithm and the hash algorithm are the application AEAD
and hash algorithms in the selected cipher suite. and hash algorithms in the selected cipher suite.
OSCORE AEAD Algorithm (int) OSCORE AEAD Algorithm (int)
10 10
OSCORE Hash Algorithm (int) OSCORE Hash Algorithm (int)
-16 -16
B.2. Test Vectors for EDHOC Authenticated with Static Diffie-Hellman C.2. Test Vectors for EDHOC Authenticated with Static Diffie-Hellman
Keys Keys
EDHOC with static Diffie-Hellman keys and raw public keys is used. EDHOC with static Diffie-Hellman keys and raw public keys is used.
In this test vector, a key identifier is used to identify the raw In this test vector, a key identifier is used to identify the raw
public key. The optional C_1 in message_1 is omitted. No auxiliary public key. The optional C_1 in message_1 is omitted. No external
data is sent in the message exchange. authorization data is sent in the message exchange.
method (Static DH Based Authentication) method (Static DH Based Authentication)
3 3
CoAP is used as transport and the Initiator acts as CoAP client: CoAP is used as transport and the Initiator acts as CoAP client:
corr (the Initiator can correlate message_1 and message_2) corr (the Initiator can correlate message_1 and message_2)
1 1
From there, METHOD_CORR has the following value: From there, METHOD_CORR has the following value:
skipping to change at page 78, line 7 skipping to change at page 80, line 7
Supported Cipher Suites (1 byte) Supported Cipher Suites (1 byte)
00 00
The Initiator selected the indicated cipher suite. The Initiator selected the indicated cipher suite.
Selected Cipher Suite (int) Selected Cipher Suite (int)
0 0
Cipher suite 0 is supported by both the Initiator and the Responder, Cipher suite 0 is supported by both the Initiator and the Responder,
see Section 3.4. see Section 3.4.
B.2.1. Message_1 C.2.1. Message_1
The Initiator generates its ephemeral key pair. The Initiator generates its ephemeral key pair.
X (Initiator's ephemeral private key) (32 bytes) X (Initiator's ephemeral private key) (32 bytes)
ae 11 a0 db 86 3c 02 27 e5 39 92 fe b8 f5 92 4c 50 d0 a7 ba 6e ea b4 ad ae 11 a0 db 86 3c 02 27 e5 39 92 fe b8 f5 92 4c 50 d0 a7 ba 6e ea b4 ad
1f f2 45 72 f4 f5 7c fa 1f f2 45 72 f4 f5 7c fa
G_X (Initiator's ephemeral public key, CBOR unencoded) (32 bytes) G_X (Initiator's ephemeral public key, CBOR unencoded) (32 bytes)
8d 3e f5 6d 1b 75 0a 43 51 d6 8a c2 50 a0 e8 83 79 0e fc 80 a5 38 a4 44 8d 3e f5 6d 1b 75 0a 43 51 d6 8a c2 50 a0 e8 83 79 0e fc 80 a5 38 a4 44
ee 9e 2b 57 e2 44 1a 7c ee 9e 2b 57 e2 44 1a 7c
skipping to change at page 78, line 32 skipping to change at page 80, line 32
16 16
Note that since C_I is a byte string in the interval h'00' to h'2f', Note that since C_I is a byte string in the interval h'00' to h'2f',
it is encoded as the corresponding integer - 24 (see bstr_identifier it is encoded as the corresponding integer - 24 (see bstr_identifier
in Section 5.1), i.e. 0x16 = 22, 22 - 24 = -2, and -2 in CBOR in Section 5.1), i.e. 0x16 = 22, 22 - 24 = -2, and -2 in CBOR
encoding is equal to 0x21. encoding is equal to 0x21.
C_I (1 byte) C_I (1 byte)
21 21
Since no auxiliary data is sent: Since no external authorization data is sent:
AD_1 (0 bytes) EAD_1 (0 bytes)
Since the list of supported cipher suites needs to contain the Since the list of supported cipher suites needs to contain the
selected cipher suite, the initiator truncates the list of supported selected cipher suite, the initiator truncates the list of supported
cipher suites to one cipher suite only, 00. cipher suites to one cipher suite only, 00.
Because one single selected cipher suite is conveyed, it is encoded Because one single selected cipher suite is conveyed, it is encoded
as an int instead of an array: as an int instead of an array:
SUITES_I (int) SUITES_I (int)
0 0
skipping to change at page 79, line 19 skipping to change at page 81, line 19
h'8D3EF56D1B750A4351D68AC250A0E883790EFC80A538A444EE9E2B57E2441A7C', h'8D3EF56D1B750A4351D68AC250A0E883790EFC80A538A444EE9E2B57E2441A7C',
-2 -2
) )
Which as a CBOR encoded data item is: Which as a CBOR encoded data item is:
message_1 (CBOR Sequence) (37 bytes) message_1 (CBOR Sequence) (37 bytes)
0d 00 58 20 8d 3e f5 6d 1b 75 0a 43 51 d6 8a c2 50 a0 e8 83 79 0e fc 80 0d 00 58 20 8d 3e f5 6d 1b 75 0a 43 51 d6 8a c2 50 a0 e8 83 79 0e fc 80
a5 38 a4 44 ee 9e 2b 57 e2 44 1a 7c 21 a5 38 a4 44 ee 9e 2b 57 e2 44 1a 7c 21
B.2.2. Message_2 C.2.2. Message_2
Since METHOD_CORR mod 4 equals 1, C_I is omitted from data_2. Since METHOD_CORR mod 4 equals 1, C_I is omitted from data_2.
The Responder generates the following ephemeral key pair. The Responder generates the following ephemeral key pair.
Y (Responder's ephemeral private key) (32 bytes) Y (Responder's ephemeral private key) (32 bytes)
c6 46 cd dc 58 12 6e 18 10 5f 01 ce 35 05 6e 5e bc 35 f4 d4 cc 51 07 49 c6 46 cd dc 58 12 6e 18 10 5f 01 ce 35 05 6e 5e bc 35 f4 d4 cc 51 07 49
a3 a5 e0 69 c1 16 16 9a a3 a5 e0 69 c1 16 16 9a
G_Y (Responder's ephemeral public key, CBOR unencoded) (32 bytes) G_Y (Responder's ephemeral public key, CBOR unencoded) (32 bytes)
skipping to change at page 80, line 24 skipping to change at page 82, line 24
G_R (Responder's public authentication key) (32 bytes) G_R (Responder's public authentication key) (32 bytes)
a3 ff 26 35 95 be b3 77 d1 a0 ce 1d 04 da d2 d4 09 66 ac 6b cb 62 20 51 a3 ff 26 35 95 be b3 77 d1 a0 ce 1d 04 da d2 d4 09 66 ac 6b cb 62 20 51
b8 46 59 18 4d 5d 9a 32 b8 46 59 18 4d 5d 9a 32
Since the Responder authenticates with a static Diffie-Hellman key, Since the Responder authenticates with a static Diffie-Hellman key,
PRK_3e2m = HKDF-Extract( PRK_2e, G_RX ), where G_RX is the ECDH PRK_3e2m = HKDF-Extract( PRK_2e, G_RX ), where G_RX is the ECDH
shared secret calculated from G_R and X, or G_X and R. shared secret calculated from G_R and X, or G_X and R.
From the Responder's authentication key and the Initiator's ephemeral From the Responder's authentication key and the Initiator's ephemeral
key (see Appendix B.2.1), the ECDH shared secret G_RX is calculated. key (see Appendix C.2.1), the ECDH shared secret G_RX is calculated.
G_RX (ECDH shared secret) (32 bytes) G_RX (ECDH shared secret) (32 bytes)
21 c7 ef f4 fb 69 fa 4b 67 97 d0 58 84 31 5d 84 11 a3 fd a5 4f 6d ad a6 21 c7 ef f4 fb 69 fa 4b 67 97 d0 58 84 31 5d 84 11 a3 fd a5 4f 6d ad a6
1d 4f cd 85 e7 90 66 68 1d 4f cd 85 e7 90 66 68
PRK_3e2m (32 bytes) PRK_3e2m (32 bytes)
75 07 7c 69 1e 35 01 2d 48 bc 24 c8 4f 2b ab 89 f5 2f ac 03 fe dd 81 3e 75 07 7c 69 1e 35 01 2d 48 bc 24 c8 4f 2b ab 89 f5 2f ac 03 fe dd 81 3e
43 8c 93 b1 0b 39 93 07 43 8c 93 b1 0b 39 93 07
The Responder chooses a connection identifier C_R. The Responder chooses a connection identifier C_R.
skipping to change at page 81, line 18 skipping to change at page 83, line 18
-24 -24
) )
Which as a CBOR encoded data item is: Which as a CBOR encoded data item is:
data_2 (CBOR Sequence) (35 bytes) data_2 (CBOR Sequence) (35 bytes)
58 20 52 fb a0 bd c8 d9 53 dd 86 ce 1a b2 fd 7c 05 a4 65 8c 7c 30 af db 58 20 52 fb a0 bd c8 d9 53 dd 86 ce 1a b2 fd 7c 05 a4 65 8c 7c 30 af db
fc 33 01 04 70 69 45 1b af 35 37 fc 33 01 04 70 69 45 1b af 35 37
From data_2 and message_1, compute the input to the transcript hash From data_2 and message_1, compute the input to the transcript hash
TH_2 = H( message_1, data_2 ), as a CBOR Sequence of these 2 data TH_2 = H( H(message_1), data_2 ), as a CBOR Sequence of these 2 data
items. items.
Input to calculate TH_2 (CBOR Sequence) (72 bytes) Input to calculate TH_2 (CBOR Sequence) (72 bytes)
0d 00 58 20 8d 3e f5 6d 1b 75 0a 43 51 d6 8a c2 50 a0 e8 83 79 0e fc 80 0d 00 58 20 8d 3e f5 6d 1b 75 0a 43 51 d6 8a c2 50 a0 e8 83 79 0e fc 80
a5 38 a4 44 ee 9e 2b 57 e2 44 1a 7c 21 58 20 52 fb a0 bd c8 d9 53 dd 86 a5 38 a4 44 ee 9e 2b 57 e2 44 1a 7c 21 58 20 52 fb a0 bd c8 d9 53 dd 86
ce 1a b2 fd 7c 05 a4 65 8c 7c 30 af db fc 33 01 04 70 69 45 1b af 35 37 ce 1a b2 fd 7c 05 a4 65 8c 7c 30 af db fc 33 01 04 70 69 45 1b af 35 37
And from there, compute the transcript hash TH_2 = SHA-256( And from there, compute the transcript hash TH_2 = SHA-256(
message_1, data_2 ) H(message_1), data_2 )
TH_2 (CBOR unencoded) (32 bytes) TH_2 (CBOR unencoded) (32 bytes)
de cf d6 4a 36 67 64 0a 02 33 b0 4a a8 aa 91 f6 89 56 b8 a5 36 d0 cf 8c de cf d6 4a 36 67 64 0a 02 33 b0 4a a8 aa 91 f6 89 56 b8 a5 36 d0 cf 8c
73 a6 e8 a7 c3 62 1e 26 73 a6 e8 a7 c3 62 1e 26
The Responder's subject name is the empty string: The Responder's subject name is the empty string:
Responder's subject name (text string) Responder's subject name (text string)
"" ""
skipping to change at page 82, line 19 skipping to change at page 84, line 19
"subject name": "" "subject name": ""
} }
Which encodes to the following byte string: Which encodes to the following byte string:
CRED_R (54 bytes) CRED_R (54 bytes)
a4 01 01 20 04 21 58 20 a3 ff 26 35 95 be b3 77 d1 a0 ce 1d 04 da d2 d4 a4 01 01 20 04 21 58 20 a3 ff 26 35 95 be b3 77 d1 a0 ce 1d 04 da d2 d4
09 66 ac 6b cb 62 20 51 b8 46 59 18 4d 5d 9a 32 6c 73 75 62 6a 65 63 74 09 66 ac 6b cb 62 20 51 b8 46 59 18 4d 5d 9a 32 6c 73 75 62 6a 65 63 74
20 6e 61 6d 65 60 20 6e 61 6d 65 60
Since no auxiliary data is sent: Since no external authorization data is sent:
AD_2 (0 bytes) EAD_2 (0 bytes)
The plaintext is defined as the empty string: The plaintext is defined as the empty string:
P_2m (0 bytes) P_2m (0 bytes)
The Enc_structure is defined as follows: [ "Encrypt0", The Enc_structure is defined as follows: [ "Encrypt0",
<< ID_CRED_R >>, << TH_2, CRED_R >> ], so ID_CRED_R is encoded as a << ID_CRED_R >>, << TH_2, CRED_R >> ], so ID_CRED_R is encoded as a
CBOR bstr, and the concatenation of the CBOR byte strings TH_2 and CBOR bstr, and the concatenation of the CBOR byte strings TH_2 and
CRED_R is wrapped in a CBOR bstr. CRED_R is wrapped in a CBOR bstr.
skipping to change at page 84, line 24 skipping to change at page 86, line 24
Since method = 2, Signature_or_MAC_2 is MAC_2: Since method = 2, Signature_or_MAC_2 is MAC_2:
Signature_or_MAC_2 (CBOR unencoded) (8 bytes) Signature_or_MAC_2 (CBOR unencoded) (8 bytes)
42 e7 99 78 43 1e 6b 8f 42 e7 99 78 43 1e 6b 8f
CIPHERTEXT_2 is the ciphertext resulting from XOR between plaintext CIPHERTEXT_2 is the ciphertext resulting from XOR between plaintext
and KEYSTREAM_2 which is derived from TH_2 and the pseudorandom key and KEYSTREAM_2 which is derived from TH_2 and the pseudorandom key
PRK_2e. PRK_2e.
The plaintext is the CBOR Sequence of the items ID_CRED_R and the The plaintext is the CBOR Sequence of the items ID_CRED_R and the
CBOR encoded Signature_or_MAC_2, in this order (AD_2 is empty). CBOR encoded Signature_or_MAC_2, in this order (EAD_2 is empty).
Note that since ID_CRED_R contains a single 'kid' parameter, i.e., Note that since ID_CRED_R contains a single 'kid' parameter, i.e.,
ID_CRED_R = { 4 : kid_R }, only the byte string kid_R is conveyed in ID_CRED_R = { 4 : kid_R }, only the byte string kid_R is conveyed in
the plaintext encoded as a bstr_identifier. kid_R is encoded as the the plaintext encoded as a bstr_identifier. kid_R is encoded as the
corresponding integer - 24 (see bstr_identifier in Section 5.1), i.e. corresponding integer - 24 (see bstr_identifier in Section 5.1), i.e.
0x05 = 5, 5 - 24 = -19, and -19 in CBOR encoding is equal to 0x32. 0x05 = 5, 5 - 24 = -19, and -19 in CBOR encoding is equal to 0x32.
The plaintext is the following: The plaintext is the following:
P_2e (CBOR Sequence) (10 bytes) P_2e (CBOR Sequence) (10 bytes)
skipping to change at page 85, line 36 skipping to change at page 87, line 36
data_2, data_2,
h'A3F1BD5D028D19CF3C99' h'A3F1BD5D028D19CF3C99'
) )
Which as a CBOR encoded data item is: Which as a CBOR encoded data item is:
message_2 (CBOR Sequence) (46 bytes) message_2 (CBOR Sequence) (46 bytes)
58 20 52 fb a0 bd c8 d9 53 dd 86 ce 1a b2 fd 7c 05 a4 65 8c 7c 30 af db 58 20 52 fb a0 bd c8 d9 53 dd 86 ce 1a b2 fd 7c 05 a4 65 8c 7c 30 af db
fc 33 01 04 70 69 45 1b af 35 37 4a a3 f1 bd 5d 02 8d 19 cf 3c 99 fc 33 01 04 70 69 45 1b af 35 37 4a a3 f1 bd 5d 02 8d 19 cf 3c 99
B.2.3. Message_3 C.2.3. Message_3
Since corr equals 1, C_R is not omitted from data_3. Since corr equals 1, C_R is not omitted from data_3.
The Initiator's static Diffie-Hellman key pair is the following: The Initiator's static Diffie-Hellman key pair is the following:
I (Initiator's private authentication key) (32 bytes) I (Initiator's private authentication key) (32 bytes)
2b be a6 55 c2 33 71 c3 29 cf bd 3b 1f 02 c6 c0 62 03 38 37 b8 b5 90 99 2b be a6 55 c2 33 71 c3 29 cf bd 3b 1f 02 c6 c0 62 03 38 37 b8 b5 90 99
a4 43 6f 66 60 81 b0 8e a4 43 6f 66 60 81 b0 8e
G_I (Initiator's public authentication key, CBOR unencoded) (32 bytes) G_I (Initiator's public authentication key, CBOR unencoded) (32 bytes)
2c 44 0c c1 21 f8 d7 f2 4c 3b 0e 41 ae da fe 9c aa 4f 4e 7a bb 83 5e c3 2c 44 0c c1 21 f8 d7 f2 4c 3b 0e 41 ae da fe 9c aa 4f 4e 7a bb 83 5e c3
0f 1d e8 8a db 96 ff 71 0f 1d e8 8a db 96 ff 71
HKDF SHA-256 is the HKDF used (as defined by cipher suite 0). HKDF SHA-256 is the HKDF used (as defined by cipher suite 0).
From the Initiator's authentication key and the Responder's ephemeral From the Initiator's authentication key and the Responder's ephemeral
key (see Appendix B.2.2), the ECDH shared secret G_IY is calculated. key (see Appendix C.2.2), the ECDH shared secret G_IY is calculated.
G_IY (ECDH shared secret) (32 bytes) G_IY (ECDH shared secret) (32 bytes)
cb ff 8c d3 4a 81 df ec 4c b6 5d 9a 57 2e bd 09 64 45 0c 78 56 3d a4 98 cb ff 8c d3 4a 81 df ec 4c b6 5d 9a 57 2e bd 09 64 45 0c 78 56 3d a4 98
1d 80 d3 6c 8b 1a 75 2a 1d 80 d3 6c 8b 1a 75 2a
PRK_4x3m = HMAC-SHA-256 (PRK_3e2m, G_IY). PRK_4x3m = HMAC-SHA-256 (PRK_3e2m, G_IY).
PRK_4x3m (32 bytes) PRK_4x3m (32 bytes)
02 56 2f 1f 01 78 5c 0a a5 f5 94 64 0c 49 cb f6 9f 72 2e 9e 6c 57 83 7d 02 56 2f 1f 01 78 5c 0a a5 f5 94 64 0c 49 cb f6 9f 72 2e 9e 6c 57 83 7d
8e 15 79 ec 45 fe 64 7a 8e 15 79 ec 45 fe 64 7a
data 3 is equal to C_R. data 3 is equal to C_R.
data_3 (CBOR Sequence) (1 byte) data_3 (CBOR Sequence) (1 byte)
37 37
From data_3, CIPHERTEXT_2, and TH_2, compute the input to the From data_3, CIPHERTEXT_2, and TH_2, compute the input to the
transcript hash TH_3 = H(TH_2 , CIPHERTEXT_2, data_3), as a CBOR transcript hash TH_3 = H( H(TH_2 , CIPHERTEXT_2), data_3), as a CBOR
Sequence of these 3 data items. Sequence of these 2 data items.
Input to calculate TH_3 (CBOR Sequence) (46 bytes) Input to calculate TH_3 (CBOR Sequence) (46 bytes)
58 20 de cf d6 4a 36 67 64 0a 02 33 b0 4a a8 aa 91 f6 89 56 b8 a5 36 d0 58 20 de cf d6 4a 36 67 64 0a 02 33 b0 4a a8 aa 91 f6 89 56 b8 a5 36 d0
cf 8c 73 a6 e8 a7 c3 62 1e 26 4a a3 f1 bd 5d 02 8d 19 cf 3c 99 37 cf 8c 73 a6 e8 a7 c3 62 1e 26 4a a3 f1 bd 5d 02 8d 19 cf 3c 99 37
And from there, compute the transcript hash TH_3 = SHA-256(TH_2 , And from there, compute the transcript hash TH_3 = SHA-256( H(TH_2 ,
CIPHERTEXT_2, data_3) CIPHERTEXT_2), data_3)
TH_3 (CBOR unencoded) (32 bytes) TH_3 (CBOR unencoded) (32 bytes)
b6 cd 80 4f c4 b9 d7 ca c5 02 ab d7 7c da 74 e4 1c b0 11 82 d7 cb 8b 84 b6 cd 80 4f c4 b9 d7 ca c5 02 ab d7 7c da 74 e4 1c b0 11 82 d7 cb 8b 84
db 03 ff a5 83 a3 5f cb db 03 ff a5 83 a3 5f cb
The initiator's subject name is the empty string: The initiator's subject name is the empty string:
Initiator's subject name (text string) Initiator's subject name (text string)
"" ""
skipping to change at page 87, line 20 skipping to change at page 89, line 20
"subject name": "" "subject name": ""
} }
Which encodes to the following byte string: Which encodes to the following byte string:
CRED_I (54 bytes) CRED_I (54 bytes)
a4 01 01 20 04 21 58 20 2c 44 0c c1 21 f8 d7 f2 4c 3b 0e 41 ae da fe 9c a4 01 01 20 04 21 58 20 2c 44 0c c1 21 f8 d7 f2 4c 3b 0e 41 ae da fe 9c
aa 4f 4e 7a bb 83 5e c3 0f 1d e8 8a db 96 ff 71 6c 73 75 62 6a 65 63 74 aa 4f 4e 7a bb 83 5e c3 0f 1d e8 8a db 96 ff 71 6c 73 75 62 6a 65 63 74
20 6e 61 6d 65 60 20 6e 61 6d 65 60
Since no auxiliary data is exchanged: Since no external authorization data is exchanged:
AD_3 (0 bytes) EAD_3 (0 bytes)
The plaintext of the COSE_Encrypt is the empty string: The plaintext of the COSE_Encrypt is the empty string:
P_3m (0 bytes) P_3m (0 bytes)
The associated data is the following: [ "Encrypt0", << ID_CRED_I >>, The associated data is the following: [ "Encrypt0", << ID_CRED_I >>,
<< TH_3, CRED_I, ? AD_3 >> ]. << TH_3, CRED_I, ? EAD_3 >> ].
A_3m (CBOR-encoded) (105 bytes) A_3m (CBOR-encoded) (105 bytes)
83 68 45 6e 63 72 79 70 74 30 44 a1 04 41 23 58 58 58 20 b6 cd 80 4f c4 83 68 45 6e 63 72 79 70 74 30 44 a1 04 41 23 58 58 58 20 b6 cd 80 4f c4
b9 d7 ca c5 02 ab d7 7c da 74 e4 1c b0 11 82 d7 cb 8b 84 db 03 ff a5 83 b9 d7 ca c5 02 ab d7 7c da 74 e4 1c b0 11 82 d7 cb 8b 84 db 03 ff a5 83
a3 5f cb a4 01 01 20 04 21 58 20 2c 44 0c c1 21 f8 d7 f2 4c 3b 0e 41 ae a3 5f cb a4 01 01 20 04 21 58 20 2c 44 0c c1 21 f8 d7 f2 4c 3b 0e 41 ae
da fe 9c aa 4f 4e 7a bb 83 5e c3 0f 1d e8 8a db 96 ff 71 6c 73 75 62 6a da fe 9c aa 4f 4e 7a bb 83 5e c3 0f 1d e8 8a db 96 ff 71 6c 73 75 62 6a
65 63 74 20 6e 61 6d 65 60 65 63 74 20 6e 61 6d 65 60
Info for K_3m is computed as follows: Info for K_3m is computed as follows:
skipping to change at page 89, line 6 skipping to change at page 91, line 6
ee 59 8e a6 61 17 dc c3 ee 59 8e a6 61 17 dc c3
Since method = 3, Signature_or_MAC_3 is MAC_3: Since method = 3, Signature_or_MAC_3 is MAC_3:
Signature_or_MAC_3 (CBOR unencoded) (8 bytes) Signature_or_MAC_3 (CBOR unencoded) (8 bytes)
ee 59 8e a6 61 17 dc c3 ee 59 8e a6 61 17 dc c3
Finally, the outer COSE_Encrypt0 is computed. Finally, the outer COSE_Encrypt0 is computed.
The plaintext is the CBOR Sequence of the items ID_CRED_I and the The plaintext is the CBOR Sequence of the items ID_CRED_I and the
CBOR encoded Signature_or_MAC_3, in this order (AD_3 is empty). CBOR encoded Signature_or_MAC_3, in this order (EAD_3 is empty).
Note that since ID_CRED_I contains a single 'kid' parameter, i.e., Note that since ID_CRED_I contains a single 'kid' parameter, i.e.,
ID_CRED_I = { 4 : kid_I }, only the byte string kid_I is conveyed in ID_CRED_I = { 4 : kid_I }, only the byte string kid_I is conveyed in
the plaintext encoded as a bstr_identifier. kid_I is encoded as the the plaintext encoded as a bstr_identifier. kid_I is encoded as the
corresponding integer - 24 (see bstr_identifier in Section 5.1), i.e. corresponding integer - 24 (see bstr_identifier in Section 5.1), i.e.
0x23 = 35, 35 - 24 = 11, and 11 in CBOR encoding is equal to 0x0b. 0x23 = 35, 35 - 24 = 11, and 11 in CBOR encoding is equal to 0x0b.
P_3ae (CBOR Sequence) (10 bytes) P_3ae (CBOR Sequence) (10 bytes)
0b 48 ee 59 8e a6 61 17 dc c3 0b 48 ee 59 8e a6 61 17 dc c3
skipping to change at page 90, line 46 skipping to change at page 92, line 46
( (
-24, -24,
h'D5535F3147E85F1CFACD9E78ABF9E0A81BBF' h'D5535F3147E85F1CFACD9E78ABF9E0A81BBF'
) )
Which encodes to the following byte string: Which encodes to the following byte string:
message_3 (CBOR Sequence) (20 bytes) message_3 (CBOR Sequence) (20 bytes)
37 52 d5 53 5f 31 47 e8 5f 1c fa cd 9e 78 ab f9 e0 a8 1b bf 37 52 d5 53 5f 31 47 e8 5f 1c fa cd 9e 78 ab f9 e0 a8 1b bf
B.2.4. OSCORE Security Context Derivation C.2.4. OSCORE Security Context Derivation
From here, the Initiator and the Responder can derive an OSCORE From here, the Initiator and the Responder can derive an OSCORE
Security Context, using the EDHOC-Exporter interface. Security Context, using the EDHOC-Exporter interface.
From TH_3 and CIPHERTEXT_3, compute the input to the transcript hash From TH_3 and CIPHERTEXT_3, compute the input to the transcript hash
TH_4 = H( TH_3, CIPHERTEXT_3 ), as a CBOR Sequence of these 2 data TH_4 = H( TH_3, CIPHERTEXT_3 ), as a CBOR Sequence of these 2 data
items. items.
Input to calculate TH_4 (CBOR Sequence) (53 bytes) Input to calculate TH_4 (CBOR Sequence) (53 bytes)
58 20 b6 cd 80 4f c4 b9 d7 ca c5 02 ab d7 7c da 74 e4 1c b0 11 82 d7 cb 58 20 b6 cd 80 4f c4 b9 d7 ca c5 02 ab d7 7c da 74 e4 1c b0 11 82 d7 cb
skipping to change at page 92, line 46 skipping to change at page 94, line 46
The AEAD Algorithm and the hash algorithm are the application AEAD The AEAD Algorithm and the hash algorithm are the application AEAD
and hash algorithms in the selected cipher suite. and hash algorithms in the selected cipher suite.
OSCORE AEAD Algorithm (int) OSCORE AEAD Algorithm (int)
10 10
OSCORE Hash Algorithm (int) OSCORE Hash Algorithm (int)
-16 -16
Appendix C. Applicability Template Appendix D. Applicability Template
This appendix contains an example of an applicability statement, see This appendix contains an example of an applicability statement, see
Section 3.7. Section 3.7.
For use of EDHOC in the XX protocol, the following assumptions are For use of EDHOC in the XX protocol, the following assumptions are
made on the parameters: made on the parameters:
* METHOD_CORR = 5 * METHOD_CORR = 5
- method = 1 (I uses signature key, R uses static DH key.) - method = 1 (I uses signature key, R uses static DH key.)
- corr = 1 (CoAP Token or other transport data enables - corr = 1 (CoAP Token or other transport data enables
correlation between message_1 and message_2.) correlation between message_1 and message_2.)
* EDHOC requests are expected by the server at /app1-edh, no * EDHOC requests are expected by the server at /app1-edh, no
Content-Format needed. Content-Format needed.
* C_1 = "null" is present to identify message_1 * C_1 = "null" is present to identify message_1
* CRED_I is an 802.1AR IDevID encoded as a C509 Certificate of type * CRED_I is an 802.1AR IDevID encoded as a C509 Certificate of type
0 [I-D.mattsson-cose-cbor-cert-compress]. 0 [I-D.ietf-cose-cbor-encoded-cert].
- R acquires CRED_I out-of-band, indicated in AD_1 - R acquires CRED_I out-of-band, indicated in EAD_1
- ID_CRED_I = {4: h''} is a kid with value empty byte string - ID_CRED_I = {4: h''} is a kid with value empty byte string
* CRED_R is a COSE_Key of type OKP as specified in Section 3.3.4. * CRED_R is a COSE_Key of type OKP as specified in Section 3.3.4.
- The CBOR map has parameters 1 (kty), -1 (crv), and -2 - The CBOR map has parameters 1 (kty), -1 (crv), and -2
(x-coordinate). (x-coordinate).
* ID_CRED_R = CRED_R * ID_CRED_R = CRED_R
* AD_1 contains Auxiliary Data of type A (TBD)
* AD_2 contains Auxiliary Data of type B (TBD)
* No use of message_4: the application sends protected messages from * No use of message_4: the application sends protected messages from
R to I. R to I.
* Auxiliary Data is processed as specified in * External authorization data is defined and processed as specified
[I-D.selander-ace-ake-authz]. in [I-D.selander-ace-ake-authz].
Appendix D. EDHOC Message Deduplication Appendix E. EDHOC Message Deduplication
EDHOC by default assumes that message duplication is handled by the EDHOC by default assumes that message duplication is handled by the
transport, in this section exemplified with CoAP. transport, in this section exemplified with CoAP.
Deduplication of CoAP messages is described in Section 4.5 of Deduplication of CoAP messages is described in Section 4.5 of
[RFC7252]. This handles the case when the same Confirmable (CON) [RFC7252]. This handles the case when the same Confirmable (CON)
message is received multiple times due to missing acknowledgement on message is received multiple times due to missing acknowledgement on
CoAP messaging layer. The recommended processing in [RFC7252] is CoAP messaging layer. The recommended processing in [RFC7252] is
that the duplicate message is acknowledged (ACK), but the received that the duplicate message is acknowledged (ACK), but the received
message is only processed once by the CoAP stack. message is only processed once by the CoAP stack.
skipping to change at page 94, line 18 skipping to change at page 96, line 18
support transport layers which does not handle message duplication. support transport layers which does not handle message duplication.
Special care is needed to avoid issues with duplicate messages, see Special care is needed to avoid issues with duplicate messages, see
Section 5.2. Section 5.2.
The guiding principle here is similar to the deduplication processing The guiding principle here is similar to the deduplication processing
on CoAP messaging layer: a received duplicate EDHOC message SHALL NOT on CoAP messaging layer: a received duplicate EDHOC message SHALL NOT
result in a response consisting of another instance of the next EDHOC result in a response consisting of another instance of the next EDHOC
message. The result MAY be that a duplicate EDHOC response is sent, message. The result MAY be that a duplicate EDHOC response is sent,
provided it is still relevant with respect the current protocol provided it is still relevant with respect the current protocol
state. In any case, the received message MUST NOT be processed more state. In any case, the received message MUST NOT be processed more
than once by the same EDHOC instance. This is called "EDHOC message than once in the same EDHOC session. This is called "EDHOC message
deduplication". deduplication".
An EDHOC implementation MAY store the previously sent EDHOC message An EDHOC implementation MAY store the previously sent EDHOC message
to be able to resend it. An EDHOC implementation MAY keep the to be able to resend it. An EDHOC implementation MAY keep the
protocol state to be able to recreate the previously sent EDHOC protocol state to be able to recreate the previously sent EDHOC
message and resend it. The previous message or protocol state MUST message and resend it. The previous message or protocol state MUST
NOT be kept longer than what is required for retransmission, for NOT be kept longer than what is required for retransmission, for
example, in the case of CoAP transport, no longer than the example, in the case of CoAP transport, no longer than the
EXCHANGE_LIFETIME (see Section 4.8.2 of [RFC7252]). EXCHANGE_LIFETIME (see Section 4.8.2 of [RFC7252]).
Note that the requirements in Section 5.2 still apply because Note that the requirements in Section 5.2 still apply because
duplicate messages are not processed by the EDHOC state machine: duplicate messages are not processed by the EDHOC state machine:
* EDHOC messages SHALL be processed according to the current * EDHOC messages SHALL be processed according to the current
protocol state. protocol state.
* Different instances of the same message MUST NOT be processed in * Different instances of the same message MUST NOT be processed in
one protocol instance. one session.
Appendix E. Change Log Appendix F. Change Log
Main changes: Main changes:
* From -06 to -07:
- Changed transcript hash definition for TH_2 and TH_3
- Removed "EDHOC signature algorithm curve" from cipher suite
- New IANA registry "EDHOC Exporter Label"
- New application defined parameter "context" in EDHOC-Exporter
- Changed normative language for failure from MUST to SHOULD send
error
- Made error codes non-negative and 0 for success
- Added detail on success error code
- Aligned terminology "protocol instance" -> "session"
- New appendix on compact EC point representation
- Added detail on use of ephemeral public keys
- Moved key derivation for OSCORE to draft-ietf-core-oscore-edhoc
- Additional security considerations
- Renamed "Auxililary Data" as "External Authorization Data"
- Added encrypted EAD_4 to message_4
* From -05 to -06: * From -05 to -06:
- New section 5.2 "Message Processing Outline" - New section 5.2 "Message Processing Outline"
- Optional inital byte C_1 = null in message_1 - Optional inital byte C_1 = null in message_1
- New format of error messages, table of error codes, IANA - New format of error messages, table of error codes, IANA
registry registry
- Change of recommendation transport of error in CoAP - Change of recommendation transport of error in CoAP
skipping to change at page 95, line 15 skipping to change at page 97, line 47
"Applicability Statement" "Applicability Statement"
- Requiring use of deterministic CBOR - Requiring use of deterministic CBOR
- New section on message deduplication - New section on message deduplication
- New appendix containin all CDDL definitions - New appendix containin all CDDL definitions
- New appendix with change log - New appendix with change log
- Removed section "Other Documents Referncing EDHOC" - Removed section "Other Documents Referencing EDHOC"
- Clarifications based on review comments - Clarifications based on review comments
* From -04 to -05: * From -04 to -05:
- EDHOC-Rekey-FS -> EDHOC-KeyUpdate - EDHOC-Rekey-FS -> EDHOC-KeyUpdate
- Clarification of cipher suite negotiation - Clarification of cipher suite negotiation
- Updated security considerations - Updated security considerations
 End of changes. 223 change blocks. 
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