draft-ietf-httpauth-mutual-06.txt   draft-ietf-httpauth-mutual-07.txt 
HTTPAUTH Working Group Y. Oiwa HTTPAUTH Working Group Y. Oiwa
Internet-Draft H. Watanabe Internet-Draft H. Watanabe
Intended status: Experimental H. Takagi Intended status: Experimental H. Takagi
Expires: July 10, 2016 ITRI, AIST Expires: November 23, 2016 ITRI, AIST
K. Maeda K. Maeda
T. Hayashi T. Hayashi
Lepidum Lepidum
Y. Ioku Y. Ioku
Individual Individual
January 7, 2016 May 22, 2016
Mutual Authentication Protocol for HTTP Mutual Authentication Protocol for HTTP
draft-ietf-httpauth-mutual-06 draft-ietf-httpauth-mutual-07
Abstract Abstract
This document specifies a mutual authentication method for the Hyper- This document specifies a mutual authentication scheme for the
text Transfer Protocol (HTTP). This method provides a true mutual Hypertext Transfer Protocol (HTTP). This scheme provides true mutual
authentication between an HTTP client and an HTTP server using authentication between an HTTP client and an HTTP server using
password-based authentication. Unlike the Basic and Digest password-based authentication. Unlike the Basic and Digest
authentication methods, the Mutual authentication method specified in authentication schemes, the Mutual authentication scheme specified in
this document assures the user that the server truly knows the user's this document assures the user that the server truly knows the user's
encrypted password. encrypted password.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on July 10, 2016. This Internet-Draft will expire on November 23, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 31 skipping to change at page 2, line 31
2.3. Alternative Flows . . . . . . . . . . . . . . . . . . . . 9 2.3. Alternative Flows . . . . . . . . . . . . . . . . . . . . 9
3. Message Syntax . . . . . . . . . . . . . . . . . . . . . . . . 10 3. Message Syntax . . . . . . . . . . . . . . . . . . . . . . . . 10
3.1. Non-ASCII extended header parameters . . . . . . . . . . . 11 3.1. Non-ASCII extended header parameters . . . . . . . . . . . 11
3.2. Values . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.2. Values . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3.2.1. Tokens . . . . . . . . . . . . . . . . . . . . . . . . 12 3.2.1. Tokens . . . . . . . . . . . . . . . . . . . . . . . . 12
3.2.2. Strings . . . . . . . . . . . . . . . . . . . . . . . 13 3.2.2. Strings . . . . . . . . . . . . . . . . . . . . . . . 13
3.2.3. Numbers . . . . . . . . . . . . . . . . . . . . . . . 13 3.2.3. Numbers . . . . . . . . . . . . . . . . . . . . . . . 13
4. Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4. Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.1. 401-INIT and 401-STALE . . . . . . . . . . . . . . . . . . 15 4.1. 401-INIT and 401-STALE . . . . . . . . . . . . . . . . . . 15
4.2. req-KEX-C1 . . . . . . . . . . . . . . . . . . . . . . . . 17 4.2. req-KEX-C1 . . . . . . . . . . . . . . . . . . . . . . . . 17
4.3. 401-KEX-S1 . . . . . . . . . . . . . . . . . . . . . . . . 18 4.3. 401-KEX-S1 . . . . . . . . . . . . . . . . . . . . . . . . 17
4.4. req-VFY-C . . . . . . . . . . . . . . . . . . . . . . . . 19 4.4. req-VFY-C . . . . . . . . . . . . . . . . . . . . . . . . 18
4.5. 200-VFY-S . . . . . . . . . . . . . . . . . . . . . . . . 20 4.5. 200-VFY-S . . . . . . . . . . . . . . . . . . . . . . . . 19
5. Authentication Realms . . . . . . . . . . . . . . . . . . . . 20 5. Authentication Realms . . . . . . . . . . . . . . . . . . . . 19
5.1. Resolving Ambiguities . . . . . . . . . . . . . . . . . . 22 5.1. Resolving Ambiguities . . . . . . . . . . . . . . . . . . 21
6. Session Management . . . . . . . . . . . . . . . . . . . . . . 22 6. Session Management . . . . . . . . . . . . . . . . . . . . . . 22
7. Host Validation Methods . . . . . . . . . . . . . . . . . . . 24 7. Host Validation Methods . . . . . . . . . . . . . . . . . . . 23
7.1. Applicability notes . . . . . . . . . . . . . . . . . . . 26 7.1. Applicability notes . . . . . . . . . . . . . . . . . . . 25
7.2. Notes on tls-unique . . . . . . . . . . . . . . . . . . . 26 7.2. Notes on tls-unique . . . . . . . . . . . . . . . . . . . 25
8. Authentication Extensions . . . . . . . . . . . . . . . . . . 27 8. Authentication Extensions . . . . . . . . . . . . . . . . . . 26
9. String Preparation . . . . . . . . . . . . . . . . . . . . . . 27 9. String Preparation . . . . . . . . . . . . . . . . . . . . . . 26
10. Decision Procedure for Clients . . . . . . . . . . . . . . . . 28 10. Decision Procedure for Clients . . . . . . . . . . . . . . . . 27
10.1. General Principles and Requirements . . . . . . . . . . . 28 10.1. General Principles and Requirements . . . . . . . . . . . 27
10.2. State machine for the client-side (informative) . . . . . 30 10.2. State machine for the client (informative) . . . . . . . . 29
11. Decision Procedure for Servers . . . . . . . . . . . . . . . . 34 11. Decision Procedure for Servers . . . . . . . . . . . . . . . . 33
12. Authentication Algorithms . . . . . . . . . . . . . . . . . . 36 12. Authentication Algorithms . . . . . . . . . . . . . . . . . . 35
12.1. Support Functions and Notations . . . . . . . . . . . . . 37 12.1. Support Functions and Notations . . . . . . . . . . . . . 36
12.2. Default Functions for Algorithms . . . . . . . . . . . . . 38 12.2. Default Functions for Algorithms . . . . . . . . . . . . . 37
13. Application Channel Binding . . . . . . . . . . . . . . . . . 39 13. Application Channel Binding . . . . . . . . . . . . . . . . . 38
14. Application for Proxy Authentication . . . . . . . . . . . . . 40 14. Application for Proxy Authentication . . . . . . . . . . . . . 39
15. Methods to Extend This Protocol . . . . . . . . . . . . . . . 40 15. Methods to Extend This Protocol . . . . . . . . . . . . . . . 40
16. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 41 16. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 40
16.1. Registry for Authentication Algorithms . . . . . . . . . . 41 16.1. Registry for Authentication Algorithms . . . . . . . . . . 40
16.2. Registry for Password Hashes . . . . . . . . . . . . . . . 42 16.2. Registry for Validation Methods . . . . . . . . . . . . . 41
16.3. Registry for Validation Methods . . . . . . . . . . . . . 42 17. Security Considerations . . . . . . . . . . . . . . . . . . . 41
17. Security Considerations . . . . . . . . . . . . . . . . . . . 43 17.1. Security Properties . . . . . . . . . . . . . . . . . . . 41
17.1. Security Properties . . . . . . . . . . . . . . . . . . . 43 17.2. Denial-of-service Attacks to Servers . . . . . . . . . . . 42
17.2. Denial-of-service Attacks to Servers . . . . . . . . . . . 44 17.2.1. On-line Active Password Attacks . . . . . . . . . . . 43
17.2.1. On-line Active Password Attacks . . . . . . . . . . . 44
17.3. Communicating the status of mutual authentication with 17.3. Communicating the status of mutual authentication with
users . . . . . . . . . . . . . . . . . . . . . . . . . . 44 users . . . . . . . . . . . . . . . . . . . . . . . . . . 43
17.4. Implementation Considerations . . . . . . . . . . . . . . 45 17.4. Implementation Considerations . . . . . . . . . . . . . . 43
17.5. Usage Considerations . . . . . . . . . . . . . . . . . . . 46 17.5. Usage Considerations . . . . . . . . . . . . . . . . . . . 44
18. Notice on Intellectual Properties . . . . . . . . . . . . . . 46 18. Notice on Intellectual Properties . . . . . . . . . . . . . . 44
19. References . . . . . . . . . . . . . . . . . . . . . . . . . . 47 19. References . . . . . . . . . . . . . . . . . . . . . . . . . . 45
19.1. Normative References . . . . . . . . . . . . . . . . . . . 47 19.1. Normative References . . . . . . . . . . . . . . . . . . . 45
19.2. Informative References . . . . . . . . . . . . . . . . . . 48 19.2. Informative References . . . . . . . . . . . . . . . . . . 46
Appendix A. (Informative) Draft Change Log . . . . . . . . . . . 49 Appendix A. (Informative) Draft Change Log . . . . . . . . . . . 47
A.1. Changes in Httpauth WG Revision 06 . . . . . . . . . . . . 49 A.1. Changes in Httpauth WG Revision 07 . . . . . . . . . . . . 48
A.2. Changes in Httpauth WG Revision 05 . . . . . . . . . . . . 50 A.2. Changes in Httpauth WG Revision 06 . . . . . . . . . . . . 48
A.3. Changes in Httpauth WG Revision 04 . . . . . . . . . . . . 50 A.3. Changes in Httpauth WG Revision 05 . . . . . . . . . . . . 48
A.4. Changes in Httpauth WG Revision 03 . . . . . . . . . . . . 50 A.4. Changes in Httpauth WG Revision 04 . . . . . . . . . . . . 48
A.5. Changes in Httpauth WG Revision 02 . . . . . . . . . . . . 50 A.5. Changes in Httpauth WG Revision 03 . . . . . . . . . . . . 48
A.6. Changes in Httpauth WG Revision 01 . . . . . . . . . . . . 50 A.6. Changes in Httpauth WG Revision 02 . . . . . . . . . . . . 48
A.7. Changes in Httpauth Revision 00 . . . . . . . . . . . . . 51 A.7. Changes in Httpauth WG Revision 01 . . . . . . . . . . . . 49
A.8. Changes in HttpBis Revision 00 . . . . . . . . . . . . . . 51 A.8. Changes in Httpauth Revision 00 . . . . . . . . . . . . . 49
A.9. Changes in Revision 12 . . . . . . . . . . . . . . . . . . 51 A.9. Changes in HttpBis Revision 00 . . . . . . . . . . . . . . 49
A.10. Changes in Revision 11 . . . . . . . . . . . . . . . . . . 51 A.10. Changes in Revision 12 . . . . . . . . . . . . . . . . . . 49
A.11. Changes in Revision 10 . . . . . . . . . . . . . . . . . . 51 A.11. Changes in Revision 11 . . . . . . . . . . . . . . . . . . 49
A.12. Changes in Revision 09 . . . . . . . . . . . . . . . . . . 52 A.12. Changes in Revision 10 . . . . . . . . . . . . . . . . . . 50
A.13. Changes in Revision 08 . . . . . . . . . . . . . . . . . . 53 A.13. Changes in Revision 09 . . . . . . . . . . . . . . . . . . 51
A.14. Changes in Revision 07 . . . . . . . . . . . . . . . . . . 53 A.14. Changes in Revision 08 . . . . . . . . . . . . . . . . . . 51
A.15. Changes in Revision 06 . . . . . . . . . . . . . . . . . . 53 A.15. Changes in Revision 07 . . . . . . . . . . . . . . . . . . 51
A.16. Changes in Revision 05 . . . . . . . . . . . . . . . . . . 54 A.16. Changes in Revision 06 . . . . . . . . . . . . . . . . . . 52
A.17. Changes in Revision 04 . . . . . . . . . . . . . . . . . . 54 A.17. Changes in Revision 05 . . . . . . . . . . . . . . . . . . 52
A.18. Changes in Revision 03 . . . . . . . . . . . . . . . . . . 54 A.18. Changes in Revision 04 . . . . . . . . . . . . . . . . . . 52
A.19. Changes in Revision 02 . . . . . . . . . . . . . . . . . . 54 A.19. Changes in Revision 03 . . . . . . . . . . . . . . . . . . 52
A.20. Changes in Revision 01 . . . . . . . . . . . . . . . . . . 55 A.20. Changes in Revision 02 . . . . . . . . . . . . . . . . . . 53
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 55 A.21. Changes in Revision 01 . . . . . . . . . . . . . . . . . . 53
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 53
1. Introduction 1. Introduction
This document specifies a mutual authentication method for Hyper-Text This document specifies a mutual authentication scheme for Hypertext
Transfer Protocol (HTTP). The method, called "Mutual Authentication Transfer Protocol (HTTP). The scheme, called "Mutual Authentication
Protocol" in this document, provides a true mutual authentication Protocol" in this document, provides true mutual authentication
between an HTTP client and an HTTP server, using just a simple between an HTTP client and an HTTP server, using just a simple
password as a credential. password as a credential.
The authentication method proposed in this document is a general The authentication scheme proposed in this document is a general
framework for using password-based authenticated key exchange (PAKE) framework for using password-based authenticated key exchange (PAKE)
and similar stronger cryptographic primitives on the HTTP. It has and similar stronger cryptographic primitives with HTTP. It has the
the following main characteristics: following main characteristics:
o It provides "true" mutual authentication: in addition to assuring o It provides "true" mutual authentication: in addition to assuring
the server that the user knows the password, it also assures the the server that the user knows the password, it also assures the
user that the server truly knows the user's encrypted password at user that the server truly knows the user's encrypted password at
the same time. This makes it impossible for fake website owners the same time. This makes it impossible for fake website owners
to persuade users that they have authenticated with the original to persuade users that they have authenticated with the original
websites. websites.
o It uses only passwords as the user's credential: unlike public- o It uses only passwords as the user's credential: unlike public-
key-based security algorithms, the method does not rely on secret key-based security algorithms, the scheme does not rely on secret
keys or other cryptographic data that have to be stored inside the keys or other cryptographic data that have to be stored inside the
users' computers. The proposed method can be used as a drop-in users' computers. The proposed scheme can be used as a drop-in
replacement to the current authentication methods like Basic or replacement to the current authentication schemes like Basic or
Digest, while ensuring a much stronger level of security. Digest, while ensuring a much stronger level of security.
o It is secure: when the server fails to authenticate with a user, o It is secure: when the server fails to authenticate with a user,
the protocol will not reveal any tiny bit of information about the the protocol will not reveal the tiniest bit of information about
user's password. the user's password.
1.1. Terminology 1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
[RFC2119]. [RFC2119].
This document distinguishes the terms "client" and "user" in the This document distinguishes the terms "client" and "user" in the
following way: A "client" is an entity understanding and talking HTTP following way: A "client" is an entity understanding and talking HTTP
and the specified authentication protocol, usually computer software; and the specified authentication protocol, usually computer software;
a "user" is a (usually natural) person who wants to access data a "user" is a (usually natural) person who wants to access data
resources using "a client". resources using a "client".
The term "natural numbers" refers to the non-negative integers The term "natural numbers" refers to the non-negative integers
(including zero) throughout this document. (including zero) throughout this document.
This document treats target (codomain) of hash functions to be octet This document treats both the input (domain) and the output
strings. The notation INT(H(s)) gives a numerical (natural-number) (codomain) of hash functions to be octet strings. When a natural
output of hash function H applied to string s. number output is required, the notation INT(H(s)) is used.
1.2. Document Structure and Related Documents 1.2. Document Structure and Related Documents
The entire document is organized as follows: The entire document is organized as follows:
o Section 2 presents an overview of the protocol design. o Section 2 presents an overview of the protocol design.
o Sections 3 to 11 define a general framework of the Mutual o Sections 3 to 11 define a general framework of the Mutual
authentication protocol. This framework is independent of authentication protocol. This framework is independent of
specific cryptographic primitives. specific cryptographic primitives.
skipping to change at page 5, line 31 skipping to change at page 5, line 31
o The sections after that contain general normative and informative o The sections after that contain general normative and informative
information about the protocol. information about the protocol.
o The appendices contain some information that may help developers o The appendices contain some information that may help developers
to implement the protocol. to implement the protocol.
In addition, there are two companion documents which are referred In addition, there are two companion documents which are referred
from/related to this specification: from/related to this specification:
o [I-D.ietf-httpauth-mutual-algo]: defines a cryptographic o [I-D.ietf-httpauth-mutual-algo]: defines cryptographic primitives
primitives which can be used with this protocol framework. which can be used with this protocol framework.
o [I-D.ietf-httpauth-extension]: defines a small but useful o [I-D.ietf-httpauth-extension]: defines small but useful extensions
extensions to the current HTTP authentication framework so that it to the current HTTP authentication framework so that it can
can support application-level semantics of existing Web systems. support application-level semantics of existing Web systems.
2. Protocol Overview 2. Protocol Overview
The protocol, as a whole, is designed as a natural extension to the The protocol, as a whole, is designed as a natural extension to the
HTTP protocol [RFC7230] using a framework defined in [RFC7235]. HTTP protocol [RFC7230] using a framework defined in [RFC7235].
Internally, the server and the client will first perform a Internally, the server and the client will first perform a
cryptographic key exchange, using the secret password as a "tweak" to cryptographic key exchange, using the secret password as a "tweak" to
the exchange. The key-exchange will only succeed when the secrets the exchange. The key exchange will only succeed when the secrets
used by the both peers are correctly related (i.e. generated from the used by the both peers are correctly related (i.e., generated from
same password). Then, both peers will verify the authentication the same password). Then, both peers will verify the authentication
results by confirming the sharing of the exchanged key. This section results by confirming the sharing of the exchanged key. This section
describes a brief image of the protocol and the exchanged messages. provides a brief outline of the protocol and the exchanged messages.
2.1. Messages Overview 2.1. Messages Overview
The authentication protocol uses seven kinds of messages to perform The authentication protocol uses seven kinds of messages to perform
mutual authentication. These messages have specific names within mutual authentication. These messages have specific names within
this specification. this specification.
o Authentication request messages: used by the servers to request o Authentication request messages: used by the servers to request
clients to start mutual authentication. clients to start mutual authentication.
* 401-INIT message: a general message to start the authentication * 401-INIT message: a general message to start the authentication
protocol. It is also used as a message indicating an protocol. It is also used as a message indicating an
authentication failure. authentication failure.
* 401-STALE message: a message indicating that it has to start a * 401-STALE message: a message indicating that client has to
new authentication trial. start a new key exchange.
o Authenticated key exchange messages: used by both peers to perform o Authenticated key exchange messages: used by both peers to perform
authentication and the sharing of a cryptographic secret. authentication and the sharing of a cryptographic secret.
* req-KEX-C1 message: a message sent from the client. * req-KEX-C1 message: a message sent from the client.
* 401-KEX-S1 message: a message sent from the server as a * 401-KEX-S1 message: a message sent from the server in response
response to a req-KEX-C1 message. to a req-KEX-C1 message.
o Authentication verification messages: used by both peers to verify o Authentication verification messages: used by both peers to verify
the authentication results. the authentication results.
* req-VFY-C message: a message used by the client, requesting * req-VFY-C message: a message used by the client, requesting the
that the server authenticates and authorizes the client. server authenticate and authorize the client.
* 200-VFY-S message: a successful response used by the server, * 200-VFY-S message: a client-authentication successful response
and also asserting that the server is authentic to the client used by the server, which also simultaneously asserts to the
simultaneously. client that the server is authentic.
In addition to the above, either a request or a response without any In addition to the above, either a request or a response without any
HTTP headers related to this specification will be hereafter called a HTTP headers related to this specification will be hereafter called a
"normal request" or a "normal response", respectively. "normal request" or a "normal response", respectively.
2.2. Typical Flows of the Protocol 2.2. Typical Flows of the Protocol
In typical cases, the client access to a resource protected by the In typical cases, the client access to a resource protected by the
Mutual authentication will follow the following protocol sequence. Mutual authentication scheme will use the following protocol
sequence.
Client Server Client Server
| | | |
| ---- (1) normal request ---------> | | ---- (1) normal request ---------> |
GET / HTTP/1.1 | GET / HTTP/1.1 |
| | | |
| <---------------- (2) 401-INIT --- | | <---------------- (2) 401-INIT --- |
| 401 Authentication Required | 401 Authentication Required
| WWW-Authenticate: Mutual realm="a realm" | WWW-Authenticate: Mutual realm="a realm"
| | | |
skipping to change at page 7, line 47 skipping to change at page 7, line 47
v v v v
Figure 1: Typical communication flow for first access to resource Figure 1: Typical communication flow for first access to resource
o As usual in general HTTP protocol designs, a client will at first o As usual in general HTTP protocol designs, a client will at first
request a resource without any authentication attempt (1). If the request a resource without any authentication attempt (1). If the
requested resource is protected by the Mutual authentication, the requested resource is protected by the Mutual authentication, the
server will respond with a message requesting authentication server will respond with a message requesting authentication
(401-INIT) (2). (401-INIT) (2).
o The client processes the body of the message, and waits for the o The client processes the body of the message and waits for the
user to input the user name and a password. If the user name and user to input the user name and a password. If the user name and
the password are available, the client will send a message with the password are available, the client will send a message with
the authenticated key exchange (req-KEX-C1) to start the the authenticated key exchange (req-KEX-C1) to start the
authentication (3). authentication (3).
o If the server has received a req-KEX-C1 message, the server looks o If the server has received a req-KEX-C1 message, the server looks
up the user's authentication information within its user database. up the user's authentication information within its user database.
Then the server creates a new session identifier (sid) that will Then the server creates a new session identifier (sid) that will
be used to identify sets of the messages that follow it, and be used to identify sets of the messages that follow it and
responds back with a message containing a server-side responds back with a message containing a server-side
authenticated key exchange value (401-KEX-S1) (4). authenticated key exchange value (401-KEX-S1) (4).
o At this point (5), both peers calculate a shared "session secret" o At this point (5), both peers calculate a shared "session secret"
using the exchanged values in the key exchange messages. Only using the exchanged values in the key exchange messages. Only
when both the server and the client have used secret credentials when both the server and the client have used secret credentials
generated from the same password,the session secret values will generated from the same password will the session secret values
match. This session secret will be used for access authentication match. This session secret will be used for access authentication
of every individual request after this point. of every individual normal after this point.
o The client will send a request with a client-side authentication o The client will send a request with a client-side authentication
verification value (req-VFY-C) (6), generated from the client- verification value (req-VFY-C) (6), calculated from the client-
owned session secret. The server will check the validity of the generated session secret. The server will check the validity of
verification value using its own session secret. the verification value using its own version of the session
secret.
o If the authentication verification value from the client was o If the authentication verification value from the client was
correct, it means that the client definitely owns the credential correct, it means that the client definitely owns the credential
based on the expected password (i.e. the client authentication based on the expected password (i.e., the client authentication
succeeded.) The server will respond with a successful message succeeded). The server will respond with a successful message
(200-VFY-S) (7). Contrary to the usual one-way authentication (200-VFY-S) (7). Contrary to the usual one-way authentication
(e.g. HTTP Basic authentication or POP APOP authentication (e.g., HTTP Basic authentication or POP APOP authentication
[RFC1939]), this message also contains a server-side [RFC1939]), this message also contains a server-side
authentication verification value. authentication verification value.
When the client's verification value is incorrect (e.g. because When the client's verification value is incorrect (e.g., because
the user-supplied password was incorrect), the server will respond the user-supplied password was incorrect), the server will respond
with the 401-INIT message (the same one as used in (2)) instead. with the 401-INIT message (the same one as used in (2)) instead.
o The client MUST first check the validity of the server-side o The client MUST first check the validity of the server-side
authentication verification value contained in the message (7). authentication verification value contained in the message (7).
If the value was equal to the expected one, the server If the value was equal to the expected one, server authentication
authentication succeeded. succeeded.
If it is not the value expected, or if the message does not If it is not the value expected, or if the message does not
contain the authentication verification value, it means that the contain the authentication verification value, it means that the
mutual authentication has been broken for some unexpected reason. mutual authentication has been broken for some unexpected reason.
The client MUST NOT process any body or header values contained in The client MUST NOT process any body or header values contained in
this case. (Note: This case should not happen between a the HTTP response in this case. (Note: This case should not
correctly-implemented server and a client without any happen between a correctly implemented server and client without
interventions. Possible cause of such cases might be either a any active attacks. The possible cause of such a case might be
man-in-the-middle attack or a mis-implementation.) either a man-in-the-middle attack or an incorrect implementation.)
2.3. Alternative Flows 2.3. Alternative Flows
As shown above, the typical flow for a first authenticated request As shown above, the typical flow for a first authentication request
requires three request-response pairs. To reduce the protocol requires three request-response pairs. To reduce the protocol
overhead, the protocol enables several short-cut flows which require overhead, the protocol enables several short-cut flows which require
fewer messages. fewer messages.
o (case A) If the client knows that the resource is likely to o (case A) If the client knows that the resource is likely to
require the authentication, the client MAY omit the first require authentication, the client MAY omit the first
unauthenticated request (1) and immediately send a key exchange unauthenticated request (1) and immediately send a key exchange
(req-KEX-C1 message). This will reduce one round-trip of (req-KEX-C1 message). This will reduce one round-trip of
messages. messages.
o (case B) If both the client and the server previously shared a o (case B) If both the client and the server previously shared a
session secret associated with a valid session identifier (sid), session secret associated with a valid session identifier (sid),
the client MAY directly send a req-VFY-C message using the the client MAY directly send a req-VFY-C message using the
existing session identifier and corresponding session secret. existing session identifier and corresponding session secret.
This will further reduce one round-trip of messages. This will further reduce one round-trip of messages.
In such cases, the server MAY have thrown out the corresponding The server MAY have thrown out the corresponding session from the
sessions from the session table. In this case, the server will session table. If so, the server will respond with a 401-STALE
respond with a 401-STALE message, indicating a new key exchange is message, indicating a new key exchange is required. The client
required. The client SHOULD retry constructing a req-KEX-C1 SHOULD retry constructing a req-KEX-C1 message in this case.
message in this case.
Figure 2 depicts the shortcut flows described above. Under the Figure 2 depicts the shortcut flows described above. Under the
appropriate settings and implementations, most of the requests to appropriate settings and implementations, most of the requests to
resources are expected to meet both the criteria, and thus only one resources are expected to meet both criteria, and thus only one
round-trip of request/responses will be required in most cases. round-trip of request/response will be required.
(A) omit first request (A) omit first request
(2 round trips) (2 round trips)
Client Server Client Server
| | | |
| --- req-KEX-C1 ----> | | --- req-KEX-C1 ----> |
| | | |
| <---- 401-KEX-S1 --- | | <---- 401-KEX-S1 --- |
| | | |
skipping to change at page 10, line 39 skipping to change at page 10, line 39
| | | | | | | |
| --- req-KEX-C1 ------> | | --- req-KEX-C1 ------> |
| | | |
| <------ 401-KEX-S1 --- | | <------ 401-KEX-S1 --- |
| | | |
| --- req-VFY-C -------> | | --- req-VFY-C -------> |
| | | |
| <------- 200-VFY-S --- | | <------- 200-VFY-S --- |
| | | |
Figure 2: Several alternative flows on protocol Figure 2: Several alternative protocol flows
For more details, see Sections 10 and 11. For more details, see Sections 10 and 11.
3. Message Syntax 3. Message Syntax
Throughout this specification, The syntax is denoted in the extended Throughout this specification, the syntax is denoted in the extended
augmented BNF syntax defined in [RFC7230] and [RFC5234]. The augmented BNF syntax defined in [RFC7230], and [RFC5234]. The
following elements are quoted from [RFC5234], [RFC7230] and following elements are quoted from [RFC5234], [RFC7230] and
[RFC7235]: DIGIT, ALPHA, SP, auth-scheme, quoted-string, auth-param, [RFC7235]: DIGIT, ALPHA, SP, auth-scheme, quoted-string, auth-param,
header-field, token, challenge, and credential. header-field, token, challenge, and credential.
The Mutual authentication protocol uses three headers: The Mutual authentication protocol uses three headers:
WWW-Authenticate (usually in responses with status code 401), WWW-Authenticate (usually in responses with status code 401),
Authorization (in requests), and Authentication-Info (in responses Authorization (in requests), and Authentication-Info (in responses
other than 401 status). These headers follow a common framework other than 401 status). These headers follow a common framework
described in [RFC7235] and [RFC7615]. The detailed meanings for described in [RFC7235] and [RFC7615]. The detailed meanings for
these headers are contained in Section 4. these headers are contained in Section 4.
skipping to change at page 11, line 23 skipping to change at page 11, line 23
WWW-Authenticate and Authorization as the syntax elements "challenge" WWW-Authenticate and Authorization as the syntax elements "challenge"
and "credentials", respectively. The "auth-scheme" contained in and "credentials", respectively. The "auth-scheme" contained in
those headers MUST be "Mutual" throughout this protocol those headers MUST be "Mutual" throughout this protocol
specification. The syntax for "challenge" and "credentials" to be specification. The syntax for "challenge" and "credentials" to be
used with the "Mutual" auth-scheme SHALL be name-value pairs (#auth- used with the "Mutual" auth-scheme SHALL be name-value pairs (#auth-
param), not the "b64token" defined in [RFC7235]. param), not the "b64token" defined in [RFC7235].
The Authentication-Info: header used in this protocol SHALL follow The Authentication-Info: header used in this protocol SHALL follow
the syntax defined in [RFC7615]. the syntax defined in [RFC7615].
In HTTP, the WWW-Authenticate header may contain more than one In HTTP, the WWW-Authenticate header may contain two or more
challenges. Client implementations SHOULD be aware of and be capable challenges. Client implementations SHOULD be aware of and be capable
of handle those cases correctly. of handling those cases correctly.
3.1. Non-ASCII extended header parameters 3.1. Non-ASCII extended header parameters
All of parameters contained in the above three headers, except the All of parameters contained in the above three headers, except the
"realm" field, MAY be extended to ISO 10646-1 values using the "realm" field, MAY be extended to ISO 10646-1 values using the
framework described in [RFC5987]. All servers and clients MUST be framework described in [RFC5987]. All servers and clients MUST be
capable of receiving and sending values encoded in [RFC5987] syntax. capable of receiving and sending values encoded in [RFC5987] syntax.
If a value to be sent contains only ASCII characters, the field MUST If a value to be sent contains only ASCII characters, the field MUST
be sent in clear using plain RFC 7235 syntax. The syntax extended by be sent using plain RFC 7235 syntax. The syntax as extended by RFC
RFC 5987 MUST NOT be used in this case. 5987 MUST NOT be used in this case.
If a value (except the "realm" header) contains one or more non-ASCII If a value (except the "realm" header) contains one or more non-ASCII
characters, the parameter SHOULD be sent using the syntax defined in characters, the parameter SHOULD be sent using the syntax defined in
Section 3.2 of [RFC5987] as "ext-parameter". Such parameter MUST Section 3.2 of [RFC5987] as "ext-parameter". Such a parameter MUST
have charset value of "UTF-8", and the language value MUST always be have a charset value of "UTF-8", and the language value MUST always
omitted (have an empty value). The same parameter MUST NOT be sent be omitted (have an empty value). The same parameter MUST NOT be
twice or more, those in both plain- and extended-syntax. sent more than once, regardless of the used syntax.
For example, a parameter "user" with value "Renee or France" SHOULD For example, a parameter "user" with value "Renee of France" SHOULD
be sent as < user="Renee of France" >. If the value is "Ren<e be sent as < user="Renee of France" >. If the value is
acute>e of France", it SHOULD be sent as < user*=UTF- "Ren<e acute>e of France", it SHOULD be sent as < user*=UTF-
8''Ren%C3%89e%20of%20France > instead. 8''Ren%C3%89e%20of%20France > instead.
[RFC7235] requires realm parameter to be exist as its plain form (not [RFC7235] requires the realm parameter to be in its plain form (not
as extended "realm*" parameter), so RFC 5987 syntax MUST NOT be used as an extended "realm*" parameter), so RFC 5987 syntax MUST NOT be
for this parameter. used for this parameter.
3.2. Values 3.2. Values
The parameter values contained in challenge/credentials MUST be The parameter values contained in challenge/credentials MUST be
parsed strictly conforming to the HTTP semantics (especially un- parsed strictly conforming to the HTTP semantics (especially un-
quoting of the string parameter values). In this protocol, those quoting of the string parameter values). In this protocol, those
values are further categorized into the following value types: tokens values are further categorized into the following value types: tokens
(bare-token and extensive-token), string, integer, hex-fixed-number, (bare-token and extensive-token), string, integer, hex-fixed-number,
and base64-fixed-number. and base64-fixed-number.
For clarity, implementations are RECOMMENDED to use the canonical For clarity, implementations are RECOMMENDED to use the canonical
representations specified in the following subsections for sending representations specified in the following subsections for sending
values. Recipients SHOULD accept both quoted and unquoted values. Recipients SHOULD accept both quoted and unquoted
representations interchangeably as specified in HTTP. representations interchangeably as specified in HTTP.
3.2.1. Tokens 3.2.1. Tokens
For sustaining both security and extensibility at the same time, this For sustaining both security and extensibility at the same time, this
protocol defines a stricter sub-syntax for the "token" to be used. protocol defines a stricter sub-syntax for the "token" to be used.
The extensive-token values SHOULD follow the following syntax (after Extensive-token values SHOULD use the following syntax (after HTTP
HTTP value parsing): value parsing):
bare-token = 1*(DIGIT / ALPHA / "-" / "_") bare-token = 1*(DIGIT / ALPHA / "-" / "_")
extension-token = "-" bare-token 1*("." bare-token) extension-token = "-" bare-token 1*("." bare-token)
extensive-token = bare-token / extension-token extensive-token = bare-token / extension-token
Figure 3: BNF syntax for token values Figure 3: BNF syntax for token values
The tokens (bare-token and extension-token) are case insensitive; The tokens (bare-token and extension-token) are case insensitive;
Senders SHOULD send these in lower-case, and receivers MUST accept Senders SHOULD send these in lower case, and receivers MUST accept
both upper- and lower-cases. When tokens are used as (partial) both upper and lower cases. When tokens are used as (partial) inputs
inputs to any hash or other mathematical functions, it MUST always be to any hash or other mathematical functions, they MUST always be used
used in lower-case. in lower case.
Extensive-tokens are used in this protocol where the set of Extensive-tokens are used in this protocol where the set of
acceptable tokens may include non-standard extensions. Any non- acceptable tokens may include non-standard extensions. Any non-
standard extensions of this protocol SHOULD use the extension-tokens standard extension of this protocol SHOULD use the extension-token
with format "-<bare-token>.<domain-name>", where <domain-name> is a with the format "-<bare-token>.<domain-name>", where <domain-name> is
validly registered (sub-)domain name on the Internet owned by the a valid (sub-)domain name on the Internet owned by the party who
party who defines the extensions. defines the extension.
Bare-tokens and extensive-tokens are also used for parameter names Bare-tokens and extensive-tokens are also used for parameter names,
(of course in the unquoted form). Requirements for using the in the unquoted form. Requirements for using the extension-token for
extension-token for the parameter names are the same as the above. the parameter names are the same as the previous paragraph.
The canonical format for bare-tokens and tokens are unquoted tokens. The canonical format for bare-tokens and extensive-tokens is the
unquoted representation.
3.2.2. Strings 3.2.2. Strings
All character strings MUST be encoded to octet strings using the All character strings MUST be encoded to octet strings using the
UTF-8 encoding [RFC3629] for the ISO 10646-1 character set UTF-8 encoding [RFC3629] for the ISO 10646-1 character set
[ISO.10646-1.1993]. Such strings MUST NOT contain any leading BOM [ISO.10646-1.1993]. Such strings MUST NOT contain any leading BOM
characters (ZERO WIDTH NO-BREAK SPACE, U+FEFF or EF BB BF). Both characters (ZERO WIDTH NO-BREAK SPACE, U+FEFF or EF BB BF). Both
peers are RECOMMENDED to reject any invalid UTF-8 sequences that peers are RECOMMENDED to reject any invalid UTF-8 sequences that
might cause decoding ambiguities (e.g., containing <"> in the second might cause decoding ambiguities (e.g., containing <"> in the second
or later bytes of the UTF-8 encoded characters). or later bytes of the UTF-8 encoded characters).
If strings are representing a domain name or URI that contains non- If strings are representing a domain name or URI that contains non-
ASCII characters, the host parts SHOULD be encoded as it is used in ASCII characters, the host parts SHOULD be encoded as it is used in
the HTTP protocol layer (e.g. in a Host: header); under current the HTTP protocol layer (e.g., in a Host: header); under current
standards it will be the one defined in [RFC5890]. It SHOULD use standards it will be the one defined in [RFC5890]. It SHOULD use
lower-case ASCII characters. lower-case ASCII characters.
The canonical format for strings are quoted-string (as it may contain The canonical format for strings is quoted-string (as it may contain
equal signs, plus signs and slashes), unless the parameter containing equal signs, plus signs and slashes), unless the parameter containing
the string value will use extended syntax defined in [RFC5987]. the string value will use extended syntax defined in [RFC5987]. (An
([RFC5987] extended parameter will have unquoted encoded value, as [RFC5987] extended parameter will have an unquoted encoded value, as
defined there.) defined therein.)
3.2.3. Numbers 3.2.3. Numbers
The following syntax definitions gives a syntax for number-type The following syntax definitions give a syntax for numeric values:
values:
integer = "0" / (%x31-39 *DIGIT) ; no leading zeros integer = "0" / (%x31-39 *DIGIT) ; no leading zeros
hex-fixed-number = 1*(2(DIGIT / %x41-46 / %x61-66)) hex-fixed-number = 1*(2(DIGIT / %x41-46 / %x61-66))
base64-fixed-number = 1*( ALPHA / DIGIT / "+" / "/" ) 0*2"=" base64-fixed-number = 1*( ALPHA / DIGIT / "+" / "/" ) 0*2"="
Figure 4: BNF syntax for number types Figure 4: BNF syntax for numbers
The syntax definition of the integers only allows representations The syntax definition of the integers only allows representations
that do not contain extra leading zeros. that do not contain leading zeros.
The numbers represented as a hex-fixed-number MUST include an even
number of characters (i.e. multiples of eight bits). Those values
are case-insensitive, and SHOULD be sent in lower-case. When these
values are generated from any cryptographic values, they SHOULD have
their "natural length": if these are generated from a hash function,
these lengths SHOULD correspond to the hash size; if these are
representing elements of a mathematical set (or group), its lengths
SHOULD be the shortest for representing all the elements in the set.
For example, any results of SHA-256 hash function will be represented
by 64 characters, and any elements in 2048-bit prime field (modulo a
2048-bit integer) will be represented by 512 characters, regardless
of how much 0's will be appear in front of such representations.
A number represented as a hex-fixed-number MUST include an even
number of hexadecimal digits (i.e., multiples of eight bits). Those
values are case-insensitive, and SHOULD be sent in lower case. When
these values are generated from any cryptographic values, they SHOULD
have their "natural length"; if these are generated from a hash
function, these lengths SHOULD correspond to the hash size; if these
are representing elements of a mathematical set (or group), its
lengths SHOULD be the shortest for representing all the elements in
the set. For example, the results of the SHA-256 hash function will
be represented by 64 digits, and any elements in a 2048-bit prime
field (modulo a 2048-bit integer) will be represented by 512 digits,
regardless of how much zeros appear in front of such representations.
Session-identifiers and other non-cryptographically generated values Session-identifiers and other non-cryptographically generated values
are represented in any (even) length determined by the side who are represented in any (even) length determined by the side that
generates it first, and the same length SHALL be used throughout the generates it first, and the same length SHALL be used throughout all
all communications by both peers. communications by both peers.
The numbers represented as base64-fixed-number SHALL be generated as The numbers represented as base64-fixed-number SHALL be generated as
follows: first, the number is converted to a big-endian radix-256 follows: first, the number is converted to a big-endian radix-256
binary representation as an octet string. The length of the binary representation as an octet string. The length of the
representation is determined in the same way as mentioned above. representation is determined in the same way as mentioned above.
Then, the string is encoded using the Base 64 encoding [RFC4648] Then, the string is encoded using the Base 64 encoding [RFC4648]
without any spaces and newlines. Implementations decoding base64- without any spaces and newlines. Implementations decoding base64-
fixed-number SHOULD reject any input data with invalid characters, fixed-number SHOULD reject any input data with invalid characters,
excess/insufficient padding, or non-canonical pad bits (See Sections excess/insufficient padding, or non-canonical pad bits (See Sections
3.1 to 3.5 of [RFC4648]). 3.1 to 3.5 of [RFC4648]).
The canonical format for integer and hex-fixed-number are unquoted The canonical format for integer and hex-fixed-number are unquoted
tokens, and that for base64-fixed-number is quoted-string. tokens, and that for base64-fixed-number is quoted-string.
4. Messages 4. Messages
In this section we define the seven kinds of messages used in the In this section we define the seven kinds of messages used in the
authentication protocol along with the formats and requirements of authentication protocol along with the formats and requirements of
the headers for each message. the headers for each message.
To determine which message are expected to be sent, see Sections 10 To determine in what circumstances each message is expected to be
and 11. sent, see Sections 10 and 11.
In the descriptions below, the type of allowable values for each In the descriptions below, the type of allowable values for each
header parameter is shown in parenthesis after each parameter name. header parameter is shown in parenthesis after each parameter name.
The "algorithm-determined" type means that the acceptable value for The "algorithm-determined" type means that the acceptable value for
the parameter is one of the types defined in Section 3, and is the parameter is one of the types defined in Section 3, and is
determined by the value of the "algorithm" parameter. The parameters determined by the value of the "algorithm" parameter. The parameters
marked "mandatory" SHALL be contained in the message. The parameters marked "mandatory" SHALL be contained in the message. The parameters
marked "non-mandatory" MAY either be contained or omitted in the marked "non-mandatory" MAY either be contained or omitted in the
message. Each parameter SHALL appear in each headers exactly once at message. Each parameter SHALL appear in each header exactly once at
most. most.
All credentials and challenges MAY contain any parameters not All credentials and challenges MAY contain any parameters not
explicitly specified in the following sections. Recipients who do explicitly specified in the following sections. Recipients that do
not understand such parameters MUST silently ignore those. However, not understand such parameters MUST silently ignore those. However,
all credentials and challenges MUST meet the following criteria: all credentials and challenges MUST meet the following criteria:
o For responses, the parameters "reason", any "ks#" (where # stands o For responses, the parameters "reason", any "ks#" (where # stands
for any decimal integers), and "vks" are mutually exclusive: any for any decimal integer), and "vks" are mutually exclusive; any
challenge MUST NOT contain two or more parameters among them. challenge MUST NOT contain two or more parameters among them.
They MUST NOT contain any "kc#" and "vkc" parameters. They MUST NOT contain any "kc#" or "vkc" parameters.
o For requests, the parameters "kc#" (where # stands for any decimal o For requests, the parameters "kc#" (where # stands for any decimal
integers), and "vkc" are mutually exclusive and any challenge integer), and "vkc" are mutually exclusive and any challenge
MUST NOT contain two or more parameters among them. They MUST NOT MUST NOT contain two or more parameters among them. They MUST NOT
contain any "ks#" and "vks" parameters. contain any "ks#" or "vks" parameters.
Every message in this section contains a "version" field, to detect Every message in this section contains a "version" field, to detect
future incompatible revisions of the protocol. Implementations of future, incompatible revisions of the protocol. Implementations of
the protocol described in this specification MUST always send a token the protocol described in this specification MUST always send a token
"-wg-draft04", and recipients MUST reject messages which contain any "1", and recipients MUST reject messages that contain any other value
other value as a version, unless another specification defines a as a version, unless another specification defines a behavior for
behavior for that version. [[Editorial Note: This token is updated that version.
on every draft revisions which will affect the wire protocol. It
will (shall) be updated to "1" in the final published RFC.]]
4.1. 401-INIT and 401-STALE 4.1. 401-INIT and 401-STALE
Every 401-INIT or 401-STALE message SHALL be a valid HTTP 401-status Every 401-INIT or 401-STALE message SHALL be a valid HTTP 401-status
(Authentication Required) message (or other 4XX statuses if sensible) (Authentication Required) message (or other 4XX status if sensible)
containing one (and only one: hereafter not explicitly noticed) containing one and only one (hereafter not explicitly noted)
"WWW-Authenticate" header containing a "reason" parameter in the "WWW-Authenticate" header containing a "reason" parameter in the
challenge. The challenge SHALL contain all of the parameters marked challenge. The challenge SHALL contain all of the parameters marked
"mandatory" below, and MAY contain those marked "non-mandatory". "mandatory" below, and MAY contain those marked "non-mandatory".
version: (mandatory extensive-token) should be the token "-wg- version: (mandatory extensive-token) should be the token "1".
draft04".
algorithm: (mandatory extensive-token) specifies the algorithm: (mandatory extensive-token) specifies the
authentication algorithm to be used. The value MUST authentication algorithm to be used. The value MUST
be one of the tokens specified in be one of the tokens specified in
[I-D.ietf-httpauth-mutual-algo] or other supplemental [I-D.ietf-httpauth-mutual-algo] or another
specification documentation. supplemental specification.
validation: (mandatory extensive-token) specifies the method of validation: (mandatory extensive-token) specifies the method of
host validation. The value MUST be one of the tokens host validation. The value MUST be one of the tokens
described in Section 7, or the tokens specified in described in Section 7 or the tokens specified in
other supplemental specification documentation. another supplemental specification.
auth-scope: (non-mandatory string) specifies the authentication auth-scope: (non-mandatory string) specifies the authentication
scope, the set of hosts for which the authentication scope, the set of hosts for which the authentication
credentials are valid. It MUST be one of the strings credentials are valid. It MUST be one of the strings
described in Section 5. If the value is omitted, it described in Section 5. If the value is omitted, it
is assumed to be the "single-server" type domain in is assumed to be the "single-server" type domain in
Section 5. Section 5.
realm: (mandatory string) is a string representing the name realm: (mandatory string) is a string representing the name
of the authentication realm inside the authentication of the authentication realm inside the authentication
skipping to change at page 16, line 4 skipping to change at page 15, line 50
scope, the set of hosts for which the authentication scope, the set of hosts for which the authentication
credentials are valid. It MUST be one of the strings credentials are valid. It MUST be one of the strings
described in Section 5. If the value is omitted, it described in Section 5. If the value is omitted, it
is assumed to be the "single-server" type domain in is assumed to be the "single-server" type domain in
Section 5. Section 5.
realm: (mandatory string) is a string representing the name realm: (mandatory string) is a string representing the name
of the authentication realm inside the authentication of the authentication realm inside the authentication
scope. As specified in [RFC7235], this value MUST scope. As specified in [RFC7235], this value MUST
always be sent in the quoted-string form, and an always be sent in the quoted-string form, and an
[RFC5987] encoding MUST NOT be used. [RFC5987] encoding MUST NOT be used.
The realm value sent from the server SHOULD be an The realm value sent from the server SHOULD be an
ASCII string. Clients MAY treat any non-ASCII value ASCII string. Clients MAY treat any non-ASCII value
received in this field as one of a binary blob, an received in this field as a binary blob, an NFC-
NFC-normalized UTF-8 string, or an error. normalized UTF-8 string, or an error.
pwd-hash: (non-mandatory extensive-token) specifies the hash
algorithm (hereafter referred to by ph) used for
additionally hashing the password. The valid tokens
are
* none: ph(p) = p
* md5: ph(p) = MD5(p)
* sha1: ph(p) = SHA1(p)
If omitted, the value "none" is assumed. The use of
"none" is desirable.
reason: (mandatory extensive-token) SHALL be an extensive- reason: (mandatory extensive-token) SHALL be an extensive-
token which describes the possible reason of the token that describes the possible reason of the failed
failed authentication/authorization. Both servers and authentication/authorization. Both servers and
clients SHALL understand and support the following clients SHALL understand and support the following
three tokens: three tokens:
* initial: authentication was not tried because there * initial: authentication was not tried because there
was no Authorization header in the corresponding was no Authorization header in the corresponding
request. request.
* stale-session: the provided sid; in the request was * stale-session: the provided sid in the request was
either unknown to or expired in the server. either unknown to or expired in the server.
* auth-failed: authentication trial was failed by * auth-failed: authentication trial was failed for
some reasons, possibly with a bad authentication some reason, possibly with a bad authentication
credentials. credential.
Implementations MAY support the following tokens or Implementations MAY support the following tokens or
any extensive-tokens defined outside this any extensive-tokens defined outside this
specification. If clients has received any unknown specification. If clients receive any unknown tokens,
tokens, these SHOULD treat these as if it were "auth- they SHOULD treat these as if they were "auth-failed"
failed" or "initial". or "initial".
* reauth-needed: server-side application requires a * reauth-needed: the server-side application requires
new authentication trial, regardless of the current a new authentication trial, regardless of the
status. current status.
* invalid-parameters: authentication was not even * invalid-parameters: the server did not attempt
tried in the server-side because some parameters authentication because some parameters were not
are not acceptable. acceptable.
* internal-error: authentication was not even tried * internal-error: the server did not attempt
in the server-side because there is some troubles authentication because there are some troubles on
on the server-side. the server-side.
* user-unknown: a special case of auth-failed, * user-unknown: this is a special case of auth-
suggesting that the provided user-name is invalid. failed, suggesting that the provided user name is
The use of this parameter is NOT RECOMMENDED for invalid. The use of this parameter is
security implications, except for special-purpose NOT RECOMMENDED due to security implications,
applications which makes this value sense. except for special-purpose applications where it
makes sense.
* invalid-credential: ditto, suggesting that the * invalid-credential: ditto, suggesting that the
provided user-name was valid but authentication was provided user name was valid but authentication
failed. The use of this parameter is still failed. The use of this parameter is
NOT RECOMMENDED as the same as the above. NOT RECOMMENDED for security reasons.
* authz-failed: authentication was successful, but * authz-failed: authentication was successful, but
access to the specified resource is not authorized access to the specified resource is not authorized
to the specific authenticated user. (It might be to the specific authenticated user. (It might be
used along with either 401 or 403 status to used along with either a 401 or 403 status to
indicate that the authentication result is one of indicate that the authentication result is one of
highly likely reasons for the failed the existing reasons for the failed authorization.)
authorization.)
The algorithm specified in this header will determine the types The algorithm specified in this header will determine the types
(among those defined in Section 3) and the values for K_c1, K_s1, (among those defined in Section 3) and the values for K_c1, K_s1,
VK_c and VK_s. VK_c and VK_s.
Among these messages, those with the reason parameter of value Among these messages, those with the reason parameter of value
"stale-session" will be called "401-STALE" messages hereafter, "stale-session" will be called "401-STALE" messages hereafter,
because these have a special meaning in the protocol flow. Messages because these have a special meaning in the protocol flow. Messages
with any other reason parameters will be called "401-INIT" messages. with any other reason parameters will be called "401-INIT" messages.
4.2. req-KEX-C1 4.2. req-KEX-C1
Every req-KEX-C1 message SHALL be a valid HTTP request message Every req-KEX-C1 message SHALL be a valid HTTP request message
containing an "Authorization" header with a credential containing a containing an "Authorization" header with a credential containing a
"kc1" parameter. "kc1" parameter.
The credential SHALL contain the parameters with the following names: The credential SHALL contain the parameters with the following names:
version: (mandatory, extensive-token) should be the token "-wg- version: (mandatory, extensive-token) should be the token "1".
draft04".
algorithm, validation, auth-scope, realm: MUST be the same value as algorithm, validation, auth-scope, realm: MUST be the same values as
it is when received from the server. received from the server.
user: (mandatory, string) is the UTF-8 encoded name of the user: (mandatory, string) is the UTF-8 encoded name of the
user. The string SHOULD be prepared according to the user. The string SHOULD be prepared according to the
method presented in Section 9. method presented in Section 9.
kc1: (mandatory, algorithm-determined) is the client-side kc1: (mandatory, algorithm-determined) is the client-side
key exchange value K_c1, which is specified by the key exchange value K_c1, which is specified by the
algorithm that is used. algorithm that is used.
4.3. 401-KEX-S1 4.3. 401-KEX-S1
Every 401-KEX-S1 message SHALL be a valid HTTP 401-status Every 401-KEX-S1 message SHALL be a valid HTTP 401-status
(Authentication Required) response message containing a (Authentication Required) response message containing a
"WWW-Authenticate" header with a challenge containing a "ks1" "WWW-Authenticate" header with a challenge containing a "ks1"
parameter. parameter.
The challenge SHALL contain the parameters with the following names: The challenge SHALL contain the parameters with the following names:
version: (mandatory, extensive-token) should be the token "-wg- version: (mandatory, extensive-token) should be the token "1".
draft04".
algorithm, validation, auth-scope, realm: MUST be the same value as algorithm, validation, auth-scope, realm: MUST be the same values as
it is when received from the client. received from the client.
sid: (mandatory, hex-fixed-number) MUST be a session sid: (mandatory, hex-fixed-number) MUST be a session
identifier, which is a random integer. The sid SHOULD identifier, which is a random integer. The sid SHOULD
have uniqueness of at least 80 bits or the square of have uniqueness of at least 80 bits or the square of
the maximal estimated transactions concurrently the maximum estimated transactions concurrently
available in the session table, whichever is larger. available in the session table, whichever is larger.
See Section 6 for more details. See Section 6 for more details.
ks1: (mandatory, algorithm-determined) is the server-side ks1: (mandatory, algorithm-determined) is the server-side
key exchange value K_s1, which is specified by the key exchange value K_s1, which is specified by the
algorithm. algorithm.
nc-max: (mandatory, integer) is the maximal value of nonce nc-max: (mandatory, integer) is the maximum value of nonce
numbers that the server accepts. numbers that the server accepts.
nc-window: (mandatory, integer) the number of available nonce nc-window: (mandatory, integer) the number of available nonce
number slots that the server will accept. The value number slots that the server will accept. The value
of the nc-window parameter is RECOMMENDED to be 128 or of the nc-window parameter is RECOMMENDED to be 128 or
more. more.
time: (mandatory, integer) represents the suggested time (in time: (mandatory, integer) represents the suggested time (in
seconds) that the client can reuse the session seconds) that the client can reuse the session
represented by the sid. It is RECOMMENDED to be at represented by the sid. It is RECOMMENDED to be at
least 60. The value of this parameter is not directly least 60. The value of this parameter is not directly
linked to the duration that the server keeps track of linked to the duration that the server keeps track for
the session represented by the sid. the session represented by the sid.
path: (non-mandatory, string) specifies which path in the path: (non-mandatory, string) specifies which path in the
URI space the same authentication is expected to be URI space the same authentication is expected to be
applied. The value is a space-separated list of URIs, applied. The value is a space-separated list of URIs,
in the same format as it was specified in domain in the same format as it was specified in domain
parameter [RFC7616] for the Digest authentications. parameter [RFC7616] for Digest authentications. All
The all path elements contained in the parameter MUST path elements contained in the parameter MUST be
be inside the specified auth-scope; if not, clients inside the specified auth-scope; if not, clients
SHOULD ignore such elements. For better performance, SHOULD ignore such elements. For better performance,
recognition of this parameter by clients are recognition of this parameter by clients is important.
significantly important.
4.4. req-VFY-C 4.4. req-VFY-C
Every req-VFY-C message SHALL be a valid HTTP request message Every req-VFY-C message SHALL be a valid HTTP request message
containing an "Authorization" header with a credential containing a containing an "Authorization" header with a credential containing a
"vkc" parameter. "vkc" parameter.
The parameters contained in the header are as follows: The parameters contained in the header are as follows:
version: (mandatory, extensive-token) should be the token "-wg- version: (mandatory, extensive-token) should be the token "1".
draft04".
algorithm, validation, auth-scope, realm: MUST be the same value as algorithm, validation, auth-scope, realm: MUST be the same values as
it is when received from the server for the session. received from the server for the session.
sid: (mandatory, hex-fixed-number) MUST be one of the sid sid: (mandatory, hex-fixed-number) MUST be one of the sid
values that was received from the server for the same values that was received from the server for the same
authentication realm. authentication realm.
nc: (mandatory, integer) is a nonce request number that is nc: (mandatory, integer) is a nonce request number that is
unique among the requests sharing the same sid. The unique among the requests sharing the same sid. The
values of the nonce numbers SHOULD satisfy the values of the nonce numbers SHOULD satisfy the
properties outlined in Section 6. properties outlined in Section 6.
vkc: (mandatory, algorithm-determined) is the client-side vkc: (mandatory, algorithm-determined) is the client-side
authentication verification value VK_c, which is authentication verification value VK_c, which is
specified by the algorithm. specified by the algorithm.
4.5. 200-VFY-S 4.5. 200-VFY-S
Every 200-VFY-S message SHALL be a valid HTTP message that is not of Every 200-VFY-S message SHALL be a valid HTTP message that does not
the 401 (Authentication Required) status, containing an have a 401 (Authentication Required) status code and SHALL contain an
"Authentication-Info" header with a "vks" parameter. "Authentication-Info" header with a "vks" parameter.
The parameters contained in the header are as follows: The parameters contained in the header are as follows:
version: (mandatory, extensive-token) should be the token "-wg- version: (mandatory, extensive-token) should be the token "1".
draft04".
sid: (mandatory, hex-fixed-number) MUST be the value sid: (mandatory, hex-fixed-number) MUST be the value
received from the client. received from the client.
vks: (mandatory, algorithm-determined) is the server-side vks: (mandatory, algorithm-determined) is the server-side
authentication verification value VK_s, which is authentication verification value VK_s, which is
specified by the algorithm. specified by the algorithm.
The header MUST be sent before the content body: it MUST NOT be sent The header MUST be sent before the content body: it MUST NOT be sent
in the trailer of a chunked-encoded response. If a "100 Continue" in the trailer of a chunked-encoded response. If a "100 Continue"
response is sent from the server, the Authentication-Info header response is sent from the server, the Authentication-Info header
SHOULD be included in that response, instead of the final response. SHOULD be included in that response, instead of the final response.
5. Authentication Realms 5. Authentication Realms
In this protocol, an "authentication realm" is defined as a set of In this protocol, an "authentication realm" is defined as a set of
resources (URIs) for which the same set of user names and passwords resources (URIs) for which the same set of user names and passwords
is valid for. If the server requests authentication for an is valid. If the server requests authentication for an
authentication realm that the client is already authenticated for, authentication realm that the client is already authenticated for,
the client will automatically perform the authentication using the the client will automatically perform the authentication using the
already-known secrets. However, for the different authentication already-known credentials. However, for different authentication
realms, the clients MUST NOT automatically reuse the user names and realms, clients MUST NOT automatically reuse user names and passwords
passwords for another realm. for another realm.
Just like in Basic and Digest access authentication protocols, Mutual Just like in the Basic and Digest access authentication protocols,
authentication protocol supports multiple, separate protection spaces the Mutual authentication protocol supports multiple, separate
to be set up inside each host. Furthermore, the protocol supports protection spaces to be set up inside each host. Furthermore, the
that a single authentication realm spans over several hosts within protocol allows a single authentication realm to span over several
the same Internet domain. hosts within the same Internet domain.
Each authentication realm is defined and distinguished by the triple Each authentication realm is defined and distinguished by the triple
of an "authentication algorithm", an "authentication scope", and a of an "authentication algorithm", an "authentication scope", and a
"realm" parameter. However, server operators are NOT RECOMMENDED to "realm" parameter. However, server operators are NOT RECOMMENDED to
use the same pair of an authentication scope and a realm for use the same pair of an authentication scope and a realm with
different authentication algorithms. different authentication algorithms.
The realm parameter is a string as defined in Section 4. The realm parameter is a string as defined in Section 4.
Authentication scopes are described in the remainder of this section. Authentication scopes are described in the remainder of this section.
An authentication scope specifies the range of hosts that the An authentication scope specifies the range of hosts that the
authentication realm spans over. In this protocol, it MUST be one of authentication realm spans over. In this protocol, it MUST be one of
the following kinds of strings. the following kinds of strings.
o Single-server type: The string in format "<scheme>://<host>" or o Single-server type: A string in the format "<scheme>://<host>" or
"<scheme>://<host>:<port>", where <scheme>, <host>, and <port> are "<scheme>://<host>:<port>", where <scheme>, <host>, and <port> are
the corresponding URI parts of the request URI. If the default the corresponding URI parts of the request URI. If the default
port (i.e. 80 for http and 443 for https) is used for the port (i.e., 80 for http and 443 for https) is used for the
underlying HTTP communications, the port part MUST be omitted, underlying HTTP communications, the port part MUST be omitted,
regardless of whether it was present in the request-URI. In other regardless of whether it was present in the request-URI. In all
cases, the port part MUST be present, and it MUST NOT contain other cases, the port part MUST be present, and it MUST NOT
leading zeros. Use this when authentication is only valid for contain leading zeros. Use this format when authentication is
specific protocol (such as https). This format is equivalent to only valid for a specific protocol (such as https). This format
the ASCII serialization of a Web Origin, presented in Section 6.2 is equivalent to the ASCII serialization of a Web Origin,
of [RFC6454]. presented in Section 6.2 of [RFC6454].
o Single-host type: The "host" part of the requested URI. This is o Single-host type: The "host" part of the requested URI. This is
the default value. Authentication realms within this kind of the default value. Authentication realms within this kind of
authentication scope will span over several protocols (i.e. http authentication scope will span over several protocols (e.g., http
and https) and ports, but not over different hosts. and https) and ports, but not over different hosts.
o Wildcard-domain type: The string in format "*.<domain-postfix>", o Wildcard-domain type: A string in the format "*.<domain-postfix>",
where <domain-postfix> is either the host part of the requested where <domain-postfix> is either the host part of the requested
URI or any domain in which the requested host is included (this URI or any domain in which the requested host is included (this
means that the specification "*.example.com" is valid for all of means that the specification "*.example.com" is valid for all of
hosts "www.example.com", "web.example.com", hosts "www.example.com", "web.example.com",
"www.sales.example.com" and "example.com"). The domain-postfix "www.sales.example.com" and "example.com"). The domain-postfix
sent from the servers MUST be equal to or included in a valid sent by the servers MUST be equal to or included in a valid
Internet domain assigned to a specific organization: if clients Internet domain assigned to a specific organization; if clients
know, by some means such as a blacklist for HTTP cookies know, by some means such as a blacklist for HTTP cookies
[RFC6265], that the specified domain is not to be assigned to any [RFC6265], that the specified domain is not to be assigned to any
specific organization (e.g. "*.com" or "*.jp"), the clients are specific organization (e.g., "*.com" or "*.jp"), clients are
RECOMMENDED to reject the authentication request. RECOMMENDED to reject the authentication request.
In the above specifications, every "scheme", "host", and "domain" In the above specifications, every "scheme", "host", and "domain"
MUST be in lower-case, and any internationalized domain names beyond MUST be in lower case, and any internationalized domain names beyond
the ASCII character set SHALL be represented in the way they are sent the ASCII character set SHALL be represented in the way they are sent
in the underlying HTTP protocol, represented in lower-case in the underlying HTTP protocol, represented in lower case
characters; i.e. these SHALL be in the form of the LDH labels in IDNA characters, i.e., these domain names SHALL be in the form of LDH
[RFC5890]. All "port"s MUST be in the shortest, unsigned, decimal labels in IDNA [RFC5890]. A "port" MUST be given in the shortest,
number notation. Not obeying these requirements will cause failure unsigned, decimal number notation. Not obeying these requirements
of valid authentication attempts. will cause failure of valid authentication attempts.
5.1. Resolving Ambiguities 5.1. Resolving Ambiguities
In the above definitions of authentication scopes, several scopes In the above definitions of authentication scopes, several scopes may
will overlap each other. If a client has already been authenticated overlap each other. If a client has already been authenticated to
to several realms applicable to the same server, the client may have several realms applicable to the same server, the client may have a
a multiple list of the "path" parameters received with the multiple lists of the "path" parameters received with the
"401-KEX-S1" message (see Section 4). If these path lists have any "401-KEX-S1" message (see Section 4). If these path lists have any
overlap, a single URI may belong to multiple possible candidate of overlap, a single URI may belong to multiple possible candidate of
realms to be authenticated to. In such cases, clients faces an realms to be authenticated to. In such cases, clients faces an
ambiguity on deciding which credentials to be sent for a new request ambiguity in deciding which credentials to send for a new request (in
(in steps 3 and 4 of the decision procedure presented in Section 10). steps 3 and 4 of the decision procedure presented in Section 10).
In such cases, clients MAY send requests which belongs to any of In such cases, a client MAY send request which belong to any of these
these candidate realms freely, or it MAY simply send an candidate realms freely, or it MAY simply send an unauthenticated
unauthenticated request and see for which realm the server request an request and see for which realm the server requests an
authentication. Server operators are RECOMMENDED to provide authentication. Server operators are RECOMMENDED to provide
properly-configured "path" parameters (more precisely, disjoint path properly-configured "path" parameters (more precisely, disjoint path
sets for each realms) for clients so that such ambiguities will not sets for each realms) for clients so that such ambiguities will not
occur. occur.
The following procedure are one of the possible tactics for resolving The following procedure is one possible tactic for resolving
ambiguity in such cases. ambiguity in such cases.
o If the client has previously sent a request to the same URI, and o If the client has previously sent a request to the same URI, and
if it remembers the authentication realm requested by 401-INIT if it remembers the authentication realm requested by the 401-INIT
messages at that time, use that realm. message at that time, use that realm.
o In other cases, use one of authentication realms representing the o In other cases, use one of the authentication realms representing
most-specific authentication scopes. From the list of possible the most-specific authentication scopes. The list of possible
domain specifications shown above, each one earlier has priority domain specifications shown above is given from most specific to
over ones described after that. least specific.
If there are several choices with different domain-postfix If there are several choices with different wildcard-domain
specifications, the one that has the longest domain-postfix has specifications, the one that has the longest domain-postfix has
priority over ones with a shorter domain-postfix. priority over ones with shorter domain-postfixes.
o If there are realms with the same authentication scope, there is o If there are realms with the same authentication scope, there is
no defined priority: the client MAY choose any one of the possible no defined priority; the client MAY choose any one of the possible
choices. choices.
6. Session Management 6. Session Management
In the Mutual authentication protocol, a session represented by an In the Mutual authentication protocol, a session represented by an
sid is set up using first four messages (first request, 401-INIT, sid is set up using four messages (first request, 401-INIT,
req-KEX-C1 and 401-KEX-S1), and a "session secret" (z) associated req-KEX-C1 and 401-KEX-S1), after which a "session secret" (z)
with the session is established. After sharing a session secret, associated with the session is established. After mutually
this session, along with the secret, can be used for one or more establishing a session secret, this session, along with the secret,
requests for resources protected by the same realm in the same can be used for one or more requests for resources protected by the
server. Note that session management is only an inside detail of the same realm on the same server. Note that session management is only
protocol and usually not visible to normal users. If a session an inside detail of the protocol and usually not visible to normal
expires, the client and server SHOULD automatically re-establish users. If a session expires, the client and server SHOULD
another session without informing the users. automatically re-establish another session without informing the
user.
Sessions and session identifiers are local to each server (defined by Sessions and session identifiers are local to each server (defined by
scheme, host and port), even if an authentication scope covers scheme, host, and port), even if an authentication scope covers
multiple servers; the clients MUST establish separate sessions for multiple servers; clients MUST establish separate sessions for each
each port of a host to be accessed. Furthermore, sessions and port of a host to be accessed. Furthermore, sessions and identifiers
identifiers are also local to each authentication realm, even if are also local to each authentication realm, even if these are
these are provided from the same server. The same session provided by the same server. The same session identifiers provided
identifiers provided either from different servers or for different either from different servers or for different realms MUST be treated
realms MUST be treated as independent ones. as independent or each other.
The server SHOULD accept at least one req-VFY-C request for each The server SHOULD accept at least one req-VFY-C request for each
session, given that the request reaches the server in a time window session, if the request reaches the server in a time window specified
specified by the timeout parameter in the 401-KEX-S1 message, and by the timeout parameter in the 401-KEX-S1 message, and there are no
that there are no emergent reasons (such as flooding attacks) to emergent reasons (such as flooding attacks) to forget the session.
forget the sessions. After that, the server MAY discard any session After that, the server MAY discard any session at any time and MAY
at any time and MAY send 401-STALE messages for any req-VFY-C send 401-STALE messages for any further req-VFY-C requests received
requests. for that session.
The client MAY send two or more requests using a single session The client MAY send two or more requests using a single session
specified by the sid. However, for all such requests, each value of specified by the sid. However, for all such requests, each value of
the nonce number (in the nc parameter) MUST satisfy the following the nonce number (in the nc parameter) MUST satisfy the following
conditions: conditions:
o It is a natural number. o It is a natural number.
o The same nonce number was not sent within the same session. o The same nonce number was not sent within the same session.
o It is not larger than the nc-max value that was sent from the o It is not larger than the nc-max value that was sent from the
server in the session represented by the sid. server in the session represented by the sid.
o It is larger than (largest-nc - nc-window), where largest-nc is o It is larger than (largest-nc - nc-window), where largest-nc is
the maximal value of nc which was previously sent in the session, the largest value of nc which was previously sent in the session,
and nc-window is the value of the nc-window parameter which was and nc-window is the value of the nc-window parameter that was
received from the server in the session. received from the server for the session.
The last condition allows servers to reject any nonce numbers that The last condition allows servers to reject any nonce numbers that
are "significantly" smaller than the "current" value (defined by the are "significantly" smaller than the "current" value (defined by the
value of nc-window) of the nonce number used in the session involved. value of nc-window) of the nonce number used in the session involved.
In other words, servers MAY treat such nonce numbers as "already In other words, servers MAY treat such nonce numbers as "already
received". This restriction enables servers to implement duplicated received". This restriction enables servers to implement duplicate
nonce detection in a constant amount of memory (for each session). nonce detection in a constant amount of memory for each session.
Servers MUST check for duplication of the received nonce numbers, and Servers MUST check for duplication of the received nonce numbers, and
if any duplication is detected, the server MUST discard the session if any duplication is detected, the server MUST discard the session
and respond with a 401-STALE message, as outlined in Section 11. The and respond with a 401-STALE message, as outlined in Section 11. The
server MAY also reject other invalid nonce numbers (such as ones server MAY also reject other invalid nonce numbers (such as ones
above the nc-max limit) by sending a 401-STALE message. above the nc-max limit) by sending a 401-STALE message.
For example, assume the nc-window value of the current session is For example, assume the nc-window value of the current session is
128, nc-max is 400, and that the client has already used the 128, nc-max is 400, and that the client has already used the
following nonce numbers: {1-120, 122, 124, 130-238, 255-360, 363- following nonce numbers: {1-120, 122, 124, 130-238, 255-360, 363-
372}. Then the nonce number that can be used for next request is one 372}. Then the nonce number that can be used for the next request is
of the following set: {245-254, 361, 362, 373-400}. The values {0, one of the following set: {245-254, 361, 362, 373-400}. The values
121, 123, 125-129, 239-244} MAY be rejected by the server, because {0, 121, 123, 125-129, 239-244} MAY be rejected by the server because
they are not above the current "window limit" (244 = 372 - 128). they are not above the current "window limit" (244 = 372 - 128).
Typically, clients can ensure the above property by using a Typically, clients can ensure the above property by using a
monotonically-increasing integer counter that counts from zero upto monotonically-increasing integer counter that counts from zero up to
the value of nc-max. the value of nc-max.
The values of the nonce numbers and any nonce-related values MUST The values of the nonce numbers and any nonce-related values MUST
always be treated as natural numbers within an infinite range. always be treated as natural numbers within an infinite range.
Implementations which uses fixed-width integer representations, Implementations which uses fixed-width integer representations,
fixed-precision floating numbers or similar representations fixed-precision floating-point numbers, or similar representations
SHOULD NOT reject any larger values which overflow such SHOULD NOT reject any larger values which overflow such
representative limits, and MUST NOT silently truncate it using any representative limits, and MUST NOT silently truncate them using any
modulus-like rounding operation (e.g. by mod 2^32). Instead, the modulus-like rounding operation (e.g., by mod 2^32). Instead, the
whole protocol is carefully designed so that recipients MAY replace whole protocol is carefully designed so that recipients MAY replace
any such overflowed values (e.g. 2^80) with some reasonably-large any such overflowing values (e.g. 2^80) with some reasonably-large
maximal representative integer (e.g. 2^31 - 1 or others). maximum representative integer (e.g., 2^31 - 1 or others).
7. Host Validation Methods 7. Host Validation Methods
The "validation method" specifies a method to "relate" (or "bind") The "validation method" specifies a method to "relate" (or "bind")
the mutual authentication processed by this protocol with other the mutual authentication processed by this protocol with other
authentications already performed in the underlying layers and to authentications already performed in the underlying layers and to
prevent man-in-the-middle attacks. It decides the value vh that is prevent man-in-the-middle attacks. It determines the value vh that
an input to the authentication protocols. is an input to the authentication protocols.
When HTTPS or other possible secure transport is used, this When HTTPS or other possible secure transport is used, this
corresponds to the idea of "channel binding" described in [RFC5929]. corresponds to the idea of "channel binding" described in [RFC5929].
Even when HTTP is used, similar, but somewhat limited, "binding" is Even when HTTP is used, similar, but somewhat limited, "binding" is
performed to prevent a malicious server from trying to authenticate performed to prevent a malicious server from trying to authenticate
themselves to another server as a valid user by forwarding the itself to another server as a valid user by forwarding the received
received credentials. credentials.
The valid tokens for the validation parameter and corresponding The valid tokens for the validation parameter and corresponding
values of vh are as follows: values of vh are as follows:
host: host-name validation: The value vh will be the ASCII host: host-name validation: The value vh will be the ASCII
string in the following format: string in the following format:
"<scheme>://<host>:<port>", where <scheme>, <host>, "<scheme>://<host>:<port>", where <scheme>, <host>,
and <port> are the URI components corresponding to the and <port> are the URI components corresponding to the
currently accessing resource. The scheme and host are currently accessing resource. The scheme and host are
in lower-case, and the port is in a shortest decimal in lower case, and the port is in a shortest decimal
representation. Even if the request-URI does not have representation. Even if the request-URI does not have
a port part, v will include the default port number. a port part, v will include the default port number.
tls-server-end-point: TLS endpoint (certificate) validation: The tls-server-end-point: TLS endpoint (certificate) validation: The
value vh will be the octet string of the hash value of value vh will be the octet string of the hash value of
the server's public key certificate used in the the server's public key certificate used in the
underlying TLS [RFC5246] (or SSL) connection, underlying TLS [RFC5246] connection, processed as
processed as specified in Section 4.1 of [RFC5929]. specified in Section 4.1 of [RFC5929].
[[Pending editorial issue: a small security issue is
pending around here, awaiting analysis and WG
discussions for final adoption.]]
tls-unique: TLS shared-key validation: The value v will be the tls-unique: TLS shared-key validation: The value vh will be the
channel binding material derived from the Finished channel binding material derived from the Finished
messages, as defined in Section 3.1 of [RFC5929]. messages, as defined in Section 3.1 of [RFC5929].
(Note: see Section 7.2 for some security notices for (Note: see Section 7.2 for some security notices when
using this validation method.) using this validation method.)
If the HTTP protocol is used on a non-encrypted channel (TCP and If HTTP is used on a non-encrypted channel (TCP and SCTP, for
SCTP, for example), the validation type MUST be "host". If HTTP/TLS example), the validation type MUST be "host". If HTTP/TLS [RFC2818]
[RFC2818] (HTTPS) protocol is used with the server certificates, the (HTTPS) is used with a server certificate, the validation type MUST
validation type MUST be "tls-server-end-point". If HTTP/TLS protocol be "tls-server-end-point". If HTTP/TLS is used with an anonymous
is used with an anonymous Diffie-Hellman key exchange, the validation Diffie-Hellman key exchange, the validation type MUST be "tls-unique"
type MUST be "tls-unique" (see the note below). (see the note below).
Implementations supporting a Mutual authentication over the HTTPS Implementations supporting Mutual authentication over HTTPS SHOULD
protocol SHOULD support the "tls-server-end-point" validation. support the "tls-server-end-point" validation. Support for
Support for "tls-unique" validation is OPTIONAL for both the servers "tls-unique" validation is OPTIONAL for both servers and clients.
and clients.
If the validation type "tls-server-end-point" is used, the server If the validation type "tls-server-end-point" is used, the server
certificate provided on TLS connection MUST be verified at least to certificate provided in the TLS connection MUST be verified at least
make sure that the server actually owns the corresponding secret key. to make sure that the server actually owns the corresponding private
(Note: this verification is automatic in some RSA-based key exchanges key. (Note: this verification is automatic in some RSA-based key
but NOT automatic in Diffie-Hellman-based key exchanges with separate exchanges but NOT automatic in Diffie-Hellman-based key exchanges
exchange for server verification.) with separate exchange for server verification.)
Clients MUST validate this parameter upon reception of the 401-INIT Clients MUST validate this parameter upon receipt of 401-INIT
messages. messages.
Note: The protocol defines two variants for validation on the TLS Note: The protocol defines two variants of validation on the TLS
connections. The "tls-unique" method is more secure. However, there connections. The "tls-unique" method is more secure. However, there
are some situations where tls-server-end-point is more preferable. are some situations where tls-server-end-point is more preferable.
o When TLS accelerating proxies are used, it is difficult for the o When TLS accelerating proxies are used, it is difficult for the
authenticating server to acquire the TLS key information that is authenticating server to acquire the TLS key information that is
used between the client and the proxy. This is not the case for used between the client and the proxy. This is not the case for
client-side "tunneling" proxies using a CONNECT method extension client-side "tunneling" proxies using the HTTP CONNECT method.
of HTTP.
o When a black-box implementation of the TLS protocol is used on o When a black-box implementation of the TLS protocol is used on
either peer. either peer.
7.1. Applicability notes 7.1. Applicability notes
When the client is a Web browser with any scripting capabilities, the When the client is a Web browser with any scripting capabilities, the
underlying TLS channel used with HTTP/TLS MUST provide server underlying TLS channel used with HTTP/TLS MUST provide server
identity verification. This means (1) the anonymous Diffie-Hellman identity verification. This means (1) anonymous Diffie-Hellman key
key exchange cipher-suite MUST NOT be used, and (2) the verification exchange cipher suites MUST NOT be used, and (2) verification of the
of the server certificate provided from the server MUST be performed. server certificate provided by the server MUST be performed.
For other systems, when the underlying TLS channel used with HTTP/TLS For other systems, when the underlying TLS channel used with HTTP/TLS
does not perform server identity verification, the client SHOULD does not perform server identity verification, the client SHOULD
ensure that all the responses are validated using the Mutual ensure that all the responses are validated using the Mutual
authentication protocol, regardless of the existence of the 401-INIT authentication protocol, regardless of the existence of 401-INIT
responses. responses.
7.2. Notes on tls-unique 7.2. Notes on tls-unique
As described in the interoperability note in the above channel As described in the interoperability note in the above channel
binding specification, the tls-unique verification value will be binding specification, the tls-unique verification value will be
changed by possible TLS renegotiation, causing an interoperability changed by possible TLS renegotiation, causing an interoperability
problem. TLS re-negotiations are used in several HTTPS server problem. TLS re-negotiations are used in several HTTPS server
implementations for enforcing some security properties (such as implementations for enforcing some security properties (such as
cryptographic strength) for some specific responses. cryptographic strength) for some specific responses.
If an implementation supports "tls-unique" verification method, the If an implementation supports the "tls-unique" verification method,
following caution SHOULD be taken: the following caution SHOULD be taken:
o Both peers must be aware that the values vh used for vkc (in o Both peers must be aware that the vh values used for vkc (in
req-VFY-C) and for vks (in 200-VFY-S) may be different. These req-VFY-C) and for vks (in 200-VFY-S) may be different. These
values MUST be retrieved from underlying TLS libraries each time values MUST be retrieved from underlying TLS libraries each time
it is used. they are used.
o After calculating value vh and vkc to send a req-VFY-C request, o After calculating the values vh and vkc to send a req-VFY-C
Clients SHOULD NOT initiate TLS renegotiation until the end of the request, Clients SHOULD NOT initiate TLS renegotiation until the
corresponding response header is received. Exceptionally, Clients end of the corresponding response header is received. An
can and SHOULD perform TLS re-negotiation as a response to exception is that clients can and SHOULD perform TLS re-
server's request for TLS renegotiation, occurring before the top negotiation as a response to the server's request for TLS
of response header. renegotiation, before receipt of the beginning of the response
header.
Also, implementer MUST take care of session resumption attacks Also, implementers MUST take care of session resumption attacks
regarding tls-unique channel binding mechanisms and master secrets. regarding tls-unique channel binding mechanisms and master secrets.
As a mitigation, a TLS extension defined in [RFC7627] SHOULD be used As a mitigation, a TLS extension defined in [RFC7627] SHOULD be used
when tls-unique host verification is to be used. when tls-unique host verification is to be used.
8. Authentication Extensions 8. Authentication Extensions
Interactive clients (e.g. Web browsers) supporting this protocol are Interactive clients (e.g., Web browsers) supporting this protocol are
RECOMMENDED to support non-mandatory authentication and the RECOMMENDED to support non-mandatory authentication and the
Authentication-Control header defined in Authentication-Control header defined in
[I-D.ietf-httpauth-extension], except the "auth-style" parameter. [I-D.ietf-httpauth-extension], except for the "auth-style" parameter.
This specification also proposes (however, not mandates) default This specification also proposes (however, does not mandate) the
"auth-style" to be "non-modal". Web applications SHOULD however default "auth-style" be "non-modal". Web applications SHOULD however
consider the security impacts of the behaviors of clients that do not consider the security impacts of the behaviors of clients that do not
support these headers. support these headers.
Authentication-initializing messages with the Authentication-initializing messages with the
Optional-WWW-Authenticate header are used only where 401-INIT Optional-WWW-Authenticate header are used only where the 401-INIT
response is valid. It will not replace other 401-type messages such response is valid. It will not replace other 401-type messages such
as 401-STALE and 401-KEX-S1. as 401-STALE and 401-KEX-S1.
9. String Preparation 9. String Preparation
It is important for interoperability that user-names and passwords It is important for interoperability that user names and passwords
used in this protocol is binary-comparable regardless of the user's used in this protocol are binary-comparable regardless of the user's
input methods and/or environments. To ensure this, the following input methods and/or environments. To ensure this, the following
preparation SHOULD be performed: preparation SHOULD be performed:
o User-names received from users SHOULD be prepared using the o User names received from users SHOULD be prepared using the
"UsernameCasePreserved" profile defined in Section 3.3 of "UsernameCasePreserved" profile defined in Section 3.3 of
[RFC7613]. [RFC7613].
o Passwords received from users SHOULD be prepared using the o Passwords received from users SHOULD be prepared using the
"OpaqueString" profile defined in Section 4.2 of [RFC7613]. "OpaqueString" profile defined in Section 4.2 of [RFC7613].
In both cases, it is the sender's duty to correctly preparing the In both cases, it is the sender's duty to correctly prepare the
character strings. If any non-normalized character string is character strings. If any non-normalized character string is
received from the other peer of the communication, recipients MAY received from the other peer of the communication, recipients MAY
either use it as a bare UTF-8 string without any preparation, perform either use it as a bare UTF-8 string without any preparation, perform
any appropriate preparations (which may cause authentication any appropriate preparations (which may cause authentication
failure), or reject any ill-prepared inputs from the sender and failure), or reject any ill-prepared inputs from the sender and
respond as a communication error. respond as a communication error.
Server applications SHOULD also prepare user-names and passwords Server applications SHOULD also prepare user names and passwords
accordingly upon registration of user credentials. accordingly upon registration of user credentials.
In addition, binary-based "interfaces" of implementations MAY require In addition, binary-based "interfaces" of implementations MAY require
and assume that the string is already prepared accordingly; in and assume that the string is already prepared accordingly; when a
detail, when a string is already stored as an binary Unicode string string is already stored as a binary Unicode string form,
form, implementations MAY omit preparation and Unicode normalization implementations MAY omit preparation and Unicode normalization
(performs UTF-8 encoding only) before using it. When a string is (performing UTF-8 encoding only) before using it. When a string is
already stored as an octet blob, implementations MAY send it as it already stored as an octet blob, implementations MAY send it as is.
is.
10. Decision Procedure for Clients 10. Decision Procedure for Clients
10.1. General Principles and Requirements 10.1. General Principles and Requirements
To securely implement the protocol, the user client must be careful To securely implement the protocol, the client must be careful about
about accepting the authenticated responses from the server. This accepting the authenticated responses from the server. This also
also holds true for the reception of "normal responses" (responses holds true for the reception of "normal responses" (responses which
which do not contain Mutual-related headers) from HTTP servers. do not contain Mutual authentication-related headers) from HTTP
servers.
As usual in the HTTP authentication, a single user-level request may As usual in the HTTP authentication, a single user-level request may
result in exchange of two-or-more HTTP requests and responses in result in exchange of two-or-more HTTP requests and responses in
sequence. The following normative rules MUST be followed by the all sequence. The following normative rules MUST be followed by the
clients implementing this protocol: clients implementing this protocol:
o Any kinds of "normal responses" MUST only be accepted for the very o Any kinds of "normal responses" MUST only be accepted for the very
first request in the sequence. Any "normal responses" returned first request in the sequence. Any "normal responses" returned
for the second or later request in the sequence SHALL be for the second or later requests in the sequence SHALL be
considered invalid. considered invalid.
o In the same principle, any responses which refer to, or request o In the same principle, any responses which refer to or request
changing to, the authentication realm different from the client's changing to an authentication realm different from the client's
request MUST only be accepted for the very first request in the request MUST only be accepted for the very first request in the
sequence. Any kind of responses referring to the different realms sequence. Any kind of responses referring to different realms
which are returned for the second or later request in the sequence which are returned for the second or later requests in the
SHALL be considered invalid. sequence SHALL be considered invalid.
o A req-KEX-C1 message MAY be sent either as a initial request or as o A req-KEX-C1 message MAY be sent either as a initial request or as
a response to 401-INIT, and 401-STALE. However, it SHOULD NOT be a response to 401-INIT or 401-STALE. However, it SHOULD NOT be
sent more than once in the sequence for a single authentication sent more than once in the sequence for a single authentication
realm, to avoid infinite loops of messages. A 401-KEX-S1 response realm, to avoid infinite loops of messages. A 401-KEX-S1 response
MUST be accepted only when the corresponding request is MUST be accepted only when the corresponding request is
req-KEX-C1. req-KEX-C1.
o A req-VFY-C message MAY be sent if there is a valid session key o A req-VFY-C message MAY be sent if there is a valid session key
shared between the client and the server, established by shared between the client and the server, established by
req-KEX-C1 and 401-KEX-S1. If any response with 401 status is req-KEX-C1 and 401-KEX-S1. If any response with 401 status is
returned for such a message, the corresponding session key SHOULD returned for such a message, the corresponding session key SHOULD
be discarded as unusable. be discarded as unusable.
Especially, upon the reception of response 401-STALE, the client Especially, upon the reception of a 401-STALE response, the client
SHOULD try establishing a new session by sending req-KEX-C1, but SHOULD try establishing a new session by sending req-KEX-C1, but
only once within the request/response sequence. only once within the request/response sequence.
o A 200-VFY-S message MUST be accepted only as a response to o A 200-VFY-S message MUST be accepted only as a response to
req-VFY-C and nothing else. The VK_s field of such response req-VFY-C and nothing else. The VK_s values of such response
message MUST always be checked against the correct value, and if messages MUST always be checked against the correct value, and if
it is incorrect, the whole response SHOULD be considered invalid. it is incorrect, the whole response SHOULD be considered invalid.
Any content, both the content body and the headers, of such an
invalid response SHOULD be ignored and discarded.
The final status of the client request following the message exchange The final status of the client request following the message exchange
sequence shall be determined as follows: sequence shall be determined as follows:
o AUTH-SUCCEED: A 200-VFY-S message with the correct VK_s value is o AUTH-SUCCEED: A 200-VFY-S message with the correct VK_s value was
returned to the req-VFY-C request in the sequence. returned in response to the req-VFY-C request in the sequence.
o AUTH-REQUIRED: Two cases exists. o AUTH-REQUIRED: Two cases exists.
* A 401-INIT message is returned from the server, and the client * A 401-INIT message was returned from the server, and the client
does not know how to authenticate to the given authentication does not know how to authenticate to the given authentication
realm. realm.
* A 401-INIT response is returned for req-VFY-C (or req-KEX-C1), * A 401-INIT response was returned for req-VFY-C (or req-KEX-C1),
which means the user-supplied authentication credentials are which means the user-supplied authentication credentials were
not accepted. not accepted.
o UNAUTHENTICATED: a normal response is returned for an initial o UNAUTHENTICATED: a normal response is returned for an initial
request of any kind in the sequence. request of any kind in the sequence.
Any kind of response (including a normal response) other than those Any kind of response (including a normal response) other than those
explicitly allowed in the above rules SHOULD be interpreted as a explicitly allowed in the above rules SHOULD be interpreted as a
fatal communication error. In such cases, the clients MUST NOT fatal communication error. In such cases, the clients MUST NOT
process any data (the response body and other content-related process any data (the response body and other content-related
headers) sent from the server. However, to handle exceptional error headers) sent from the server. However, to handle exceptional error
cases, clients MAY accept a message without an Authentication-Info cases, clients MAY accept a message without an Authentication-Info
header, if it is a Server-Error (5xx) status. In such cases, they header, if it has a Server-Error (5xx) status code. In such cases,
SHOULD be careful about processing the body of the content (ignoring they SHOULD be careful about processing the body of the content
it is still RECOMMENDED, as it may possibly be forged by intermediate (ignoring it is still RECOMMENDED, as it may possibly be forged by
attackers,) and the client will be in the "UNAUTHENTICATED" status intermediate attackers), and the client will be in the
then. "UNAUTHENTICATED" status then.
If a request is a sub-request for a resource included in another If a request is a sub-request for a resource included in another
resources (e.g., embedded images, style sheets, frames etc.), clients resource (e.g., embedded images, style sheets, frames etc.), clients
MAY treat an AUTH-REQUESTED status as the same as UNAUTHENTICATED MAY treat an AUTH-REQUESTED status as the same as an UNAUTHENTICATED
status. In other words, the client MAY ignore server's request to status. In other words, the client MAY ignore server's request to
start authentication with new credentials via sub-requests. start authentication with new credentials via sub-requests.
10.2. State machine for the client-side (informative) 10.2. State machine for the client (informative)
The following state machine describes the possible request-response The following state machine describes the possible request-response
sequences derived from the above normative rules. If implementer are sequences derived from the above normative rules. If implementers
not quite sure on the security consequences of the above rules, it is are not quite sure on the security consequences of the above rules,
strongly advised to follow the decision procedure below. In it is strongly advised to follow the decision procedure below. In
particular, clients SHOULD NOT accept "normal responses" unless particular, clients SHOULD NOT accept "normal responses" unless
explicitly allowed in the rules. The labels on the steps are for explicitly allowed in the rules. The labels on the steps are for
informational purposes only. Action entries within each step are informational purposes only. Action entries within each step are
checked in top-to-bottom order, and the first clause satisfied is to checked in top-to-bottom order, and the first clause satisfied is to
be followed. be followed.
Step 1 (step_new_request): Step 1 (step_new_request):
If the client software needs to access a new Web resource, check If the client software needs to access a new Web resource, check
whether the resource is expected to be inside some authentication whether the resource is expected to be inside some authentication
realm for which the user has already been authenticated by the realm for which the user has already been authenticated by the
Mutual authentication scheme. If yes, go to Step 2. Otherwise, Mutual authentication scheme. If yes, go to Step 2. Otherwise,
go to Step 5. go to Step 5.
Step 2: Step 2:
Check whether there is an available sid for the authentication Check whether there is an available sid for the expected
realm you expect. If there is one, go to Step 3. Otherwise, go authentication realm. If there is one, go to Step 3. Otherwise,
to Step 4. go to Step 4.
Step 3 (step_send_vfy_1): Step 3 (step_send_vfy_1):
Send a req-VFY-C request. Send a req-VFY-C request.
* If you receive a 401-INIT message with a different * If you receive a 401-INIT message with a different
authentication realm than expected, go to Step 6. authentication realm than expected, go to Step 6.
* If you receive a 401-STALE message, go to Step 9. * If a 401-STALE message is received, go to Step 9.
* If you receive a 401-INIT message, go to Step 13. * If a 401-INIT message is received, go to Step 13.
* If you receive a 200-VFY-S message, go to Step 14. * If a 200-VFY-S message is received, go to Step 14.
* If you receive a normal response, go to Step 11. * If a normal response is received, go to Step 11.
Step 4 (step_send_kex1_1): Step 4 (step_send_kex1_1):
Send a req-KEX-C1 request. Send a req-KEX-C1 request.
* If you receive a 401-INIT message with a different * If a 401-INIT message is received with a different
authentication realm than expected, go to Step 6. authentication realm than expected, go to Step 6.
* If you receive a 401-KEX-S1 message, go to Step 10. * If a 401-KEX-S1 message is received, go to Step 10.
* If you receive a 401-INIT message with the same authentication * If a 401-INIT message is received with the same authentication
realm, go to Step 13 (see Note 1). realm, go to Step 13 (see Note 1).
* If you receive a normal response, go to Step 11. * If a normal response is received, go to Step 11.
Step 5 (step_send_normal_1): Step 5 (step_send_normal_1):
Send a request without any Mutual authentication headers. Send a request without any Mutual authentication headers.
* If you receive a 401-INIT message, go to Step 6. * If a 401-INIT message is received, go to Step 6.
* If you receive a normal response, go to Step 11. * If a normal response is received, go to Step 11.
Step 6 (step_rcvd_init): Step 6 (step_rcvd_init):
Check whether you know the user's password for the requested Check whether the user's password for the requested
authentication realm. If yes, go to Step 7. Otherwise, go to authentication realm is known. If yes, go to Step 7. Otherwise,
Step 12. go to Step 12.
Step 7: Step 7:
Check whether there is an available sid for the authentication Check whether there is an available sid for the expected
realm you expect. If there is one, go to Step 8. Otherwise, go authentication realm. If there is one, go to Step 8. Otherwise,
to Step 9. go to Step 9.
Step 8 (step_send_vfy): Step 8 (step_send_vfy):
Send a req-VFY-C request. Send a req-VFY-C request.
* If you receive a 401-STALE message, go to Step 9. * If a 401-STALE message is received, go to Step 9.
* If you receive a 401-INIT message, go to Step 13. * If a 401-INIT message is received, go to Step 13.
* If you receive a 200-VFY-S message, go to Step 14. * If a 200-VFY-S message is received, go to Step 14.
Step 9 (step_send_kex1): Step 9 (step_send_kex1):
Send a req-KEX-C1 request. Send a req-KEX-C1 request.
* If you receive a 401-KEX-S1 message, go to Step 10. * If a 401-KEX-S1 message is received, go to Step 10.
* If you receive a 401-INIT message, go to Step 13 (See Note 1). * If a 401-INIT message is received, go to Step 13 (See Note 1).
Step 10 (step_rcvd_kex1): Step 10 (step_rcvd_kex1):
Send a req-VFY-C request. Send a req-VFY-C request.
* If you receive a 401-INIT message, go to Step 13. * If a 401-INIT message is received, go to Step 13.
* If you receive a 200-VFY-S message, go to Step 14. * If a 200-VFY-S message is received, go to Step 14.
Step 11 (step_rcvd_normal): Step 11 (step_rcvd_normal):
The requested resource is out of the authenticated area. The The requested resource is out of the authenticated area. The
client will be in the "UNAUTHENTICATED" status. If the response client will be in the "UNAUTHENTICATED" status. If the response
contains a request for authentications other than Mutual, it MAY contains a request for authentications other than Mutual, it MAY
be handled normally. be handled normally.
Step 12 (step_rcvd_init_unknown): Step 12 (step_rcvd_init_unknown):
The requested resource requires a Mutual authentication, and the The requested resource requires Mutual authentication, and the
user is not yet authenticated. The client will be in the "AUTH- user is not yet authenticated. The client will be in the "AUTH-
REQUESTED" status, and is RECOMMENDED to process the content sent REQUESTED" status, and is RECOMMENDED to process the content sent
from the server, and to ask user for a user name and a password. from the server, and to ask the user for a user name and a
When those are supplied from the user, proceed to Step 9. password. When those are supplied from the user, proceed to Step
9.
Step 13 (step_rcvd_init_failed): Step 13 (step_rcvd_init_failed):
For some reason the authentication failed: possibly the password For some reason the authentication failed: possibly the password
or the username is invalid for the authenticated resource. or the username is invalid for the authenticated resource.
Forget the password for the authentication realm and go to Step Forget the user-provided credentials for the authentication realm
12. and go to Step 12.
Step 14 (step_rcvd_vfy): Step 14 (step_rcvd_vfy):
The received message is the 200-VFY-S message, which SHALL always The received message is the 200-VFY-S message, which always
contain a vks field. Check the validity of the received VK_s contains a vks field. Check the validity of the received VK_s
value. If it is equal to the expected value, it means that the value. If it is equal to the expected value, it means that the
mutual authentication has succeeded. The client will be in the mutual authentication has succeeded. The client will be in the
"AUTH-SUCCEEDED" status. "AUTH-SUCCEEDED" status.
If the value is unexpected, it is a fatal communication error. If the value is unexpected, it is a fatal communication error.
If a user explicitly requests to log out (via user interfaces), If a user explicitly requests to log out (via the user
the client MUST forget the user's password, go to step 5 and interface), the client MUST forget the user's password, go to
reload the current resource without an authentication header. step 5, and reload the current resource without an authentication
header.
Note 1: These transitions MAY be accepted by clients, but Note 1: These transitions MAY be accepted by clients, but are
NOT RECOMMENDED for servers to initiate. NOT RECOMMENDED for servers to initiate.
Figure 5 shows an informative diagram of the client-side state. Figure 5 shows an informative diagram of the client state.
=========== -(11)------------ =========== -(11)------------
NEW REQUEST ( UNAUTHENTICATED ) NEW REQUEST ( UNAUTHENTICATED )
=========== ----------------- =========== -----------------
| ^ normal | ^ normal
v | response v | response
+(1)-------------------+ NO +(5)----------+ +(1)-------------------+ NO +(5)----------+
| The requested URI |--------------------------->| send normal | | The requested URI |--------------------------->| send normal |
| known to be auth'ed? | | request | | known to be auth'ed? | | request |
+----------------------+ +-------------+ +----------------------+ +-------------+
skipping to change at page 34, line 8 skipping to change at page 33, line 8
v \ -(14)--------- / USER/PASS INPUTTED v \ -(14)--------- / USER/PASS INPUTTED
-(11)------------ ------->( AUTH-SUCCEED )<-- ================== -(11)------------ ------->( AUTH-SUCCEED )<-- ==================
( UNAUTHENTICATED ) -------------- ( UNAUTHENTICATED ) --------------
----------------- -----------------
Figure 5: State diagram for clients Figure 5: State diagram for clients
11. Decision Procedure for Servers 11. Decision Procedure for Servers
Each server SHOULD have a table of session states. This table need Each server SHOULD have a table of session states. This table need
not be persistent over a long term; it MAY be cleared upon server not be persistent over the long term; it MAY be cleared upon server
restart, reboot, or others. Each entry in the table SHOULD contain restart, reboot, or for other reasons. Each entry in the table
at least the following information: SHOULD contain at least the following information:
o The session identifier, the value of the sid parameter. o The session identifier, which is the value of the sid parameter.
o The algorithm used. o The algorithm used.
o The authentication realm. o The authentication realm.
o The state of the protocol: one of "key exchanging", o The state of the protocol: one of "key exchanging",
"authenticated", "rejected", or "inactive". "authenticated", "rejected", or "inactive".
o The user name received from the client o The user name received from the client.
o The boolean flag noting whether or not the session is fake. o A boolean flag representing whether or not the session is fake.
o When the state is "key exchanging", the values of K_c1 and S_s1. o When the state is "key exchanging", the values of K_c1 and S_s1.
o When the state is "authenticated", the following information: o When the state is "authenticated", the following information:
* The value of the session secret z * The value of the session secret, z
* The largest nc received from the client (largest-nc) * The largest nc received from the client (largest-nc)
* For each possible nc values between (largest-nc - nc- * For each possible nc values between (largest-nc - nc-
window + 1) and max_nc, a flag whether or not a request with window + 1) and max_nc, a boolean flag whether or not a request
the corresponding nc has been received. with the corresponding nc has been received.
The table MAY contain other information. The table MAY contain other information.
Servers SHOULD respond to the client requests according to the Servers SHOULD respond to the client requests according to the
following procedure: (See Note 1 below for 401-INIT message with * following procedure: (See Note 1 below for 401-INIT message with a
marks) plus sign)
o When the server receives a normal request: o When the server receives a normal request:
* If the requested resource is not protected by the Mutual * If the requested resource is not protected by the Mutual
Authentication, send a normal response. authentication, send a normal response.
* If the resource is protected by the Mutual Authentication, send * If the resource is protected by the Mutual authentication, send
a 401-INIT response. a 401-INIT response.
o When the server receives a req-KEX-C1 request: o When the server receives a req-KEX-C1 request:
* If the requested resource is not protected by the Mutual * If the requested resource is not protected by the Mutual
Authentication, send a normal response. authentication, send a normal response.
* If the authentication realm specified in the req-KEX-C1 request * If the authentication realm specified in the req-KEX-C1 request
is not the expected one, send a 401-INIT response. is not the expected one, send a 401-INIT response.
* If the server cannot validate the parameter kc1, send a * If the server cannot validate the parameter kc1, send a
401-INIT (*) response. 401-INIT (+) response.
* If the received user name is either invalid, unknown or * If the received user name is either invalid, unknown or
unacceptable, create a new session, mark it a "fake" session, unacceptable, create a new session, mark it a "fake" session,
compute a random value as K_s1, and send a fake 401-KEX-S1 compute a random value as K_s1, and send a fake 401-KEX-S1
response. (Note 2) response. (See Note 2.)
* Otherwise, create a new session, compute K_s1 and send a * Otherwise, create a new session, compute K_s1 and send a
401-KEX-S1 response. 401-KEX-S1 response. The created session is marked as not
fake, and its largest-nc is initialized to zero.
The created session has the "key exchanging" state. The created session has the "key exchanging" state.
o When the server receives a req-VFY-C request: o When the server receives a req-VFY-C request:
* If the requested resource is not protected by the Mutual * If the requested resource is not protected by the Mutual
Authentication, send a normal response. authentication, send a normal response.
* If the authentication realm specified in the req-VFY-C request * If the authentication realm specified in the req-VFY-C request
is not the expected one, send a 401-INIT response. is not the expected one, send a 401-INIT response.
If none of above holds true, the server will lookup the session If none of above holds true, the server will look up the session
corresponding to the received sid and the authentication realm. corresponding to the received sid and the authentication realm.
* If the session corresponding to the received sid could not be * If the session corresponding to the received sid could not be
found, or it is in the "inactive" state, send a 401-STALE found, or it is in the "inactive" state, send a 401-STALE
response. response.
* If the session is in the "rejected" state, send either a * If the session is in the "rejected" state, send either a
401-INIT (*) or a 401-STALE message. 401-INIT (+) or a 401-STALE message.
* If the session is in the "authenticated" state, and the request
has an nc value that was previously received from the client,
send a 401-STALE message. The session SHOULD be changed to the
"inactive" status.
* If the nc value in the request is larger than the nc-max * If the nc value in the request is larger than the nc-max
parameter sent from the server, or if it is not larger then parameter sent from the server, or if it is not larger then
(largest-nc - nc-window) (when in "authenticated" status), the (largest-nc - nc-window) (when in "authenticated" status), the
server MAY (but not REQUIRED to) send a 401-STALE message. The server MAY (but is not REQUIRED to; See Note 3) send a
session SHOULD be changed to the "inactive" status if so. 401-STALE message. The session SHOULD be changed to the
"inactive" state if so.
* If the session is in the "authenticated" state, and the request
has an nc value that was previously received from the client,
send a 401-STALE message. The session SHOULD be changed to the
"inactive" state.
* If the session is a "fake" session, or if the received vkc is * If the session is a "fake" session, or if the received vkc is
incorrect, then send a 401-INIT (*) response. If the session incorrect, then send a 401-INIT (+) response. If the session
is in the "key exchanging" state, it SHOULD be changed to the is in the "key exchanging" state, it SHOULD be changed to the
"rejected" state; otherwise, it MAY either be changed to the "rejected" state; otherwise, it MAY either be changed to the
"rejected" status or kept in the previous state. "rejected" state or kept in the previous state.
* Otherwise, send a 200-VFY-S response. If the session was in * Otherwise, send a 200-VFY-S response. If the session was in
the "key exchanging" state, the session SHOULD be changed to an the "key exchanging" state, the session SHOULD be changed to an
"authenticated" state. The maximum nc and nc flags of the "authenticated" state. The maximum nc and nc flags of the
state SHOULD be updated properly. state SHOULD be updated appropriate.
At any time, the server MAY change any state entries with both the At any time, the server MAY change any state entries with both the
"rejected" and "authenticated" statuses to the "inactive" status, and "rejected" and "authenticated" states to the "inactive" status, and
MAY discard any "inactive" states from the table. The entries with MAY discard any "inactive" states from the table. Entries with the
the "key exchanging" status SHOULD be kept unless there is an "key exchanging" state SHOULD be kept unless there is an emergency
emergency situation such as a server reboot or a table capacity situation such as a server reboot or a table capacity overflow.
overflow.
Note 1: In relation with, and following the specification of the Note 1: In relation with and following the specification of the
optional authentication defined in [I-D.ietf-httpauth-extension], the optional authentication defined in [I-D.ietf-httpauth-extension], the
401-INIT messages marked with the asterisks can not be replaced with 401-INIT messages marked with the pluses cannot be replaced with a
a successful responses with an Optional-WWW-Authenticate header. successful responses with an Optional-WWW-Authenticate header. Every
Every other 401-INIT can be a response with an other 401-INIT can be a response with an Optional-WWW-Authenticate.
Optional-WWW-Authenticate.
Note 2: the server SHOULD NOT send a 401-INIT response in this case, Note 2: the server SHOULD NOT send a 401-INIT response in this case,
because it will leak the information to the client that the specified because it will leak the information to the client that the specified
user will not be accepted. Instead, postpone it to the response for user name will not be accepted. Instead, postpone it to the response
the next req-VFY-C request. for the next req-VFY-C request.
Note 3: The next case implies that, when the request is not rejected
under this clause, the server MUST be decidable whether the same nc
value was previously received from the client. If the server does
not remember a whole history of the nc values received from the
client, the server MUST send a 401-STALE message in this clause.
12. Authentication Algorithms 12. Authentication Algorithms
Cryptographic authentication algorithms which are used with this Cryptographic authentication algorithms which are used with this
protocol will be defined separately. The algorithm definition MUST protocol will be defined separately. The algorithm definition MUST
at least provide a definitions for the following functions: at least provide definitions for the following functions:
o The server-side authentication credential J, derived from user- o The server-side authentication credential J, derived from client-
side authentication credential pi. side authentication credential pi.
o Key exchange values K_c1, K_s1 (exchanged on wire) and S_c1, S_s1 o Key exchange values K_c1, K_s1 (exchanged on wire) and S_c1, S_s1
(kept secret in each peer). (kept secret in each peer).
o Shared secret z, to be computed in both server-side and client o Shared secret z, to be computed by both server and client.
side.
o A hash function H to be used with the protocol, along with its o A hash function H to be used with the protocol, along with its
output size hSize. output size hSize.
o The number of iterations for password hashing nIterPi, if it uses o The number of iterations for password hashing nIterPi, if it uses
the default password hashing function defined below. the default password hashing function defined below.
Specifications for cryptographic algorithms used with this framework Specifications for cryptographic algorithms used with this framework
MUST specify whether these will use the default functions defined MUST specify whether these will use the default functions defined
below for the functions pi, VK_c, and VK_s; or, these will define below for values pi, VK_c, and VK_s; or, these will define their own
their own versions for these functions. versions for these.
All algorithm used with this protocol SHOULD provide secure mutual All algorithm used with this protocol SHOULD provide secure mutual
authentication between client and servers, and generate a authentication between client and servers, and generate a
cryptographically strong shared secret value z, equivalently strong cryptographically strong shared secret value z, equivalently strong
to or stronger than the hash function H. If any passwords (or pass- to or stronger than the hash function H. If any passwords (or pass-
phrases or any equivalents, i.e. weak secrets) are involved, these phrases or any equivalents, i.e., weak secrets) are involved, these
SHOULD NOT be guessable from any data transmitted in the protocol, SHOULD NOT be guessable from any data transmitted in the protocol,
even if an attacker (either an eavesdropper or an active server) even if an attacker (either an eavesdropper or an active server)
knows the possible thoroughly-searchable candidate list of the knows the possible thoroughly-searchable candidate list of the
passwords. Furthermore, if possible, the function for deriving passwords. Furthermore, if possible, the function J for deriving
server-side authentication credential J is RECOMMENDED to be one-way server-side authentication credential J(pi) is RECOMMENDED to be one-
so that pi should not be easily computed from J(pi). way so that pi should not be easily computed from J(pi).
12.1. Support Functions and Notations 12.1. Support Functions and Notations
In this section we define several support functions and notations to In this section we define several support functions and notations to
be shared by several algorithm definitions: be shared by several algorithm definitions.
The integers in the specification are in decimal, or in hexadecimal The integers in the specification are in decimal, or in hexadecimal
when prefixed with "0x". when prefixed with "0x".
The function octet(c) generates a single octet string whose code The function octet(i) generates an octet string containing a single
value is equal to c. The operator |, when applied to octet strings, octet of value i. The operator |, when applied to octet strings,
denotes the concatenation of two operands. denotes the concatenation of two operands.
The function VI encodes natural numbers into octet strings in the The function VI encodes natural numbers into octet strings in the
following manner: numbers are represented in big-endian radix-128 following manner: numbers are represented as big-endian radix-128
string, where each digit is represented by a octet within 0x80-0xff strings, where each digit is represented by an octet within the range
except the last digit represented by a octet within 0x00-0x7f. The 0x80-0xff except the last digit, which is represented by a octet
first octet MUST NOT be 0x80. For example, VI(i) = octet(i) for i < within the range 0x00-0x7f. The first octet MUST NOT be 0x80. For
128, and VI(i) = octet(0x80 + (i >> 7)) | octet(i & 127) for 128 <= i example, VI(i) = octet(i) for i < 128, and VI(i) = octet(0x80 + (i >>
< 16384. This encoding is the same as the one used for the sub- 7)) | octet(i & 127) for 128 <= i < 16384. This encoding is the same
components of object identifiers in the ASN.1 encoding as the one used for the sub-components of object identifiers in the
[ITU.X690.1994], and available as a "w" conversion in the pack ASN.1 encoding [ITU.X690.1994], and available as a "w" conversion in
function of several scripting languages. the "pack" function of several scripting languages.
The function VS encodes a variable-length octet string into a The function VS encodes a variable-length octet string into a
uniquely-decoded, self-delimited octet string, as in the following uniquely-decoded, self-delimited octet string, as in the following
manner: manner:
VS(s) = VI(length(s)) | s VS(s) = VI(length(s)) | s
where length(s) is a number of octets (not characters) in s. where length(s) is a number of octets (not characters) in s.
Some examples: Some examples:
skipping to change at page 38, line 34 skipping to change at page 37, line 39
VS("Caf<e acute>" [in UTF-8]) = "\005Caf\303\251" VS("Caf<e acute>" [in UTF-8]) = "\005Caf\303\251"
VS([10000 "a"s]) = "\316\020aaaaa..." (10002 octets) VS([10000 "a"s]) = "\316\020aaaaa..." (10002 octets)
(Note: Unlike the colon-separated notion used in the Basic/Digest (Note: Unlike the colon-separated notion used in the Basic/Digest
HTTP authentication scheme, the string generated by a concatenation HTTP authentication scheme, the string generated by a concatenation
of the VS-encoded strings will be unique, regardless of the of the VS-encoded strings will be unique, regardless of the
characters included in the strings to be encoded.) characters included in the strings to be encoded.)
The function OCTETS converts an integer into the corresponding radix- The function OCTETS converts an integer into the corresponding radix-
256 big-endian octet string having its natural length: See 256 big-endian octet string having its natural length. See
Section 3.2.3 for the definition of "natural length". Section 3.2.3 for the definition of "natural length".
The function INT converts an octet string into a natural number, The function INT converts an octet string into a natural number,
where the input string is treated as a radix-256 big-endian notation. where the input string is treated as being in radix-256 big-endian
The identity INT(OCTETS(n)) = n always holds for any natural number notation. The identity INT(OCTETS(n)) = n always holds for any
n. natural number n.
12.2. Default Functions for Algorithms 12.2. Default Functions for Algorithms
The functions defined in this section are common default functions The functions defined in this section are common default functions
among authentication algorithms. among authentication algorithms.
The client-side password-based (credential) pi used by this The client-side password-based (credential) pi used by this
authentication is a natural number derived in the following manner: authentication is a natural number derived in the following manner:
pi = INT(PBKDF2(HMAC_H, ph(password), VS(algorithm) | VS(auth-scope) pi = INT(PBKDF2(HMAC_H, password, VS(algorithm) | VS(auth-scope) |
| VS(realm) | VS(username), nIterPi, hSize / 8)), VS(realm) | VS(username), nIterPi, hSize / 8)),
where where
o PBKDF2 is the password-based key derivation function defined in o PBKDF2 is the password-based key derivation function defined in
[RFC2898], [RFC2898],
o HMAC_H is the HMAC function, defined in [RFC2104], composed from o HMAC_H is the HMAC function, defined in [RFC2104], composed from
the hash function H, and the hash function H, and
o hSize is the output size of hash H, counted in bits. o hSize is the output size of hash H in bits.
The values of algorithm, realm, and auth-scope are taken from the The values of algorithm, realm, and auth-scope are taken from the
values contained in the 401-INIT message. The function ph is values contained in the 401-INIT message. If the password comes from
determined by the value of the pwd-hash parameter given in a 401-INIT user input, it SHOULD first be prepared according to the method
message. If the password comes from a user input, it SHOULD first be presented in Section 9. Then, the password SHALL be encoded as a
prepared according to the method presented in Section 9. Then, the UTF-8 string.
password SHALL be encoded as a UTF-8 string before passed to ph.
The values VK_c and VK_s are derived by the following equation. The values VK_c and VK_s are derived by the following equation.
VK_c = INT(H(octet(4) | OCTETS(K_c1) | OCTETS(K_s1) | OCTETS(z) | VK_c = INT(H(octet(4) | OCTETS(K_c1) | OCTETS(K_s1) | OCTETS(z) |
VI(nc) | VS(vh))) VI(nc) | VS(vh)))
VK_s = INT(H(octet(3) | OCTETS(K_c1) | OCTETS(K_s1) | OCTETS(z) | VK_s = INT(H(octet(3) | OCTETS(K_c1) | OCTETS(K_s1) | OCTETS(z) |
VI(nc) | VS(vh))) VI(nc) | VS(vh)))
13. Application Channel Binding 13. Application Channel Binding
Applications and upper-layer communication protocols may need Applications and upper-layer communication protocols may need
authentication binding to the HTTP-layer authenticated user. Such authentication binding to the HTTP-layer authenticated user. Such
applications MAY use the following values as a standard shared applications MAY use the following values as a standard shared
secret. secret.
These values are parameterized with an optional octet string (t) These values are parameterized with an optional octet string (t)
which may be arbitrarily chosen by each applications or protocols. which may be arbitrarily chosen by each application or protocol. If
If there is no appropriate value to be specified, use a null string there is no appropriate value to be specified, use an empty string
for t. for t.
For applications requiring binding to either an authenticated user or For applications requiring binding to either an authenticated user or
a shared-key session (to ensure that the requesting client is a shared-key session (to ensure that the requesting client is
certainly authenticated), the following value b_1 MAY be used. certainly authenticated), the following value b_1 MAY be used.
b_1 = H(H(octet(6) | OCTETS(K_c1) | OCTETS(K_s1) | OCTETS(z) | VI(0) b_1 = H(H(octet(6) | OCTETS(K_c1) | OCTETS(K_s1) | OCTETS(z) | VI(0)
| VS(vh)) | VS(t)). | VS(vh)) | VS(t)).
For applications requiring binding to a specific request (to ensure For applications requiring binding to a specific request (to ensure
skipping to change at page 40, line 14 skipping to change at page 39, line 19
b_2 = H(H(octet(7) | OCTETS(K_c1) | OCTETS(K_s1) | OCTETS(z) | VI(nc) b_2 = H(H(octet(7) | OCTETS(K_c1) | OCTETS(K_s1) | OCTETS(z) | VI(nc)
| VS(vh)) | VS(t)). | VS(vh)) | VS(t)).
Note: Channel bindings to lower-layer transports (TCP and TLS) are Note: Channel bindings to lower-layer transports (TCP and TLS) are
defined in Section 7. defined in Section 7.
14. Application for Proxy Authentication 14. Application for Proxy Authentication
The authentication scheme defined by the previous sections can be The authentication scheme defined by the previous sections can be
applied (with modifications) for proxy authentications. In such applied (with modifications) for proxy authentication. In such
cases, the following alterations MUST be applied: cases, the following alterations MUST be applied:
o The 407 status is to be sent and recognized for places where the o The 407 status is to be sent and recognized in places where the
401 status is used, 401 status is used,
o Proxy-Authenticate: header is to be used for places where WWW- o Proxy-Authenticate header is to be used in places where WWW-
Authenticate: is used, Authenticate is used,
o Proxy-Authorization: header is to be used for places where o Proxy-Authorization header is to be used in places where
Authorization: is used, Authorization is used,
o Proxy-Authentication-Info: header is to be used for places where o Proxy-Authentication-Info header is to be used in places where
Authentication-Info: is used, Authentication-Info is used,
o The auth-scope parameter is fixed to the host-name of the proxy, o The auth-scope parameter is fixed to the host-name of the proxy,
which means to cover all requests processed through the specific which means it covers all requests processed through the specific
proxy, proxy,
o The limitation for the paths contained in the path parameter of o The limitation for the paths contained in the path parameter of
401-KEX-S1 messages is disregarded, 401-KEX-S1 messages is disregarded,
o The omission of the path parameter of 401-KEX-S1 messages means o The omission of the path parameter of 401-KEX-S1 messages means
that the authentication realm will potentially cover all requests that the authentication realm will potentially cover all requests
processed by the proxy, processed by the proxy,
o The scheme, host name and the port of the proxy is used for host o The scheme, host name, and the port of the proxy is used for host
validation tokens, and validation tokens, and
o Authentication extensions in [I-D.ietf-httpauth-extension] are not o Authentication extensions in [I-D.ietf-httpauth-extension] are not
applicable. applicable.
15. Methods to Extend This Protocol 15. Methods to Extend This Protocol
If a private extension to this protocol is implemented, it MUST use If a private extension to this protocol is implemented, it MUST use
the extension-tokens defined in Section 3 to avoid conflicts with the extension-tokens defined in Section 3 to avoid conflicts with
this protocol and other extensions. (standardized or being- this protocol and other extensions. (Standardized or being-
standardizing extensions MAY use either bare-tokens or extension- standardized extensions MAY use either bare-tokens or extension-
tokens.) tokens.)
Specifications defining authentication algorithms MAY use other Specifications defining authentication algorithms MAY use other
representations for the parameters "kc1", "ks1", "vkc", and "vks", representations for the parameters "kc1", "ks1", "vkc", and "vks",
replace those parameter names, and/or add parameters to the messages replace those parameter names, and/or add parameters to the messages
containing those parameters in supplemental specifications, provided containing those parameters in supplemental specifications, provided
that syntactic and semantic requirements in Section 3, [RFC7230] and that syntactic and semantic requirements in Section 3, [RFC7230] and
[RFC7235] are satisfied. Any parameters starting with "kc", "ks", [RFC7235] are satisfied. Any parameters starting with "kc", "ks",
"vkc" or "vks" and followed by decimal natural numbers (e.g. kc2, "vkc" or "vks" and followed by decimal natural numbers (e.g. kc2,
ks0, vkc1, vks3 etc.) are reserved for this purpose. If those ks0, vkc1, vks3 etc.) are reserved for this purpose. If those
specifications use names other than those mentioned above, it is specifications use names other than those mentioned above, it is
RECOMMENDED to use extension-tokens to avoid any parameter name RECOMMENDED to use extension-tokens to avoid any parameter name
conflict with the future extension of this protocol. conflict with future extensions to this protocol.
Extension-tokens MAY be freely used for any non-standard, private, Extension-tokens MAY be freely used for any non-standard, private,
and/or experimental uses for those parameters provided that the and/or experimental uses for those parameters provided that the
domain part in the token is appropriately used. domain part in the token is used in the manner defined in Section 3.
16. IANA Considerations 16. IANA Considerations
When bare-tokens are used for the authentication-algorithm, pwd-hash, When bare-tokens are used for the authentication-algorithm, pwd-hash,
and validation parameters MUST be allocated by IANA. To acquire and validation parameters, these MUST be allocated by IANA. To
registered tokens, a specification for the use of such tokens MUST be acquire registered tokens, a specification for the use of such tokens
reviewed by a designated expert, as outlined in [RFC5226]. MUST be reviewed by a designated expert, as outlined in [RFC5226].
16.1. Registry for Authentication Algorithms 16.1. Registry for Authentication Algorithms
This document establishes a registry for HTTP Mutual authentication This document establishes a registry for HTTP Mutual authentication
algorithms. The registry manages a case-insensitive ASCII strings. algorithms. The registry manages case-insensitive ASCII strings.
The string MUST follow the extensive-token syntax defined in The strings MUST follow the extensive-token syntax defined in
Section 3. Section 3.
Registrations for authentication algorithms are required to include a Registrations for an authentication algorithm are required to include
description of the key exchange algorithms. Reviewers assigned by a description of the authentication algorithms. Reviewers assigned
IESG are advised to examine minimum security requirements and by IESG are advised to examine minimum security requirements and
consistency of the key exchange algorithm descriptions. consistency of the key exchange algorithm descriptions.
New registrations are advised to provide the following information: New registrations are advised to provide the following information:
o Token: a token used in HTTP headers for identifying the algorithm. o Token: a token used in HTTP headers for identifying the algorithm.
o Description: A brief description of the algorithm. o Description: A brief description of the algorithm.
o Specification: A reference for a specification defining the o Specification: A reference for a specification defining the
algorithm. algorithm.
The initial content of this registry is empty. [[Editorial Note: A The initial content of this registry is empty. [[Editorial Note: A
separate document [I-D.ietf-httpauth-mutual-algo] will effectively separate document [I-D.ietf-httpauth-mutual-algo] will effectively
define the initial content of the registry.]] define the initial content of the registry.]]
16.2. Registry for Password Hashes 16.2. Registry for Validation Methods
This document establishes a registry for HTTP Mutual authentication
password hashes. The registry manages a case-insensitive ASCII
strings. The string MUST follow the extensive-token syntax defined
in Section 3.
Registrations for authentication algorithms are required to include a
description of the key exchange algorithms. Reviewers assigned by
IESG are advised to examine its use-case requirements and security
consequence of its introduction.
New registrations are advised to provide the following information:
o Token: a token used in HTTP headers for identifying the algorithm.
o Description: A brief description of the algorithm.
o Specification: A reference for a specification defining the
algorithm.
The initial content of this registry is as follows:
+------------+------------------------------------+---------------+
| Token | Description | Specification |
+------------+------------------------------------+---------------+
| none | No additional hashing, recommended | Section 4.1 |
| md5 | MD5-based preprocessing | Section 4.1 |
| digest-md5 | Digest-compatible preprocessing | Section 4.1 |
| sha1 | SHA1-based preprocessing | Section 4.1 |
+------------+------------------------------------+---------------+
16.3. Registry for Validation Methods
This document establishes a registry for HTTP Mutual authentication This document establishes a registry for HTTP Mutual authentication
host validations. The registry manages a case-insensitive ASCII host validation methods. The registry manages case-insensitive ASCII
strings. The string MUST follow the extensive-token syntax defined strings. The strings MUST follow the extensive-token syntax defined
in Section 3. in Section 3.
Registrations for authentication algorithms are required to include a Registrations for a validation method are required to include a
description of the key exchange algorithms. Reviewers assigned by description of the validation method. Reviewers assigned by IESG are
IESG are advised to examine its use-case requirements and security advised to examine its use-case requirements and security consequence
consequence of its introduction. of its introduction.
New registrations are advised to provide the following information: New registrations are advised to provide the following information:
o Token: a token used in HTTP headers for identifying the algorithm. o Token: a token used in HTTP headers for identifying the method.
o Description: A brief description of the algorithm. o Description: A brief description of the method.
o Specification: A reference for a specification defining the o Specification: A reference for a specification defining the
algorithm. method.
The initial content of this registry is as follows: The initial content of this registry is as follows:
+----------------------+----------------------------+---------------+ +----------------------+----------------------------+---------------+
| Token | Description | Specification | | Token | Description | Specification |
+----------------------+----------------------------+---------------+ +----------------------+----------------------------+---------------+
| host | Host name verification | Section 7 | | host | Host name verification | Section 7 |
| | only | | | | only | |
| tls-server-end-point | TLS certificate-based | Section 7 | | tls-server-end-point | TLS certificate-based | Section 7 |
| tls-unique | TLS unique key-based | Section 7 | | tls-unique | TLS unique key-based | Section 7 |
skipping to change at page 44, line 8 skipping to change at page 42, line 26
attacks for each HTTP request/response pair. However, in such attacks for each HTTP request/response pair. However, in such
cases, JavaScript or similar scripting facilities can be used to cases, JavaScript or similar scripting facilities can be used to
affect the Mutually-authenticated contents from other contents not affect the Mutually-authenticated contents from other contents not
protected by this authentication mechanism. This is the reason protected by this authentication mechanism. This is the reason
why this protocol requires that valid TLS server certificates MUST why this protocol requires that valid TLS server certificates MUST
be presented (Section 7). be presented (Section 7).
17.2. Denial-of-service Attacks to Servers 17.2. Denial-of-service Attacks to Servers
The protocol requires a server-side table of active sessions, which The protocol requires a server-side table of active sessions, which
may become a critical point of the server resource consumption. For may become a critical point for server resource consumption. For
proper operation, the protocol requires that at least one key proper operation, the protocol requires that at least one key
verification request is processed for each session identifier. After verification request is processed for each session identifier. After
that, servers MAY discard sessions internally at any time, without that, servers MAY discard sessions internally at any time, without
causing any operational problems to clients. Clients will silently causing any operational problems to clients. Clients will silently
reestablishes a new session then. reestablish a new session then.
However, if a malicious client sends too many requests of key However, if a malicious client sends too many requests for key
exchanges (req-KEX-C1 messages) only, resource starvation might exchanges (req-KEX-C1 messages) only, resource starvation might
occur. In such critical situations, servers MAY discard any kind of occur. In such critical situations, servers MAY discard any kind of
existing sessions regardless of these statuses. One way to mitigate existing sessions regardless of their statuses. One way to mitigate
such attacks are that servers MAY have a number and a time limits for such attacks is that servers MAY have a number and a time limit for
unverified pending key exchange requests (in the "key exchanging" unverified, pending key exchange requests (in the "key exchanging"
status). state).
This is a common weakness of authentication protocols with almost any This is a common weakness of authentication protocols with almost any
kind of negotiations or states, including Digest authentication kind of negotiations or states, including Digest authentication
method and most Cookie-based authentication implementations. scheme and most Cookie-based authentication implementations.
However, regarding the resource consumption, a situation of the However, regarding the resource consumption, the situation for the
mutual authentication method is a slightly better than the Digest, mutual authentication scheme is a slightly better than for Digest,
because HTTP requests without any kind of authentication requests because HTTP requests without any kind of authentication requests
will not generate any kind of sessions. Session identifiers are only will not generate any kind of sessions. Session identifiers are only
generated after a client starts a key negotiation. It means that generated after a client starts a key negotiation. It means that
simple clients such as web crawlers will not accidentally consume simple clients such as Web crawlers will not accidentally consume
server-side resources for session managements. server-side resources for session managements.
17.2.1. On-line Active Password Attacks 17.2.1. On-line Active Password Attacks
Although the protocol provides very strong protection against off- Although the protocol provides very strong protection against off-
line dictionary attacks from eavesdropped traffics, the protocol, by line dictionary attacks from eavesdropped traffic, the protocol, by
its nature, can not prevent an active password attacks which the its nature, cannot prevent active password attacks in which the
attackers sends so many authentication trial requests for every attackers sends so many authentication trial requests for every
possible passwords. possible password.
Possible countermeasures for preventing such attacks may be rate- Possible countermeasures for preventing such attacks may be rate-
limiting of the password authentication trials, statistics-based limiting of password authentication trials, statistics-based
intrusion detection measures or similar protection schemes. If the intrusion detection measures, or similar protection schemes. If the
server operators assume that the passwords of users are not strong server operators assume that the passwords of users are not strong
enough, it may be desirable to introduce such ad-hoc countermeasures. enough, it may be desirable to introduce such ad-hoc countermeasures.
17.3. Communicating the status of mutual authentication with users 17.3. Communicating the status of mutual authentication with users
This protocol is designed for two goals. The first goal is just This protocol is designed for two goals. The first goal is just
providing a secure alternative for existing Basic and Digest providing a secure alternative for existing Basic and Digest
authentication. The second goal is to provide users a way to detect authentication. The second goal is to provide users a way to detect
forged rogue servers imitating user's registered account on server- forged rogue servers imitating a user's registered account on a
side, commonly known as (a part or kind of) Phishing attacks. server, commonly known as (a part or kind of) Phishing attacks.
For this protocol to effectively work as some countermeasures to such For this protocol to effectively work as some countermeasure to such
attacks, it is very important that end users of clients will be attacks, it is very important that end users of clients be notified
notified of the result of mutual authentication performed by this of the result of the mutual authentication performed by this
protocol, especially the three states "AUTH-SUCCEED", protocol, especially the three states "AUTH-SUCCEED",
"UNAUTHENTICATED" and "AUTH-REQUIRED" defined in Section 10. The "UNAUTHENTICATED", and "AUTH-REQUIRED" defined in Section 10. The
design of secure users' interfaces of the HTTP interactive clients design of secure user interfaces of the HTTP interactive clients is
are out of the scope of this document, but if possible, having some out of the scope of this document, but if possible, having some kind
kind of UI indication for the three states above will be desirable of UI indication for the three states above will be desirable for the
for user's benefits on their security. user's security benefit.
Of course, in such cases, the user interfaces for asking passwords Of course, in such cases, the user interfaces for asking passwords
for this authentication shall be clearly identifiable against for this authentication shall be clearly identifiable against
imitation by other insecure password input fields (such as forms). imitation by other insecure password input fields (such as forms).
If the passwords are known to malicious attackers outside of the If the passwords are known to malicious attackers outside of the
protocol, the protocol can not work as an effective security protocol, the protocol cannot work as an effective security measures.
measures.
17.4. Implementation Considerations 17.4. Implementation Considerations
o To securely implement the protocol, the Authentication-Info o To securely implement the protocol, the Authentication-Info
headers in the 200-VFY-S messages MUST always be validated by the headers in the 200-VFY-S messages MUST always be validated by the
client. If the validation fails, the client MUST NOT process any client. If the validation fails, the client MUST NOT process any
content sent with the message, including other headers and the content sent with the message, including other headers and the
body part. Non-compliance to this requirement will allow phishing body part. Non-compliance to this requirement will allow phishing
attacks. attacks.
o For HTTP/TLS communications, when a web form is submitted from o For HTTP/TLS communications, when a web form is submitted from
Mutually-authenticated pages with the "tls-server-end-point" Mutually-authenticated pages with the "tls-server-end-point"
validation method to a URI that is protected by the same realm (so validation method to a URI that is protected by the same realm (so
indicated by the path parameter), if the server certificate has indicated by the path parameter), if the server certificate has
been changed since the pages were received, the peer is been changed since the pages were received, the peer is
RECOMMENDED to be re-validated using a req-KEX-C1 message with an RECOMMENDED to be re-validated using a req-KEX-C1 message with an
"Expect: 100-continue" header. The same applies when the page is "Expect: 100-continue" header. The same applies when the page is
received with the "tls-unique" validation method, and when the TLS received with the "tls-unique" validation method, and when the TLS
session has expired. session has expired.
o For better protection against possible password database steal, o For better protection against possible password database stealing,
Server-side storage of user passwords are better containing the server-side storage of user passwords should contain the values
values encrypted by one-way function J(pi), instead of the real encrypted by the one-way function J(pi), instead of the real
passwords, those hashed by ph, or pi. passwords or those hashed by pi.
17.5. Usage Considerations 17.5. Usage Considerations
o The user-names inputted by a user may be sent automatically to any o The user names inputted by a user may be sent automatically to any
servers sharing the same auth-scope. This means that when host- servers sharing the same auth-scope. This means that when a host-
type auth-scope is used for authentication on an HTTPS site, and type auth-scope is used for authentication on an HTTPS site, and
when an HTTP server on the same host requests Mutual when an HTTP server on the same host requests Mutual
authentication within the same realm, the client will send the authentication within the same realm, the client will send the
user-name in a clear text. If user-names have to be kept secret user name in clear text. If user names have to be kept secret
against eavesdropping, the server must use full-scheme-type auth- against eavesdropping, the server must use the full-scheme-type
scope parameter and HTTPS. Contrarily, passwords are not exposed auth-scope parameter and HTTPS. Contrarily, passwords are not
to eavesdroppers even on HTTP requests. exposed to eavesdroppers even on HTTP requests.
o The "pwd-hash" parameter is only provided for backward
compatibility of password databases. The use of "none" function
is the most secure choice and is RECOMMENDED. If values other
than "none" are used, you MUST ensure that the hash values of the
passwords were not exposed to the public. Note that hashed
password databases for plain-text authentications are usually not
considered secret.
o If the server provides several ways for storing server-side o If the server provides several ways for storing server-side
password secrets into the password database, it is desirable for password secrets in the password database, it is desirable for
better security to store the values encrypted by using the one-way better security to store the values encrypted by using the one-way
function J(pi), instead of the real passwords, those hashed by ph, function J(pi), instead of the real passwords or those hashed by
or pi. pi.
18. Notice on Intellectual Properties 18. Notice on Intellectual Properties
The National Institute of Advanced Industrial Science and Technology The National Institute of Advanced Industrial Science and Technology
(AIST) and Yahoo! Japan, Inc. has jointly submitted a patent (AIST) and Yahoo! Japan, Inc. have jointly submitted a patent
application on the protocol proposed in this documentation to the application to the Patent Office of Japan for the protocol proposed
Patent Office of Japan. The patent is intended to be open to any in this documentation. The patent is intended to be open to any
implementer of this protocol and its variants under non-exclusive implementer of this protocol and its variants under non-exclusive
royalty-free manner. For the details of the patent application and royalty-free terms. For the details of the patent application and
its status, please contact the author of this document. its status, please contact the authors of this document.
The elliptic-curve based authentication algorithms might involve The elliptic-curve based authentication algorithms might involve
several existing third-party patents. The authors of the document several existing third-party patents. The authors of the document
take no position regarding the validity or scope of such patents, and take no position regarding the validity or scope of such patents and
other patents as well. other patents as well.
19. References 19. References
19.1. Normative References 19.1. Normative References
[I-D.ietf-httpauth-extension] [I-D.ietf-httpauth-extension]
Oiwa, Y., Watanabe, H., Takagi, H., Hayashi, T., and Y. Oiwa, Y., Watanabe, H., Takagi, H., Hayashi, T., and Y.
Ioku, "HTTP Authentication Extensions for Interactive Ioku, "HTTP Authentication Extensions for Interactive
Clients", draft-ietf-httpauth-extension-05 (work in Clients", draft-ietf-httpauth-extension-06 (work in
progress), January 2016. progress), January 2016.
[RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed- [RFC2104] Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
Hashing for Message Authentication", RFC 2104, Hashing for Message Authentication", RFC 2104,
DOI 10.17487/RFC2104, February 1997, DOI 10.17487/RFC2104, February 1997,
<http://www.rfc-editor.org/info/rfc2104>. <http://www.rfc-editor.org/info/rfc2104>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/ Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997, RFC2119, March 1997,
skipping to change at page 48, line 29 skipping to change at page 46, line 32
Authentication-Info Response Header Fields", RFC 7615, Authentication-Info Response Header Fields", RFC 7615,
DOI 10.17487/RFC7615, September 2015, DOI 10.17487/RFC7615, September 2015,
<http://www.rfc-editor.org/info/rfc7615>. <http://www.rfc-editor.org/info/rfc7615>.
19.2. Informative References 19.2. Informative References
[I-D.ietf-httpauth-mutual-algo] [I-D.ietf-httpauth-mutual-algo]
Oiwa, Y., Watanabe, H., Takagi, H., Maeda, K., Hayashi, Oiwa, Y., Watanabe, H., Takagi, H., Maeda, K., Hayashi,
T., and Y. Ioku, "Mutual Authentication Protocol for HTTP: T., and Y. Ioku, "Mutual Authentication Protocol for HTTP:
KAM3-based Cryptographic Algorithms", KAM3-based Cryptographic Algorithms",
draft-ietf-httpauth-mutual-algo-04 (work in progress), draft-ietf-httpauth-mutual-algo-05 (work in progress),
January 2016. January 2016.
[ISO.10646-1.1993] [ISO.10646-1.1993]
International Organization for Standardization, International Organization for Standardization,
"Information Technology - Universal Multiple-octet coded "Information Technology - Universal Multiple-octet coded
Character Set (UCS) - Part 1: Architecture and Basic Character Set (UCS) - Part 1: Architecture and Basic
Multilingual Plane", ISO Standard 10646-1, May 1993. Multilingual Plane", ISO Standard 10646-1, May 1993.
[ITU.X690.1994] [ITU.X690.1994]
International Telecommunications Union, "Information International Telecommunications Union, "Information
skipping to change at page 49, line 46 skipping to change at page 47, line 48
<http://www.rfc-editor.org/info/rfc7616>. <http://www.rfc-editor.org/info/rfc7616>.
[RFC7627] Bhargavan, K., Ed., Delignat-Lavaud, A., Pironti, A., [RFC7627] Bhargavan, K., Ed., Delignat-Lavaud, A., Pironti, A.,
Langley, A., and M. Ray, "Transport Layer Security (TLS) Langley, A., and M. Ray, "Transport Layer Security (TLS)
Session Hash and Extended Master Secret Extension", Session Hash and Extended Master Secret Extension",
RFC 7627, DOI 10.17487/RFC7627, September 2015, RFC 7627, DOI 10.17487/RFC7627, September 2015,
<http://www.rfc-editor.org/info/rfc7627>. <http://www.rfc-editor.org/info/rfc7627>.
Appendix A. (Informative) Draft Change Log Appendix A. (Informative) Draft Change Log
A.1. Changes in Httpauth WG Revision 06 [To be removed on final publication]
A.1. Changes in Httpauth WG Revision 07
o Several comments from reviewers are reflected to the text.
o The password-hash has been completely dropped.
o The version token is raised to "1".
A.2. Changes in Httpauth WG Revision 06
o The auth-domain parameter has been renamed to auth-scope, o The auth-domain parameter has been renamed to auth-scope,
following suggestions on the mailing list. following suggestions on the mailing list.
o The digest-md5 password-hash has been dropped, as Digest with MD5 o The digest-md5 password-hash has been dropped, as Digest with MD5
hash is now obsoleted. hash is now obsoleted.
A.2. Changes in Httpauth WG Revision 05 A.3. Changes in Httpauth WG Revision 05
o Minimum nonce number window has increased to 128. (HTTP 2.0 o Minimum nonce number window has increased to 128. (HTTP 2.0
recommends at least 100 concurrent sessions to exist) recommends at least 100 concurrent sessions to exist)
o Reference to TLS session hash extension added for tls-unique o Reference to TLS session hash extension added for tls-unique
security issues. security issues.
o Comments in the previous F2F meeting has been reflected to the o Comments in the previous F2F meeting has been reflected to the
text. text.
A.3. Changes in Httpauth WG Revision 04 A.4. Changes in Httpauth WG Revision 04
o Merged httpauthprep proposal into general PRECIS Username/Password o Merged httpauthprep proposal into general PRECIS Username/Password
profile. profile.
o Adopting RFC 5987 extended syntax for non-ASCII parameter values. o Adopting RFC 5987 extended syntax for non-ASCII parameter values.
o Refer draft-ietf-httpbis-auth-info for Authentication-Info header. o Refer draft-ietf-httpbis-auth-info for Authentication-Info header.
This results in a different syntax for that header. This results in a different syntax for that header.
A.4. Changes in Httpauth WG Revision 03 A.5. Changes in Httpauth WG Revision 03
o Incompatible change: Single-port type authentication realm label o Incompatible change: Single-port type authentication realm label
has been changed to harmonize with Web Origin. (That is, the has been changed to harmonize with Web Origin. (That is, the
default ports (80 and 443) are to be omitted.) default ports (80 and 443) are to be omitted.)
A.5. Changes in Httpauth WG Revision 02 A.6. Changes in Httpauth WG Revision 02
o Major change: introduction of password-strengthening function o Major change: introduction of password-strengthening function
PBKDF2. PBKDF2.
o Changed Section 10 to adopt "list of requirements" style. Strict o Changed Section 10 to adopt "list of requirements" style. Strict
definition of state machine is now a derived, informational definition of state machine is now a derived, informational
definition. definition.
A.6. Changes in Httpauth WG Revision 01 A.7. Changes in Httpauth WG Revision 01
o Changed "tls-key" verification to "tls-unique" verification, and o Changed "tls-key" verification to "tls-unique" verification, and
"tls-cert" to "tls-server-end-point", adopting RFC 5929. "tls-cert" to "tls-server-end-point", adopting RFC 5929.
o Adopted PRECIS framework [RFC7564]. o Adopted PRECIS framework [RFC7564].
o Reverted reservation of "rekey-sid" and "rekey-method" parameters. o Reverted reservation of "rekey-sid" and "rekey-method" parameters.
o Degraded secure UI requirement to application note level, non- o Degraded secure UI requirement to application note level, non-
normative. normative.
o Adjusted levels of several requirements. o Adjusted levels of several requirements.
o Added warning text for handling of exceptional 5XX responses. o Added warning text for handling of exceptional 5XX responses.
o Dropped several references for optional authentications, except o Dropped several references for optional authentications, except
one "Note". one "Note".
o Several textual fixes, improvements and revisions. o Several textual fixes, improvements and revisions.
A.7. Changes in Httpauth Revision 00 A.8. Changes in Httpauth Revision 00
o Changed the version token. o Changed the version token.
o Renamed "verification tokens" to "Host verification tokens" and o Renamed "verification tokens" to "Host verification tokens" and
variables "v" to "vh" for clarification. (Back-ported from variables "v" to "vh" for clarification. (Back-ported from
draft-oiwa-httpauth-multihop-template-00) draft-oiwa-httpauth-multihop-template-00)
A.8. Changes in HttpBis Revision 00 A.9. Changes in HttpBis Revision 00
None. None.
A.9. Changes in Revision 12 A.10. Changes in Revision 12
o Added a reason "authz-failed". o Added a reason "authz-failed".
A.10. Changes in Revision 11 A.11. Changes in Revision 11
o Message syntax definition reverted to pre-07 style as httpbis-p1 o Message syntax definition reverted to pre-07 style as httpbis-p1
and p7 now defines a precise rule for parameter value parsing. and p7 now defines a precise rule for parameter value parsing.
o Replaced "stale" parameter with more informative/extensive o Replaced "stale" parameter with more informative/extensive
"reason" parameter in 401-INIT and 401-STALE. "reason" parameter in 401-INIT and 401-STALE.
o Reserved "rekey-sid" and "rekey-method" parameters for future o Reserved "rekey-sid" and "rekey-method" parameters for future
extensions. extensions.
o Added descriptions for replacing/non-replacing existing o Added descriptions for replacing/non-replacing existing
technologies. technologies.
A.11. Changes in Revision 10 A.12. Changes in Revision 10
o The authentication extension parts (non-mandatory authentication o The authentication extension parts (non-mandatory authentication
and authentication controls) are separated to yet another draft. and authentication controls) are separated to yet another draft.
o The default auth-domain parameter is changed to the full scheme- o The default auth-domain parameter is changed to the full scheme-
host-port syntax, which is consistent with usual HTTP host-port syntax, which is consistent with usual HTTP
authentication framework behavior. authentication framework behavior.
o Provision for application channel binding is added. o Provision for application channel binding is added.
skipping to change at page 52, line 40 skipping to change at page 51, line 5
+------------+----------+-------------------------------------------+ +------------+----------+-------------------------------------------+
| S_c1, S_s1 | s_a, s_b | client/server-side secret randoms | | S_c1, S_s1 | s_a, s_b | client/server-side secret randoms |
| K_c1, K_s1 | w_a, w_b | client/server-side exchanged key | | K_c1, K_s1 | w_a, w_b | client/server-side exchanged key |
| | | components | | | | components |
| kc1, ks1 | wa, wb | parameter names for those | | kc1, ks1 | wa, wb | parameter names for those |
| VK_c, VK_s | o_a, o_b | client/server-side key verifiers | | VK_c, VK_s | o_a, o_b | client/server-side key verifiers |
| vkc, vks | oa, ob | parameter names for those | | vkc, vks | oa, ob | parameter names for those |
| z | z | session secrets | | z | z | session secrets |
+------------+----------+-------------------------------------------+ +------------+----------+-------------------------------------------+
A.12. Changes in Revision 09 A.13. Changes in Revision 09
o The (default) cryptographic algorithms are separated to another o The (default) cryptographic algorithms are separated to another
draft. draft.
o Names of the messages are changed to more informative ones than o Names of the messages are changed to more informative ones than
before. The following is the correspondence table of those names: before. The following is the correspondence table of those names:
+-------------------+-----------------+-----------------------------+ +-------------------+-----------------+-----------------------------+
| new name | old name | description | | new name | old name | description |
+-------------------+-----------------+-----------------------------+ +-------------------+-----------------+-----------------------------+
skipping to change at page 53, line 20 skipping to change at page 51, line 28
| req-KEX-C1 | req-A1 | client->server key exchange | | req-KEX-C1 | req-A1 | client->server key exchange |
| 401-KEX-S1 | 401-B1 | server->client key exchange | | 401-KEX-S1 | 401-B1 | server->client key exchange |
| req-VFY-C | req-A3 | client->server auth. | | req-VFY-C | req-A3 | client->server auth. |
| | | verification | | | | verification |
| 200-VFY-S | 200-B4 | server->client auth. | | 200-VFY-S | 200-B4 | server->client auth. |
| | | verification | | | | verification |
| 200-Optional-INIT | 200-Optional-B0 | initial with non-mandatory | | 200-Optional-INIT | 200-Optional-B0 | initial with non-mandatory |
| | | authentication | | | | authentication |
+-------------------+-----------------+-----------------------------+ +-------------------+-----------------+-----------------------------+
A.13. Changes in Revision 08 A.14. Changes in Revision 08
o The English text has been revised. o The English text has been revised.
A.14. Changes in Revision 07 A.15. Changes in Revision 07
o Adapt to httpbis HTTP/1.1 drafts: o Adapt to httpbis HTTP/1.1 drafts:
* Changed definition of extensive-token. * Changed definition of extensive-token.
* LWSP continuation-line (%0D.0A.20) deprecated. * LWSP continuation-line (%0D.0A.20) deprecated.
o To simplify the whole spec, the type of nonce-counter related o To simplify the whole spec, the type of nonce-counter related
parameters are change from hex-integer to integer. parameters are change from hex-integer to integer.
o Algorithm tokens are renamed to include names of hash algorithms. o Algorithm tokens are renamed to include names of hash algorithms.
o Clarified the session management, added details of server-side o Clarified the session management, added details of server-side
protocol decisions. protocol decisions.
o The whole draft was reorganized; introduction and overview has o The whole draft was reorganized; introduction and overview has
been rewritten. been rewritten.
A.15. Changes in Revision 06 A.16. Changes in Revision 06
o Integrated Optional Mutual Authentication to the main part. o Integrated Optional Mutual Authentication to the main part.
o Clarified the decision procedure for message recognitions. o Clarified the decision procedure for message recognitions.
o Clarified that a new authentication request for any sub-requests o Clarified that a new authentication request for any sub-requests
in interactive clients may be silently discarded. in interactive clients may be silently discarded.
o Typos and confusing phrases are fixed. o Typos and confusing phrases are fixed.
o Several "future considerations" are added. o Several "future considerations" are added.
A.16. Changes in Revision 05 A.17. Changes in Revision 05
o A new parameter called "version" is added for supporting future o A new parameter called "version" is added for supporting future
incompatible changes with a single implementation. In the (first) incompatible changes with a single implementation. In the (first)
final specification its value will be changed to 1. final specification its value will be changed to 1.
o A new header "Authentication-Control" is added for precise control o A new header "Authentication-Control" is added for precise control
of application-level authentication behavior. of application-level authentication behavior.
A.17. Changes in Revision 04 A.18. Changes in Revision 04
o Changed text of patent licenses: the phrase "once the protocol is o Changed text of patent licenses: the phrase "once the protocol is
accepted as an Internet standard" is removed so that the sentence accepted as an Internet standard" is removed so that the sentence
also covers the draft versions of this protocol. also covers the draft versions of this protocol.
o The "tls-key" verification is now OPTIONAL. o The "tls-key" verification is now OPTIONAL.
o Several description fixes and clarifications. o Several description fixes and clarifications.
A.18. Changes in Revision 03 A.19. Changes in Revision 03
o Wildcard domain specifications (e.g. "*.example.com") are allowed o Wildcard domain specifications (e.g. "*.example.com") are allowed
for auth-domain parameters (Section 4.1). for auth-domain parameters (Section 4.1).
o Specification of the tls-cert verification is updated o Specification of the tls-cert verification is updated
(incompatible change). (incompatible change).
o State transitions fixed. o State transitions fixed.
o Requirements for servers concerning w_a values are clarified. o Requirements for servers concerning w_a values are clarified.
o RFC references are updated. o RFC references are updated.
A.19. Changes in Revision 02 A.20. Changes in Revision 02
o Auth-realm is extended to allow full-scheme type. o Auth-realm is extended to allow full-scheme type.
o A decision diagram for clients and decision procedures for servers o A decision diagram for clients and decision procedures for servers
are added. are added.
o 401-B1 and req-A3 messages are changed to contain authentication o 401-B1 and req-A3 messages are changed to contain authentication
realm information. realm information.
o Bugs on equations for o_A and o_B are fixed. o Bugs on equations for o_A and o_B are fixed.
o Detailed equations for the entire algorithm are included. o Detailed equations for the entire algorithm are included.
o Elliptic-curve algorithms are updated. o Elliptic-curve algorithms are updated.
o Several clarifications and other minor updates. o Several clarifications and other minor updates.
A.20. Changes in Revision 01 A.21. Changes in Revision 01
o Several texts are rewritten for clarification. o Several texts are rewritten for clarification.
o Added several security consideration clauses. o Added several security consideration clauses.
Authors' Addresses Authors' Addresses
Yutaka Oiwa Yutaka Oiwa
National Institute of Advanced Industrial Science and Technology National Institute of Advanced Industrial Science and Technology
Information Technology Research Institute Information Technology Research Institute
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