draft-ietf-lamps-documentsigning-eku-02.txt   draft-ietf-lamps-documentsigning-eku-03.txt 
LAMPS Working Group T. Ito LAMPS Working Group T. Ito
Internet-Draft SECOM CO., LTD. Internet-Draft SECOM CO., LTD.
Intended status: Standards Track T. Okubo Intended status: Standards Track T. Okubo
Expires: 8 September 2022 DigiCert, Inc. Expires: 3 October 2022 DigiCert, Inc.
S. Turner S. Turner
sn3rd sn3rd
7 March 2022 1 April 2022
General Purpose Extended Key Usage (EKU) for Document Signing X.509 General Purpose Extended Key Usage (EKU) for Document Signing X.509
Certificates Certificates
draft-ietf-lamps-documentsigning-eku-02 draft-ietf-lamps-documentsigning-eku-03
Abstract Abstract
RFC5280 specifies several extended key purpose identifiers RFC5280 specifies several extended key purpose identifiers
(KeyPurposeIds) for X.509 certificates. This document defines a (KeyPurposeIds) for X.509 certificates. This document defines a
general purpose document signing KeyPurposeId for inclusion in the general purpose document signing KeyPurposeId for inclusion in the
Extended Key Usage (EKU) extension of X.509 public key certificates. Extended Key Usage (EKU) extension of X.509 public key certificates.
Document Signing applications may require that the EKU extension be Document Signing applications may require that the EKU extension be
present and that a document signing KeyPurposeId be indicated in present and that a document signing KeyPurposeId be indicated in
order for the certificate to be acceptable to that Document Signing order for the certificate to be acceptable to that Document Signing
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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 https://datatracker.ietf.org/drafts/current/. Drafts is at https://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 8 September 2022. This Internet-Draft will expire on 3 October 2022.
Copyright Notice Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the Copyright (c) 2022 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 (https://trustee.ietf.org/ Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document. license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights Please review these documents carefully, as they describe your rights
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This specification defines the KeyPurposeId id-kp-documentSigning. This specification defines the KeyPurposeId id-kp-documentSigning.
As described in [RFC5280], If the Extended Key Usage extension is As described in [RFC5280], If the Extended Key Usage extension is
present, then the certificate MUST only be used for one of the present, then the certificate MUST only be used for one of the
purposes indicated. [RFC5280] also describes that If multiple key purposes indicated. [RFC5280] also describes that If multiple key
purposes are indicated the application need not recognize all purposes are indicated the application need not recognize all
purposes indicated, as long as the intended purpose is present. purposes indicated, as long as the intended purpose is present.
Document Signing applications MAY require that the Extended Key Usage Document Signing applications MAY require that the Extended Key Usage
extension be present and that a id-kp-documentSigning be indicated in extension be present and that the id-kp-documentSigning be indicated
order for the certificate to be acceptable to that Document Signing in order for the certificate to be acceptable to that Document
application. Signing application.
The term "Document Signing" in this document refers to digitally The term "Document Signing" in this document refers to digitally
signing contents that are consumed by people. To be more precise, signing contents that are consumed by people. To be more precise,
contents are intended to be shown to a person with printable or contents are intended to be shown to a person with printable or
displayable form by means of services or software, rather than displayable form by means of services or software, rather than
processed by machines. processed by machines.
3.1. Including the Extended Key Purpose for Document Signing in 3.1. Including the Extended Key Purpose for Document Signing in
Certificates Certificates
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the certified public key is valid. The EKU extension can be used in the certified public key is valid. The EKU extension can be used in
conjunction with the key usage extension, which indicates the set of conjunction with the key usage extension, which indicates the set of
basic cryptographic operations for which the certified key may be basic cryptographic operations for which the certified key may be
used. used.
The EKU extension syntax is repeated here for convenience: The EKU extension syntax is repeated here for convenience:
ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId ExtKeyUsageSyntax ::= SEQUENCE SIZE (1..MAX) OF KeyPurposeId
KeyPurposeId ::= OBJECT IDENTIFIER KeyPurposeId ::= OBJECT IDENTIFIER
As described in [RFC5280], EKU extension may, at the option of the
certificate issuer, be either critical or non-critical.
This specification defines the KeyPurposeId id-kp-documentSigning. This specification defines the KeyPurposeId id-kp-documentSigning.
Inclusion of this KeyPurposeId in a certificate indicates that the Inclusion of this KeyPurposeId in a certificate indicates that the
public key encoded in the certificate has been certified to be used public key encoded in the certificate has been certified to be used
for cryptographic operations on contents that are consumed by people. for cryptographic operations on contents that are consumed by people.
id-kp OBJECT IDENTIFIER ::= id-kp OBJECT IDENTIFIER ::=
{ iso(1) identified-organization(3) dod(6) internet(1) { iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) 3 } security(5) mechanisms(5) pkix(7) 3 }
id-kp-documentSigning OBJECT IDENTIFIER ::= { id-kp XX } id-kp-documentSigning OBJECT IDENTIFIER ::= { id-kp XX }
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during certificate validation: during certificate validation:
The implementation MAY examine the KeyPurposeId(s) included in the The implementation MAY examine the KeyPurposeId(s) included in the
Extended Key Usage extension as follows: A Restriction on Extended Extended Key Usage extension as follows: A Restriction on Extended
Key Usage is derived and implemented from (or configured with) the Key Usage is derived and implemented from (or configured with) the
policy to which the implementation conforms. policy to which the implementation conforms.
1. If there are no restrictions set for the relying party and the 1. If there are no restrictions set for the relying party and the
relying party software, the certificate is acceptable. relying party software, the certificate is acceptable.
2. If there are restrictions set for the replying party and relying 2. If there are restrictions set for the relying party and relying
party software, then process the KeyPurposeId(s) as described party software, then process the KeyPurposeId(s) as described
below. below.
Each restriction on "Excluded KeyPurposeId" or "Permitted Each restriction on "Excluded KeyPurposeId" or "Permitted
KeyPurposeId" is handled as described below. KeyPurposeId" is handled as described below.
This procedure is intended to permit or prohibit presence of a This procedure is intended to permit or prohibit presence of a
certain KeyPurposeId or complete absence of KeyPurposeIds. It is certain KeyPurposeId or complete absence of KeyPurposeIds. It is
outside the scope of this document, but the relying party can outside the scope of this document, but the relying party can
permit or prohibit combinations of KeyPurposeIds. A permit or prohibit combinations of KeyPurposeIds. A
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Excluded KeyPurposeId procedure: "Excluded KeyPurposeId" is a Excluded KeyPurposeId procedure: "Excluded KeyPurposeId" is a
KeyPurposeId which the relying party or the relying party KeyPurposeId which the relying party or the relying party
software prohibits. Examples of "Excluded KeyPurposeId" are, software prohibits. Examples of "Excluded KeyPurposeId" are,
presence of the anyExtendedKeyUsage KeyPurposeId or complete presence of the anyExtendedKeyUsage KeyPurposeId or complete
absence of the EKU extension in a certificate. If a absence of the EKU extension in a certificate. If a
KeyPurposeId of the certificate meets the conditions set by KeyPurposeId of the certificate meets the conditions set by
the "Excluded KeyPurposeId" restriction, the relying party or the "Excluded KeyPurposeId" restriction, the relying party or
the relying party software rejects the certificate. the relying party software rejects the certificate.
Permitted KeyPurposeId procedure: Permitted KeyPurposeId procedure: "Permitted KeyPurposeId" is a
KeyPurposeId which the relying party or the relying party
: "Permitted KeyPurposeId" is a KeyPurposeId which the relying software accepts. Examples of "Permitted KeyPurposeId" are,
party or the relying party software accepts. Examples of presence of this general document signing KeyPurposeId and/or
"Permitted KeyPurposeId" are, presence of this general document protocol specific document signing-type KeyPurposeIds. If a
signing KeyPurposeId and/or protocol specific document signing- KeyPurposeId of the certificate meets the condition set by a
type KeyPurposeIds. If a KeyPurposeId of the certificate meets "Permitted KeyPurposeId" restriction, the certificate is
the condition set by a "Permitted KeyPurposeId" restriction, the acceptable. Otherwise, relying party or the relying party
certificate is acceptable. Otherwise, relying party or the software rejects the certificate.
relying party software rejects the certificate.
When a single application has the capability to process various data When a single application has the capability to process various data
formats, the software may choose to make the excluded and permitted formats, the software may choose to make the excluded and permitted
decisions separately in accordance with the format it is handling decisions separately in accordance with the format it is handling
(e.g. text, pdf, etc). (e.g. text, pdf, etc).
5. Implications for a Certification Authority 5. Implications for a Certification Authority
The procedures and practices employed by a certification authority The procedures and practices employed by a certification authority
MUST ensure that the correct values for the EKU extension are MUST ensure that the correct values for the EKU extension are
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To reduce the risk of specific cross-protocol attacks, the relying To reduce the risk of specific cross-protocol attacks, the relying
party or relying party software may additionally prohibit use of party or relying party software may additionally prohibit use of
specific combinations of KeyPurposeIds. specific combinations of KeyPurposeIds.
While a specific protocol or signing scheme may choose to come up While a specific protocol or signing scheme may choose to come up
with their own KeyPurposeIds, some may not have significant motive or with their own KeyPurposeIds, some may not have significant motive or
resources to set up and manage their own KeyPurposeIds. This general resources to set up and manage their own KeyPurposeIds. This general
document signing KeyPurposeId may be used as a stop-gap for those document signing KeyPurposeId may be used as a stop-gap for those
that intend to define their own KeyPurposeId or those who do not that intend to define their own KeyPurposeId or those who do not
intend to set up an KeyPurposeId but still would like to distinguish intend to set up a KeyPurposeId but still would like to distinguish
document signing from other usages. document signing from other usages.
Introduction of this id-kp-documentSigning KeyPurposeId does not Introduction of this id-kp-documentSigning KeyPurposeId does not
introduce any new security or privacy concerns. introduce any new security or privacy concerns.
7. IANA Considerations 7. IANA Considerations
This document requests that IANA make two assignments. One This document requests that IANA make two assignments. One
assignment is for the addition of the id-kp-documentSigning object assignment is for the addition of the id-kp-documentSigning object
identifier (OID), as defined in Section 3.1, to the "SMI Security for identifier (OID), as defined in Section 3.1, to the "SMI Security for
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-- Document Signing Extended Key Usage -- -- Document Signing Extended Key Usage --
id-kp-documentSigning OBJECT IDENTIFIER ::= { id-kp TBD2 } id-kp-documentSigning OBJECT IDENTIFIER ::= { id-kp TBD2 }
END END
Acknowledgments Acknowledgments
We would like to thank Russ Housley for verifying the ASN.1 module. We would like to thank Russ Housley for verifying the ASN.1 module.
Additionally, we would like to thank Corey Bonnell, Wendy Brown, Russ
Housley, Prachi Jain, and Stefan Santesson for their comments.
Authors' Addresses Authors' Addresses
Tadahiko Ito Tadahiko Ito
SECOM CO., LTD. SECOM CO., LTD.
Email: tadahiko.ito.public@gmail.com Email: tadahiko.ito.public@gmail.com
Tomofumi Okubo Tomofumi Okubo
DigiCert, Inc. DigiCert, Inc.
Email: tomofumi.okubo+ietf@gmail.com Email: tomofumi.okubo+ietf@gmail.com
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