Internet Engineering Task Force (IETF) T. Ito
Request for Comments: 8813 SECOM CO., LTD.
Updates: 5480 S. Turner
Category: Standards Track sn3rd
ISSN: 2070-1721 August 2020
Clarifications for Elliptic Curve Cryptography Subject Public Key
Information
Abstract
This document updates RFC 5480 to specify semantics for the
keyEncipherment and dataEncipherment key usage bits when used in
certificates that support Elliptic Curve Cryptography.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8813.
Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction
2. Terminology
3. Updates to Section 3
4. Security Considerations
5. IANA Considerations
6. Normative References
Authors' Addresses
1. Introduction
[RFC5480] specifies the syntax and semantics for the Subject Public
Key Information field in certificates that support Elliptic Curve
Cryptography. As part of these semantics, it defines what
combinations are permissible for the values of the key usage
extension [RFC5280]. [RFC5480] specifies 7 of the 9 values; it makes
no mention of the keyEncipherment and dataEncipherment key usage
bits. This document corrects this omission by updating Section 3 of
[RFC5480] to make it clear that neither keyEncipherment nor the
dataEncipherment key usage bits are set for key agreement algorithms
defined therein. The additions are to be made to the end of
Section 3 of [RFC5480].
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Updates to Section 3
If the keyUsage extension is present in a certificate that indicates
id-ecPublicKey in SubjectPublicKeyInfo, then the following values
MUST NOT be present:
keyEncipherment; and
dataEncipherment.
If the keyUsage extension is present in a certificate that indicates
id-ecDH or id-ecMQV in SubjectPublicKeyInfo, then the following
values also MUST NOT be present:
keyEncipherment; and
dataEncipherment.
4. Security Considerations
This document introduces no new security considerations beyond those
found in [RFC5480].
5. IANA Considerations
This document has no IANA actions.
6. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<https://www.rfc-editor.org/info/rfc5280>.
[RFC5480] Turner, S., Brown, D., Yiu, K., Housley, R., and T. Polk,
"Elliptic Curve Cryptography Subject Public Key
Information", RFC 5480, DOI 10.17487/RFC5480, March 2009,
<https://www.rfc-editor.org/info/rfc5480>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Authors' Addresses
Tadahiko Ito
SECOM CO., LTD.
Email: tadahiko.ito.public@gmail.com
Sean Turner
sn3rd
Email: sean@sn3rd.com
