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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.

 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (https://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.

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