Clarifications for Ed25519, Ed448, X25519, and X448 Algorithm Identifierssn3rdsean@sn3rd.comSJD ABsimon@josefsson.orgSquare Inc.daniel@binaryparadox.netSECOM CO., LTD.tadahiko.ito.public@gmail.com
sec
lampsPKIXX.509keyUsageElliptic Curve CryptographyThis document updates RFC 8410 to clarify existing semantics, and specify
missing semantics, for key usage bits when used in certificates
that support the Ed25519, Ed448, X25519, and X448 Elliptic Curve
Cryptography algorithms.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
.
Copyright Notice
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Table of Contents
. Introduction
. Terminology
. New Section 5 for RFC 8410
. Security Considerations
. IANA Considerations
. References
. Normative References
. Informative References
Acknowledgments
Authors' Addresses
Introduction specifies the syntax and semantics for the Subject Public
Key Information field in certificates that support Ed25519, Ed448,
X25519, and X448 Elliptic Curve Cryptography (ECC) algorithms. As part
of these semantics, it defines what combinations are permissible for the
values of the keyUsage extension . did not
define what values are not permissible, nor did it refer to
keyEncipherment or dataEncipherment. has also been submitted
to clarify that keyCertSign is always set in certification authority
certificates. To address these changes, this document replaces
with .TerminologyThe 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
when, and only
when, they appear in all capitals, as shown here.New Section 5 for RFC 8410The intended application for the key is indicated in the keyUsage
certificate extension.If the keyUsage extension is present in a certificate that indicates
id-X25519 or id-X448 in SubjectPublicKeyInfo, then the following MUST
be present:
keyAgreement
One of the following MAY also be present:
encipherOnly
decipherOnly
and any of the following MUST NOT be present:
digitalSignature
nonRepudiation
keyEncipherment
dataEncipherment
keyCertSign
cRLSign
If the keyUsage extension is present in an end-entity
certificate that indicates id-Ed25519 or id-Ed448 in
SubjectPublicKeyInfo, then the keyUsage extension MUST contain at least
one of the following:
nonRepudiation
digitalSignature
cRLSign
and any of the following MUST NOT be present:
keyEncipherment
dataEncipherment
keyAgreement
keyCertSign
encipherOnly
decipherOnly
If the keyUsage extension is present in a CRL issuer certificate that
indicates id-Ed25519 or id-Ed448 in SubjectPublicKeyInfo, then the
keyUsage extension MUST contain:
cRLSign
and zero or more of the following:
nonRepudiation
digitalSignature
and any of the following MUST NOT be present:
keyEncipherment
dataEncipherment
keyAgreement
encipherOnly
decipherOnly
and if the CRL issuer is also a certification authority, then the
keyUsage extension MUST also contain:
keyCertSign
If the keyUsage extension is present in a certification authority
certificate that indicates id-Ed25519 or id-Ed448 in
SubjectPublicKeyInfo, then the keyUsage extension MUST contain:
keyCertSign
and zero or more of the following:
nonRepudiation
digitalSignature
cRLSign
and any of the following MUST NOT be present:
keyEncipherment
dataEncipherment
keyAgreement
encipherOnly
decipherOnly
Security ConsiderationsThis document introduces no new security considerations beyond those
found in .IANA ConsiderationsThis document has no IANA actions.ReferencesNormative ReferencesKey words for use in RFCs to Indicate Requirement LevelsIn many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) ProfileThis memo profiles the X.509 v3 certificate and X.509 v2 certificate revocation list (CRL) for use in the Internet. An overview of this approach and model is provided as an introduction. The X.509 v3 certificate format is described in detail, with additional information regarding the format and semantics of Internet name forms. Standard certificate extensions are described and two Internet-specific extensions are defined. A set of required certificate extensions is specified. The X.509 v2 CRL format is described in detail along with standard and Internet-specific extensions. An algorithm for X.509 certification path validation is described. An ASN.1 module and examples are provided in the appendices. [STANDARDS-TRACK]Ambiguity of Uppercase vs Lowercase in RFC 2119 Key WordsRFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings.Algorithm Identifiers for Ed25519, Ed448, X25519, and X448 for Use in the Internet X.509 Public Key InfrastructureThis document specifies algorithm identifiers and ASN.1 encoding formats for elliptic curve constructs using the curve25519 and curve448 curves. The signature algorithms covered are Ed25519 and Ed448. The key agreement algorithms covered are X25519 and X448. The encoding for public key, private key, and Edwards-curve Digital Signature Algorithm (EdDSA) structures is provided.Informative ReferencesErratum ID 5696RFC ErrataRFC 8410AcknowledgmentsWe would like to thank , , and
for their comments.Authors' Addressessn3rdsean@sn3rd.comSJD ABsimon@josefsson.orgSquare Inc.daniel@binaryparadox.netSECOM CO., LTD.tadahiko.ito.public@gmail.com