| Internet-Draft | C509 Revocation | May 2025 |
| Preuß Mattsson, et al. | Expires 24 November 2025 | [Page] |
This document specifies CBOR encodings of messages for certificate revocation lists, and¶
This note is to be removed before publishing as an RFC.¶
Status information for this document may be found at https://datatracker.ietf.org/doc/draft-cose-cbor-revocation-management/.¶
Discussion of this document takes place on the CBOR Object Signing and Encryption Working Group mailing list (mailto:cose@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/cose/. Subscribe at https://www.ietf.org/mailman/listinfo/cose/.¶
Source for this draft and an issue tracker can be found at https://github.com/cose-wg/CBOR-certificates.¶
This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.¶
Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.¶
Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."¶
This Internet-Draft will expire on 24 November 2025.¶
Copyright (c) 2025 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 Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License.¶
One of the challenges with deploying a Public Key Infrastructure (PKI) for the Internet of Things (IoT) is the management of X.509 public key certificates [RFC5280], since that is not optimized for constrained environments with restricted hardware definitions and data transport capabilities, see [RFC7228].¶
A more compact representation of X.509 certificates has been specified through the use of the Concise Binary Object Representation (CBOR, [RFC8949]). This CBOR encoding of X.509 certificates, referred to as C509 [I-D.ietf-cose-cbor-encoded-cert], also enables reduced code complexity, code size, memory and CPU usage, while allowing compatibility with ordinary ASN.1 DER-encoded X.509 for use with legacy deployments. A "native" C509 encoding is specified, identical to the backwards compatible format except for the scope of the signature, suitable for very constrained greenfield deployments.¶
The current specification adds to this work by specifying corresponding revokation related encoding and strucure.¶
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.¶
This specification makes use of the terminology in [RFC5280], and [RFC6960]. When referring to CBOR, this specification always refers to Deterministically Encoded CBOR as specified in Sections 4.2.1 and 4.2.2 of [RFC8949].¶
The section defines the C509 Certificate Revocation List (CRL) format based on and compatible with [RFC5280] reusing the formatting for C509 certificates defined in [I-D.ietf-cose-cbor-encoded-cert].¶
C509CertificateRevocationList = [
TBSCertificateRevocationList,
issuerSignatureValue : any,
]
; The elements of the following group are used in a CBOR Sequence:
TBSCertificateRevocationList = (
C509CertificateRevocationListType: int,
issuer: Name,
thisUpdate: Time,
nextUpdate: Time,
revokedCertificates: RevokedCertificates,
crlExtensions: Extensions,
issuerSignatureAlgorithm: AlgorithmIdentifier,
)
RevokedCertificates = [
userCertificate: CertificateSerialNumber,
revocationDate: Time,
crlEntryExtensions: Extensions,
]
To encode OCSP requests, the CDDL below gives the cbor encoding corresponding to the ASN.1 encoding defined in RFC 6960 [RFC6960].¶
C509OCSPRequest = [
TBSRequest,
optionalSignature : *any,
]
TBSRequest = [
version : uint .default 1,
requestorName : *GeneralName,
requestList : [+Request],
requestExtensions : *[+extension]
]
Request = [
reqCert : CertID,
singleRequestExtensions : *[+extension]
]
CertID = [
hashAlgorithm : AlgorithmIdentifier,
issuerNameHash : bytes, -- Hash of issuer's DN
issuerKeyHash : bytes, -- Hash of issuer's public key
serialNumber : CertificateSerialNumber
]
extension = TBD
IMPORTS
GeneralName, AlgorithmIdentifier, CertificateSerialNumber
FROM
Main C509 document
Concerning OCSP responses we address the id-pkix-ocsp-basic response type as defined in defined in RFC 6960 [RFC6960].¶
C509OCSPResponse = [
responseStatus : C509OCSPResponseStatus,
responseBytes : *BasicOCSPResponse
]
OCSPResponseStatus = 0..6 ; inclusive range
; semantics of integer values as in rfc6960, 4.2.1. ASN.1 Specification of the OCSP Response
BasicOCSPResponse = [
tbsResponseData : ResponseData,
signatureAlgorithm : AlgorithmIdentifier,
signature : any,
certs : *[C509Certificate]
]
ResponseData = [
version : uint .default 1,
responderID : ResponderID,
producedAt : Time,
responses : [+SingleResponse],
responseExtensions : *[+extension]
ResponderID = Name / KeyHash
Name = TBD
KeyHash = bytes -- SHA-1 hash of responder's public key (excluding the tag and length fields)
; OBSOLETE, but needed if we want to fully recreate RFC6960 style messages
SingleResponse = [
certID : CertID,
certStatus : CertStatus,
thisUpdate : Time,
nextUpdate : *Time,
singleExtensions : *[+extension]
]
CertStatus = {1: NULL} / {2: RevokedInfo} / {3: NULL}
; good / revoked / unknown, semantics from RFC6960
RevokedInfo = (
revocationTime : Time,
revocationReason : *CRLReason
)
CRLReason = 0..10 ; inclusive range
; semantics of integer values from RFC6960, 5.3.1.
TODO¶