CBOR Object Signing and Encryption (cose) Internet Drafts

      
 CBOR Encoded X.509 Certificates (C509 Certificates)
 
 draft-ietf-cose-cbor-encoded-cert-20.txt
 Date: 30/06/2026
 Authors: John Mattsson, Goeran Selander, Shahid Raza, Joel Hoglund, Martin Furuhed, Lijun Liao
 Working Group: CBOR Object Signing and Encryption (cose)
 This document specifies a CBOR encoding of X.509 certificates. The resulting certificates are called C509 certificates. The CBOR encoding supports a large subset of RFC 5280 and common certificate profiles, and it is extensible. Two types of C509 certificates are defined. One type is an invertible CBOR re-encoding of DER-encoded X.509 certificates with the signature field copied from the DER encoding. The other type is identical except that the signature is computed over the CBOR encoding instead of the DER encoding, thereby avoiding the use of ASN.1. Both types of certificates have the same semantics as X.509 while providing comparable size reduction. This document also specifies CBOR-encoded data structures for certification requests and certification request templates, new COSE headers, as well as a TLS certificate type and a file format for C509. This document updates RFC 6698 by extending the TLSA selectors registry to include C509 certificates.
 Use of Hybrid Public-Key Encryption (HPKE) with CBOR Object Signing and Encryption (COSE)
 
 draft-ietf-cose-hpke-27.txt
 Date: 12/09/2026
 Authors: Hannes Tschofenig, Michael Jones, Orie Steele, Ajitomi, Daisuke, Laurence Lundblade
 Working Group: CBOR Object Signing and Encryption (cose)
 This specification defines hybrid public-key encryption (HPKE) for use with CBOR Object Signing and Encryption (COSE). HPKE offers a variant of public-key encryption of arbitrary-sized plaintexts for a recipient public key. HPKE is a general encryption framework utilizing an asymmetric key encapsulation mechanism (KEM), a key derivation function (KDF), and an Authenticated Encryption with Associated Data (AEAD) algorithm. This document defines the use of HPKE with COSE. Authentication for HPKE in COSE is provided by COSE-native security mechanisms or by the pre-shared key authenticated variant of HPKE.
 SLH-DSA for JOSE and COSE
 
 draft-ietf-cose-sphincs-plus-10.txt
 Date: 28/07/2026
 Authors: Michael Prorock, Orie Steele, Hannes Tschofenig
 Working Group: CBOR Object Signing and Encryption (cose)
 Digital signatures are used within JSON Object Signing and Encryption (JOSE) and CBOR Object Signing and Encryption (COSE) to protect the integrity and authenticity of messages, such as JSON Web Signatures and signed COSE structures. This document specifies JOSE and COSE serializations for the Stateless Hash-Based Digital Signature Standard (SLH-DSA), a Post-Quantum Cryptography (PQC) digital signature scheme defined in US NIST FIPS 205. The conventions for the associated algorithm identifiers, signatures, public keys, and private keys are also specified.
 Test Vectors for CBOR-Encoded X.509 (C509) Certificates
 
 draft-ietf-cose-c509-test-vectors-02.txt
 Date: 22/07/2026
 Authors: Lijun Liao, Goeran Selander, John Mattsson
 Working Group: CBOR Object Signing and Encryption (cose)
 This document contains examples of CBOR-encoded X.509 (C509) certificates, certification requests, and certification request templates.
 Split Signing Algorithms for COSE
 
 draft-ietf-cose-split-signing-algs-01.txt
 Date: 05/07/2026
 Authors: Emil Lundberg, Michael Jones
 Working Group: CBOR Object Signing and Encryption (cose)
 This specification defines COSE algorithm identifiers for negotiating how to split a signature algorithm between two cooperating parties. Typically the first party hashes the data to be signed and the second party finishes the signature over the hashed data. This is a common technique, useful for example when the signing private key is held in a smart card or similar hardware component with limited processing power and communication bandwidth. The resulting signatures are identical in structure to those computed by a single party, and can be verified using the same verification algorithm without additional steps to preprocess the signed data.
 AES-CMAC for COSE
 
 draft-ietf-cose-cmac-01.txt
 Date: 29/07/2026
 Authors: Brian Sipos
 Working Group: CBOR Object Signing and Encryption (cose)
 The CBOR Object Signing and Encryption (COSE) specification defines structures for generating, conveying, and verifying Message Authentication Code (MAC) tags. This document registers code points for using the Advanced Encryption Standard (AES) block cipher in Cipher-based Message Authentication Code (CMAC) mode within those COSE structures. Specifically, these uses are for computing MAC tag values with no additional parameters.
 COSE HPKE PQ & PQ/T Algorithm Registrations
 
 draft-ietf-cose-hpke-pq-pqt-01.txt
 Date: 21/07/2026
 Authors: Tirumaleswar Reddy.K, Hannes Tschofenig, Filip Skokan
 Working Group: CBOR Object Signing and Encryption (cose)
 This document registers Post-Quantum (PQ) and Post-Quantum/ Traditional (PQ/T) hybrid algorithm identifiers for use with CBOR Object Signing and Encryption (COSE), building on the Hybrid Public Key Encryption (HPKE) framework.

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CBOR Object Signing and Encryption (cose)

WG Name CBOR Object Signing and Encryption
Acronym cose
Area Security Area (sec)
State Active
Charter charter-ietf-cose-05 Approved
Document dependencies
Additional resources Issue tracker, Wiki, Zulip Stream
Personnel Chairs Ivaylo Petrov, Michael B. Jones
Area Director Christopher Inacio
Mailing list Address [email protected]
To subscribe https://www.ietf.org/mailman/listinfo/cose
Archive https://mailarchive.ietf.org/arch/browse/cose/
Chat Room address https://zulip.ietf.org/#narrow/stream/cose

Charter for Working Group

CBOR Object Signing and Encryption (COSE, RFC 9052) describes how to
create and process signatures, message authentication codes, and
encryption using Concise Binary Object Representation (CBOR, RFC 8949)
for serialization. COSE additionally describes a representation for
cryptographic keys.

The COSE working group handles four types of (intended status Standard Track) documents:

  1. Documents that describe the use of cryptographic algorithms in COSE.
  2. Documents that describe additional attributes for COSE.
  3. Documents that define header parameters to be used in COSE objects.
  4. Documents that define COSE key representations.

The WG will evaluate, and potentially adopt, documents dealing with algorithms
that would fit the criteria of being IETF consensus algorithms.

Key management and binding of keys to identities are out of scope for
the working group. The COSE WG will not innovate in terms of
cryptography. The specification of algorithms in COSE is limited to
those in RFCs, active IRTF CFRG or IETF WG documents, or algorithms which
have been positively reviewed by the IRTF CFRG.

The COSE WG will also work on a CBOR encoding of the certificate profile
defined in RFC 5280. It is expected that the encoding works with RFC 7925.
The main objective is to define a method of encoding current X.509
certificates that meet a specific profile into a smaller format. This
encoding shall be invertible, so they can be expanded and normal X.509 certificate
processing can be used. This work is currently happening in draft-ietf-cose-cbor-encoded-cert.

Milestones

Date Milestone Associated documents
Jan 2026 One or more documents describing the proper use of algorithms. draft-ietf-cose-sphincs-plus
draft-ietf-cose-hpke
rfc9964 (was draft-ietf-cose-dilithium)
draft-ietf-cose-falcon
Nov 2025 A CBOR encoding of the certificate profile to the IESG draft-ietf-cose-cbor-encoded-cert
Jul 2025 COSE header parameters for COSE objects that carry a payload that is an output of a hash function on an original payload to IESG rfc9995 (was draft-ietf-cose-hash-envelope)
Jun 2025 COSE header parameters for incorporating “COSE Receipts” into COSE objects to IESG rfc9942 (was draft-ietf-cose-merkle-tree-proofs)
Jun 2025 COSE header parameters for RFC 3161-based timestamping into COSE objects to IESG rfc9921 (was draft-ietf-cose-tsa-tst-header-parameter)