Archive for April, 2016

April 6, 2016
Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs) is now RFC 7800

IETF logoThe Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs) specification is now RFC 7800 – an IETF standard. The abstract describes the specification as:

This specification describes how to declare in a JSON Web Token (JWT) that the presenter of the JWT possesses a particular proof-of-possession key and how the recipient can cryptographically confirm proof of possession of the key by the presenter. Being able to prove possession of a key is also sometimes described as the presenter being a holder-of-key.

Thanks to John Bradley, Hannes Tschofenig, and the OAuth working group for their work on this specification.

April 4, 2016
Using RSA Algorithms with COSE Messages

IETF logoI have published draft-jones-cose-rsa, which defines algorithm encodings and representations enabling RSA algorithms to be used for COSE messages. This addresses COSE Issue #21: Restore RSA-PSS and the “RSA” key type. The initial version of this specification incorporates text from draft-ietf-cose-msg-05 – the last COSE message specification version before the RSA algorithms were removed.

The specification is available at:

An HTML-formatted version is also available at: