The “CBOR Web Token (CWT)” specification is now RFC 8392 – an IETF standard. The abstract for the specification is:
CBOR Web Token (CWT) is a compact means of representing claims to be transferred between two parties. The claims in a CWT are encoded in the Concise Binary Object Representation (CBOR) and CBOR Object Signing and Encryption (COSE) is used for added application-layer security protection. A claim is a piece of information asserted about a subject and is represented as a name/value pair consisting of a claim name and a claim value. CWT is derived from JSON Web Token (JWT) but uses CBOR rather than JSON.
Next up – finishing “Proof-of-Possession Key Semantics for CBOR Web Tokens (CWTs)”, provides the CWT equivalent of “Proof-of-Possession Key Semantics for JSON Web Tokens (JWTs)” [RFC 7800].