3.3.7. JSON Web Signature (JWS) Algorithms

3.3.7. JSON Web Signature (JWS) Algorithms

If the signing algorithm is a JSON Object Signing and Encryption (JOSE) signing algorithm from the "JSON Web Signature and Encryption Algorithms" registry established by [RFC7518], the JWS algorithm definition determines the signature and hashing algorithms to apply for both signing and verification.

For both signing and verification, the HTTP message's signature base (Section 2.5) is used as the entire "JWS Signing Input". The JOSE Header [JWS] [RFC7517] is not used, and the signature base is not first encoded in Base64 before applying the algorithm. The output of the JWS Signature is taken as a byte array prior to the Base64url encoding used in JOSE.

The JWS algorithm MUST NOT be "none" and MUST NOT be any algorithm with a JOSE Implementation Requirement of "Prohibited".

JSON Web Algorithm (JWA) values from the "JSON Web Signature and Encryption Algorithms" registry are not included as signature parameters. Typically, the JWS algorithm can be signaled using JSON Web Keys (JWKs) or other mechanisms common to JOSE implementations. In fact, JWA values are not registered in the "HTTP Signature Algorithms" registry (Section 6.2), and so the explicit alg signature parameter is not used at all when using JOSE signing algorithms.