1. Introduction
This specification registers cryptographic algorithms and identifiers to be used with the JSON Web Signature (JWS) [JWS], JSON Web Encryption (JWE) [JWE], and JSON Web Key (JWK) [JWK] specifications. It defines several IANA registries for these identifiers. All of these specifications use JSON-based [RFC7159] data structures. This specification also describes the semantics and operations that are specific to these algorithms and key types.
Registering the algorithms and identifiers here, rather than in the JWS, JWE, and JWK specifications, is intended to allow them to remain unchanged in the face of changes in the set of Required, Recommended, Optional, and Deprecated algorithms over time. This also allows for changes to the JWS, JWE, and JWK specifications without requiring this document to be updated.
The names defined herein are all short because a core goal is for the resulting representations to be compact.
1.1 Notational Conventions
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 "Key words for use in RFCs to Indicate Requirement Levels" [RFC2119]. The interpretation should only be applied when the terms appear in all capital letters.
BASE64URL(OCTETS) denotes the base64url encoding of OCTETS, per Section 2 of [JWS].
UTF8(STRING) denotes the octets of the UTF-8 [RFC3629] representation of STRING, where STRING is a sequence of zero or more Unicode [UNICODE] characters.
ASCII(STRING) denotes the octets of the ASCII [RFC20] representation of STRING, where STRING is a sequence of zero or more ASCII characters.
The concatenation of two values A and B is denoted as A || B.