## OIDC, oAuth2.0, JWT, RS256, HS256, Tokens - don’t let the jargons be a barrier!

Key points


  • An id_token is a JWT - make note of that!
  • It contains claims about the identity of the user/resource owner
  • Having a valid id_token means that the user is authenticated


  • An access_token is a bearer token
  • A bearer token means that the bearer can access the resource without further identification
  • An access_token can be a JWT (see Appendix point 1.) or opaque


  • Are long lived opaque tokens used to obtain new access_token


id_token is typically used for:

  • Stateless sessions: The presence of a valid id_token (jwt) provides information about the session. e.g. For browsers, cookies can store id_token
  • User information: The client app receives claims about the user as part of the id_token
  • Token exchange: The ID token may be exchanged for an access token at the token endpoint of an OAuth 2.0 authorization server. (see Appendix 3.)


  • Has one and only one use, i.e. to establish which resource the bearer has access to
  • The token is meant to be opaque to the client application
  • But for the resource server, the access_token maps to the scope or claims that the bearer has
  • If this is a jwt, it may contain scope as part of the token; which the resource server can verify on the fly (without introspection)

    If you are looking for a practical example on how jwt are used as access_tokens, I wrote an authentication-authorization piece for graphql here: https://github.com/mannharleen/graphql-auth-implementation

The story of scopes & claims

Remember: Claims are grouped under Scope. e.g. claims ‘email’, ‘name’, ‘age’, etc. are part of the scope called ‘profile’


A scope is a space separated list of identifiers that specify what access privileges are being requested by the client application


A claim is a key-value pair that contain some information, e.g. user information


  1. JWT as access_token: this is in practice by providers like Auth0 & Okta, but the specification is still in draft stage, see: https://tools.ietf.org/html/draft-ietf-oauth-access-token-jwt-00
  2. If you are eager to read more, checkout the following literature:
    • OpenID Connect Core 1.0: https://openid.net/specs/openid-connect-core-1_0.html#IDTokenValidation
    • The OAuth 2.0 Authorization Framework: https://tools.ietf.org/html/rfc6749
  3. OAuth 2.0 Token Exchange: https://tools.ietf.org/html/draft-ietf-oauth-token-exchange-12