This article demonstrates different types of tokens in OpenID Connect. At the end of this article, you will have clear understanding on the below points,
- About JSON Web Tokens (JWT)
- What is Access Token?
- Example of Access Token
- Why we need Access Token?
- What is ID Token?
- Example of ID Token
- Why we need ID Token?
- What is Refresh Token?
- Example of Refresh Token
- Why we need Refresh Token?
- OAuth2.0 And OpenID Connect (OIDC) Core Concepts – What? Why? How?
- Understanding Workflow Of OAuth2.0 Authorization Grant Types
About JSON Web Tokens (JWT)
JWT i.e. Json Web Tokens, are an important piece in ensuring trust and security in your application. JWT allows claims such as user data to be represented in a secure manner.
A JWT is represented as a sequence of base64url encoded values that are separated by dot character. It’s ideal format is like “Header.Payload.Signature”, where header keeps metadata for the token. The payload is basically the claims of the entity (typically user) and a signature for the signed token.
The Signed token is generated by combining the encoded JWT header and Payload and it is signed by using encryption algorithm like HMAC SHA–256. The signature private key is always held by server so it will be able to verify existing token as well as sign new token.
JWT could be used as an opaque identifier and could be inspected for additional information – such as identity attributes which it represents as claims.
Sample JWT token format could look like,
What is Access Token?
Access tokens are credentials used to access protected resources.
Access tokens are used as bearer tokens. A bearer token means that the bearer (who holds the access token) can access authorized resources without further identification.
Because of this, it is important that bearer tokens be protected.
These tokens usually have a short lifespan for security purpose. When it expires, the user must authenticate again to get a new access token limiting the exposure of the fact that it is a bearer token.
Access token must never be used for authentication. Access tokens cannot tell if the user has authenticated. The only user information the access token processes is the user id, located in sub claims.
The application receives an access token after a user successfully authenticates and authorizes access. Itis usually in JWT format but do not have to be.
The application should treat access tokens as opaque strings since they are meant for APIs. Your application should not attempt to decode them or expect receive token in a
This token does not contain any information about the user itself besides theirs ID (“sub”).It only contains authorization information about which actions the application is allowed to perform at the API (“scope”). This is what makes it useful for securing an API, but not for authenticating a user.
An access token is put in the Authorization header of your request, usually looks like Bearer “access_token” that the API you are calling can verify and grant you access.
Example of Access Token
Here is the sample response from the token endpoint! The response includes the ID token and access token. Your application can use the access token to make API requests on behalf of the user.