Best HTTP Authorization header type for JWT

Question

I'm wondering what is the best appropriate Authorization HTTP header type for JWT tokens.

One of the probably most popular type is Basic. For instance:

Authorization: Basic QWxhZGRpbjpvcGVuIHNlc2FtZQ==

It handle two parameters such as a login and a password. So it is not relevant for JWT tokens.

Also, I heard about Bearer type, for instance:

Authorization: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiYWRtaW4iOnRydWV9.TJVA95OrM7E2cBab30RMHrHDcEfxjoYZgeFONFh7HgQ

However, I don't know its meaning. Is it related to bears?

Is there a particular way to use JWT tokens in the HTTP Authorization header? Should we use Bearer, or should we simplify and just use:

Authorization: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiYWRtaW4iOnRydWV9.TJVA95OrM7E2cBab30RMHrHDcEfxjoYZgeFONFh7HgQ

Thanks.

Edit:

Or maybe, just a JWT HTTP header:

JWT: eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiIxMjM0NTY3ODkwIiwibmFtZSI6IkpvaG4gRG9lIiwiYWRtaW4iOnRydWV9.TJVA95OrM7E2cBab30RMHrHDcEfxjoYZgeFONFh7HgQ

Answer 1

The best HTTP header for your client to send an access token (JWT or any other token) is the Authorization header with the Bearer authentication scheme.

This scheme is described by the RFC6750.

Example:

GET /resource HTTP/1.1
Host: server.example.com
Authorization: Bearer eyJhbGciOiJIUzI1NiIXVCJ9TJV...r7E20RMHrHDcEfxjoYZgeFONFh7HgQ

If you need stronger security protection, you may also consider the following IETF draft: https://datatracker.ietf.org/doc/html/draft-ietf-oauth-pop-architecture. This draft seems to be a good alternative to the (abandoned?) https://datatracker.ietf.org/doc/html/draft-ietf-oauth-v2-http-mac.

Note that even if this RFC and the above specifications are related to the OAuth2 Framework protocol, they can be used in any other contexts that require a token exchange between a client and a server.

Unlike the custom JWT scheme you mention in your question, the Bearer one is registered at the IANA.

Concerning the Basic and Digest authentication schemes, they are dedicated to authentication using a username and a secret (see RFC7616 and RFC7617) so not applicable in that context.