JWT token is "invalid signature"?

[tyf]

Hey again!

@kkrp1

Firstly, is this the right flow?

You’re on the right track!

@kkrp1

What am I missing here - why does everything basically work, but JWT.io says the token’s signature is invalid, resulting in no payload shown?

My guess is that this token is missing the audience - If you do not specify an audience (aud claim) then the access token you get back will be opaque (not a jwt). That is, it cannot be decoded but can be used against the /userinfo endpoint. Some more on that here:

Why is my access token not a JWT? (Opaque Token)

Question: Why is my access token not a JWT? (Opaque Token) Answer: An access token will be issued in one of the following formats: JSON Web Token (JWT) : Tokens that conform to the JSON Web Token standard and contain information about an entity in the form of claims. They are self-contained in that it is not necessary for the recipient to call a server to validate the token. Access Tokens issued for the Auth0 Management API and Access Tokens issued for any custom API that you have registere…

And a helpful FAQ on audience in general:

What is the Audience?

Question: What is the Audience? Answer: The audience parameter exists as part of the OAuth2.0 protocol. You can read more information from the specification here. What is it? The audience (presented as the aud claim in the access token) defines the intended consumer of the token. This is typically the resource server (API, in the dashboard) that a client (Application) would like to access. It can be added to the request to authorize i.e. audience: 'https://test-api' Here is an example where …

Hope this helps!