Unable to verify the token signature of a token received by the msal-typescript library

[exhuma]

I use the msal typescript library to retrieve a token. I can use the token to access the graph-api from microsoft.

But I can't use the token to access my own fast-api endpoints. It always fails with an error on signature verification. What am I missing?

I added some logging and am seeing this:

Signature verification failed.
Traceback (most recent call last):
  File "/workspaces/backend/env/lib/python3.11/site-packages/jose/jws.py", line 262, in _verify_signature
    raise JWSSignatureError()
jose.exceptions.JWSSignatureError

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/workspaces/backend/env/lib/python3.11/site-packages/jose/jwt.py", line 142, in decode
    payload = jws.verify(token, key, algorithms, verify=verify_signature)
              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/workspaces/backend/env/lib/python3.11/site-packages/jose/jws.py", line 73, in verify
    _verify_signature(signing_input, header, signature, key, algorithms)
  File "/workspaces/backend/env/lib/python3.11/site-packages/jose/jws.py", line 264, in _verify_signature
    raise JWSError("Signature verification failed.")
jose.exceptions.JWSError: Signature verification failed.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/workspaces/backend/env/lib/python3.11/site-packages/fastapi_microsoft_identity/auth_service.py", line 192, in __decode_JWT
    payload = jwt.decode(
              ^^^^^^^^^^^
  File "/workspaces/backend/env/lib/python3.11/site-packages/jose/jwt.py", line 144, in decode
    raise JWTError(e)
jose.exceptions.JWTError: Signature verification failed.