Invalid Assertion - Client Assertion could not be parsed

[Vandhana Gopinath]

Hi,

I'm posting below details to the below token endpoint to get an access token for authorization on behalf of a system:

https://authorization.cerner.com/tenants/ec2458f2-1e24-41c8-b71b-0e701af7583d/protocols/oauth2/profiles/smart-v1/token

Request Body comprises of:

• grant_type:  client_credentials
• client_assertion_type:  urn:ietf:params:oauth:client-assertion-type:jwt-bearer
• client_assertion: RS384-encoded signed using private key and the corresponding public key is uploaded in system accounts as JWKS.

Client Assertion could not be parsed.

Error Code:

urn:cerner:error:authorization-server:client-assertion:jwt-bearer:invalid-assertion

Correlation ID:

6a7c6de3-045f-49fa-928f-edf8ba1e0ba6.

To double check I validated my token in jwt.io against the public key that is uploaded, and signature is getting verified.

However Basic Auth with secret works.

Any help is appreciated. Thanks in advance.