The usage of the credential key. The credential key usage can either be set to "sign" or "verify" a token. The default setting ...

            The usage of the credential key. The credential key usage can either be set to "sign" or "verify" a token.  The default setting is "verify".  Sign is allowed ONLY for symmetric keys.  Verify is allowed for all key types.
            A "verify" credential key is required by the Microsoft Azure Active Directory directory to verify that the request token was sent by your application (represented by this service principal). Your application may optionally require that Microsoft Azure Active Directory services issue tokens to your application signed with your signing key rather than the asymmetric public key identifying Microsoft Azure Active Directory. In this case, provide a "sign" credential key for your service principal.