Consider creating ClientAssertionCredential and implementing WorkloadIdentityCredential in terms of it

[ahsonkhan]

Other languages like .NET and GoLang have this credential. We can start with this being private implementation detail of WIC and turn it to be public once there is a customer need for it in C++.

https://github.com/Azure/azure-sdk-for-net/blob/a932f53e2fc200cee443614a0bf991b02b518055/sdk/identity/Azure.Identity/src/Credentials/ClientAssertionCredential.cs#L18
https://github.com/Azure/azure-sdk-for-go/blob/e7968b534c61da1e38a683e21ac690deb14833c7/sdk/azidentity/client_assertion_credential.go#L26

WIC composing CAC:
https://github.com/Azure/azure-sdk-for-go/blob/e7968b534c61da1e38a683e21ac690deb14833c7/sdk/azidentity/workload_identity.go#L28

cc @chlowell

[ahsonkhan]

This is needed for #4968

[sershe-ms]

Hmm, since #4968 is closed, is it possible to expose this class for compatibility with the C# SDK?

[ahsonkhan]

We are looking for scenarios where customers would need a ClientAssertionCredential, exposed publicly in C++.

Can you please share details on how you'd use it and what your requirements are for using this credential in C++? What's motivating the need for C# compatibility?

[sershe-ms]

We are adding Azure support as a plugin to librdkafka Kafka client library. Some of the users of the library are using federated credentials, not just pure MSI, to have more fine-grained access control (as far as I understand)