Make TimestampAuthorityClient public

[SequeI]

Description

Within model_transparency, we are adding RFC 3161 Timestamp Authority support for PKI signing. It all works fine, however we have to import this class for usage, and it is private.

from sigstore._internal.timestamp import TimestampAuthorityClient

Could we make it public for our usage? Here is the PR in model-transparency for more context.
sigstore/model-transparency#620

[jku]

It might be possible. Another option is that you use rfc3161_client directly: TimestampAuthorityClient is basically just

• call to rfc3161_client.TimestampRequestBuilder()
• HTTP POST
• call to rfc3161_client.decode_timestamp_response()

so not rocket science

[woodruffw]

I am not inherently opposed to this, but if we're making this API public we need to make sure that we don't inadvertently expose other APIs as public (and that we're not constraining our internal usages). If direct use of rfc3161-client would address the same use case, then I'm inclined to point to that instead of exposing more public API surface 🙂