[openssl-users] How to use Poly1305 with EVP interfaces?

[Jeffrey Walton]

I'm working from Master. I'm having trouble locating the message
digest for Poly1305, and how to use it with
https://wiki.openssl.org/index.php/EVP_Message_Digests.

At the moment I can only find EVP_chacha20_poly1305. It seems like if
Poly1305 is going to be paired with something, it would be AES, and
not TLS-ChaCha. I tried to use it with EVP_Message_Digests, but its
having a lot of trouble.

>From the type of EVP_chacha20_poly1305() and some of the error
messages, it looks like I may need to use the authenticated encryption
interfaces. I guess (maybe?) use AAD data only? If so, how do we
handle the per-message nonce?

How do I use the EVP interfaces to create a MAC with Poly1305?

Thanks in advance.