Robust authentication and integrity for short OTP message Using any of the wonders of modern cryptographic technology, how is it possible to package a tweet-sized plaintext, which is to be encrypted with a proper one-time pad, to ensure its integrity and give it authentication? For these last two services we aim for at least a 128-bit level of assurance. We also want to indicate message order, with a tag, at the same level of protection.

Here are some ways to do it:

1.) One method would be to use a Carter-Wegman MAC.

2.) Another would be to use NaCl / Libsodium with the ChaCha20 stream cipher and the Poly1305 authenticator.

3.) Use an HMAC such as HMAC-SHA-256. 

Is there another way that is reliable? 

Thank you very much.
If you want to be consistent with OTP usage, then you should use a One Time MAC. Currently it seems the easiest path for that is to simply use Poly1305, but remember that you must never reuse keys for Poly1305, just like you can't reuse keys in OTP. (In particular, don't use the key generation routine used by ChaCha20-Poly1305 to derive the Poly1305 key from a nonce/key pair).

Using HMAC doesn't make much sense: if you're using OTP, that's probably because you don't trust any particular block cipher, so you shouldn't trust any particular hash or MAC algorithm.