Perform authenticated encryption on a plaintext and some additional authenticated data, given a 256-bit key and 96-bit nonce, using AEAD-ChaCha20-Poly1305.

Produces a ciphertext and 128-bit message authentication code pair.

>>> let key = "don't tell anyone my secret key!"
>>> let non = "or my nonce!"
>>> let pan = "and here's my plaintext"
>>> let aad = "i approve this message"
>>> let Right (cip, mac) = encrypt aad key nonce pan
>>> (cip, mac)
<(ciphertext, 128-bit MAC)>

Decrypt an authenticated ciphertext, given a message authentication code and some additional authenticated data, via a 256-bit key and 96-bit nonce.

>>> decrypt aad key non (cip, mac)
Right "and here's my plaintext"
>>> decrypt aad key non (cip, "it's a valid mac")
Left InvalidMAC

Error values.