Function generate_crypt_setup 

pub fn generate_crypt_setup(
    rng: &SystemRandom,
) -> Result<(CryptSetup, CryptState)>

Generate a fresh OCB2 key and the two nonces for a new connection.

REF: references/mumble/src/murmur/Messages.cpp : msgAuthenticate sets server_nonce = getEncryptIV() and client_nonce = getDecryptIV(), so on the server the encrypt IV is the server nonce (S2C) and the decrypt IV is the client nonce (C2S).

Errors

When the system randomness source fails.