initialize :: (ByteArrayAccess key, ByteArrayAccess nonce)=> Intnumber of rounds (8,12,20)
-> keythe key (128 or 256 bits)
-> noncethe nonce (64 or 96 bits)
-> Statethe initial ChaCha state
Initialize a new ChaCha context with the number of rounds, the key and the nonce associated. To use ChaCha20 defined in RFC 8439, 20, 256bits-key and 96-bits nonce must be used.