// salsa2020XORKeyStream is implemented in salsa20_amd64.s. func salsa2020XORKeyStream(out, in *byte, n uint64, nonce, key *byte) // XORKeyStream crypts bytes from in to out using the given key and counters. // In and out must overlap entirely or not at all. Counter // contains the raw salsa20 counter bytes (both nonce and block counter). func XORKeyStream(out, in []byte, counter *[16]byte, key *[32]byte) { … }