// Xor XORs plain-text byte slice m with XSalsa20 stream generated from 24-byte
// nonce n and 32-byte key k, and puts the result into byte slice c, which must
// have length equal to or greater than the length of m.
func Xor(c, m []byte, n *[24]byte, k *[32]byte) {
var subkey [32]byte
hn := [16]byte{n[0], n[1], n[2], n[3], n[4], n[5], n[6], n[7], n[8], n[9], n[10], n[11], n[12], n[13], n[14], n[15]}
sn := [8]byte{n[16], n[17], n[18], n[19], n[20], n[21], n[22], n[23]}
hsalsa20.Core(&subkey, &hn, k, &sigma)
salsa20.Xor(c, m, &sn, &subkey)
}
func Before(k *[32]byte, pk, sk *[32]byte) {
curve25519.ScalarMult(k, sk, pk)
hsalsa20.Core(k, &beforen, k, &sigma)
}