public static int CryptoSecretboxOpen(byte[] M, byte[] C, long Clen, byte[] N, byte[] K)
{
if (Clen < 32)
{
return(-1);
}
byte[] subkeyp = new byte[32];
Xsalsa20.CryptoStream(subkeyp, 32, N, K);
if (Poly1305.CryptoOnetimeauthVerify(C, 16, C, 32, Clen - 32, subkeyp) != 0)
{
return(-1);
}
Xsalsa20.CryptoStreamXor(M, C, Clen, N, K);
for (int i = 0; i < 32; ++i)
{
M[i] = 0;
}
return(0);
}