public static byte[] Hash(byte[] data, int offset, int count)
{
Sha512 hasher = new Sha512();
hasher.Update(data, offset, count);
return(hasher.Finish());
}
public static void KeyExchange(ArraySegment <byte> sharedKey, ArraySegment <byte> publicKey,
ArraySegment <byte> privateKey)
{
if (sharedKey.Array == null)
{
throw new ArgumentNullException(nameof(sharedKey));
}
if (publicKey.Array == null)
{
throw new ArgumentNullException(nameof(sharedKey));
}
if (privateKey.Array == null)
{
throw new ArgumentNullException("privateKey");
}
if (sharedKey.Count != 32)
{
throw new ArgumentException("sharedKey.Count != 32");
}
if (publicKey.Count != 32)
{
throw new ArgumentException("publicKey.Count != 32");
}
if (privateKey.Count != 64)
{
throw new ArgumentException("privateKey.Count != 64");
}
FieldOperations.fe_frombytes(out FieldElement edwardsY, publicKey.Array, publicKey.Offset);
FieldOperations.fe_1(out FieldElement edwardsZ);
MontgomeryCurve25519.EdwardsToMontgomeryX(out FieldElement montgomeryX, ref edwardsY, ref edwardsZ);
byte[] h = Sha512.Hash(privateKey.Array, privateKey.Offset, 32);
ScalarOperations.ScClamp(h, 0);
MontgomeryOperations.ScalarMult(out FieldElement sharedMontgomeryX, h, 0, ref montgomeryX);
CryptoBytes.Wipe(h);
FieldOperations.fe_tobytes(sharedKey.Array, sharedKey.Offset, ref sharedMontgomeryX);
MontgomeryCurve25519.KeyExchangeOutputHashNaCl(sharedKey.Array, sharedKey.Offset);
}