public static void KeyExchange(Span <byte> sharedKey, ReadOnlySpan <byte> publicKey, ReadOnlySpan <byte> privateKey)
{
if (sharedKey.Length != 32)
{
throw new ArgumentException("sharedKey.Count != 32");
}
if (publicKey.Length != 32)
{
throw new ArgumentException("publicKey.Count != 32");
}
if (privateKey.Length != 64)
{
throw new ArgumentException("privateKey.Count != 64");
}
FieldOperations.fe_frombytes(out var edwardsY, publicKey);
FieldOperations.fe_1(out var edwardsZ);
MontgomeryCurve25519.EdwardsToMontgomeryX(out var montgomeryX, ref edwardsY, ref edwardsZ);
Span <byte> h = stackalloc byte[64];
Sha512.Hash(privateKey.Slice(0, 32), h);
ScalarOperations.sc_clamp(h);
MontgomeryOperations.scalarmult(out var sharedMontgomeryX, h, in montgomeryX);
CryptoBytes.Wipe(h);
FieldOperations.fe_tobytes(sharedKey, in sharedMontgomeryX);
}
public static void KeyExchange(ArraySegment \ \ sharedKey, ArraySegment \ \ publicKey, ArraySegment \ \ privateKey)
{
if (sharedKey.Array == null)
{
throw new ArgumentNullException("sharedKey.Array");
}
if (publicKey.Array == null)
{
throw new ArgumentNullException("publicKey.Array");
}
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");
}
FieldElement montgomeryX, edwardsY, edwardsZ, sharedMontgomeryX;
FieldOperations.fe_frombytes(out edwardsY, publicKey.Array, publicKey.Offset);
FieldOperations.fe_1(out edwardsZ);
MontgomeryCurve25519.EdwardsToMontgomeryX(out montgomeryX, ref edwardsY, ref edwardsZ);
byte[] h = Sha512.Hash(privateKey.Array, privateKey.Offset, 32);//ToDo: Remove alloc
ScalarOperations.sc_clamp(h, 0);
MontgomeryOperations.scalarmult(out sharedMontgomeryX, h, 0, ref montgomeryX);
CryptoBytes.Wipe(h);
FieldOperations.fe_tobytes(sharedKey.Array, sharedKey.Offset, ref sharedMontgomeryX);
MontgomeryCurve25519.KeyExchangeOutputHashNaCl(sharedKey.Array, sharedKey.Offset);
}