internal byte[] Sign(byte[] message, string secretPhrase)
{
var p = new byte[32];
var s = new byte[32];
using (var incrementalHash = IncrementalHash.CreateHash(HashAlgorithmName.SHA256))
using (var sha256 = SHA256.Create())
{
Curve25519.Keygen(p, s, sha256.ComputeHash(Encoding.UTF8.GetBytes(secretPhrase)));
var m = sha256.ComputeHash(message);
incrementalHash.AppendData(m);
incrementalHash.AppendData(s);
var x = incrementalHash.GetHashAndReset();
var y = new byte[32];
Curve25519.Keygen(y, null, x);
incrementalHash.AppendData(m);
incrementalHash.AppendData(y);
var h = incrementalHash.GetHashAndReset();
var v = new byte[32];
Curve25519.Sign(v, h, x, s);
var signature = v.Concat(h).ToArray();
return(signature);
}
}
public byte[] Sign(byte[] message, string secretPhrase)
{
var p = new byte[32];
var s = new byte[32];
var sha256 = SHA256.Create();
Curve25519.Keygen(p, s, sha256.ComputeHash(Encoding.UTF8.GetBytes(secretPhrase)));
var m = sha256.ComputeHash(message);
sha256.TransformBlock(m, 0, m.Length, m, 0);
sha256.TransformFinalBlock(s, 0, s.Length);
var x = sha256.Hash;
var y = new byte[32];
Curve25519.Keygen(y, null, x);
sha256 = SHA256.Create();
sha256.TransformBlock(m, 0, m.Length, m, 0);
sha256.TransformFinalBlock(y, 0, y.Length);
var h = sha256.Hash;
var v = new byte[32];
Curve25519.Sign(v, h, x, s);
var signature = v.Concat(h).ToArray();
return(signature);
}
private byte[] GetPrivateKeyBytes(string secretPhrase)
{
using (var sha256 = SHA256.Create())
{
var privateKeyBytes = sha256.ComputeHash(Encoding.UTF8.GetBytes(secretPhrase));
Curve25519.Clamp(privateKeyBytes);
return(privateKeyBytes);
}
}
private byte[] GetSharedSecret(byte[] theirPublicKey, byte[] nonce, byte[] myPrivateKey)
{
var sharedSecret = new byte[32];
Curve25519.Curve(sharedSecret, myPrivateKey, theirPublicKey);
for (var i = 0; i < 32; i++)
{
sharedSecret[i] ^= nonce[i];
}
return(ComputeHash(sharedSecret));
}
internal BinaryHexString GetPublicKey(string secretPhrase)
{
var publicKey = new byte[32];
var encodedSecretPhrase = Encoding.UTF8.GetBytes(secretPhrase);
var hashedSecretPhrase = ComputeHash(encodedSecretPhrase);
Curve25519.Keygen(publicKey, null, hashedSecretPhrase);
var binaryHexString = new BinaryHexString(publicKey);
return(binaryHexString);
}
private bool Verify(byte[] signature, byte[] message, byte[] publicKey, bool enforceCanonical)
{
try
{
if (signature.Length != 64 ||
(enforceCanonical && !Curve25519.IsCanonicalSignature(signature)) ||
(enforceCanonical && !Curve25519.IsCanonicalPublicKey(publicKey)))
{
return(false);
}
var y = new byte[32];
var v = signature.Take(32).ToArray();
var h = signature.Skip(32).ToArray();
Curve25519.Verify(y, v, h, publicKey);
var h2 = HashIncremental(message, y);
return(h.SequenceEqual(h2));
}
catch (Exception)
{
return(false);
}
}