void PointCompressTest(int bits, ECGroup group, ECPoint p, int repeats, string name)
{
int bytes = (bits >> 3) + ((bits & 7) == 0 ? 0 : 1) + 1;
for (int i = 0; i < repeats; i++)
{
byte[] tmp = p.ToByteArray(true);
Assert.IsTrue(tmp.Length == bytes, name + " #1");
ECPoint x = new ECPoint(group, tmp).Export();
ECPoint p2 = p.Export();
Assert.IsTrue(x.X.CompareTo(p2.X) == 0, name + " #2");
Assert.IsTrue(x.Y.CompareTo(p2.Y) == 0, name + " #3");
p = p.Multiply(Number.CreateRandomElement(group.P));
}
}
public byte[] PerformKeyAgreement(byte[] otherPublicKey1, byte[] otherPublicKey2, int keyDataLength)
{
ECPoint otherQ1 = new ECPoint(_params.Domain.Group, otherPublicKey1);
ECPoint otherQ2 = new ECPoint(_params.Domain.Group, otherPublicKey2);
IFiniteField ff = _params.Domain.FieldN;
// MQV Primitives
if (_params.KeyPair1.D == null)
{
_params.KeyPair1.CreateNewPrivateKey();
}
if (_params.KeyPair2.D == null)
{
_params.KeyPair2.CreateNewPrivateKey();
}
if (_params.KeyPair2.Q == null)
{
_params.KeyPair2.CreatePublicKeyFromPrivateKey();
}
int logBits = _params.Domain.N.BitCount();
logBits = (logBits >> 1) + ((logBits & 1) == 0 ? 0 : 1);
Number mod = Number.One << logBits;
Number mask = mod - Number.One;
Number q2u = (_params.KeyPair2.Q.Export().X & mask) + mod;
Number s = ff.Add(_params.KeyPair2.D, ff.Multiply(q2u, _params.KeyPair1.D));
Number q2v = (otherQ2.Export().X & mask) + mod;
ECPoint P = otherQ2.Add(otherQ1.Multiply(q2v)).Multiply(s * new Number(new uint[] { _params.Domain.H }));
if (P.IsInifinity())
{
throw new CryptographicException();
}
int keyBytes = (int)((_params.Domain.Bits >> 3) + ((_params.Domain.Bits & 7) == 0 ? 0 : 1));
byte[] sharedSecretValue = P.Export().X.ToByteArray(keyBytes, false);
// KDF
_kdf.SharedInfo = _sharedInfo;
return(_kdf.Calculate(sharedSecretValue, keyDataLength));
}