public void DoHandshake(string signedPrime, string signedGenerator)
{
if (IsInitiator) return;
byte[] signedPrimeAsBytes = HexToBytes(signedPrime);
Rsa.Verify(ref signedPrimeAsBytes);
byte[] signedGeneratorAsBytes = HexToBytes(signedGenerator);
Rsa.Verify(ref signedGeneratorAsBytes);
DhPrime = new BigInteger(Encoding.Default.GetString(signedPrimeAsBytes), 10);
DhGenerator = new BigInteger(Encoding.Default.GetString(signedGeneratorAsBytes), 10);
if (DhPrime <= 2)
throw new Exception("Prime cannot be <= 2!\nPrime: " + DhPrime);
if (DhGenerator >= DhPrime)
throw new Exception($"Generator cannot be >= Prime!\nPrime: {DhPrime}\nGenerator: {DhGenerator}");
DhPrivate = new BigInteger(RandomHex(30), _bitSize);
DhPublic = DhGenerator.ModPow(DhPrivate, DhPrime);
}
public void DoHandshake(Bitmap banner, string token)
{
IsBannerHandshake = true;
var bannerData = new byte[banner.Width * banner.Height * 4];
for (int y = 0, i = 0; y < banner.Height; y++)
{
for (int x = 0; x < banner.Width; x++)
{
int pixelArgb = banner.GetPixel(x, y).ToArgb();
bannerData[i++] = (byte)((pixelArgb >> 24) & 255);
bannerData[i++] = (byte)((pixelArgb >> 16) & 255);
bannerData[i++] = (byte)((pixelArgb >> 8) & 255);
bannerData[i++] = (byte)(pixelArgb & 255);
}
}
string bannerChunk = Xor(Decode(bannerData), token);
int bannerSize = bannerChunk[0];
bannerChunk = bannerChunk.Substring(1);
DhPrime = new BigInteger(bannerChunk.Substring(0, bannerSize), 10);
bannerChunk = bannerChunk.Substring(bannerSize);
bannerSize = bannerChunk[0];
bannerChunk = bannerChunk.Substring(1);
DhGenerator = new BigInteger(bannerChunk.Substring(0, bannerSize), 10);
DhPrivate = new BigInteger(RandomHex(30), _bitSize);
DhPublic = DhGenerator.ModPow(DhPrivate, DhPrime);
}
public byte[] GetSharedKey(string publicKey)
{
if (!IsBannerHandshake)
{
byte[] paddedPublicKeyAsBytes = HexToBytes(publicKey);
if (IsInitiator) Rsa.Decrypt(ref paddedPublicKeyAsBytes);
else Rsa.Verify(ref paddedPublicKeyAsBytes);
publicKey = Encoding.Default.GetString(paddedPublicKeyAsBytes);
}
var unpaddedPublicKey = new BigInteger(publicKey, 10);
return unpaddedPublicKey.ModPow(DhPrivate, DhPrime).ToBytes();
}
/// <summary>
/// Probabilistic prime test based on Rabin-Miller's test.
/// </summary>
/// <param name="confidence">The amount of times/iterations to check the primality of the current instance.</param>
/// <returns>true if the current instance is a strong pseudo-prime to randomly chosen bases, otherwise false if not prime.</returns>
public bool RabinMillerTest(int confidence)
{
BigInteger thisVal;
if ((_data[MAX_LENGTH - 1] & 0x80000000) != 0)
thisVal = -this;
else
thisVal = this;
if (thisVal.DataLength == 1)
{
if (thisVal._data[0] == 0 || thisVal._data[0] == 1)
return false;
else if (thisVal._data[0] == 2 || thisVal._data[0] == 3)
return true;
}
if ((thisVal._data[0] & 0x1) == 0)
return false;
BigInteger p_sub1 = thisVal - (new BigInteger(1));
int s = 0;
for (int index = 0; index < p_sub1.DataLength; index++)
{
uint mask = 0x01;
for (int i = 0; i < 32; i++)
{
if ((p_sub1._data[index] & mask) != 0)
{
index = p_sub1.DataLength;
break;
}
mask <<= 1;
s++;
}
}
BigInteger t = p_sub1 >> s;
int bits = thisVal.BitCount();
BigInteger a = new BigInteger();
Random rand = new Random();
for (int round = 0; round < confidence; round++)
{
bool done = false;
while (!done)
{
int testBits = 0;
while (testBits < 2)
testBits = (int)(rand.NextDouble() * bits);
a.GenRandomBits(testBits, rand);
int byteLen = a.DataLength;
if (byteLen > 1 || (byteLen == 1 && a._data[0] != 1))
done = true;
}
BigInteger gcdTest = a.Gcd(thisVal);
if (gcdTest.DataLength == 1 && gcdTest._data[0] != 1)
return false;
BigInteger b = a.ModPow(t, thisVal);
bool result = false;
if (b.DataLength == 1 && b._data[0] == 1)
result = true;
for (int j = 0; result == false && j < s; j++)
{
if (b == p_sub1)
{
result = true;
break;
}
b = (b * b) % thisVal;
}
if (result == false)
return false;
}
return true;
}
private BigInteger DoPublic(BigInteger x) => x.ModPow(E, N);
private BigInteger DoPrivate(BigInteger x)
{
if (P == null && Q == null)
return x.ModPow(D, N);
BigInteger xp = (x % P).ModPow(Dmp1, P);
BigInteger xq = (x % Q).ModPow(Dmq1, Q);
while (xp < xq) xp = xp + P;
return ((((xp - xq) * (Iqmp)) % P) * Q) + xq;
}