/// <summary>
/// Raises this BigNum to a power and takes the modulus
/// </summary>
/// <param name="exp">The exponent</param>
/// <param name="mod">Value to use when taking the modulus</param>
/// <returns>this**exp % mod</returns>
public BigNum PowMod(BigNum exp, BigNum mod)
{
if (fDisposed)
throw new ObjectDisposedException("this");
if (exp.fDisposed)
throw new ObjectDisposedException("exp");
if (mod.fDisposed)
throw new ObjectDisposedException("mod");
IntPtr r = OpenSSL.BN_new();
IntPtr ctx = OpenSSL.BN_CTX_new();
OpenSSL.BN_mod_exp(r, fBigNum, exp.fBigNum, mod.fBigNum, ctx);
OpenSSL.BN_CTX_free(ctx);
return new BigNum(r);
}
private byte[] ISetupKeys(plBufferedStream s, int gval)
{
BigNum b = BigNum.Random(512);
BigNum n = new BigNum(fN);
BigNum x = new BigNum(fX);
// Calculate seeds
BigNum client_seed = x.PowMod(b, n);
BigNum server_seed = new BigNum(gval).PowMod(b, n);
byte[] cliSeed = client_seed.ToLittleArray();
IWriteNetClientConnect(s, server_seed.ToLittleArray());
// Dispose of this crap...
b.Dispose();
n.Dispose();
x.Dispose();
client_seed.Dispose();
server_seed.Dispose();
return cliSeed;
}
/// <summary>
/// Generates a random BigNum
/// </summary>
/// <param name="bits">How many bits the generated random number shoud have</param>
/// <returns>Generated random number</returns>
public static BigNum Random(int bits)
{
RNG.Seed();
BigNum rand = new BigNum();
OpenSSL.BN_rand(rand.fBigNum, bits, 1, 1);
return rand;
}
/// <summary>
/// Replaces the content of the BigNum with a random BigNum
/// </summary>
/// <param name="bn">BigNum to replace</param>
/// <param name="bits">How many bits the generated random number shoud have</param>
public static void Random(BigNum bn, int bits)
{
if (bn.fDisposed)
throw new ObjectDisposedException("BigNum");
RNG.Seed();
OpenSSL.BN_rand(bn.fBigNum, bits, 1, 1);
}
static void IGenerateTheKey(string name, int g)
{
BigNum K = BigNum.GeneratePrime(512);
BigNum N = BigNum.GeneratePrime(512);
BigNum X = new BigNum(g).PowMod(K, N);
// We store the keys as base64 strings in OpenSSL byte order (BE)
string k = Convert.ToBase64String(K.ToBigArray());
string n = Convert.ToBase64String(N.ToBigArray());
string x = Convert.ToBase64String(X.ToBigArray());
Console.WriteLine(String.Format("Server.{0}.K \"{1}\"", name, k));
Console.WriteLine(String.Format("Server.{0}.N \"{1}\"", name, n));
Console.WriteLine(String.Format("Server.{0}.X \"{1}\"", name, x));
Console.WriteLine();
}
private bool ISetupKeys(int g)
{
BigNum b = new BigNum(Helpers.StrongRandom(64));
BigNum N = new BigNum(fN);
BigNum X = new BigNum(fX);
//Calculate seeds
BigNum client_seed = X.PowMod(b, N);
BigNum server_seed = new BigNum(g).PowMod(b, N);
//Dump data
fDhData = server_seed.ToArray();
fClientSeed = client_seed.ToArray();
//Explicitly dispose unmanaged OpenSSL resources
b.Dispose();
N.Dispose();
X.Dispose();
client_seed.Dispose();
server_seed.Dispose();
return true;
}
protected bool SetupEncryption(byte[] pubKey, byte[] privKey)
{
NetworkStream ns = new NetworkStream(fSocket, false);
plBufferedStream temp = new plBufferedStream(ns);
byte[] yData = IReadNetCliConnect(temp);
if (yData != null) {
BigNum Y = new BigNum(yData);
BigNum N = new BigNum(pubKey);
BigNum K = new BigNum(privKey);
// Generate some randomness and do Y**K%N to get the key components
byte[] server_seed = RNG.Random(7);
BigNum client_seed = Y.PowMod(K, N);
byte[] seed_data = client_seed.ToLittleArray();
// Grab the first 7 bytes and xor it with some randomness to make our key
byte[] key = new byte[7];
for (int i = 0; i < key.Length; i++)
if (i >= seed_data.Length) key[i] = server_seed[i];
else key[i] = (byte)(seed_data[i] ^ server_seed[i]);
// Final setup
fStream = new plBufferedStream(new pnSocketStream(fSocket, key));
IWriteNetCliEncrypt(temp, server_seed);
// Explicitly clean up some resources so that we don't pressure the GC too much.
// Those explicit finalizers really suck.
Y.Dispose();
N.Dispose();
K.Dispose();
client_seed.Dispose();
} else
// Write the error code to the unencrypted buffer
temp.WriteByte(plNetCore.kNetCliError);
temp.Flush();
temp.Close();
ns.Close();
return (yData != null);
}