Srp6Client
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Security;
namespace Org.BouncyCastle.Crypto.Agreement.Srp
{
public class Srp6Client
{
protected BigInteger N;
protected BigInteger g;
protected BigInteger privA;
protected BigInteger pubA;
protected BigInteger B;
protected BigInteger x;
protected BigInteger u;
protected BigInteger S;
protected BigInteger M1;
protected BigInteger M2;
protected BigInteger Key;
protected IDigest digest;
protected SecureRandom random;
public virtual void Init(BigInteger N, BigInteger g, IDigest digest, SecureRandom random)
{
this.N = N;
this.g = g;
this.digest = digest;
this.random = random;
}
public virtual void Init(Srp6GroupParameters group, IDigest digest, SecureRandom random)
{
Init(group.N, group.G, digest, random);
}
public virtual BigInteger GenerateClientCredentials(byte[] salt, byte[] identity, byte[] password)
{
x = Srp6Utilities.CalculateX(digest, N, salt, identity, password);
privA = SelectPrivateValue();
pubA = g.ModPow(privA, N);
return pubA;
}
public virtual BigInteger CalculateSecret(BigInteger serverB)
{
B = Srp6Utilities.ValidatePublicValue(N, serverB);
u = Srp6Utilities.CalculateU(digest, N, pubA, B);
S = CalculateS();
return S;
}
protected virtual BigInteger SelectPrivateValue()
{
return Srp6Utilities.GeneratePrivateValue(digest, N, g, random);
}
private BigInteger CalculateS()
{
BigInteger val = Srp6Utilities.CalculateK(digest, N, g);
BigInteger e = u.Multiply(x).Add(privA);
BigInteger n = g.ModPow(x, N).Multiply(val).Mod(N);
return B.Subtract(n).Mod(N).ModPow(e, N);
}
public virtual BigInteger CalculateClientEvidenceMessage()
{
if (pubA == null || B == null || S == null)
throw new CryptoException("Impossible to compute M1: some data are missing from the previous operations (A,B,S)");
M1 = Srp6Utilities.CalculateM1(digest, N, pubA, B, S);
return M1;
}
public virtual bool VerifyServerEvidenceMessage(BigInteger serverM2)
{
if (pubA == null || M1 == null || S == null)
throw new CryptoException("Impossible to compute and verify M2: some data are missing from the previous operations (A,M1,S)");
if (Srp6Utilities.CalculateM2(digest, N, pubA, M1, S).Equals(serverM2)) {
M2 = serverM2;
return true;
}
return false;
}
public virtual BigInteger CalculateSessionKey()
{
if (S == null || M1 == null || M2 == null)
throw new CryptoException("Impossible to compute Key: some data are missing from the previous operations (S,M1,M2)");
Key = Srp6Utilities.CalculateKey(digest, N, S);
return Key;
}
}
}