ECGost3410Signer
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Math.EC;
using Org.BouncyCastle.Math.EC.Multiplier;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Utilities;
using System;
namespace Org.BouncyCastle.Crypto.Signers
{
public class ECGost3410Signer : IDsa
{
private ECKeyParameters key;
private SecureRandom random;
private bool forSigning;
public virtual string AlgorithmName => key.AlgorithmName;
public virtual BigInteger Order => key.Parameters.N;
public virtual void Init(bool forSigning, ICipherParameters parameters)
{
this.forSigning = forSigning;
if (forSigning) {
ParametersWithRandom parametersWithRandom = parameters as ParametersWithRandom;
if (parametersWithRandom != null) {
random = parametersWithRandom.Random;
parameters = parametersWithRandom.Parameters;
} else
random = CryptoServicesRegistrar.GetSecureRandom();
ECPrivateKeyParameters eCPrivateKeyParameters = parameters as ECPrivateKeyParameters;
if (eCPrivateKeyParameters == null)
throw new InvalidKeyException("EC private key required for signing");
key = eCPrivateKeyParameters;
} else {
ECPublicKeyParameters eCPublicKeyParameters = parameters as ECPublicKeyParameters;
if (eCPublicKeyParameters == null)
throw new InvalidKeyException("EC public key required for verification");
key = eCPublicKeyParameters;
}
}
public virtual BigInteger[] GenerateSignature(byte[] message)
{
if (!forSigning)
throw new InvalidOperationException("not initialized for signing");
BigInteger val = new BigInteger(1, message, false);
ECDomainParameters parameters = key.Parameters;
BigInteger n = parameters.N;
BigInteger d = ((ECPrivateKeyParameters)key).D;
ECMultiplier eCMultiplier = CreateBasePointMultiplier();
BigInteger bigInteger2;
BigInteger bigInteger3;
while (true) {
BigInteger bigInteger = BigIntegers.CreateRandomBigInteger(n.BitLength, random);
if (bigInteger.SignValue != 0) {
bigInteger2 = eCMultiplier.Multiply(parameters.G, bigInteger).Normalize().AffineXCoord.ToBigInteger().Mod(n);
if (bigInteger2.SignValue != 0) {
bigInteger3 = bigInteger.Multiply(val).Add(d.Multiply(bigInteger2)).Mod(n);
if (bigInteger3.SignValue != 0)
break;
}
}
}
return new BigInteger[2] {
bigInteger2,
bigInteger3
};
}
public virtual bool VerifySignature(byte[] message, BigInteger r, BigInteger s)
{
if (forSigning)
throw new InvalidOperationException("not initialized for verification");
BigInteger x = new BigInteger(1, message, false);
BigInteger n = key.Parameters.N;
if (r.CompareTo(BigInteger.One) < 0 || r.CompareTo(n) >= 0)
return false;
if (s.CompareTo(BigInteger.One) < 0 || s.CompareTo(n) >= 0)
return false;
BigInteger val = BigIntegers.ModOddInverseVar(n, x);
BigInteger a = s.Multiply(val).Mod(n);
BigInteger b = n.Subtract(r).Multiply(val).Mod(n);
ECPoint g = key.Parameters.G;
ECPoint q = ((ECPublicKeyParameters)key).Q;
ECPoint eCPoint = ECAlgorithms.SumOfTwoMultiplies(g, a, q, b).Normalize();
if (eCPoint.IsInfinity)
return false;
return eCPoint.AffineXCoord.ToBigInteger().Mod(n).Equals(r);
}
protected virtual ECMultiplier CreateBasePointMultiplier()
{
return new FixedPointCombMultiplier();
}
}
}