Gost3410Signer
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Security;
namespace Org.BouncyCastle.Crypto.Signers
{
public class Gost3410Signer : IDsa
{
private Gost3410KeyParameters key;
private SecureRandom random;
public virtual string AlgorithmName => "GOST3410";
public virtual BigInteger Order => key.Parameters.Q;
public virtual void Init(bool forSigning, ICipherParameters parameters)
{
if (forSigning) {
ParametersWithRandom parametersWithRandom = parameters as ParametersWithRandom;
if (parametersWithRandom != null) {
random = parametersWithRandom.Random;
parameters = parametersWithRandom.Parameters;
} else
random = CryptoServicesRegistrar.GetSecureRandom();
if (!(parameters is Gost3410PrivateKeyParameters))
throw new InvalidKeyException("GOST3410 private key required for signing");
key = (Gost3410PrivateKeyParameters)parameters;
} else {
if (!(parameters is Gost3410PublicKeyParameters))
throw new InvalidKeyException("GOST3410 public key required for signing");
key = (Gost3410PublicKeyParameters)parameters;
}
}
public virtual BigInteger[] GenerateSignature(byte[] message)
{
BigInteger val = new BigInteger(1, message, false);
Gost3410Parameters parameters = key.Parameters;
BigInteger bigInteger;
do {
bigInteger = new BigInteger(parameters.Q.BitLength, random);
} while (bigInteger.CompareTo(parameters.Q) >= 0);
BigInteger bigInteger2 = parameters.A.ModPow(bigInteger, parameters.P).Mod(parameters.Q);
BigInteger bigInteger3 = bigInteger.Multiply(val).Add(((Gost3410PrivateKeyParameters)key).X.Multiply(bigInteger2)).Mod(parameters.Q);
return new BigInteger[2] {
bigInteger2,
bigInteger3
};
}
public virtual bool VerifySignature(byte[] message, BigInteger r, BigInteger s)
{
BigInteger bigInteger = new BigInteger(1, message, false);
Gost3410Parameters parameters = key.Parameters;
if (r.SignValue < 0 || parameters.Q.CompareTo(r) <= 0)
return false;
if (s.SignValue < 0 || parameters.Q.CompareTo(s) <= 0)
return false;
BigInteger val = bigInteger.ModPow(parameters.Q.Subtract(BigInteger.Two), parameters.Q);
BigInteger e = s.Multiply(val).Mod(parameters.Q);
BigInteger e2 = parameters.Q.Subtract(r).Multiply(val).Mod(parameters.Q);
e = parameters.A.ModPow(e, parameters.P);
e2 = ((Gost3410PublicKeyParameters)key).Y.ModPow(e2, parameters.P);
return e.Multiply(e2).Mod(parameters.P).Mod(parameters.Q)
.Equals(r);
}
}
}