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