Gost3410DigestSigner
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Security;
using System;
namespace Org.BouncyCastle.Crypto.Signers
{
public class Gost3410DigestSigner : ISigner
{
private readonly IDigest digest;
private readonly IDsa dsaSigner;
private readonly int size;
private int halfSize;
private bool forSigning;
public virtual string AlgorithmName => digest.AlgorithmName + "with" + dsaSigner.AlgorithmName;
public Gost3410DigestSigner(IDsa signer, IDigest digest)
{
dsaSigner = signer;
this.digest = digest;
halfSize = digest.GetDigestSize();
size = halfSize * 2;
}
public virtual void Init(bool forSigning, ICipherParameters parameters)
{
this.forSigning = forSigning;
ParametersWithRandom parametersWithRandom = parameters as ParametersWithRandom;
AsymmetricKeyParameter asymmetricKeyParameter = (parametersWithRandom == null) ? ((AsymmetricKeyParameter)parameters) : ((AsymmetricKeyParameter)parametersWithRandom.Parameters);
if (forSigning && !asymmetricKeyParameter.IsPrivate)
throw new InvalidKeyException("Signing Requires Private Key.");
if (!forSigning && asymmetricKeyParameter.IsPrivate)
throw new InvalidKeyException("Verification Requires Public Key.");
Reset();
dsaSigner.Init(forSigning, parameters);
}
public virtual void Update(byte input)
{
digest.Update(input);
}
public virtual void BlockUpdate(byte[] input, int inOff, int inLen)
{
digest.BlockUpdate(input, inOff, inLen);
}
public virtual int GetMaxSignatureSize()
{
return size;
}
public virtual byte[] GenerateSignature()
{
if (forSigning) {
byte[] array = new byte[digest.GetDigestSize()];
digest.DoFinal(array, 0);
try {
BigInteger[] array2 = dsaSigner.GenerateSignature(array);
byte[] array3 = new byte[size];
byte[] array4 = array2[0].ToByteArrayUnsigned();
byte[] array5 = array2[1].ToByteArrayUnsigned();
array5.CopyTo(array3, halfSize - array5.Length);
array4.CopyTo(array3, size - array4.Length);
return array3;
} catch (Exception ex) {
throw new SignatureException(ex.Message, ex);
}
}
throw new InvalidOperationException("GOST3410DigestSigner not initialised for signature generation.");
}
public virtual bool VerifySignature(byte[] signature)
{
if (forSigning)
throw new InvalidOperationException("DSADigestSigner not initialised for verification");
byte[] array = new byte[digest.GetDigestSize()];
digest.DoFinal(array, 0);
BigInteger r;
BigInteger s;
try {
r = new BigInteger(1, signature, halfSize, halfSize);
s = new BigInteger(1, signature, 0, halfSize);
} catch (Exception innerException) {
throw new SignatureException("error decoding signature bytes.", innerException);
}
return dsaSigner.VerifySignature(array, r, s);
}
public virtual void Reset()
{
digest.Reset();
}
}
}