Gost3410DigestSigner
using Org.BouncyCastle.Math;
using Org.BouncyCastle.Security;
using Org.BouncyCastle.Utilities;
using System;
namespace Org.BouncyCastle.Crypto.Signers
{
public class Gost3410DigestSigner : ISigner
{
private readonly IDsa m_dsa;
private readonly IDigest m_digest;
private readonly int m_digestSize;
private bool m_forSigning;
public virtual string AlgorithmName => m_digest.AlgorithmName + "with" + m_dsa.AlgorithmName;
public Gost3410DigestSigner(IDsa signer, IDigest digest)
{
if (signer == null)
throw new ArgumentNullException("signer");
m_dsa = signer;
if (digest == null)
throw new ArgumentNullException("digest");
m_digest = digest;
m_digestSize = digest.GetDigestSize();
}
public virtual void Init(bool forSigning, ICipherParameters parameters)
{
m_forSigning = forSigning;
AsymmetricKeyParameter asymmetricKeyParameter = (AsymmetricKeyParameter)ParameterUtilities.IgnoreRandom(parameters);
if (forSigning && !asymmetricKeyParameter.IsPrivate)
throw new InvalidKeyException("Signing requires private key.");
if (!forSigning && asymmetricKeyParameter.IsPrivate)
throw new InvalidKeyException("Verification requires public key.");
Reset();
m_dsa.Init(forSigning, parameters);
}
public virtual void Update(byte input)
{
m_digest.Update(input);
}
public virtual void BlockUpdate(byte[] input, int inOff, int inLen)
{
m_digest.BlockUpdate(input, inOff, inLen);
}
public virtual void BlockUpdate(ReadOnlySpan<byte> input)
{
m_digest.BlockUpdate(input);
}
public virtual int GetMaxSignatureSize()
{
return m_digestSize * 2;
}
public virtual byte[] GenerateSignature()
{
if (m_forSigning) {
byte[] message = DigestUtilities.DoFinal(m_digest);
try {
BigInteger[] array = m_dsa.GenerateSignature(message);
int digestSize = m_digestSize;
byte[] array2 = new byte[digestSize * 2];
BigIntegers.AsUnsignedByteArray(array[1], array2, 0, digestSize);
BigIntegers.AsUnsignedByteArray(array[0], array2, digestSize, digestSize);
return array2;
} 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 (m_forSigning)
throw new InvalidOperationException("GOST3410DigestSigner not initialised for verification");
byte[] message = DigestUtilities.DoFinal(m_digest);
BigInteger r;
BigInteger s;
try {
int digestSize = m_digestSize;
r = new BigInteger(1, signature, digestSize, digestSize);
s = new BigInteger(1, signature, 0, digestSize);
} catch (Exception innerException) {
throw new SignatureException("error decoding signature bytes.", innerException);
}
return m_dsa.VerifySignature(message, r, s);
}
public virtual void Reset()
{
m_digest.Reset();
}
}
}