146 lines
3.2 KiB
C#
146 lines
3.2 KiB
C#
using System;
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using System.Collections;
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using System.IO;
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using System.Text;
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using Org.BouncyCastle.Asn1;
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using Org.BouncyCastle.Crypto.Signers;
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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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{
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public class Gost3410DigestSigner
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: ISigner
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{
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private readonly IDigest digest;
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private readonly IDsa dsaSigner;
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private bool forSigning;
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public Gost3410DigestSigner(
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IDsa signer,
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IDigest digest)
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{
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this.dsaSigner = signer;
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this.digest = digest;
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}
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public string AlgorithmName
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{
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get { return digest.AlgorithmName + "with" + dsaSigner.AlgorithmName; }
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}
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public void Init(
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bool forSigning,
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ICipherParameters parameters)
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{
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this.forSigning = forSigning;
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AsymmetricKeyParameter k;
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if (parameters is ParametersWithRandom)
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{
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k = (AsymmetricKeyParameter)((ParametersWithRandom)parameters).Parameters;
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}
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else
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{
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k = (AsymmetricKeyParameter)parameters;
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}
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if (forSigning && !k.IsPrivate)
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{
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throw new InvalidKeyException("Signing Requires Private Key.");
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}
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if (!forSigning && k.IsPrivate)
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{
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throw new InvalidKeyException("Verification Requires Public Key.");
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}
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Reset();
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dsaSigner.Init(forSigning, parameters);
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}
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/**
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* update the internal digest with the byte b
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*/
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public void Update(
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byte input)
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{
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digest.Update(input);
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}
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/**
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* update the internal digest with the byte array in
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*/
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public void BlockUpdate(
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byte[] input,
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int inOff,
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int length)
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{
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digest.BlockUpdate(input, inOff, length);
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}
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/**
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* Generate a signature for the message we've been loaded with using
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* the key we were initialised with.
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*/
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public byte[] GenerateSignature()
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{
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if (!forSigning)
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throw new InvalidOperationException("GOST3410DigestSigner not initialised for signature generation.");
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byte[] hash = new byte[digest.GetDigestSize()];
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digest.DoFinal(hash, 0);
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try
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{
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BigInteger[] sig = dsaSigner.GenerateSignature(hash);
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byte[] sigBytes = new byte[64];
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// TODO Add methods to allow writing BigInteger to existing byte array?
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byte[] r = sig[0].ToByteArrayUnsigned();
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byte[] s = sig[1].ToByteArrayUnsigned();
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s.CopyTo(sigBytes, 32 - s.Length);
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r.CopyTo(sigBytes, 64 - r.Length);
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return sigBytes;
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}
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catch (Exception e)
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{
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throw new SignatureException(e.Message, e);
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}
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}
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/// <returns>true if the internal state represents the signature described in the passed in array.</returns>
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public bool VerifySignature(
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byte[] signature)
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{
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if (forSigning)
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throw new InvalidOperationException("DSADigestSigner not initialised for verification");
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byte[] hash = new byte[digest.GetDigestSize()];
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digest.DoFinal(hash, 0);
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BigInteger R, S;
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try
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{
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R = new BigInteger(1, signature, 32, 32);
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S = new BigInteger(1, signature, 0, 32);
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}
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catch (Exception e)
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{
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throw new SignatureException("error decoding signature bytes.", e);
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}
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return dsaSigner.VerifySignature(hash, R, S);
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}
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/// <summary>Reset the internal state</summary>
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public void Reset()
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{
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digest.Reset();
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}
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}
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}
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