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output/Libraries/BouncyCastle.Crypto/Org/BouncyCastle/Crypto/Signers/Gost3410DigestSigner.cs

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+using System;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Math;
+using Org.BouncyCastle.Security;
+
+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;
+		AsymmetricKeyParameter asymmetricKeyParameter = ((!(parameters is ParametersWithRandom)) ? ((AsymmetricKeyParameter)parameters) : ((AsymmetricKeyParameter)((ParametersWithRandom)parameters).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 length)
+	{
+		digest.BlockUpdate(input, inOff, length);
+	}
+
+	public virtual byte[] GenerateSignature()
+	{
+		if (!forSigning)
+		{
+			throw new InvalidOperationException("GOST3410DigestSigner not initialised for signature generation.");
+		}
+		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);
+		}
+	}
+
+	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 exception)
+		{
+			throw new SignatureException("error decoding signature bytes.", exception);
+		}
+		return dsaSigner.VerifySignature(array, r, s);
+	}
+
+	public virtual void Reset()
+	{
+		digest.Reset();
+	}
+}