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using System;
using System.IO;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math.EC.Rfc8032;
using Org.BouncyCastle.Utilities;
namespace Org.BouncyCastle.Crypto.Signers
{
public class Ed25519phSigner
: ISigner
{
private readonly IDigest prehash = Ed25519.CreatePrehash();
private readonly byte[] context;
private bool forSigning;
private Ed25519PrivateKeyParameters privateKey;
private Ed25519PublicKeyParameters publicKey;
public Ed25519phSigner(byte[] context)
{
this.context = Arrays.Clone(context);
}
public virtual string AlgorithmName
{
get { return "Ed25519ph"; }
}
public virtual void Init(bool forSigning, ICipherParameters parameters)
{
this.forSigning = forSigning;
if (forSigning)
{
// TODO Allow AsymmetricCipherKeyPair to be a CipherParameters?
this.privateKey = (Ed25519PrivateKeyParameters)parameters;
this.publicKey = privateKey.GeneratePublicKey();
}
else
{
this.privateKey = null;
this.publicKey = (Ed25519PublicKeyParameters)parameters;
}
Reset();
}
public virtual void Update(byte b)
{
prehash.Update(b);
}
public virtual void BlockUpdate(byte[] buf, int off, int len)
{
prehash.BlockUpdate(buf, off, len);
}
public virtual byte[] GenerateSignature()
{
if (!forSigning || null == privateKey)
throw new InvalidOperationException("Ed25519phSigner not initialised for signature generation.");
byte[] msg = new byte[Ed25519.PrehashSize];
if (Ed25519.PrehashSize != prehash.DoFinal(msg, 0))
throw new InvalidOperationException("Prehash digest failed");
byte[] signature = new byte[Ed25519PrivateKeyParameters.SignatureSize];
privateKey.Sign(Ed25519.Algorithm.Ed25519ph, publicKey, context, msg, 0, Ed25519.PrehashSize, signature, 0);
return signature;
}
public virtual bool VerifySignature(byte[] signature)
{
if (forSigning || null == publicKey)
throw new InvalidOperationException("Ed25519phSigner not initialised for verification");
if (Ed25519.SignatureSize != signature.Length)
return false;
byte[] pk = publicKey.GetEncoded();
return Ed25519.VerifyPrehash(signature, 0, pk, 0, context, prehash);
}
public void Reset()
{
prehash.Reset();
}
}
}
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