Ed448phSigner
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Math.EC.Rfc8032;
using System;
namespace Org.BouncyCastle.Crypto.Signers
{
    public class Ed448phSigner : ISigner
    {
        private readonly IXof prehash = Ed448.CreatePrehash();
        private readonly byte[] context;
        private bool forSigning;
        private Ed448PrivateKeyParameters privateKey;
        private Ed448PublicKeyParameters publicKey;
        public virtual string AlgorithmName => "Ed448ph";
        public Ed448phSigner(byte[] context)
        {
            if (context == null)
                throw new ArgumentNullException("context");
            this.context = (byte[])context.Clone();
        }
        public virtual void Init(bool forSigning, ICipherParameters parameters)
        {
            this.forSigning = forSigning;
            if (forSigning) {
                privateKey = (Ed448PrivateKeyParameters)parameters;
                publicKey = null;
            } else {
                privateKey = null;
                publicKey = (Ed448PublicKeyParameters)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 int GetMaxSignatureSize()
        {
            return Ed448.SignatureSize;
        }
        public virtual byte[] GenerateSignature()
        {
            if (!forSigning || privateKey == null)
                throw new InvalidOperationException("Ed448phSigner not initialised for signature generation.");
            byte[] array = new byte[Ed448.PrehashSize];
            if (Ed448.PrehashSize != prehash.OutputFinal(array, 0, Ed448.PrehashSize))
                throw new InvalidOperationException("Prehash calculation failed");
            byte[] array2 = new byte[Ed448PrivateKeyParameters.SignatureSize];
            privateKey.Sign(Ed448.Algorithm.Ed448ph, context, array, 0, Ed448.PrehashSize, array2, 0);
            return array2;
        }
        public virtual bool VerifySignature(byte[] signature)
        {
            if (forSigning || publicKey == null)
                throw new InvalidOperationException("Ed448phSigner not initialised for verification");
            if (Ed448.SignatureSize != signature.Length) {
                prehash.Reset();
                return false;
            }
            byte[] array = new byte[Ed448.PrehashSize];
            if (Ed448.PrehashSize != prehash.OutputFinal(array, 0, Ed448.PrehashSize))
                throw new InvalidOperationException("Prehash calculation failed");
            return publicKey.Verify(Ed448.Algorithm.Ed448ph, context, array, 0, Ed448.PrehashSize, signature, 0);
        }
        public void Reset()
        {
            prehash.Reset();
        }
    }
}