C# FNV1a 1024Bit Implementation

FNV1a1024.cs

public class FNV1a1024 : HashAlgorithm
    {
        private readonly BigInteger _K = "5016456510113118655434598811035278955030765345404790744303017523831112055108147451509157692220295382716162651878526895249385292291816524375083746691371804094271873160484737966720260389217684476157468082573".NewBigInteger10();
        private BigInteger _hash;
        private readonly BigInteger Seed = "14197795064947621068722070641403218320880622795441933960878474914617582723252296732303717722150864096521202355549365628174669108571814760471015076148029755969804077320157692458563003215304957150157403644460363550505412711285966361610267868082893823963790439336411086884584107735010676915".NewBigInteger10();
        public FNV1a1024()
        {
            _hash = Seed;
        }
        public FNV1a1024(string seed)
        {
            Seed = seed.NewBigInteger10();
            _hash = Seed;
        }
        public override int HashSize => 1024;
        public override void Initialize()
        {
            _hash = Seed;
        }
        protected override void HashCore(byte[] bytes, int ibStart, int cbSize)
        {
            Hash(bytes, ibStart, cbSize);
        }
        private void Hash(byte[] bytes, int ibStart, int cbSize)
        {
            if (bytes == null)
                return;
            if (ibStart >= bytes.Length || cbSize > bytes.Length)
                return;
            var p = 0;
            while (cbSize > 0)
            {
                _hash ^= bytes[p + ibStart];
                _hash *= _K;
                cbSize--;
                p++;
            }

            _hash = _hash ^ (_hash >> 512);
        }
        /// <summary>
        /// BigInteger does not overflow, so we limit the output to 1024Bits.
        /// </summary>
        protected override byte[] HashFinal()
        {
            return _hash.ToByteArray().SubByte(0, 128);
        }
    }