protected void CopyIn(GeneralDigest t)
        {
            Array.Copy(t.xBuf, 0, xBuf, 0, t.xBuf.Length);

            xBufOff   = t.xBufOff;
            byteCount = t.byteCount;
        }
 internal GeneralDigest(GeneralDigest t)
 {
     xBuf = new byte[t.xBuf.Length];
     CopyIn(t);
 }