private void Init(byte[] key)
        {
            Debug.Assert(key.Length==24);
            _buffer = new byte[8];
            _DESCipher1 = new DES();
            _DESCipher2 = new DES();
            _DESCipher3 = new DES();

            _DESCipher1.InitializeKey(key, 0);
            _DESCipher2.InitializeKey(key, 8);
            _DESCipher3.InitializeKey(key,16);
        }
        public TripleDESCipher1(byte[] key)
        {
            Debug.Assert(key.Length==24);
            _DESCipher1 = new DES();
            _DESCipher2 = new DES();
            _DESCipher3 = new DES();

            _DESCipher1.InitializeKey(key, 0);
            _DESCipher2.InitializeKey(key, 8);
            _DESCipher3.InitializeKey(key,16);

            _buffer = new byte[8];
        }