throws GeneralSecurityException {
        byte[] response = new byte[24];
        MessageDigest hmac = Crypto.getHMACT64(passwordHash);
        hmac.update(Strings.getUNIBytes(user.toUpperCase()));
        hmac.update(Strings.getUNIBytes(domain.toUpperCase()));
        hmac = Crypto.getHMACT64(hmac.digest());
        hmac.update(challenge);
        hmac.update(clientChallenge);
        hmac.digest(response, 0, 16);

                    }
                }

                MessageDigest hmac = Crypto.getHMACT64(ntHash);
                hmac.update(Strings.getUNIBytes(this.username.toUpperCase()));
                hmac.update(Strings.getUNIBytes(this.domain.toUpperCase()));
                byte[] ntlmv2Hash = hmac.digest();
                hmac = Crypto.getHMACT64(ntlmv2Hash);
                hmac.update(chlng);

            throw new CIFSUnsupportedCryptoException(e);
        }
    }


    /**
     * 
     * @param key
     * @return HMACT64 MAC
     */
    public static MessageDigest getHMACT64 ( byte[] key ) {
        return new HMACT64(key);
    }


    /**
     * 
     * @param key
     * @return RC4 cipher
     */
    public static Cipher getArcfour ( byte[] key ) {

        }

        int seqNum = this.signSequence.getAndIncrement();
        byte[] seqBytes = new byte[4];
        SMBUtil.writeInt4(seqNum, seqBytes, 0);

        MessageDigest mac = Crypto.getHMACT64(sk);
        mac.update(seqBytes); // sequence
        mac.update(data); // data
        byte[] dgst = mac.digest();
        byte[] trunc = new byte[8];
        System.arraycopy(dgst, 0, trunc, 0, 8);

                MessageDigest md4 = Crypto.getMD4();
                md4.update(passwordHash);
                byte[] userSessionKey = md4.digest();

                MessageDigest hmac = Crypto.getHMACT64(userSessionKey);
                hmac.update(sessionNonce);
                byte[] ntlm2SessionKey = hmac.digest();

                if ( getFlag(NTLMSSP_NEGOTIATE_KEY_EXCH) ) {