HMACT64 hmac = new HMACT64(TEST_KEY);
        // MD5 digest length is 16 bytes
        assertEquals(16, hmac.engineGetDigestLength());
    }

    @Test
    void testEngineDigest() {
        // Test engineDigest()
        HMACT64 hmac = new HMACT64(TEST_KEY);
        hmac.engineUpdate(TEST_DATA, 0, TEST_DATA.length);
        byte[] result = hmac.engineDigest();

        assertNotNull(result);

        }
    }

    // Integration test with actual MD5 to verify HMAC calculation logic
    @Test
    void testHMACT64WithActualMD5() throws NoSuchAlgorithmException {
        // This test uses a real MD5 instance to verify the HMAC calculation logic
        // HMACT64 is a modified HMAC-MD5 where the key is truncated at 64 bytes
        // instead of being hashed when it exceeds the block size.

                }

                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);
                hmac.update(this.clientChallenge);

        final 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);

            HMACT64 hmac = new HMACT64(md4.digest());
            hmac.update(user.toUpperCase().getBytes(SmbConstants.UNI_ENCODING));
            hmac.update(domain.toUpperCase().getBytes(SmbConstants.UNI_ENCODING));
            hmac = new HMACT64(hmac.digest());
            hmac.update(challenge);
            hmac.update(clientChallenge);
            hmac.digest(response, 0, 16);

                    md4.update(responseKeyNT);
                    final byte[] userSessionKey = md4.digest();

                    final HMACT64 hmac = new HMACT64(userSessionKey);
                    hmac.update(sessionNonce);
                    final byte[] ntlm2SessionKey = hmac.digest();

                    if ((getFlags() & NTLMSSP_NEGOTIATE_KEY_EXCH) != 0) {
                        masterKey = new byte[16];

                md4.update(passwordHash);
                final byte[] userSessionKey = md4.digest();

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

                if (getFlag(NTLMSSP_NEGOTIATE_KEY_EXCH)) {
                    this.masterKey = new byte[16];

        assertFalse(Arrays.equals(viaPassword, differentDomain), "Different domain should produce a different key");
    }

    @Test
    @DisplayName("computeResponse: HMAC(server||clientData) prepended to clientData")
    void testComputeResponse_basic() {
        // Arrange
        byte[] key = hex("0102030405060708090A0B0C0D0E0F10");
        byte[] serverChallenge = hex("1122334455667788");

            m = Mac.getInstance(this.algorithmName, this.provider);
        } else {
            m = Mac.getInstance(this.algorithmName);
        }
        m.init(new SecretKeySpec(this.signingKey, "HMAC"));
        return m;
    }

    /**
     * {@inheritDoc}
     *
     * @see jcifs.internal.SMBSigningDigest#sign(byte[], int, int, jcifs.internal.CommonServerMessageBlock,

   * Returns a hash function implementing the Message Authentication Code (MAC) algorithm, using the
   * MD5 (128 hash bits) hash function and the given secret key.
   *
   * <p>If you are designing a new system that needs HMAC, prefer {@link #hmacSha256} or other
   * future-proof algorithms <a
   * href="https://datatracker.ietf.org/doc/html/rfc6151#section-2.3">over {@code hmacMd5}</a>.
   *
   * @param key the secret key