/**
     * Creates a new MD4 message digest instance.
     * Initializes the digest with the MD4 algorithm parameters.
     */
    public MD4() {
        super("MD4");
        engineReset();
    }

    /**
     *    This constructor is here to implement cloneability of this class.
     */
    private MD4(final MD4 md) {
        this();
        context = md.context.clone();

    @Test
    @DisplayName("Should calculate MD4 hash correctly")
    void testMD4Hash() {
        // Given
        String input = "Hello World";
        byte[] data = input.getBytes();

        // When
        MessageDigest md4 = Crypto.getMD4();
        byte[] hash = md4.digest(data);

        // Then
        assertNotNull(hash);
        assertEquals(16, hash.length); // MD4 produces 128-bit hash
    }

    @Test

    /**
     *
     */
    private Crypto() {
    }

    /**
     * Get an MD4 message digest instance.
     * @return MD4 digest instance
     */
    public static MessageDigest getMD4() {
        try {
            return MessageDigest.getInstance("MD4", getProvider());
        } catch (final NoSuchAlgorithmException e) {
            throw new CIFSUnsupportedCryptoException(e);
        }

            return;
        }
        try {
            final MD4 md4 = new MD4();
            md4.update(password.getBytes(SmbConstants.UNI_ENCODING));
            switch (LM_COMPATIBILITY) {
            case 0:
            case 1:
            case 2:
                md4.update(md4.digest());
                md4.digest(dest, offset, 16);
                break;
            case 3:
            case 4:

        MessageDigest md4 = Crypto.getMD4();
        char[] pwd = getPasswordAsCharArray();
        if (pwd == null || pwd.length == 0) {
            md4.update(Strings.getUNIBytes(""));
            return md4.digest();
        }

        String tempStr = new String(pwd);
        try {
            md4.update(Strings.getUNIBytes(tempStr));
            return md4.digest();
        } finally {

        if (password == null) {
            throw new NullPointerException("Password parameter is required");
        }
        final MessageDigest md4 = Crypto.getMD4();
        md4.update(Strings.getUNIBytes(password));
        return md4.digest();
    }

    /**
     * Generates the NT password hash for the given password.
     * This version accepts char[] for better security.
     *

                    System.arraycopy(clientChallenge, 0, sessionNonce, 8, 8);

                    final MD4 md4 = new MD4();
                    md4.update(responseKeyNT);
                    final byte[] userSessionKey = md4.digest();

                    final HMACT64 hmac = new HMACT64(userSessionKey);
                    hmac.update(sessionNonce);

                System.arraycopy(clientChallenge, 0, sessionNonce, 8, 8);

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

                final MessageDigest hmac = Crypto.getHMACT64(userSessionKey);
                hmac.update(sessionNonce);

    @Test
    @DisplayName("getNTHash: known vector for 'password'")
    void testGetNTHash_knownVector() {
        // Arrange
        String password = "password";
        // Known NT hash for "password" (UTF-16LE MD4)
        // This is a well-known test vector: password -> 8846F7EAEE8FB117AD06BDD830B7586C
        byte[] expected = hex("8846F7EAEE8FB117AD06BDD830B7586C");

        // Act
        byte[] actual = NtlmUtil.getNTHash(password);