Mac mac = Mac.getInstance("HmacMD5");
    mac.init(MD5_KEY);
    mac.update(input.getBytes(UTF_8));
    assertThat(HashCode.fromBytes(mac.doFinal()).toString()).isEqualTo(knownOutput);
    assertThat(HashCode.fromBytes(mac.doFinal(input.getBytes(UTF_8))).toString())
        .isEqualTo(knownOutput);
    assertThat(hmacMd5(MD5_KEY).hashString(input, UTF_8).toString()).isEqualTo(knownOutput);

        encryptCipher.init(Cipher.ENCRYPT_MODE, new SecretKeySpec(key, "RC4"));
        byte[] encrypted = encryptCipher.doFinal(plaintext);

        Cipher decryptCipher = Crypto.getArcfour(key);
        decryptCipher.init(Cipher.DECRYPT_MODE, new SecretKeySpec(key, "RC4"));
        byte[] decrypted = decryptCipher.doFinal(encrypted);

        // Then
        assertNotNull(encrypted);
        assertNotNull(decrypted);

        int ms_usage = mapArcfourMD5KeyUsage(keyusage);
        Mac mac = Mac.getInstance("HmacMD5");
        MessageDigest md = MessageDigest.getInstance("MD5");
        mac.init(key);
        byte[] dk = mac.doFinal(MD5_CONSTANT);
        try {
            // little endian
            md.update((byte) (ms_usage & 0xFF));
            md.update((byte) (ms_usage >> 8 & 0xFF));
            md.update((byte) (ms_usage >> 16 & 0xFF));

     * @return the encrypted data
     */
    public byte[] encrypt(final byte[] data) {
        final Cipher cipher = pollEncryptoCipher();
        byte[] encrypted;
        try {
            encrypted = cipher.doFinal(data);
        } catch (final IllegalBlockSizeException e) {
            throw new IllegalBlockSizeRuntimeException(e);
        } catch (final BadPaddingException e) {
            throw new BadPaddingRuntimeException(e);

        cipher.init(Cipher.DECRYPT_MODE, dataKey);

        int plainDataLength = data.length - KerberosConstants.CHECKSUM_SIZE;
        byte[] plainData = cipher.doFinal(data, KerberosConstants.CHECKSUM_SIZE, plainDataLength);

        byte[] plainDataChecksum = getHmac(plainData, codeHmac);
        if (plainDataChecksum.length >= KerberosConstants.CHECKSUM_SIZE) {

                throw new RuntimeException("Failed to create Mac instance", e);
            }

            mac.update(data, offset, length);
            final byte[] sig = mac.doFinal();
            System.arraycopy(sig, 0, data, offset + SIGNATURE_OFFSET, SIGNATURE_LENGTH);
        } finally {
            this.signingLock.unlock();
        }
    }

    /**
     *

        // Process message (will be encrypted)
        final byte[] output = new byte[cipher.getOutputSize(message.length)];
        int len = cipher.processBytes(message, 0, message.length, output, 0);
        len += cipher.doFinal(output, len);

        // Split ciphertext and authentication tag
        final int tagLength = getAuthTagLength();
        final byte[] ciphertext = new byte[message.length];

            GCMParameterSpec gcmSpec = new GCMParameterSpec(GCM_TAG_SIZE, iv);
            cipher.init(Cipher.ENCRYPT_MODE, masterKey, gcmSpec);

            // Encrypt
            byte[] ciphertext = cipher.doFinal(plaintextBytes);

            // Combine IV and ciphertext
            byte[] result = new byte[GCM_IV_SIZE + ciphertext.length];
            System.arraycopy(iv, 0, result, 0, GCM_IV_SIZE);

            log.debug("Truncated " + Hexdump.toHexString(trunc));
        }

        if ((this.ntlmsspFlags & NtlmFlags.NTLMSSP_NEGOTIATE_KEY_EXCH) != 0) {
            try {
                trunc = this.sealClientHandle.doFinal(trunc);
                if (log.isDebugEnabled()) {
                    log.debug("Encrypted " + Hexdump.toHexString(trunc));
                }
            } catch (final GeneralSecurityException e) {

            for (int i = 0; i < SIGNATURE_LENGTH; i++) {
                data[SIGNATURE_OFFSET + i] = 0;
            }

            mac.update(data, 0, data.length);
            byte[] signature = mac.doFinal();

            // Place signature in data
            System.arraycopy(signature, 0, data, SIGNATURE_OFFSET, SIGNATURE_LENGTH);

            boolean result = digest.verify(data, 0, data.length, 0, msg);