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 ));

        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 )

        }

        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 ( GeneralSecurityException e ) {

        Mac m = Mac.getInstance("HmacMD5");
        m.init(new SecretKeySpec(Hex.decode(key), "HMAC"));
        byte[] mac = m.doFinal(bytes);
        checkBytes(Hex.decode(expect), mac);
    }


    @Test
    public void testRC4Checksum1 () throws PACDecodingException, GeneralSecurityException {
        String data = "fifteen sixteen";

        int flags = oldFlags | ServerMessageBlock2.SMB2_FLAGS_SIGNED;
        SMBUtil.writeInt4(flags, data, offset + 16);

        this.digest.update(data, offset, length);

        byte[] sig = this.digest.doFinal();
        System.arraycopy(sig, 0, data, offset + SIGNATURE_OFFSET, SIGNATURE_LENGTH);
    }


    /**
     * 
     * {@inheritDoc}
     *