public byte[] encrypto(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);

        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 ));

        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}
     *

      checkState(!done, "Cannot re-use a Hasher after calling hash() on it");
    }

    @Override
    public HashCode hash() {
      checkNotDone();
      done = true;
      return HashCode.fromBytesNoCopy(mac.doFinal());
    }
  }

   202E; RIGHT-TO-LEFT OVERRIDE
   206A; INHIBIT SYMMETRIC SWAPPING
   206B; ACTIVATE SYMMETRIC SWAPPING
   206C; INHIBIT ARABIC FORM SHAPING
   206D; ACTIVATE ARABIC FORM SHAPING
   206E; NATIONAL DIGIT SHAPES

    assertThat(stringPrep("\u200e")).isNull() // LEFT-TO-RIGHT MARK
    assertThat(stringPrep("\u206e")).isNull() // NATIONAL DIGIT SHAPES
    assertThat(stringPrep("\u206f")).isNull() // NOMINAL DIGIT SHAPES
  }

  @Test fun prohibitionTaggingCharacters() {
    assertThat(stringPrep("\udb40\udc01")).isNull() // Note that this is one code point.