Decryption support

Relies on three primary classes:

  - \Smalot\PdfParser\Encryption\Info
  - \Smalot\PdfParser\Encryption\FileKey
  - \Smalot\PdfParser\Encryption\Stream

This namespace also has a number of exception classes.

\Smalot\PdfParser\RawData\RawDataParser interacts with decryption
support via:

  - $decryptionHelper variable
  - decodeStream() now handles decryption after header processing and
    before the object filters are invoked
  - parseData() calls setupDecryption() if the document has an Encrypt object

Also added is \Smalot\PdfParser\Utils with a number of static utility
methods for binary string processing, etc.

src/Smalot/PdfParser/Encryption/DecryptionError.php

@@ -0,0 +1,49 @@
+<?php
+
+/**
+ * This file is based on code of tecnickcom/TCPDF PDF library.
+ *
+ * Original author Nicola Asuni ([email protected]) and
+ * contributors (https://github.com/tecnickcom/TCPDF/graphs/contributors).
+ *
+ * @see https://github.com/tecnickcom/TCPDF
+ *
+ * Original code was licensed on the terms of the LGPL v3.
+ *
+ * ------------------------------------------------------------------------------
+ *
+ * @file This file is part of the PdfParser library.
+ *
+ * @author  Alastair Irvine <[email protected]>
+ *
+ * @date    2024-01-12
+ *
+ * @license LGPLv3
+ *
+ * @url     <https://github.com/smalot/pdfparser>
+ *
+ *  PdfParser is a pdf library written in PHP, extraction oriented.
+ *  Copyright (C) 2017 - Sébastien MALOT <[email protected]>
+ *
+ *  This program is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU Lesser General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public License
+ *  along with this program.
+ *  If not, see <http://www.pdfparser.org/sites/default/LICENSE.txt>.
+ */
+
+namespace Smalot\PdfParser\Encryption;
+
+/**
+ */
+class DecryptionError extends \RuntimeException
+{
+}