Ignore encryption (#653)

* Add ability to ingore PDF encryption check

* Switch to ! syntax

* Update src/Smalot/PdfParser/Parser.php

* Additional changes for #488

doc/Usage.md:

  - Moved description of `setIgnoreEncryption` option to doc/CustomConfig.md
  - Added brief "PDF encryption" section

doc/CustomConfig.md: added `setIgnoreEncryption` option and section to describe it.

src/Smalot/PdfParser/Config.php: Doc comment for Config::setIgnoreEncryption()

Added tests/PHPUnit/Integration/EncryptionTest.php

Added samples/not_really_encrypted.pdf (thanks to @parijke who
orginially created this as test.pdf)

See #653

* src/Smalot/PdfParser/Config.php: PHP-CS-Fixer issue fixed

* Update CustomConfig.md

refined texts

* Config.php: use explicit PHP doc entities

* ParserTest.php: moved tests

* removed EncryptionTest.php

---------

Co-authored-by: Jordan Hall <[email protected]>
Co-authored-by: Konrad Abicht <[email protected]>

Author: 3 people

doc/CustomConfig.md

@@ -21,6 +21,7 @@ The `Config` class has the following options:
 |--------------------------|---------|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------|
 | `setDecodeMemoryLimit`   | Integer | `0`             | If parsing fails because of memory exhaustion, you can set a lower memory limit for decoding operations.                                             |
 | `setFontSpaceLimit`      | Integer | `-50`           | Changing font space limit can be helpful when `Parser::getText()` returns a text with too many spaces.                                               |
+| `setIgnoreEncryption`    | Boolean | `false`         | Read PDFs that are not encrypted but have the encryption flag set. This is a temporary workaround, don't rely on it.                                 |
 | `setHorizontalOffset`    | String  | ` `             | When words are broken up or when the structure of a table is not preserved, you may get better results when adapting `setHorizontalOffset`.          |
 | `setPdfWhitespaces`      | String  | `\0\t\n\f\r `   |                                                                                                                                                      |
 | `setPdfWhitespacesRegex` | String  | `[\0\t\n\f\r ]` |                                                                                                                                                      |
@@ -63,3 +64,17 @@ $config->setFontSpaceLimit(-60);
 $parser = new \Smalot\PdfParser\Parser([], $config);
 $pdf = $parser->parseFile('document.pdf');
 ```
+
+## option setIgnoreEncryption
+
+In some cases PDF files may be internally marked as encrypted even though the content is not encrypted and can be read.
+This can be caused by the PDF being created by a tool that does not properly set the encryption flag.
+If you are sure that the PDF is not encrypted, you can ignore the encryption flag by setting the `ignoreEncryption` flag to `true` in a custom `Config` instance.
+
+```php
+$config = new \Smalot\PdfParser\Config();
+$config->setIgnoreEncryption(true);
+
+$parser = new \Smalot\PdfParser\Parser([], $config);
+$pdf = $parser->parseFile('document.pdf');
+```

doc/Usage.md

@@ -230,3 +230,14 @@ foreach ($pages as $page) {
     ];
 }
 ```
+
+## PDF encryption
+
+This library cannot currently read encrypted PDF files, i.e. those with
+a read password.  Attempting to do so produces this error:
+```
+Exception: Secured pdf file are currently not supported.
+```
+
+See `setIgnoreEncryption` option in [CustomConfig.md](CustomConfig.md)
+for how to override the check in specific cases.

samples/not_really_encrypted.pdf

@@ -82,6 +82,13 @@ class Config
      */
     private $dataTmFontInfoHasToBeIncluded = false;
 
+    /**
+     * Whether to attempt to read PDFs even if they are marked as encrypted.
+     *
+     * @var bool
+     */
+    private $ignoreEncryption = false;
+
     public function getFontSpaceLimit()
     {
         return $this->fontSpaceLimit;
@@ -151,4 +158,18 @@ public function setDataTmFontInfoHasToBeIncluded(bool $dataTmFontInfoHasToBeIncl
     {
         $this->dataTmFontInfoHasToBeIncluded = $dataTmFontInfoHasToBeIncluded;
     }
+
+    public function getIgnoreEncryption(): bool
+    {
+        return $this->ignoreEncryption;
+    }
+
+    /**
+     * @deprecated this is a temporary workaround, don't rely on it
+     * @see https://github.com/smalot/pdfparser/pull/653
+     */
+    public function setIgnoreEncryption(bool $ignoreEncryption): void
+    {
+        $this->ignoreEncryption = $ignoreEncryption;
+    }
 }

src/Smalot/PdfParser/Config.php

@@ -102,7 +102,7 @@ public function parseContent(string $content): Document
         // Create structure from raw data.
         list($xref, $data) = $this->rawDataParser->parseData($content);
 
-        if (isset($xref['trailer']['encrypt'])) {
+        if (isset($xref['trailer']['encrypt']) && false === $this->config->getIgnoreEncryption()) {
             throw new \Exception('Secured pdf file are currently not supported.');
         }
 

src/Smalot/PdfParser/Parser.php

@@ -403,6 +403,41 @@ public function testRetainImageContentImpact(): void
         $this->assertLessThan($baselineMemory * 1.05, $usedMemory, 'Memory is '.$usedMemory);
         $this->assertTrue('' !== $document->getText());
     }
+
+    /**
+     * Tests handling of encrypted PDF.
+     *
+     * @see https://github.com/smalot/pdfparser/pull/653
+     */
+    public function testNoIgnoreEncryption(): void
+    {
+        $filename = $this->rootDir.'/samples/not_really_encrypted.pdf';
+        $threw = false;
+        try {
+            (new Parser([]))->parseFile($filename);
+        } catch (\Exception $e) {
+            // we expect an exception to be thrown if an encrypted PDF is encountered.
+            $threw = true;
+        }
+        $this->assertTrue($threw);
+    }
+
+    /**
+     * Tests behavior if encryption is ignored.
+     *
+     * @see https://github.com/smalot/pdfparser/pull/653
+     */
+    public function testIgnoreEncryption(): void
+    {
+        $config = new Config();
+        $config->setIgnoreEncryption(true);
+
+        $filename = $this->rootDir.'/samples/not_really_encrypted.pdf';
+
+        $this->assertTrue((new Parser([], $config))->parseFile($filename) instanceof Document);
+
+        // without the configuration option set, an exception would be thrown.
+    }
 }
 
 class ParserSub extends Parser