Merge from 1.6. New class FPDF_Protection. See bug #5855.

diff --git a/lib/fpdf/fpdfprotection.php b/lib/fpdf/fpdfprotection.php
new file mode 100644 (file)
index 0000000..125d3bf
--- /dev/null
+++ b/lib/fpdf/fpdfprotection.php
@@ -0,0 +1,207 @@
+<?php
+/****************************************************************************
+* Software: FPDF_Protection                                                 *
+* Version:  1.02                                                            *
+* Date:     2005/05/08                                                      *
+* Author:   Klemen VODOPIVEC                                                *
+* License:  Freeware                                                        *
+*                                                                           *
+* You may use and modify this software as you wish as stated in original    *
+* FPDF package.                                                             *
+*                                                                           *
+* Thanks: Cpdf (http://www.ros.co.nz/pdf) was my working sample of how to   *
+* implement protection in pdf.                                              *
+****************************************************************************/
+
+require_once('fpdf.php');
+
+class FPDF_Protection extends FPDF
+{
+    var $encrypted;          //whether document is protected
+    var $Uvalue;             //U entry in pdf document
+    var $Ovalue;             //O entry in pdf document
+    var $Pvalue;             //P entry in pdf document
+    var $enc_obj_id;         //encryption object id
+    var $last_rc4_key;       //last RC4 key encrypted (cached for optimisation)
+    var $last_rc4_key_c;     //last RC4 computed key
+
+    function FPDF_Protection($orientation='P',$unit='mm',$format='A4') {
+        parent::FPDF($orientation,$unit,$format);
+
+        $this->encrypted=false;
+        $this->last_rc4_key='';
+        $this->padding="\x28\xBF\x4E\x5E\x4E\x75\x8A\x41\x64\x00\x4E\x56\xFF\xFA\x01\x08".
+                        "\x2E\x2E\x00\xB6\xD0\x68\x3E\x80\x2F\x0C\xA9\xFE\x64\x53\x69\x7A";
+    }
+
+    /**
+    * Function to set permissions as well as user and owner passwords
+    *
+    * - permissions is an array with values taken from the following list:
+    *   copy, print, modify, annot-forms
+    *   If a value is present it means that the permission is granted
+    * - If a user password is set, user will be prompted before document is opened
+    * - If an owner password is set, document can be opened in privilege mode with no
+    *   restriction if that password is entered
+    */
+    function SetProtection($permissions=array(),$user_pass='',$owner_pass=null) {
+        $options = array('print' => 4, 'modify' => 8, 'copy' => 16, 'annot-forms' => 32 );
+        $protection = 192;
+        foreach($permissions as $permission){
+            if (!isset($options[$permission]))
+                $this->Error('Incorrect permission: '.$permission);
+            $protection += $options[$permission];
+        }
+        if ($owner_pass === null)
+            $owner_pass = uniqid(rand());
+        $this->encrypted = true;
+        $this->_generateencryptionkey($user_pass, $owner_pass, $protection);
+    }
+
+/****************************************************************************
+*                                                                           *
+*                              Private methods                              *
+*                                                                           *
+****************************************************************************/
+
+    function _putstream($s) {
+        if ($this->encrypted) {
+            $s = $this->_RC4($this->_objectkey($this->n), $s);
+        }
+        parent::_putstream($s);
+    }
+
+    function _textstring($s) {
+        if ($this->encrypted) {
+            $s = $this->_RC4($this->_objectkey($this->n), $s);
+        }
+        return parent::_textstring($s);
+    }
+
+    /**
+    * Compute key depending on object number where the encrypted data is stored
+    */
+    function _objectkey($n) {
+        return substr($this->_md5_16($this->encryption_key.pack('VXxx',$n)),0,10);
+    }
+
+    /**
+    * Escape special characters
+    */
+    function _escape($s) {
+        $s=str_replace('\\','\\\\',$s);
+        $s=str_replace(')','\\)',$s);
+        $s=str_replace('(','\\(',$s);
+        $s=str_replace("\r",'\\r',$s);
+        return $s;
+    }
+
+    function _putresources() {
+        parent::_putresources();
+        if ($this->encrypted) {
+            $this->_newobj();
+            $this->enc_obj_id = $this->n;
+            $this->_out('<<');
+            $this->_putencryption();
+            $this->_out('>>');
+            $this->_out('endobj');
+        }
+    }
+
+    function _putencryption() {
+        $this->_out('/Filter /Standard');
+        $this->_out('/V 1');
+        $this->_out('/R 2');
+        $this->_out('/O ('.$this->_escape($this->Ovalue).')');
+        $this->_out('/U ('.$this->_escape($this->Uvalue).')');
+        $this->_out('/P '.$this->Pvalue);
+    }
+
+    function _puttrailer() {
+        parent::_puttrailer();
+        if ($this->encrypted) {
+            $this->_out('/Encrypt '.$this->enc_obj_id.' 0 R');
+            $this->_out('/ID [()()]');
+        }
+    }
+
+    /**
+    * RC4 is the standard encryption algorithm used in PDF format
+    */
+    function _RC4($key, $text) {
+        if ($this->last_rc4_key != $key) {
+            $k = str_repeat($key, 256/strlen($key)+1);
+            $rc4 = range(0,255);
+            $j = 0;
+            for ($i=0; $i<256; $i++){
+                $t = $rc4[$i];
+                $j = ($j + $t + ord($k{$i})) % 256;
+                $rc4[$i] = $rc4[$j];
+                $rc4[$j] = $t;
+            }
+            $this->last_rc4_key = $key;
+            $this->last_rc4_key_c = $rc4;
+        } else {
+            $rc4 = $this->last_rc4_key_c;
+        }
+
+        $len = strlen($text);
+        $a = 0;
+        $b = 0;
+        $out = '';
+        for ($i=0; $i<$len; $i++){
+            $a = ($a+1)%256;
+            $t= $rc4[$a];
+            $b = ($b+$t)%256;
+            $rc4[$a] = $rc4[$b];
+            $rc4[$b] = $t;
+            $k = $rc4[($rc4[$a]+$rc4[$b])%256];
+            $out.=chr(ord($text{$i}) ^ $k);
+        }
+
+        return $out;
+    }
+
+    /**
+    * Get MD5 as binary string
+    */
+    function _md5_16($string) {
+        return pack('H*',md5($string));
+    }
+
+    /**
+    * Compute O value
+    */
+    function _Ovalue($user_pass, $owner_pass) {
+        $tmp = $this->_md5_16($owner_pass);
+        $owner_RC4_key = substr($tmp,0,5);
+        return $this->_RC4($owner_RC4_key, $user_pass);
+    }
+
+    /**
+    * Compute U value
+    */
+    function _Uvalue() {
+        return $this->_RC4($this->encryption_key, $this->padding);
+    }
+
+    /**
+    * Compute encryption key
+    */
+    function _generateencryptionkey($user_pass, $owner_pass, $protection) {
+        // Pad passwords
+        $user_pass = substr($user_pass.$this->padding,0,32);
+        $owner_pass = substr($owner_pass.$this->padding,0,32);
+        // Compute O value
+        $this->Ovalue = $this->_Ovalue($user_pass,$owner_pass);
+        // Compute encyption key
+        $tmp = $this->_md5_16($user_pass.$this->Ovalue.chr($protection)."\xFF\xFF\xFF");
+        $this->encryption_key = substr($tmp,0,5);
+        // Compute U value
+        $this->Uvalue = $this->_Uvalue();
+        // Compute P value
+        $this->Pvalue = -(($protection^255)+1);
+    }
+}
+
+?>
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