From 68efe393f62babe1156f5241007e76343c0edbb5 Mon Sep 17 00:00:00 2001 From: vyshane Date: Mon, 19 Jun 2006 02:41:44 +0000 Subject: [PATCH] Merge from 1.6. New class FPDF_Protection. See bug #5855. --- lib/fpdf/fpdfprotection.php | 207 ++++++++++++++++++++++++++++++++++++ 1 file changed, 207 insertions(+) create mode 100644 lib/fpdf/fpdfprotection.php diff --git a/lib/fpdf/fpdfprotection.php b/lib/fpdf/fpdfprotection.php new file mode 100644 index 0000000000..125d3bf74d --- /dev/null +++ b/lib/fpdf/fpdfprotection.php @@ -0,0 +1,207 @@ +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); + } +} + +?> \ No newline at end of file -- 2.39.5