522 lines
12 KiB
PHP
522 lines
12 KiB
PHP
<?php
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/**
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* CodeIgniter
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*
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* An open source application development framework for PHP
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*
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* This content is released under the MIT License (MIT)
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*
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* Copyright (c) 2014 - 2018, British Columbia Institute of Technology
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*
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* @package CodeIgniter
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* @author EllisLab Dev Team
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* @copyright Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
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* @copyright Copyright (c) 2014 - 2018, British Columbia Institute of Technology (http://bcit.ca/)
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* @license http://opensource.org/licenses/MIT MIT License
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* @link https://codeigniter.com
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* @since Version 1.0.0
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* @filesource
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*/
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defined('BASEPATH') OR exit('No direct script access allowed');
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/**
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* CodeIgniter Encryption Class
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*
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* Provides two-way keyed encoding using Mcrypt
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*
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* @package CodeIgniter
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* @subpackage Libraries
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* @category Libraries
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* @author EllisLab Dev Team
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* @link https://codeigniter.com/user_guide/libraries/encryption.html
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*/
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class CI_Encrypt {
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/**
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* Reference to the user's encryption key
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*
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* @var string
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*/
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public $encryption_key = '';
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/**
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* Type of hash operation
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*
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* @var string
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*/
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protected $_hash_type = 'sha1';
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/**
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* Flag for the existence of mcrypt
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*
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* @var bool
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*/
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protected $_mcrypt_exists = FALSE;
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/**
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* Current cipher to be used with mcrypt
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*
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* @var string
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*/
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protected $_mcrypt_cipher;
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/**
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* Method for encrypting/decrypting data
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*
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* @var int
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*/
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protected $_mcrypt_mode;
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/**
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* Initialize Encryption class
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*
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* @return void
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*/
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public function __construct()
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{
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if (($this->_mcrypt_exists = function_exists('mcrypt_encrypt')) === FALSE)
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{
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show_error('The Encrypt library requires the Mcrypt extension.');
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}
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log_message('info', 'Encrypt Class Initialized');
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}
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// --------------------------------------------------------------------
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/**
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* Fetch the encryption key
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*
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* Returns it as MD5 in order to have an exact-length 128 bit key.
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* Mcrypt is sensitive to keys that are not the correct length
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*
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* @param string
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* @return string
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*/
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public function get_key($key = '')
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{
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if ($key === '')
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{
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if ($this->encryption_key !== '')
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{
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return $this->encryption_key;
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}
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$key = config_item('encryption_key');
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if ( ! self::strlen($key))
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{
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show_error('In order to use the encryption class requires that you set an encryption key in your config file.');
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}
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}
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return md5($key);
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}
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// --------------------------------------------------------------------
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/**
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* Set the encryption key
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*
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* @param string
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* @return CI_Encrypt
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*/
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public function set_key($key = '')
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{
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$this->encryption_key = $key;
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return $this;
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}
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// --------------------------------------------------------------------
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/**
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* Encode
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*
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* Encodes the message string using bitwise XOR encoding.
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* The key is combined with a random hash, and then it
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* too gets converted using XOR. The whole thing is then run
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* through mcrypt using the randomized key. The end result
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* is a double-encrypted message string that is randomized
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* with each call to this function, even if the supplied
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* message and key are the same.
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*
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* @param string the string to encode
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* @param string the key
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* @return string
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*/
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public function encode($string, $key = '')
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{
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return base64_encode($this->mcrypt_encode($string, $this->get_key($key)));
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}
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// --------------------------------------------------------------------
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/**
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* Decode
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*
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* Reverses the above process
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*
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* @param string
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* @param string
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* @return string
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*/
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public function decode($string, $key = '')
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{
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if (preg_match('/[^a-zA-Z0-9\/\+=]/', $string) OR base64_encode(base64_decode($string)) !== $string)
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{
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return FALSE;
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}
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return $this->mcrypt_decode(base64_decode($string), $this->get_key($key));
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}
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// --------------------------------------------------------------------
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/**
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* Encode from Legacy
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*
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* Takes an encoded string from the original Encryption class algorithms and
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* returns a newly encoded string using the improved method added in 2.0.0
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* This allows for backwards compatibility and a method to transition to the
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* new encryption algorithms.
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*
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* For more details, see https://codeigniter.com/user_guide/installation/upgrade_200.html#encryption
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*
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* @param string
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* @param int (mcrypt mode constant)
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* @param string
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* @return string
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*/
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public function encode_from_legacy($string, $legacy_mode = MCRYPT_MODE_ECB, $key = '')
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{
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if (preg_match('/[^a-zA-Z0-9\/\+=]/', $string))
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{
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return FALSE;
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}
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// decode it first
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// set mode temporarily to what it was when string was encoded with the legacy
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// algorithm - typically MCRYPT_MODE_ECB
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$current_mode = $this->_get_mode();
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$this->set_mode($legacy_mode);
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$key = $this->get_key($key);
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$dec = base64_decode($string);
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if (($dec = $this->mcrypt_decode($dec, $key)) === FALSE)
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{
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$this->set_mode($current_mode);
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return FALSE;
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}
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$dec = $this->_xor_decode($dec, $key);
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// set the mcrypt mode back to what it should be, typically MCRYPT_MODE_CBC
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$this->set_mode($current_mode);
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// and re-encode
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return base64_encode($this->mcrypt_encode($dec, $key));
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}
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// --------------------------------------------------------------------
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/**
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* XOR Decode
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*
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* Takes an encoded string and key as input and generates the
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* plain-text original message
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*
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* @param string
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* @param string
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* @return string
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*/
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protected function _xor_decode($string, $key)
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{
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$string = $this->_xor_merge($string, $key);
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$dec = '';
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for ($i = 0, $l = self::strlen($string); $i < $l; $i++)
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{
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$dec .= ($string[$i++] ^ $string[$i]);
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}
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return $dec;
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}
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// --------------------------------------------------------------------
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/**
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* XOR key + string Combiner
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*
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* Takes a string and key as input and computes the difference using XOR
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*
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* @param string
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* @param string
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* @return string
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*/
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protected function _xor_merge($string, $key)
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{
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$hash = $this->hash($key);
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$str = '';
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for ($i = 0, $ls = self::strlen($string), $lh = self::strlen($hash); $i < $ls; $i++)
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{
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$str .= $string[$i] ^ $hash[($i % $lh)];
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}
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return $str;
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}
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// --------------------------------------------------------------------
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/**
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* Encrypt using Mcrypt
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*
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* @param string
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* @param string
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* @return string
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*/
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public function mcrypt_encode($data, $key)
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{
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$init_size = mcrypt_get_iv_size($this->_get_cipher(), $this->_get_mode());
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$init_vect = mcrypt_create_iv($init_size, MCRYPT_DEV_URANDOM);
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return $this->_add_cipher_noise($init_vect.mcrypt_encrypt($this->_get_cipher(), $key, $data, $this->_get_mode(), $init_vect), $key);
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}
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// --------------------------------------------------------------------
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/**
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* Decrypt using Mcrypt
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*
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* @param string
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* @param string
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* @return string
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*/
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public function mcrypt_decode($data, $key)
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{
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$data = $this->_remove_cipher_noise($data, $key);
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$init_size = mcrypt_get_iv_size($this->_get_cipher(), $this->_get_mode());
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if ($init_size > self::strlen($data))
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{
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return FALSE;
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}
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$init_vect = self::substr($data, 0, $init_size);
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$data = self::substr($data, $init_size);
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return rtrim(mcrypt_decrypt($this->_get_cipher(), $key, $data, $this->_get_mode(), $init_vect), "\0");
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}
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// --------------------------------------------------------------------
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/**
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* Adds permuted noise to the IV + encrypted data to protect
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* against Man-in-the-middle attacks on CBC mode ciphers
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* http://www.ciphersbyritter.com/GLOSSARY.HTM#IV
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*
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* @param string
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* @param string
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* @return string
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*/
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protected function _add_cipher_noise($data, $key)
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{
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$key = $this->hash($key);
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$str = '';
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for ($i = 0, $j = 0, $ld = self::strlen($data), $lk = self::strlen($key); $i < $ld; ++$i, ++$j)
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{
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if ($j >= $lk)
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{
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$j = 0;
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}
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$str .= chr((ord($data[$i]) + ord($key[$j])) % 256);
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}
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return $str;
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}
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// --------------------------------------------------------------------
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/**
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* Removes permuted noise from the IV + encrypted data, reversing
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* _add_cipher_noise()
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*
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* Function description
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*
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* @param string $data
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* @param string $key
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* @return string
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*/
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protected function _remove_cipher_noise($data, $key)
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{
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$key = $this->hash($key);
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$str = '';
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for ($i = 0, $j = 0, $ld = self::strlen($data), $lk = self::strlen($key); $i < $ld; ++$i, ++$j)
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{
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if ($j >= $lk)
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{
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$j = 0;
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}
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$temp = ord($data[$i]) - ord($key[$j]);
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if ($temp < 0)
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{
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$temp += 256;
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}
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$str .= chr($temp);
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}
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return $str;
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}
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// --------------------------------------------------------------------
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/**
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* Set the Mcrypt Cipher
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*
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* @param int
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* @return CI_Encrypt
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*/
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public function set_cipher($cipher)
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{
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$this->_mcrypt_cipher = $cipher;
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return $this;
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}
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// --------------------------------------------------------------------
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/**
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* Set the Mcrypt Mode
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*
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* @param int
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* @return CI_Encrypt
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*/
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public function set_mode($mode)
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{
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$this->_mcrypt_mode = $mode;
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return $this;
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}
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// --------------------------------------------------------------------
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/**
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* Get Mcrypt cipher Value
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*
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* @return int
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*/
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protected function _get_cipher()
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{
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if ($this->_mcrypt_cipher === NULL)
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{
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return $this->_mcrypt_cipher = MCRYPT_RIJNDAEL_256;
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}
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return $this->_mcrypt_cipher;
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}
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// --------------------------------------------------------------------
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/**
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* Get Mcrypt Mode Value
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*
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* @return int
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*/
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protected function _get_mode()
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{
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if ($this->_mcrypt_mode === NULL)
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{
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return $this->_mcrypt_mode = MCRYPT_MODE_CBC;
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}
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return $this->_mcrypt_mode;
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}
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// --------------------------------------------------------------------
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/**
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* Set the Hash type
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*
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* @param string
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* @return void
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*/
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public function set_hash($type = 'sha1')
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{
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$this->_hash_type = in_array($type, hash_algos()) ? $type : 'sha1';
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}
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// --------------------------------------------------------------------
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/**
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* Hash encode a string
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*
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* @param string
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* @return string
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*/
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public function hash($str)
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{
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return hash($this->_hash_type, $str);
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}
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// --------------------------------------------------------------------
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/**
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* Byte-safe strlen()
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*
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* @param string $str
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* @return int
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*/
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protected static function strlen($str)
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{
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return defined('MB_OVERLOAD_STRING')
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? mb_strlen($str, '8bit')
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: strlen($str);
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}
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// --------------------------------------------------------------------
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/**
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* Byte-safe substr()
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*
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* @param string $str
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* @param int $start
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* @param int $length
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* @return string
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*/
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protected static function substr($str, $start, $length = NULL)
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{
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if (defined('MB_OVERLOAD_STRING'))
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{
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// mb_substr($str, $start, null, '8bit') returns an empty
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// string on PHP 5.3
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isset($length) OR $length = ($start >= 0 ? self::strlen($str) - $start : -$start);
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return mb_substr($str, $start, $length, '8bit');
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}
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return isset($length)
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? substr($str, $start, $length)
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: substr($str, $start);
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}
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}
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