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<?php
/**
* CodeIgniter
*
* An open source application development framework for PHP
*
* This content is released under the MIT License (MIT)
*
* Copyright (c) 2014 - 2017, British Columbia Institute of Technology
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
* @package CodeIgniter
* @author EllisLab Dev Team
* @copyright Copyright (c) 2008 - 2014, EllisLab, Inc. (https://ellislab.com/)
* @copyright Copyright (c) 2014 - 2017, British Columbia Institute of Technology (http://bcit.ca/)
* @license http://opensource.org/licenses/MIT MIT License
* @link https://codeigniter.com
* @since Version 1.0.0
* @filesource
*/
defined('BASEPATH') OR exit('No direct script access allowed');
/**
* CodeIgniter Encryption Class
*
* Provides two-way keyed encoding using Mcrypt
*
* @package CodeIgniter
* @subpackage Libraries
* @category Libraries
* @author EllisLab Dev Team
* @link https://codeigniter.com/user_guide/libraries/encryption.html
*/
class CI_Encrypt {
/**
* Reference to the user's encryption key
*
* @var string
*/
public $encryption_key = '';
/**
* Type of hash operation
*
* @var string
*/
protected $_hash_type = 'sha1';
/**
* Flag for the existence of mcrypt
*
* @var bool
*/
protected $_mcrypt_exists = FALSE;
/**
* Current cipher to be used with mcrypt
*
* @var string
*/
protected $_mcrypt_cipher;
/**
* Method for encrypting/decrypting data
*
* @var int
*/
protected $_mcrypt_mode;
/**
* Initialize Encryption class
*
* @return void
*/
public function __construct()
{
if (($this->_mcrypt_exists = function_exists('mcrypt_encrypt')) === FALSE)
{
show_error('The Encrypt library requires the Mcrypt extension.');
}
log_message('info', 'Encrypt Class Initialized');
}
// --------------------------------------------------------------------
/**
* Fetch the encryption key
*
* Returns it as MD5 in order to have an exact-length 128 bit key.
* Mcrypt is sensitive to keys that are not the correct length
*
* @param string
* @return string
*/
public function get_key($key = '')
{
if ($key === '')
{
if ($this->encryption_key !== '')
{
return $this->encryption_key;
}
$key = config_item('encryption_key');
if ( ! self::strlen($key))
{
show_error('In order to use the encryption class requires that you set an encryption key in your config file.');
}
}
return md5($key);
}
// --------------------------------------------------------------------
/**
* Set the encryption key
*
* @param string
* @return CI_Encrypt
*/
public function set_key($key = '')
{
$this->encryption_key = $key;
return $this;
}
// --------------------------------------------------------------------
/**
* Encode
*
* Encodes the message string using bitwise XOR encoding.
* The key is combined with a random hash, and then it
* too gets converted using XOR. The whole thing is then run
* through mcrypt using the randomized key. The end result
* is a double-encrypted message string that is randomized
* with each call to this function, even if the supplied
* message and key are the same.
*
* @param string the string to encode
* @param string the key
* @return string
*/
public function encode($string, $key = '')
{
return base64_encode($this->mcrypt_encode($string, $this->get_key($key)));
}
// --------------------------------------------------------------------
/**
* Decode
*
* Reverses the above process
*
* @param string
* @param string
* @return string
*/
public function decode($string, $key = '')
{
if (preg_match('/[^a-zA-Z0-9\/\+=]/', $string) OR base64_encode(base64_decode($string)) !== $string)
{
return FALSE;
}
return $this->mcrypt_decode(base64_decode($string), $this->get_key($key));
}
// --------------------------------------------------------------------
/**
* Encode from Legacy
*
* Takes an encoded string from the original Encryption class algorithms and
* returns a newly encoded string using the improved method added in 2.0.0
* This allows for backwards compatibility and a method to transition to the
* new encryption algorithms.
*
* For more details, see https://codeigniter.com/user_guide/installation/upgrade_200.html#encryption
*
* @param string
* @param int (mcrypt mode constant)
* @param string
* @return string
*/
public function encode_from_legacy($string, $legacy_mode = MCRYPT_MODE_ECB, $key = '')
{
if (preg_match('/[^a-zA-Z0-9\/\+=]/', $string))
{
return FALSE;
}
// decode it first
// set mode temporarily to what it was when string was encoded with the legacy
// algorithm - typically MCRYPT_MODE_ECB
$current_mode = $this->_get_mode();
$this->set_mode($legacy_mode);
$key = $this->get_key($key);
$dec = base64_decode($string);
if (($dec = $this->mcrypt_decode($dec, $key)) === FALSE)
{
$this->set_mode($current_mode);
return FALSE;
}
$dec = $this->_xor_decode($dec, $key);
// set the mcrypt mode back to what it should be, typically MCRYPT_MODE_CBC
$this->set_mode($current_mode);
// and re-encode
return base64_encode($this->mcrypt_encode($dec, $key));
}
// --------------------------------------------------------------------
/**
* XOR Decode
*
* Takes an encoded string and key as input and generates the
* plain-text original message
*
* @param string
* @param string
* @return string
*/
protected function _xor_decode($string, $key)
{
$string = $this->_xor_merge($string, $key);
$dec = '';
for ($i = 0, $l = self::strlen($string); $i < $l; $i++)
{
$dec .= ($string[$i++] ^ $string[$i]);
}
return $dec;
}
// --------------------------------------------------------------------
/**
* XOR key + string Combiner
*
* Takes a string and key as input and computes the difference using XOR
*
* @param string
* @param string
* @return string
*/
protected function _xor_merge($string, $key)
{
$hash = $this->hash($key);
$str = '';
for ($i = 0, $ls = self::strlen($string), $lh = self::strlen($hash); $i < $ls; $i++)
{
$str .= $string[$i] ^ $hash[($i % $lh)];
}
return $str;
}
// --------------------------------------------------------------------
/**
* Encrypt using Mcrypt
*
* @param string
* @param string
* @return string
*/
public function mcrypt_encode($data, $key)
{
$init_size = mcrypt_get_iv_size($this->_get_cipher(), $this->_get_mode());
$init_vect = mcrypt_create_iv($init_size, MCRYPT_DEV_URANDOM);
return $this->_add_cipher_noise($init_vect.mcrypt_encrypt($this->_get_cipher(), $key, $data, $this->_get_mode(), $init_vect), $key);
}
// --------------------------------------------------------------------
/**
* Decrypt using Mcrypt
*
* @param string
* @param string
* @return string
*/
public function mcrypt_decode($data, $key)
{
$data = $this->_remove_cipher_noise($data, $key);
$init_size = mcrypt_get_iv_size($this->_get_cipher(), $this->_get_mode());
if ($init_size > self::strlen($data))
{
return FALSE;
}
$init_vect = self::substr($data, 0, $init_size);
$data = self::substr($data, $init_size);
return rtrim(mcrypt_decrypt($this->_get_cipher(), $key, $data, $this->_get_mode(), $init_vect), "\0");
}
// --------------------------------------------------------------------
/**
* Adds permuted noise to the IV + encrypted data to protect
* against Man-in-the-middle attacks on CBC mode ciphers
* http://www.ciphersbyritter.com/GLOSSARY.HTM#IV
*
* @param string
* @param string
* @return string
*/
protected function _add_cipher_noise($data, $key)
{
$key = $this->hash($key);
$str = '';
for ($i = 0, $j = 0, $ld = self::strlen($data), $lk = self::strlen($key); $i < $ld; ++$i, ++$j)
{
if ($j >= $lk)
{
$j = 0;
}
$str .= chr((ord($data[$i]) + ord($key[$j])) % 256);
}
return $str;
}
// --------------------------------------------------------------------
/**
* Removes permuted noise from the IV + encrypted data, reversing
* _add_cipher_noise()
*
* Function description
*
* @param string $data
* @param string $key
* @return string
*/
protected function _remove_cipher_noise($data, $key)
{
$key = $this->hash($key);
$str = '';
for ($i = 0, $j = 0, $ld = self::strlen($data), $lk = self::strlen($key); $i < $ld; ++$i, ++$j)
{
if ($j >= $lk)
{
$j = 0;
}
$temp = ord($data[$i]) - ord($key[$j]);
if ($temp < 0)
{
$temp += 256;
}
$str .= chr($temp);
}
return $str;
}
// --------------------------------------------------------------------
/**
* Set the Mcrypt Cipher
*
* @param int
* @return CI_Encrypt
*/
public function set_cipher($cipher)
{
$this->_mcrypt_cipher = $cipher;
return $this;
}
// --------------------------------------------------------------------
/**
* Set the Mcrypt Mode
*
* @param int
* @return CI_Encrypt
*/
public function set_mode($mode)
{
$this->_mcrypt_mode = $mode;
return $this;
}
// --------------------------------------------------------------------
/**
* Get Mcrypt cipher Value
*
* @return int
*/
protected function _get_cipher()
{
if ($this->_mcrypt_cipher === NULL)
{
return $this->_mcrypt_cipher = MCRYPT_RIJNDAEL_256;
}
return $this->_mcrypt_cipher;
}
// --------------------------------------------------------------------
/**
* Get Mcrypt Mode Value
*
* @return int
*/
protected function _get_mode()
{
if ($this->_mcrypt_mode === NULL)
{
return $this->_mcrypt_mode = MCRYPT_MODE_CBC;
}
return $this->_mcrypt_mode;
}
// --------------------------------------------------------------------
/**
* Set the Hash type
*
* @param string
* @return void
*/
public function set_hash($type = 'sha1')
{
$this->_hash_type = in_array($type, hash_algos()) ? $type : 'sha1';
}
// --------------------------------------------------------------------
/**
* Hash encode a string
*
* @param string
* @return string
*/
public function hash($str)
{
return hash($this->_hash_type, $str);
}
// --------------------------------------------------------------------
/**
* Byte-safe strlen()
*
* @param string $str
* @return int
*/
protected static function strlen($str)
{
return defined('MB_OVERLOAD_STRING')
? mb_strlen($str, '8bit')
: strlen($str);
}
// --------------------------------------------------------------------
/**
* Byte-safe substr()
*
* @param string $str
* @param int $start
* @param int $length
* @return string
*/
protected static function substr($str, $start, $length = NULL)
{
if (defined('MB_OVERLOAD_STRING'))
{
// mb_substr($str, $start, null, '8bit') returns an empty
// string on PHP 5.3
isset($length) OR $length = ($start >= 0 ? self::strlen($str) - $start : -$start);
return mb_substr($str, $start, $length, '8bit');
}
return isset($length)
? substr($str, $start, $length)
: substr($str, $start);
}
}
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