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+<?php
+/**
+ * CodeIgniter
+ *
+ * An open source application development framework for PHP 5.2.4 or newer
+ *
+ * NOTICE OF LICENSE
+ *
+ * Licensed under the Open Software License version 3.0
+ *
+ * This source file is subject to the Open Software License (OSL 3.0) that is
+ * bundled with this package in the files license.txt / license.rst. It is
+ * also available through the world wide web at this URL:
+ * http://opensource.org/licenses/OSL-3.0
+ * If you did not receive a copy of the license and are unable to obtain it
+ * through the world wide web, please send an email to
+ * licensing@ellislab.com so we can send you a copy immediately.
+ *
+ * @package CodeIgniter
+ * @author EllisLab Dev Team
+ * @copyright Copyright (c) 2008 - 2014, EllisLab, Inc. (http://ellislab.com/)
+ * @license http://opensource.org/licenses/OSL-3.0 Open Software License (OSL 3.0)
+ * @link http://codeigniter.com
+ * @since Version 3.0
+ * @filesource
+ */
+defined('BASEPATH') OR exit('No direct script access allowed');
+
+/**
+ * CodeIgniter Encryption Class
+ *
+ * Provides two-way keyed encryption via PHP's MCrypt and/or OpenSSL extensions.
+ *
+ * @package CodeIgniter
+ * @subpackage Libraries
+ * @category Libraries
+ * @author Andrey Andreev
+ * @link http://codeigniter.com/user_guide/libraries/encryption.html
+ */
+class CI_Encryption {
+
+ /**
+ * Encryption cipher
+ *
+ * @var string
+ */
+ protected $_cipher = 'aes-128';
+
+ /**
+ * Cipher mode
+ *
+ * @var string
+ */
+ protected $_mode = 'cbc';
+
+ /**
+ * Cipher handle
+ *
+ * @var mixed
+ */
+ protected $_handle;
+
+ /**
+ * Encryption key
+ *
+ * @var string
+ */
+ protected $_key;
+
+ /**
+ * PHP extension to be used
+ *
+ * @var string
+ */
+ protected $_driver;
+
+ /**
+ * List of usable drivers (PHP extensions)
+ *
+ * @var array
+ */
+ protected $_drivers = array();
+
+ /**
+ * List of available modes
+ *
+ * @var array
+ */
+ protected $_modes = array(
+ 'mcrypt' => array(
+ 'cbc' => 'cbc',
+ 'ecb' => 'ecb',
+ 'ofb' => 'nofb',
+ 'ofb8' => 'ofb',
+ 'cfb' => 'ncfb',
+ 'cfb8' => 'cfb',
+ 'ctr' => 'ctr',
+ 'stream' => 'stream'
+ ),
+ 'openssl' => array(
+ 'cbc' => 'cbc',
+ 'ecb' => 'ecb',
+ 'ofb' => 'ofb',
+ 'cfb' => 'cfb',
+ 'cfb8' => 'cfb8',
+ 'ctr' => 'ctr',
+ 'stream' => '',
+ 'gcm' => 'gcm',
+ 'xts' => 'xts'
+ )
+ );
+
+ /**
+ * List of supported HMAC algorightms
+ *
+ * name => digest size pairs
+ *
+ * @var array
+ */
+ protected $_digests = array(
+ 'sha224' => 28,
+ 'sha256' => 32,
+ 'sha384' => 48,
+ 'sha512' => 64
+ );
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Class constructor
+ *
+ * @param array $params Configuration parameters
+ * @return void
+ */
+ public function __construct(array $params = array())
+ {
+ $this->_drivers = array(
+ 'mcrypt' => defined('MCRYPT_DEV_URANDOM'),
+ // While OpenSSL is available for PHP 5.3.0, an IV parameter
+ // for the encrypt/decrypt functions is only available since 5.3.3
+ 'openssl' => (is_php('5.3.3') && extension_loaded('openssl'))
+ );
+
+ if ( ! $this->_drivers['mcrypt'] && ! $this->_drivers['openssl'])
+ {
+ return show_error('Encryption: Unable to find an available encryption driver.');
+ }
+
+ $this->initialize($params);
+ if ( ! isset($this->_key) && strlen($key = config_item('encryption_key')) > 0)
+ {
+ $this->_key = $key;
+ }
+
+ log_message('debug', 'Encryption Class Initialized');
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Initialize
+ *
+ * @param array $params Configuration parameters
+ * @return CI_Encryption
+ */
+ public function initialize(array $params)
+ {
+ if ( ! empty($params['driver']))
+ {
+ if (isset($this->_drivers[$params['driver']]))
+ {
+ if ($this->_drivers[$params['driver']])
+ {
+ $this->_driver = $params['driver'];
+ }
+ else
+ {
+ log_message('error', "Encryption: Driver '".$params['driver']."' is not available.");
+ }
+ }
+ else
+ {
+ log_message('error', "Encryption: Unknown driver '".$params['driver']."' cannot be configured.");
+ }
+ }
+
+ if (empty($this->_driver))
+ {
+ $this->_driver = ($this->_drivers['openssl'] === TRUE)
+ ? 'openssl'
+ : 'mcrypt';
+
+ log_message('debug', "Encryption: Auto-configured driver '".$this->_driver."'.");
+ }
+
+ empty($params['key']) OR $this->_key = $params['key'];
+ $this->{'_'.$this->_driver.'_initialize'}($params);
+ return $this;
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Initialize MCrypt
+ *
+ * @param array $params Configuration parameters
+ * @return void
+ */
+ protected function _mcrypt_initialize($params)
+ {
+ if ( ! empty($params['cipher']))
+ {
+ $params['cipher'] = strtolower($params['cipher']);
+ $this->_cipher_alias($params['cipher']);
+
+ if ( ! in_array($params['cipher'], mcrypt_list_algorithms(), TRUE))
+ {
+ log_message('error', 'Encryption: MCrypt cipher '.strtoupper($params['cipher']).' is not available.');
+ }
+ else
+ {
+ $this->_cipher = $params['cipher'];
+ }
+ }
+
+ if ( ! empty($params['mode']))
+ {
+ $params['mode'] = strtolower($params['mode']);
+ if ( ! isset($this->_modes['mcrypt'][$params['mode']]))
+ {
+ log_message('error', 'Encryption: MCrypt mode '.strtotupper($params['mode']).' is not available.');
+ }
+ else
+ {
+ $this->_mode = $this->_modes['mcrypt'][$params['mode']];
+ }
+ }
+
+ if (isset($this->_cipher, $this->_mode))
+ {
+ if (is_resource($this->_handle)
+ && (strtolower(mcrypt_enc_get_algorithms_name($this->_handle)) !== $this->_cipher
+ OR strtolower(mcrypt_enc_get_modes_name($this->_handle)) !== $this->_mode)
+ )
+ {
+ mcrypt_module_close($this->_handle);
+ }
+
+ if ($this->_handle = mcrypt_module_open($this->_cipher, '', $this->_mode, ''))
+ {
+ log_message('debug', 'Encryption: MCrypt cipher '.strtoupper($this->_cipher).' initialized in '.strtoupper($this->_mode).' mode.');
+ }
+ else
+ {
+ log_message('error', 'Encryption: Unable to initialize MCrypt with cipher '.strtoupper($this->_cipher).' in '.strtoupper($this->_mode).' mode.');
+ }
+ }
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Initialize OpenSSL
+ *
+ * @param array $params Configuration parameters
+ * @return void
+ */
+ protected function _openssl_initialize($params)
+ {
+ if ( ! empty($params['cipher']))
+ {
+ $params['cipher'] = strtolower($params['cipher']);
+ $this->_cipher_alias($params['cipher']);
+ $this->_cipher = $params['cipher'];
+ }
+
+ if ( ! empty($params['mode']))
+ {
+ $params['mode'] = strtolower($params['mode']);
+ if ( ! isset($this->_modes['openssl'][$params['mode']]))
+ {
+ log_message('error', 'Encryption: OpenSSL mode '.strtotupper($params['mode']).' is not available.');
+ }
+ else
+ {
+ $this->_mode = $this->_modes['openssl'][$params['mode']];
+ }
+ }
+
+ if (isset($this->_cipher, $this->_mode))
+ {
+ // This is mostly for the stream mode, which doesn't get suffixed in OpenSSL
+ $handle = empty($this->_mode)
+ ? $this->_cipher
+ : $this->_cipher.'-'.$this->_mode;
+
+ if ( ! in_array($handle, openssl_get_cipher_methods(), TRUE))
+ {
+ $this->_handle = NULL;
+ log_message('error', 'Encryption: Unable to initialize OpenSSL with method '.strtoupper($handle).'.');
+ }
+ else
+ {
+ $this->_handle = $handle;
+ log_message('debug', 'Encryption: OpenSSL initialized with method '.strtoupper($handle).'.');
+ }
+ }
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Encrypt
+ *
+ * @param string $data Input data
+ * @param array $params Input parameters
+ * @return string
+ */
+ public function encrypt($data, array $params = NULL)
+ {
+ if (($params = $this->_get_params($params)) === FALSE)
+ {
+ return FALSE;
+ }
+
+ isset($params['key']) OR $params['key'] = $this->hkdf($this->_key, 'sha512', NULL, strlen($this->_key), 'encryption');
+
+ if (($data = $this->{'_'.$this->_driver.'_encrypt'}($data, $params)) === FALSE)
+ {
+ return FALSE;
+ }
+
+ $params['base64'] && $data = base64_encode($data);
+
+ if (isset($params['hmac_digest']))
+ {
+ isset($params['hmac_key']) OR $params['hmac_key'] = $this->hkdf($this->_key, 'sha512', NULL, NULL, 'authentication');
+ return hash_hmac($params['hmac_digest'], $data, $params['hmac_key'], ! $params['base64']).$data;
+ }
+
+ return $data;
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Encrypt via MCrypt
+ *
+ * @param string $data Input data
+ * @param array $params Input parameters
+ * @return string
+ */
+ protected function _mcrypt_encrypt($data, $params)
+ {
+ if ( ! is_resource($params['handle']))
+ {
+ return FALSE;
+ }
+ elseif ( ! isset($params['iv']))
+ {
+ // The greater-than-1 comparison is mostly a work-around for a bug,
+ // where 1 is returned for ARCFour instead of 0.
+ $params['iv'] = (($iv_size = mcrypt_enc_get_iv_size($params['handle'])) > 1)
+ ? mcrypt_create_iv($iv_size, MCRYPT_DEV_URANDOM)
+ : NULL;
+ }
+
+ // CAST-128 compatibility (http://tools.ietf.org/rfc/rfc2144.txt)
+ //
+ // RFC2144 says that keys shorter than 16 bytes are to be padded with
+ // zero bytes to 16 bytes, but (surprise) MCrypt doesn't do that.
+ if ($params['cipher'] === 'cast-128' && ($kl = strlen($params['key'])) < 16)
+ {
+ $params['key'] .= str_repeat("\x0", 16 - $kl);
+ }
+
+ if (mcrypt_generic_init($params['handle'], $params['key'], $params['iv']) < 0)
+ {
+ if ($params['handle'] !== $this->_handle)
+ {
+ mcrypt_module_close($params['handle']);
+ }
+
+ return FALSE;
+ }
+
+ // Use PKCS#7 padding in order to ensure compatibility with OpenSSL
+ // and other implementations outside of PHP.
+ if (in_array(strtolower(mcrypt_enc_get_modes_name($params['handle'])), array('cbc', 'ecb'), TRUE))
+ {
+ $block_size = mcrypt_enc_get_block_size($params['handle']);
+ $pad = $block_size - (strlen($data) % $block_size);
+ $data .= str_repeat(chr($pad), $pad);
+ }
+
+ // Work-around for yet another strange behavior in MCrypt.
+ //
+ // When encrypting in ECB mode, the IV is ignored. Yet
+ // mcrypt_enc_get_iv_size() returns a value larger than 0
+ // even if ECB is used AND mcrypt_generic_init() complains
+ // if you don't pass an IV with length equal to the said
+ // return value.
+ //
+ // This probably would've been fine (even though still wasteful),
+ // but OpenSSL isn't that dumb and we need to make the process
+ // portable, so ...
+ $data = (mcrypt_enc_get_modes_name($params['handle']) !== 'ECB')
+ ? $params['iv'].mcrypt_generic($params['handle'], $data)
+ : mcrypt_generic($params['handle'], $data);
+
+ mcrypt_generic_deinit($params['handle']);
+ if ($params['handle'] !== $this->_handle)
+ {
+ mcrypt_module_close($params['handle']);
+ }
+
+ return $data;
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Encrypt via OpenSSL
+ *
+ * @param string $data Input data
+ * @param array $params Input parameters
+ * @return string
+ */
+ protected function _openssl_encrypt($data, $params)
+ {
+ if (empty($params['handle']))
+ {
+ return FALSE;
+ }
+ elseif ( ! isset($params['iv']))
+ {
+ $params['iv'] = ($iv_size = openssl_cipher_iv_length($params['handle']))
+ ? openssl_random_pseudo_bytes($iv_size)
+ : NULL;
+ }
+
+ $data = openssl_encrypt(
+ $data,
+ $params['handle'],
+ $params['key'],
+ 1, // DO NOT TOUCH!
+ $params['iv']
+ );
+
+ if ($data === FALSE)
+ {
+ return FALSE;
+ }
+
+ return $params['iv'].$data;
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Decrypt
+ *
+ * @param string $data Encrypted data
+ * @param array $params Input parameters
+ * @return string
+ */
+ public function decrypt($data, array $params = NULL)
+ {
+ if (($params = $this->_get_params($params)) === FALSE)
+ {
+ return FALSE;
+ }
+
+ if (isset($params['hmac_digest']))
+ {
+ // This might look illogical, but it is done during encryption as well ...
+ // The 'base64' value is effectively an inverted "raw data" parameter
+ $digest_size = ($params['base64'])
+ ? $this->_digests[$params['hmac_digest']] * 2
+ : $this->_digests[$params['hmac_digest']];
+
+ if (strlen($data) <= $digest_size)
+ {
+ return FALSE;
+ }
+
+ $hmac_input = substr($data, 0, $digest_size);
+ $data = substr($data, $digest_size);
+
+ isset($params['hmac_key']) OR $params['hmac_key'] = $this->hkdf($this->_key, 'sha512', NULL, NULL, 'authentication');
+ $hmac_check = hash_hmac($params['hmac_digest'], $data, $params['hmac_key'], ! $params['base64']);
+
+ // Time-attack-safe comparison
+ $diff = 0;
+ for ($i = 0; $i < $digest_size; $i++)
+ {
+ $diff |= ord($hmac_input[$i]) ^ ord($hmac_check[$i]);
+ }
+
+ if ($diff !== 0)
+ {
+ return FALSE;
+ }
+ }
+
+ if ($params['base64'])
+ {
+ $data = base64_decode($data);
+ }
+
+ if (isset($params['iv']) && strncmp($params['iv'], $data, $iv_size = strlen($params['iv'])) === 0)
+ {
+ $data = substr($data, $iv_size);
+ }
+
+ isset($params['key']) OR $params['key'] = $this->hkdf($this->_key, 'sha512', NULL, strlen($this->_key), 'encryption');
+
+ return $this->{'_'.$this->_driver.'_decrypt'}($data, $params);
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Decrypt via MCrypt
+ *
+ * @param string $data Encrypted data
+ * @param array $params Input parameters
+ * @return string
+ */
+ protected function _mcrypt_decrypt($data, $params)
+ {
+ if ( ! is_resource($params['handle']))
+ {
+ return FALSE;
+ }
+ elseif ( ! isset($params['iv']))
+ {
+ // The greater-than-1 comparison is mostly a work-around for a bug,
+ // where 1 is returned for ARCFour instead of 0.
+ if (($iv_size = mcrypt_enc_get_iv_size($params['handle'])) > 1)
+ {
+ if (mcrypt_enc_get_modes_name($params['handle']) !== 'ECB')
+ {
+ $params['iv'] = substr($data, 0, $iv_size);
+ $data = substr($data, $iv_size);
+ }
+ else
+ {
+ // MCrypt is dumb and this is ignored, only size matters
+ $params['iv'] = str_repeat("\x0", $iv_size);
+ }
+ }
+ else
+ {
+ $params['iv'] = NULL;
+ }
+ }
+
+ // CAST-128 compatibility (http://tools.ietf.org/rfc/rfc2144.txt)
+ //
+ // RFC2144 says that keys shorter than 16 bytes are to be padded with
+ // zero bytes to 16 bytes, but (surprise) MCrypt doesn't do that.
+ if ($params['cipher'] === 'cast-128' && ($kl = strlen($params['key'])) < 16)
+ {
+ $params['key'] .= str_repeat("\x0", 16 - $kl);
+ }
+
+ if (mcrypt_generic_init($params['handle'], $params['key'], $params['iv']) < 0)
+ {
+ if ($params['handle'] !== $this->_handle)
+ {
+ mcrypt_module_close($params['handle']);
+ }
+
+ return FALSE;
+ }
+
+ $data = mdecrypt_generic($params['handle'], $data);
+ // Remove PKCS#7 padding, if necessary
+ if (in_array(strtolower(mcrypt_enc_get_modes_name($params['handle'])), array('cbc', 'ecb'), TRUE))
+ {
+ $data = substr($data, 0, -ord($data[strlen($data)-1]));
+ }
+
+ mcrypt_generic_deinit($params['handle']);
+ if ($params['handle'] !== $this->_handle)
+ {
+ mcrypt_module_close($params['handle']);
+ }
+
+ return $data;
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Decrypt via OpenSSL
+ *
+ * @param string $data Encrypted data
+ * @param array $params Input parameters
+ * @return string
+ */
+ protected function _openssl_decrypt($data, $params)
+ {
+ if ( ! isset($params['iv']))
+ {
+ if ($iv_size = openssl_cipher_iv_length($params['handle']))
+ {
+ $params['iv'] = substr($data, 0, $iv_size);
+ $data = substr($data, $iv_size);
+ }
+ else
+ {
+ $params['iv'] = NULL;
+ }
+ }
+
+ return empty($params['handle'])
+ ? FALSE
+ : openssl_decrypt(
+ $data,
+ $params['handle'],
+ $params['key'],
+ 1, // DO NOT TOUCH!
+ $params['iv']
+ );
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Get params
+ *
+ * @param array $params Input parameters
+ * @return array
+ */
+ protected function _get_params($params)
+ {
+ if (empty($params))
+ {
+ return isset($this->_cipher, $this->_mode, $this->_key, $this->_handle)
+ ? array(
+ 'handle' => $this->_handle,
+ 'cipher' => $this->_cipher,
+ 'mode' => $this->_mode,
+ 'key' => NULL,
+ 'base64' => TRUE,
+ 'hmac_digest' => ($this->_mode !== 'gcm' ? 'sha512' : NULL),
+ 'hmac_key' => NULL
+ )
+ : FALSE;
+ }
+ elseif ( ! isset($params['cipher'], $params['mode'], $params['key']))
+ {
+ return FALSE;
+ }
+
+ if (isset($params['mode']))
+ {
+ $params['mode'] = strtolower($params['mode']);
+ if ( ! isset($this->_modes[$this->_driver][$params['mode']]))
+ {
+ return FALSE;
+ }
+ else
+ {
+ $params['mode'] = $this->_modes[$this->_driver][$params['mode']];
+ }
+ }
+
+ if ($params['mode'] === 'gcm' OR (isset($params['hmac']) && $params['hmac'] === FALSE))
+ {
+ $params['hmac_digest'] = $params['hmac_key'] = NULL;
+ }
+ else
+ {
+ if ( ! isset($params['hmac_key']))
+ {
+ return FALSE;
+ }
+ elseif (isset($params['hmac_digest']))
+ {
+ $params['hmac_digest'] = strtolower($params['hmac_digest']);
+ if ( ! isset($this->_digests[$params['hmac_digest']]))
+ {
+ return FALSE;
+ }
+ }
+ else
+ {
+ $params['hmac_digest'] = 'sha512';
+ }
+ }
+
+ $params = array(
+ 'handle' => NULL,
+ 'cipher' => $params['cipher'],
+ 'mode' => $params['mode'],
+ 'key' => $params['key'],
+ 'iv' => isset($params['iv']) ? $params['iv'] : NULL,
+ 'base64' => isset($params['raw_data']) ? ! $params['raw_data'] : FALSE,
+ 'hmac_digest' => $params['hmac_digest'],
+ 'hmac_key' => $params['hmac_key']
+ );
+
+ $this->_cipher_alias($params['cipher']);
+ $params['handle'] = ($params['cipher'] !== $this->_cipher OR $params['mode'] !== $this->_mode)
+ ? $this->{'_'.$this->_driver.'_get_handle'}($params['cipher'], $params['mode'])
+ : $this->_handle;
+
+ return $params;
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Get MCrypt handle
+ *
+ * @param string $cipher Cipher name
+ * @param string $mode Encryption mode
+ * @return resource
+ */
+ protected function _mcrypt_get_handle($cipher, $mode)
+ {
+ return mcrypt_module_open($cipher, '', $mode, '');
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Get OpenSSL handle
+ *
+ * @param string $cipher Cipher name
+ * @param string $mode Encryption mode
+ * @return string
+ */
+ protected function _openssl_get_handle($cipher, $mode)
+ {
+ // OpenSSL methods aren't suffixed with '-stream' for this mode
+ return ($mode === 'stream')
+ ? $cipher
+ : $cipher.'-'.$mode;
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * Cipher alias
+ *
+ * Tries to translate cipher names between MCrypt and OpenSSL's "dialects".
+ *
+ * @param string $cipher Cipher name
+ * @return void
+ */
+ protected function _cipher_alias(&$cipher)
+ {
+ static $dictionary;
+
+ if (empty($dictionary))
+ {
+ $dictionary = array(
+ 'mcrypt' => array(
+ 'aes-128' => 'rijndael-128',
+ 'aes-192' => 'rijndael-128',
+ 'aes-256' => 'rijndael-128',
+ 'des3-ede3' => 'tripledes',
+ 'bf' => 'blowfish',
+ 'cast5' => 'cast-128',
+ 'rc4' => 'arcfour',
+ 'rc4-40' => 'arcfour'
+ ),
+ 'openssl' => array(
+ 'rijndael-128' => 'aes-128',
+ 'tripledes' => 'des-ede3',
+ 'blowfish' => 'bf',
+ 'cast-128' => 'cast5',
+ 'arcfour' => 'rc4-40',
+ 'rc4' => 'rc4-40'
+ )
+ );
+
+ // Notes:
+ //
+ // - Rijndael-128 is, at the same time all three of AES-128,
+ // AES-192 and AES-256. The only difference between them is
+ // the key size. Rijndael-192, Rijndael-256 on the other hand
+ // also have different block sizes and are NOT AES-compatible.
+ //
+ // - Blowfish is said to be supporting key sizes between
+ // 4 and 56 bytes, but it appears that between MCrypt and
+ // OpenSSL, only those of 16 and more bytes are compatible.
+ // Also, don't know what MCrypt's 'blowfish-compat' is.
+ //
+ // - CAST-128/CAST5 produces a longer cipher when encrypted via
+ // OpenSSL, but (strangely enough) can be decrypted by either
+ // extension anyway.
+ // Also, RFC2144 says that the cipher supports key sizes
+ // between 5 and 16 bytes by the implementation actually
+ // zero-padding them to 16 bytes, but MCrypt doesn't do that.
+ //
+ // - RC4 (ARCFour) has a strange implementation under OpenSSL.
+ // Its 'rc4-40' cipher method seems to work flawlessly, yet
+ // there's another one, 'rc4' that only works with a 16-byte key.
+ //
+ // - DES is compatible, but doesn't need an alias.
+ //
+ // Other seemingly matching ciphers between MCrypt, OpenSSL:
+ //
+ // - RC2 is NOT compatible and only an obscure forum post
+ // confirms that it is MCrypt's fault.
+ }
+
+ if (isset($dictionary[$this->_driver][$cipher]))
+ {
+ $cipher = $dictionary[$this->_driver][$cipher];
+ }
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * HKDF
+ *
+ * @link https://tools.ietf.org/rfc/rfc5869.txt
+ * @param $key Input key
+ * @param $digest A SHA-2 hashing algorithm
+ * @param $salt Optional salt
+ * @param $length Output length (defaults to the selected digest size)
+ * @param $info Optional context/application-specific info
+ * @return string A pseudo-random key
+ */
+ public function hkdf($key, $digest = 'sha512', $salt = NULL, $length = NULL, $info = '')
+ {
+ if ( ! isset($this->_digests[$digest]))
+ {
+ return FALSE;
+ }
+
+ if (empty($length) OR ! is_int($length))
+ {
+ $length = $this->_digests[$digest];
+ }
+ elseif ($length > (255 * $this->_digests[$digest]))
+ {
+ return FALSE;
+ }
+
+ isset($salt) OR $salt = str_repeat("\0", $this->_digests[$digest]);
+
+ $prk = hash_hmac($digest, $key, $salt, TRUE);
+ $key = '';
+ for ($key_block = '', $block_index = 1; strlen($key) < $length; $block_index++)
+ {
+ $key_block = hash_hmac($digest, $key_block.$info.chr($block_index), $prk, TRUE);
+ $key .= $key_block;
+ }
+
+ return substr($key, 0, $length);
+ }
+
+ // --------------------------------------------------------------------
+
+ /**
+ * __get() magic
+ *
+ * @param string $key Property name
+ * @return mixed
+ */
+ public function __get($key)
+ {
+ // Because aliases
+ if ($key === 'mode')
+ {
+ return array_search($this->_mode, $this->_modes[$this->_driver], TRUE);
+ }
+ elseif (in_array($key, array('cipher', 'driver', 'drivers', 'digests'), TRUE))
+ {
+ return $this->{'_'.$key};
+ }
+
+ return NULL;
+ }
+
+}
+
+/* End of file Encryption.php */
+/* Location: ./system/libraries/Encryption.php */ \ No newline at end of file