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943 lines (834 loc) · 23 KB
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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 - 2016, 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 - 2016, British Columbia Institute of Technology (http://bcit.ca/)
* @license http://opensource.org/licenses/MIT MIT License
* @link https://codeigniter.com
* @since Version 3.0.0
* @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 https://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' => '',
'xts' => 'xts'
)
);
/**
* List of supported HMAC algorithms
*
* name => digest size pairs
*
* @var array
*/
protected $_digests = array(
'sha224' => 28,
'sha256' => 32,
'sha384' => 48,
'sha512' => 64
);
/**
* mbstring.func_override flag
*
* @var bool
*/
protected static $func_override;
// --------------------------------------------------------------------
/**
* Class constructor
*
* @param array $params Configuration parameters
* @return void
*/
public function __construct(array $params = array())
{
$this->_drivers = array(
'mcrypt' => defined('MCRYPT_DEV_URANDOM'),
'openssl' => extension_loaded('openssl')
);
if ( ! $this->_drivers['mcrypt'] && ! $this->_drivers['openssl'])
{
show_error('Encryption: Unable to find an available encryption driver.');
}
isset(self::$func_override) OR self::$func_override = (extension_loaded('mbstring') && ini_get('mbstring.func_override'));
$this->initialize($params);
if ( ! isset($this->_key) && self::strlen($key = config_item('encryption_key')) > 0)
{
$this->_key = $key;
}
log_message('info', '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['cipher']) && $params['cipher'] = $this->_cipher;
empty($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 '.strtoupper($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, '', $this->_mode, ''))
{
log_message('info', 'Encryption: MCrypt cipher '.strtoupper($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 '.strtoupper($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 = $handle;
log_message('info', 'Encryption: OpenSSL initialized with method '.strtoupper($handle).'.');
}
}
}
// --------------------------------------------------------------------
/**
* Create a random key
*
* @param int $length Output length
* @return string
*/
public function create_key($length)
{
if (function_exists('random_bytes'))
{
try
{
return random_bytes((int) $length);
}
catch (Exception $e)
{
log_message('error', $e->getMessage());
return FALSE;
}
}
elseif (defined('MCRYPT_DEV_URANDOM'))
{
return mcrypt_create_iv($length, MCRYPT_DEV_URANDOM);
}
$is_secure = NULL;
$key = openssl_random_pseudo_bytes($length, $is_secure);
return ($is_secure === TRUE)
? $key
: FALSE;
}
// --------------------------------------------------------------------
/**
* 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, self::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;
}
// The greater-than-1 comparison is mostly a work-around for a bug,
// where 1 is returned for ARCFour instead of 0.
$iv = (($iv_size = mcrypt_enc_get_iv_size($params['handle'])) > 1)
? $this->create_key($iv_size)
: NULL;
if (mcrypt_generic_init($params['handle'], $params['key'], $iv) < 0)
{
if ($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 = $block_size - (self::strlen($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')
? $iv.mcrypt_generic($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;
}
$iv = ($iv_size = openssl_cipher_iv_length($params['handle']))
? $this->create_key($iv_size)
: NULL;
$data = openssl_encrypt(
$data,
$params['handle'],
$params['key'],
1, // DO NOT TOUCH!
$iv
);
if ($data === FALSE)
{
return FALSE;
}
return $iv.$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 (self::strlen($data) <= $digest_size)
{
return FALSE;
}
$hmac_input = self::substr($data, 0, $digest_size);
$data = self::substr($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);
}
isset($params['key']) OR $params['key'] = $this->hkdf($this->_key, 'sha512', NULL, self::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;
}
// 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')
{
$iv = self::substr($data, 0, $iv_size);
$data = self::substr($data, $iv_size);
}
else
{
// MCrypt is dumb and this is ignored, only size matters
$iv = str_repeat("\x0", $iv_size);
}
}
else
{
$iv = NULL;
}
if (mcrypt_generic_init($params['handle'], $params['key'], $iv) < 0)
{
if ($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))
{
$data = self::substr($data, 0, -ord($data[self::strlen($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, $params)
{
if ($iv_size = openssl_cipher_iv_length($params['handle']))
{
$iv = self::substr($data, 0, $iv_size);
$data = self::substr($data, $iv_size);
}
else
{
$iv = NULL;
}
return empty($params['handle'])
? FALSE
: openssl_decrypt(
$data,
$params['handle'],
$params['key'],
1, // DO NOT TOUCH!
$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' => $this->_mode,
'key' => NULL,
'base64' => TRUE,
'hmac_digest' => 'sha512',
'hmac_key' => NULL
)
: FALSE;
}
elseif ( ! isset($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][$params['mode']];
}
}
if (isset($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' => $params['key'],
'base64' => isset($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))
{
$dictionary = array(
'mcrypt' => array(
'aes-128' => 'rijndael-128',
'aes-192' => 'rijndael-128',
'aes-256' => 'rijndael-128',
'des3-ede3' => 'tripledes',
'bf' => 'blowfish',
'cast5' => 'cast-128',
'rc4' => 'arcfour',
'rc4-40' => 'arcfour'
),
'openssl' => array(
'rijndael-128' => 'aes-128',
'tripledes' => 'des-ede3',
'blowfish' => 'bf',
'cast-128' => 'cast5',
'arcfour' => 'rc4-40',
'rc4' => 'rc4-40'
)
);
// Notes:
//
// - Rijndael-128 is, at the same time all three of AES-128,
// AES-192 and AES-256. The only difference between them is
// the key size. Rijndael-192, Rijndael-256 on the other hand
// also have different block sizes and are NOT AES-compatible.
//
// - Blowfish is said to be supporting key sizes between
// 4 and 56 bytes, but it appears that between MCrypt and
// OpenSSL, only those of 16 and more bytes are compatible.
// Also, don't know what MCrypt's 'blowfish-compat' is.
//
// - CAST-128/CAST5 produces a longer cipher when encrypted via
// OpenSSL, but (strangely enough) can be decrypted by either
// extension anyway.
// Also, it appears that OpenSSL uses 16 rounds regardless of
// the key size, while RFC2144 says that for key sizes lower
// than 11 bytes, only 12 rounds should be used. This makes
// it portable only with keys of between 11 and 16 bytes.
//
// - RC4 (ARCFour) has a strange implementation under OpenSSL.
// Its 'rc4-40' cipher method seems to work flawlessly, yet
// there's another one, 'rc4' that only works with a 16-byte key.
//
// - DES is compatible, but doesn't need an alias.
//
// Other seemingly matching ciphers between MCrypt, OpenSSL:
//
// - RC2 is NOT compatible and only an obscure forum post
// confirms that it is MCrypt's fault.
}
if (isset($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;
}
self::strlen($salt) OR $salt = str_repeat("\0", $this->_digests[$digest]);
$prk = hash_hmac($digest, $key, $salt, TRUE);
$key = '';
for ($key_block = '', $block_index = 1; self::strlen($key) < $length; $block_index++)
{
$key_block = hash_hmac($digest, $key_block.$info.chr($block_index), $prk, TRUE);
$key .= $key_block;
}
return self::substr($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;
}
// --------------------------------------------------------------------
/**
* Byte-safe strlen()
*
* @param string $str
* @return integer
*/
protected static function strlen($str)
{
return (self::$func_override)
? mb_strlen($str, '8bit')
: strlen($str);
}
// --------------------------------------------------------------------
/**
* Byte-safe substr()
*
* @param string $str
* @param int $start
* @param int $length
* @return string
*/
protected static function substr($str, $start, $length = NULL)
{
if (self::$func_override)
{
// 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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