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<?php
/**
* Gibberish AES, a PHP Implementation
*
* @author Ivan Tcholakov <ivantcholakov@gmail.com>, 2012-2013.
* @link https://github.com/ivantcholakov/gibberish-aes-php
*
* @license The MIT License (MIT)
* @link http://opensource.org/licenses/MIT
*
* This class is based on initial code proposed by nbari at dalmp dot com
* @link http://www.php.net/manual/en/function.openssl-decrypt.php#107210
*
* See also Gibberish AES javascript encryption library
* @link https://github.com/mdp/gibberish-aes
*
* Requirements:
*
* OpenSSL functions installed and PHP version >= 5.3.3 (preferred case)
* or
* Mcrypt functions installed.
*
* Usage:
*
* // This is a secret key, keep it in a safe place and don't loose it.
* $key = 'my secret key';
*
* // The string to be encrypted.
* $string = 'my secret message';
*
* // This is the result after encryption of the given string.
* $encrypted_string = GibberishAES::enc($string, $key);
*
* // This is the result after decryption of the previously encrypted string.
* // $decrypted_string == $string (should be).
* $decrypted_string = GibberishAES::dec($encrypted_string, $key);
*
*/
class GibberishAES {
protected static $openssl_random_pseudo_bytes_exists;
protected static $openssl_encrypt_exists;
protected static $openssl_decrypt_exists;
// This is a static class, instances are disabled.
final private function __construct() {}
final private function __clone() {}
/**
* Crypt AES 256
*
* @param data $string
* @param string $pass
* @return base64 encrypted string
*/
public static function enc($string, $pass) {
// Set a random salt.
$salt = self::random_pseudo_bytes(8);
$salted = '';
$dx = '';
// Salt the key(32) and iv(16) = 48
while (strlen($salted) < 48) {
$dx = md5($dx.$pass.$salt, true);
$salted .= $dx;
}
$key = substr($salted, 0, 32);
$iv = substr($salted, 32, 16);
return base64_encode('Salted__' . $salt . self::aes_256_cbc_encrypt($string, $key, $iv));
}
/**
* Decrypt AES 256
*
* @param data $string
* @param string $pass
* @return dencrypted string
*/
public static function dec($string, $pass) {
$data = base64_decode($string);
$salt = substr($data, 8, 8);
$ct = substr($data, 16);
/**
* From https://github.com/mdp/gibberish-aes
*
* Number of rounds depends on the size of the AES in use
* 3 rounds for 256
* 2 rounds for the key, 1 for the IV
* 2 rounds for 128
* 1 round for the key, 1 round for the IV
* 3 rounds for 192 since it's not evenly divided by 128 bits
*/
$rounds = 3;
$data00 = $pass.$salt;
$md5_hash = array();
$md5_hash[0] = md5($data00, true);
$result = $md5_hash[0];
for ($i = 1; $i < $rounds; $i++) {
$md5_hash[$i] = md5($md5_hash[$i - 1].$data00, true);
$result .= $md5_hash[$i];
}
$key = substr($result, 0, 32);
$iv = substr($result, 32, 16);
return self::aes_256_cbc_decrypt($ct, $key, $iv);
}
// Non-public methods ------------------------------------------------------
protected static function random_pseudo_bytes($length) {
if (!isset(self::$openssl_random_pseudo_bytes_exists)) {
self::$openssl_random_pseudo_bytes_exists = function_exists('openssl_random_pseudo_bytes');
}
if (self::$openssl_random_pseudo_bytes_exists) {
return openssl_random_pseudo_bytes($length);
}
// Borrowed from http://phpseclib.com/
$rnd = '';
for ($i = 0; $i < $length; $i++) {
$sha = hash('sha256', mt_rand());
$char = mt_rand(0, 30);
$rnd .= chr(hexdec($sha[$char].$sha[$char + 1]));
}
return $rnd;
}
protected static function aes_256_cbc_encrypt($string, $key, $iv) {
if (!isset(self::$openssl_encrypt_exists)) {
self::$openssl_encrypt_exists = function_exists('openssl_encrypt')
&& version_compare(PHP_VERSION, '5.3.3', '>='); // We need $iv parameter.
}
if (self::$openssl_encrypt_exists) {
return openssl_encrypt($string, 'aes-256-cbc', $key, true, $iv);
}
// Info: http://www.chilkatsoft.com/p/php_aes.asp
$cipher = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_CBC, '');
if (mcrypt_generic_init($cipher, $key, $iv) != -1) {
$encrypted = mcrypt_generic($cipher, self::pkcs7_pad($string));
mcrypt_generic_deinit($cipher);
mcrypt_module_close($cipher);
return $encrypted;
}
return false;
}
protected static function aes_256_cbc_decrypt($crypted, $key, $iv) {
if (!isset(self::$openssl_decrypt_exists)) {
self::$openssl_decrypt_exists = function_exists('openssl_decrypt')
&& version_compare(PHP_VERSION, '5.3.3', '>='); // We need $iv parameter.
}
if (self::$openssl_decrypt_exists) {
return openssl_decrypt($crypted, 'aes-256-cbc', $key, true, $iv);
}
$cipher = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_CBC, '');
if (mcrypt_generic_init($cipher, $key, $iv) != -1) {
$decrypted = mdecrypt_generic($cipher, $crypted);
mcrypt_generic_deinit($cipher);
mcrypt_module_close($cipher);
return self::remove_pkcs7_pad($decrypted);
}
return false;
}
// See http://www.php.net/manual/en/function.mcrypt-decrypt.php#105985
protected static function pkcs7_pad($string) {
$blocksize = 16; // 128 bits: $blocksize = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
$pad = $blocksize - (strlen($string) % $blocksize);
return $string.str_repeat(chr($pad), $pad);
}
protected static function remove_pkcs7_pad($string) {
$blocksize = 16; // 128 bits: $blocksize = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
$len = strlen($string);
$pad = ord($string[$len - 1]);
if ($pad > 0 && $pad <= $blocksize) {
$valid_pad = true;
for ($i = 1; $i <= $pad; $i++) {
if (ord($string[$len - $i]) != $pad) {
$valid_pad = false;
break;
}
}
if ($valid_pad) {
$string = substr($string, 0, $len - $pad);
}
}
return $string;
}
}
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