Php Aes encryption program code sharing_PHP tutorial

/**
*php AES encryption and decryption class
* Because Java only supports 128-bit encryption, PHP also uses 128-bit encryption and can be converted to Java.
* At the same time, the AES standard is also 128 bits. Only the RIJNDAEL algorithm can support 128, 192 and 256-bit encryption.
*
* @author Terry
*
*/
class PhpAes
{
/**
* This was AES-128 / CBC / ZeroBytePadding encrypted.
* return base64_encode string
* @author Terry
* @param string $plaintext
* @param string $key
*/
public static function AesEncrypt($plaintext,$key = null)
{
if ($plaintext == '') return '';
if(!extension_loaded('mcrypt'))
throw new CException(Yii::t('yii','AesEncrypt requires PHP mcrypt extension to be loaded in order to use data encryption feature.'));
$size = mcrypt_get_block_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
$plaintext = self::PKCS5Padding($plaintext, $size);
$module = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_CBC, '');
$key=self::substr($key===null ? Yii::app()->params['encryptKey'] : $key, 0, mcrypt_enc_get_key_size($module));
/* Create the IV and determine the keysize length, use MCRYPT_RAND
* on Windows instead */
$iv = substr(md5($key),0,mcrypt_enc_get_iv_size($module));
/* Initialize encryption */
mcrypt_generic_init($module, $key, $iv);

/* Encrypt data */
$encrypted = mcrypt_generic($module, $plaintext);

/* Terminate encryption handler */
mcrypt_generic_deinit($module);
mcrypt_module_close($module);
return base64_encode(trim($encrypted));
}

/**
* This was AES-128 / CBC / ZeroBytePadding decrypted.
* @author Terry
* @param string $encrypted base64_encode encrypted string
* @param string $key
* @throws CException
* @return string
*/
public static function AesDecrypt($encrypted, $key = null)
{
if ($encrypted == '') return '';
if(!extension_loaded('mcrypt'))
throw new CException(Yii::t('yii','AesDecrypt requires PHP mcrypt extension to be loaded in order to use data encryption feature.'));

$ciphertext_dec = base64_decode($encrypted);
$module = mcrypt_module_open(MCRYPT_RIJNDAEL_128, '', MCRYPT_MODE_CBC, '');
$key=self::substr($key===null ? Yii::app()->params['encryptKey'] : $key, 0, mcrypt_enc_get_key_size($module));

$iv = substr(md5($key),0,mcrypt_enc_get_iv_size($module));

/* Initialize encryption module for decryption */
mcrypt_generic_init($module, $key, $iv);

/* Decrypt encrypted string */
$decrypted = mdecrypt_generic($module, $ciphertext_dec);

/* Terminate decryption handle and close module */
mcrypt_generic_deinit($module);
mcrypt_module_close($module);
return self::UnPKCS5Padding($decrypted);
}

private static function strlen($string)
{
return extension_loaded('mbstring') ? mb_strlen($string,'8bit') : strlen($string);
}

private static function substr($string,$start,$length)
{
return extension_loaded('mbstring') ? mb_substr($string,$start,$length,'8bit') : substr($string,$start,$length);
}

private static function PKCS5Padding ($text, $blocksize) {
$pad = $blocksize - (self::strlen($text) % $blocksize);
return $text . str_repeat(chr($pad), $pad);
}

private static function UnPKCS5Padding($text)
{
$pad = ord($text{self::strlen($text)-1});
if ($pad > self::strlen($text)) return false;
if (strspn($text, chr($pad), self::strlen($text) - $pad) != $pad) return false;
return substr($text, 0, -1 * $pad);
}
}