AES-256 加密 PHP实现

class aes {

	static public $mode = MCRYPT_MODE_NOFB;
	
	static public function generateKey($length=32) {
		if (!in_array($length,array(16,24,32)))
			return False;

		$str = '';
		for ($i=0;$i<$length;$i++) {
			$str .= chr(rand(33,126));
		}

		return $str;
	}

	static public function encrypt($data, $key) {

		if (strlen($key) > 32 || !$key)
			return trigger_error('key too large or key is empty.', E_USER_WARNING) && False;

		$ivSize = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, self::$mode);
		$iv = mcrypt_create_iv($ivSize, (substr(PHP_OS,0,1) == 'W' ? MCRYPT_RAND : MCRYPT_DEV_URANDOM ));
		$encryptedData = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $data, self::$mode, $iv);
		$encryptedData = $iv . $encryptedData;

		return base64_encode($encryptedData);
	}

	static public function decrypt($data, $key) {

		if (strlen($key) > 32 || !$key)
			return trigger_error('key too large or key is empty.', E_USER_WARNING) && False;

		$data = base64_decode($data);
		if (!$data)
			return False;

		$ivSize = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, self::$mode);
		$iv = substr($data, 0, $ivSize);

		$data = substr($data, $ivSize);

		$decryptData = mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $data, self::$mode, $iv);

		return $decryptData;
	}
}