AES-256 加密 PHP實現

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;
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