about Encryption Library

Hello, I have 2 function for encode and decode.

So I upgrade php to php7.1 and I can not use encrypt old library.

now I try to using encryption new library.

and I get string / = + after encrypt because / it make can not pass string on url

Pls, I need you help.

PHP Code:

public function encode_me($string, $key = '') {
        //$this->load->library('encrypt');
        //return rtrim(strtr(base64_encode($this->encrypt->mcrypt_encode($string, $this->encrypt->get_key($key))), '+/', '-_'), '=');

        $this->load->library('encryption');
        return $this->encryption->encrypt($string);
    }

    public function decode_me($string, $key = '') {
        //$this->load->library('encrypt');
        //return $this->encrypt->mcrypt_decode(base64_decode(str_pad(strtr($string, '-_', '+/'), strlen($string) % 4, '=', STR_PAD_RIGHT)), $this->encrypt->get_key($key));

        $this->load->library('encryption');
        return $this->encryption->decrypt($string);
    }