AES Encryption And Deception

   function dec_enc($action, $string) {
            $output = false;
       
            $encrypt_method = "AES-256-CBC";
            $secret_key = 'This is my secret key';
            $secret_iv = 'This is my secret iv';
       
            // hash
            $key = hash('sha256', $secret_key);
           
            // iv - encrypt method AES-256-CBC expects 16 bytes - else you will get a warning
            $iv = substr(hash('sha256', $secret_iv), 0, 16);
       
            if( $action == 'encrypt' ) {
                $output = openssl_encrypt($string, $encrypt_method, $key, 0, $iv);
                $output = base64_encode($output);
            }
            else if( $action == 'decrypt' ){
                $output = openssl_decrypt(base64_decode($string), $encrypt_method, $key, 0, $iv);
            }
       
            return $output;
        }