OK got it to make things safe, but in the case of using it to get back the user id from the token ?
Are you sure that the decrypt of [get_token] will give back the user id ? or is it better to use a parse function and which one ?

Yep thanks a lot, I reverted to openssl base64_encode and decode to avoid all strange characters and it works fine

I must thank you so much to have allowed me to learn how to code during these last years.
It's not possible on Joomla extensions to write multiple reviews about components so please accept my deepest thanks for all your support