How to relate fields saved in two different submission

[verdeandrea]

Hi guys,

here is my scenario.

In my page everyone can submit a simple form with just a input text. User (guest user, no registration needed) writes something in this field and the submits it (the form is submitted via ajax so i don't refresh the page). Every text submitted is saved as a new page.
After this step i ask to the user if he/she wants to register his email in order to be updated with infos about his submission.
Now, if the user decide to leave his email i need to relate this email with the previously submitted text.

What's the best way to do that? Working with some session variable? Putting the new page id in an hidden field? Cookies? Something else?

Thanks!

[LostKobrakai]

I'd return a hashed id – two way hashing, just to to disguise the real id – with the ajax call and put that one in a hidden field. 

[verdeandrea]

Thanks @LostKobrakai!

Why do you think that is better than a session variable? (I'm asking just to understand better)

[LostKobrakai]

I'm not really a friend of the session variable, so mostly personal preference.