title: User security - cache password temporarily
body: <p>I have a system that signs users up to a service. They register their account and choose their payment option at the same time. In order to integrate PayPal, the user must be redirected to PayPal, then return to my site. To do this, before redirecting to PayPal, I send all the user settings from the form to my backend to save it in a session. That is, fname, lname, email, and password (plain text of course).</p>
  
  <p>The question is, how do I safely cache their password? I don't see in any way how a user could exploit this system, but there's always something...</p>