I want to give a newsletter subscriber the possibility to change his information. Since we're using an external company for sending our newsletter I can't put a key right into the newsletter (or not without much effort).
I created a form where you can enter your email and after checking if it's a subscriber, it sends an email with a link to change your information.
The link contains the plain e-mail and a hashed key which is made like sha1(email + "someString") so for example:
In my script, I then check if the given email + "someString" results the same as the key.
I know the link would stay the same to change your information, but I wanted to ask if there is any security issue in doing this whole thing this way, or should I rather create unique keys and store them in the database?
It would only be to change your prename, last name - maybe I bother too much.