I'm going to create a survey in Drupal 7 with the webform module, installed on a debian system which may be adapted in every way. The users (personally known, approx. 120) doing that survey will walk into a room and complete the survey in browsers on different computers. After that, they'll leave the room and other persons will enter, complete the survey on the same computers and so on. Each user may enter only one submission. The process needs to be anonymous, i. e. I mustn't have any idea of who did wich submission.

My current solution is to generate random one-time-passwords and hand out one password per user (without noting who got which password). Within the survey there will be a password field where the one-time-password is entered. The value is checked by webform to be unique. I'll get the data via csv or Excel and verify the passwords manually in excel by comparing them to the list of valid passwords.

The problem is: I don't like the idea of manually generating the password list, copying it to excel and doing a manual check. That's a good idea for one-time-use, but we're going to repeat the survey every once in a while. I'd rather generate one-time-logins (like user0001/fdlkjewf, user0002/dfrefnnr, ...) for each survey, hand them out to the users and let drupal/debian/whatever check whether a submission is valid or not.

Do you have any idea how to batch-generate about 120 users with one-time-passwords in Drupal 7 and verify that each user may submit the form only once? Do you even have a better idea how to accomplish the task within the intranet?

Thank you for your help.