Here's another brain teaser for you worth 500 lovelies :
I have several domains on one server each of which has a perl script called one.cgi in the cgi-bin.
I want to occasionally let other people run this script but ONLY ONCE by giving them a "works once only" password and a hidden clickable link to one of those cgi-bin/one.cgi scripts so that they can't just go straight to the script afterwards...
So to summarize :
1.They need a login screen for their name and email address which sends a mail to me allowing me to validate that they can use the script.
2.After validation they get a mail with their "once only password" and a url/cgi to go to that will accept it.
3.They are then validated against username or email and the given password after which they are given a domain.com/cgi-bin/one.cgi page chosen from a hidden list (in rotation or randomly assigned from a list of URLs) BUT which they cannot see the URL of when they are there (ie CGI hides it).
4.They run the "one.cgi" and their password then becomes invalid and they have to register for another one if they want to use the script again.
5. The whole thing generates a log of who used the script.
Anyone up to the challenge ?