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Old 2007-11-23, 19:42   #1
jasong
 
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"Jason Goatcher"
Mar 2005

DB116 Posts
Default password bug puzzle

I have no idea how to even begin to solve this, I just want to see what strategies people use. :)

It is imperative that you break into a facility that's protected by keycards. You need access to all the sections.(I'm not going to say how many sections there are, we'll make that an open variable to study) You have one computer and a card attached to it, so you can come up with any passcode combination. Each time you attempt a combination that's wrong you're locked out for one minute. The passcode is 64 bits, meaning 2^64 combinations, but there's a bug in the software. Each time you attempt a guess, you find out if the number of bits that are correct is odd or even(you impersonate a specific employee with the card, so the passcode is the same for individual sections). For each section, you have to guess a new 64-bit passcode.

Also, there is a master passcode, but it's 512 bits. After we figure out the approximate time for the 64-bit passcode, we want to know how many sections in the facility there would have to be for it to be a good idea to go straight for the 512-bit passcode.

For the sake of the puzzle, the guards are all looking at porn on the Internet and will never notice you're there. ;)
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