Plaid CTF 2012 – Debit or Credit

Ca-Ching! Do you think robots have headphone jacks?
Title: Debit or Credit
Solved: 16 teams solved this!
Points: 200
Category: Potpourri

In this challenge we received a sound (.wav) file. Seeing the challenge title and description we quickly got the idea that this might be a recorded magnetic card swipe. Looking at the sound file in audacity we can see the wave form and from this wave form we can recover the magnetic card swipe. We printed the whole wave form and started out doing this challenge on paper, after we got a solid idea on how to finish this challenges we switched to the computer to work it out further.
{Read More}