I had very tight schedule to finish some courses and only one weekend to so a statistics excercise. I only noticed after business hours that it is necessary to

I had very tight schedule to finish some courses and only one weekend to so a statistics excercise. I only noticed after business hours that it is necessary to use DOS software build by the professor, and it is impossible to buy it during the weekends. It was available in the computer rooms, but I had no access. I got a copy of the SW in the net, but needed a license key. It was based on a challenge. Luckily I had a friend who had the SW, and could give me a sample license key. I figured the challange would be based on time, and I was right, it was using epoch as a seed. So I made a script that booted a DOS box, and brute forced one license key a time. It took me a few hours but I succeeded in cracking the SW so I could start the excercise.