I've been having some fun lately reverse engineering the "password" systems that some console games used prior to memory cards and backup RAM.
Some are very straightforward - just an encoding of which level you were on, your score, etc.
Others are that plus a halfhearted checksum, or an actual standard CRC checksum.
Still others are these elaborate obfuscation schemes with encryption using a fixed key, then scrambling, then a checksum.
My favorite so far: ThunderStrike 2 does a few things, and one of them XORs your input with the string "NOSEY GIT". I took it to mean the original programmer was chiding me for trying to cheat at the game.
NOSEY GIT sounds very British :) I had to look it up -- Core Design. I knew some of the guys there at the time, but none of those in credits for ThunderStrike. Does the original game have the same XOR string?
I remember spending more time on Ecco the Dolphin cracking the password system than playing the game because it was so damned hard. I bought the game on day of release using every penny I had saved, then ruined it by cracking the code on the 2nd day and teleporting straight to the end.
Some are very straightforward - just an encoding of which level you were on, your score, etc.
Others are that plus a halfhearted checksum, or an actual standard CRC checksum.
Still others are these elaborate obfuscation schemes with encryption using a fixed key, then scrambling, then a checksum.
My favorite so far: ThunderStrike 2 does a few things, and one of them XORs your input with the string "NOSEY GIT". I took it to mean the original programmer was chiding me for trying to cheat at the game.