In high school "AP CS" class in the early 90s, a friend of mine was annoyed at the stupid "security" software the school installed on the macs (system 7). It wa

In high school "AP CS" class in the early 90s, a friend of mine was annoyed at the stupid "security" software the school installed on the macs (system 7). It was basically just a system extension that asked for a password on startup. Poking around, my friend noticed a slightly hidden/obscured file that had a file size that matched the number of characters in the password. N char password, N byte file. The file didn't have the password in plaintext, so my friend asked the teacher of a common way to scramble a byte. The teacher quickly suggested, "XOR?" So my friend decided to try XORing the bytes in the file with a few values to see what happend. His first guess was right: the password was "obscured" with: for (char *p = password_str; p != NULL; p++) { *p ^= 0xC9; } Why did he guess 0xC9? He was a total Trekkie/Trekker. 0xC9 in binary is 11001001. https://memory-alpha.fandom.com/wiki/11001001_%28episode%29 https://memory-alpha.fandom.com/wiki/11001001_%28episode%29 I guess we know what show the author of the "security software" likes to watch... Epilogue: my friend quickly did the obvious thing and made a boot floppy with a small program that printed out the password, so we had access to most of the computer in the school and discovered all the passwords we weren't supposed to know. I think we only used that to play bolo (early tank proto-battle-royale). However... several years later in my first year at university, I happened to talk to someone attending the local high school. The had a copy of my friend's boot floppy! I know we never bothered to upload it a BBS, but somehow it ended up in the hands of quite a few high school hackers in multiple cities.