| my rAnd0m m1ndfl0w |
| #whoami $bl0g /script.s retr0gaming |
Disobey 2023 - CTF - Substitution Ciphers ----------------------------------------- This one was quick and dirty, the assignment being: A very simple way to encrypt a message is to swap the meaning of the written letters, for example so that the plaintext letter M always becomes N in the ciphertext. When every letter is thos replaced, the method is called a substitution cipher. The earliest of them are very easy to crack, like this one: FU UV CSVUF And again, if you know what you're looking at, it is actually quite easy to brute force. In this case the described cipher is Caesar cipher. Named after Julius Caesar who's been said to have used it with a shift of three. Bruteforcing this was fast and this time I used some old JavaScript+HTML doohickey I made years ago. The results for first 25 rotations: GVVWDTWVG HWWXEUXWH IXXYFVYXI JYYZGWZYJ KZZAHXAZK LAABIYBAL MBBCJZCBM NCCDKADCN ODDELBEDO PEEFMCFEP QFFGNDGFQ RGGHOEHGR SHHIPFIHS TIIJQGJIT UJJKRHKJU VKKLSILKV WLLMTJMLW XMMNUKNMX YNNOVLONY ZOOPWMPOZ APPQXNQPA BQQRYORQB CRRSZPSRC DSSTAQTSD ETTUBRUTE And yet again history repeats itself, Caesar is betrayed by Brutus and we get to shout out another non standard flag: ET TU BRUTE |