[https://git.fh-campuswien.ac.at/CampusCyberSecurityTeam/ctfs/blob/master/crypto/easyctf2017-flip-my-letters.md](https://git.fh-campuswien.ac.at/CampusCyberSecurityTeam/ctfs/blob/master/crypto/easyctf2017-flip-my-letters.md)

Original writeup (https://git.fh-campuswien.ac.at/CampusCyberSecurityTeam/ctfs/blob/master/crypto/easyctf2017-flip-my-letters.md).