https://medium.com/@0x000c0ded/ritsec-ctf-2018-cryptography-who-drew-on-my-program-350pts-ac6f356276c6

Original writeup (https://medium.com/@0x000c0ded/ritsec-ctf-2018-cryptography-who-drew-on-my-program-350pts-ac6f356276c6).