Rating: 5.0

tldr (no pwn);
- random seed is based on time
- it's a bit expensive to precompute 1000000 values (without optimisations)
- instead, reduce the bruteforce range by measuring the average time offset from connecting and the server generating the seed (see writeup for details)
- this reduces the range of bruteforce to about ~800 which easily runs within the 1 minute timeout


Original writeup (https://jsur.in/posts/2021-03-07-zer0pts-ctf-2021-crypto-writeups#signme).