## 2021 Longyuan anti epidemic WriteUp

I hope the epidemic will end soon
Note: the * is played after the game
Always wp wait for the legend of Nanshen to post the team wp link
Misc
soEasyCheckin
base32, but there is a problem. The countdown appears 0 $, 0 – > O, $- > s, and a string of hex is obtained. As a result, there was another problem with hex, specifically ...

Posted on *Mon, 08 Nov 2021 03:14:49 -0500* by **rawb**

## CTF crypto 2021-10-4 record

Basic knowledge
CBC flip attack
Introduction:
When one of our values C is obtained by the exclusive or of A and B C = A XOR B that A XOR B XOR C is obviously = 0 When we know B and C, it's easy to get the value of A A = B XOR C Therefore, A XOR B XOR C is equal to 0. With this formula, we can set our own value at the end of XOR operat ...

Posted on *Mon, 04 Oct 2021 16:36:34 -0400* by **gitosh**