CTFlearn-5x5 Crypto

Ever heard of the 5x5 secret message system? If not, basically it’s a 5x5 grid with all letters of the alphabet in order, without k because c is represented to make the k sound only. Google it if you need to. A letter is identified by Row-Column. All values are in caps.

1-3,4-4,2-1,{,4-4,2-3,4-5,3-2,1-2,4-3,_,4-5,3-5,}

說了是5 x 5 crypto, wiki一下
https://en.wikipedia.org/wiki/Polybius_square
大概意思是, 按行列序表示字母

典型格式如上
比如 BAT 可以表示為 12 11 44

理解之後用這個工具可以解密
https://cryptii.com/pipes/polybius-square

注意特殊符號不會解密, 自己加上去

CTF{THUMBS_UP}