Project Sekai - ✅-crypto-galois-t-is-this

Galois-t is this? - 500 points

Category: Crypto Description: I'm expecting a super secret message... If you can give it to me, I'll give you a flag! nc galois.wolvctf.io 1337 Files:

Tags: IridescentFreeze#1034, Easy

Sutx pinned a message to this channel. 03/17/2023 1:00 PM

@deuterium wants to collaborate

gcm gcm

ok checking

marked as easy, code is so long

looks easy enough

@layka_ wants to collaborate

ok no nonce reuse i guess

nonce is just +1 ed

15:11

so first use nonce -1, get encryption of 0 which is used to calculate ghash (edited)

15:12

I am just sleepy so feeling very lazy to write out a script

me too i had a rough day .. can you point on some ctf writeups of ressources ! cuz i didn"t understand the -1 part

no need, just read the code a bit is similar to gcm

yes i've read it .. but didn"t know how to pass literally "-1" .. i am just thinking of any other value

'f'*32

15:17

I think other values could also work, we need encryption of 0

deuterium

'f'*32

genius !

almost done

1

deuterium

used /ctf solve

✅ Challenge solved.