superguess++

Three years since you faced RCTF 2022 — solved it, or failed to. Let’s see if you’ve truly learned anything about lattice.

from Crypto.Util.number import getPrime from secrets import randbelow import signal

with open("flag.txt", "rb") as f: flag = f.read()

signal.alarm(300)

q = getPrime(182) x = randbelow(q) l = 2 T = [] U = [] for i in range(93): t = randbelow(q) u = (x * t - randbelow(q >> l)) % q T.append(t) U.append(u)

print(f"q = {q}") print(f"T = {T}") print(f"U = {U}")

guess = int(input("x = ").strip()) if guess == x: print(flag)