asisctf2020

Dead Drop (ASISCTF2020)

Introduction I participated in ASIS CTF 2020, and really enjoyed solving crypto stuffs. Here is the writeup for Dead Drop1/2, which is a crypto problem with the least solved whole team. The challenge (Dead Drop 1) For Dead Drop1, the following program is given. from Crypto.Util.number import * import random from flag import flag p = 22883778425835100065427559392880895775739 flag_b = bin(bytes_to_long(flag))[2:] l = len(flag_b) enc = [] for _ in range(l): a = [random.