RomainL972

Google CTF 2022 Writeup - Enigma

Hi, and welcome to this writeup for the crypto Enigma challenge.

At the end of the CTF, it had 9 solves and awarded 373 points. My team (PolyHx) was the 4th to crack it.

Introduction

Since I've always had a passion for cryptography, I was interested as soon as I saw the challenge title.

RomainL972

#!/usr/bin/env python3

import requests
from dateutil.parser import parse

def main():
    fromcur = input("From currency : ")
    tocur = input("To currency : ")
    amount = float(input("Amount : "))
    date = input("Date : ")

RomainL972

array = [-2, 2, 4, 8, 9]
target = 13

def function(array, target):
    for f in range(len(array)):
        for s in range(f+1, len(array)-f):
            if array[f] + array[s] == target:
                return True
    return False

RomainL972

from math import exp

u = 1/2
p=0
uplus1= (7*exp(u)+1)/(exp(u)+3)
while uplus1 - u >= pow(10,-5):
    u = uplus1
    uplus1 = (7*exp(u)+1)/(exp(u)+3)
    p += 1
print(p)

RomainL972

<?php
if($argc < 2)
  die("Give modpack url as argument");

$url = $argv[1] . "/files/latest";

$modpack_headers = get_headers($url, 1);

if(!in_array("HTTP/1.1 200 OK", $modpack_headers))
  die("URL isn't valid\n");