Hack-The-Boo-2024 Practice: Sekur Julius Writeup

Challenge Overview

Description

Hidden deep in the forest was an ancient scroll, rumored to grant immense power to anyone who could read its shifting symbols. On Halloween, a curious traveler found the scroll, its letters strangely out of order. As they deciphered the message, the words slowly rearranged themselves, revealing a dark spell. But with the final shift, the traveler felt a cold presence behind them, whispering, "You were never meant to understand." The forest grew silent, but the spell was already cast.

Process

Upon downloading the assistive ZIP file, I found two files: output.txt and source.py.

Contents of output.txt

LTARDBT0ID0WPRZIWTQDD0ILDIWDJHPCSILTCINUDJG!

0IWXH0XH0P0EGDDU0DU0RDCRTEI0ID0EGDKT0NDJ0IWPI0IWT0RPTHPG0RXEWTG0XH0XCHTRJGT0CD0BPIITG0WDL0BPCN0IXBTH0NDJ0PEEAN0XI.
0IWT0HTRJGXIN0DU0P0IWDJHPCS0SXHIXCRI0HWXUIH0XH0TKTCIJPAAN0IWT0HPBT0PH0IWPI0DU0P0HXCVAT0HWXUI.
0TCDJVW0BJBQAXCV,0IPZT0NDJG0UAPV0PCS0TCYDN0IWT0GTHI0DU0IWT0RDCITHI.
0BPZT0HJGT0NDJ0LGPE0IWT0UDAADLXCV0ITMI0LXIW0IWT0WIQ0UAPV0UDGBPI0HTRJGXINDUPIWDJHPCSDGHTRJGXINDUPHXCVAT.

Contents of source.py

from random import choices 

def julius_encrypt(msg, shift): 
	ct = ''
	for p in msg:
		if p == ' ':
			ct += '0'
		elif not ord('A') <= ord(p) <= ord('Z'): 
			ct += p 
		else:
			o = ord(p) - 65
				ct += chr(65 + (o + shift) % 26) return ct 
				
def encrypt(msg, key): 
	for shift in key: 
		msg = julius_encrypt(msg, shift) 
	return msg 
	
msg = open('secret.txt').read().upper() secure_key = os.urandom(1337) 

with open('output.txt', 'w') as f: f.write(encrypt(msg, secure_key))