Misc

Challenge	Link
leaving soon (406 pts)	Here

leaving soon (406 pts)

Description

My friend wanted to rewatch this cool miniseries on Catflix but it looks like they removed it. Can you help him recover all episodes from the network capture?

Solution

My solver during the competition.

import glob
import re
import requests
import os

def get_key(pssh):
	burp0_url = "https://cdrm-project.com:443/"
	burp0_headers = {"Sec-Ch-Ua": "\"Not-A.Brand\";v=\"99\", \"Chromium\";v=\"124\"", "Sec-Ch-Ua-Platform": "\"macOS\"", "Sec-Ch-Ua-Mobile": "?0", "User-Agent": "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/124.0.6367.118 Safari/537.36", "Content-Type": "application/json", "Accept": "*/*", "Origin": "https://cdrm-project.com", "Sec-Fetch-Site": "same-origin", "Sec-Fetch-Mode": "cors", "Sec-Fetch-Dest": "empty", "Referer": "https://cdrm-project.com/", "Accept-Encoding": "gzip, deflate, br", "Accept-Language": "en-US,en;q=0.9", "Priority": "u=1, i", "Connection": "close"}
	burp0_json={"Cookies": "", "Data": "", "Headers": "", "JSON": "", "License URL": "https://proxy.uat.widevine.com/proxy", "Proxy": "", "PSSH": pssh}
	resp = requests.post(burp0_url, headers=burp0_headers, json=burp0_json)
	return resp.json()["Message"]

def split_key(data):
	key = []
	for i in data.split("\n"):
		key.append(i.split(":")[-1])
	return key


fmt = "ffmpeg -decryption_key {} -i {} -codec copy {}"
for i in glob.glob("mpd/*"):
	fn = i
	print(fn)
	tmp_fn = fn.split("/")[-1].split(".")[0]
	fn_video = f"video/{tmp_fn}_video.mp4"
	f = open(fn, "r").read()
	found = re.findall(r"<cenc:pssh>(.*?)</cenc:pssh>", f)[0]
	resp = get_key(found)
	list_key = split_key(resp)
	for j in list_key:
		fn_dec = f"dec/{tmp_fn}_video_{j}.mp4"
		# print(fn_dec)
		tmp_command = fmt.format(j, fn_video, fn_dec)
		os.system(tmp_command)

For detailed writeup, take a look on SKSD official writeup.