josephsurin / ctf_archive

Hosting awesome cryptography CTF challenges for more than just a weekend

CryptoHack CTF Archive

There are so many CTFs these days and CTFs often have cool cryptography challenges. This repo contains past CTF cryptography challenges that are so good we want to host them permanently.

You can play the challenges at CryptoHack.org CTF Archive category.

License

Please be aware that all challenges submitted to this repository are released under the terms of the MIT license. Challenges will appear on CryptoHack with credit given to the author and the original CTF the challenge came from.

Submission

To submit a challenge, all you need to do is open a pull request that adds a directory to this repo that respects the following formats:

Static Challenges

To submit a static challenge to the archive, you must use the following directory structure:

your_challenge
├── description.yml
├── release_files
│   ├── your_files.py
│   └── go_in_here.sage

For an example of a static challenge to copy, see ICC Athens: Unbalanced.

• description.yml
  • Data in description.yml is used to set metadata for the challenge
  • Please ensure to base64 encode your flag
• release_files/YOUR_CHALLENGE_FILES
  • All files within release_files will be made available to the players of your challenge

Dynamic Challenges

To submit a dynamic challenge to the archive, you must use the following directory structure:

your_challenge
├── description.yml
├── server_files
│   ├── secret_server_file.py
|   ├── public_file.py
│   └── Dockerfile
├── release_files
│   ├── public_file.py@ -> server_files/public_file.py
│   └── maybe_another_one.py@ -> server_files/maybe_another_one.py

For an example of a dynamic challenge to copy, see ICC Athens: ed25519.

• description.yml
  • Data in this file is used to set the metadata for the challenge
  • Please ensure to base64 encode your flag
• Dockerfile
  • All dynamic challenges must be built from a Dockerfile. socat or xinetd can be used to bind a challenge file to a port.
  • For the Dockerfile base image, please use a specific version not latest, e.g. use ubuntu:22.04 not ubuntu:latest - this ensures the challenge will still work in the future.
  • Listen on port 1337 in your container that hosts the challenge. A random port will automatically be mapped from the host to port 1337 in your container.
  • The flag within description.yml is decoded and set as the environment variable FLAG within the container automatically. So you can load the flag using flag = os.environ["FLAG"] instead of importing a file.
• server_files/YOUR_CHALLENGE_FILES
  • The files in server_files will be hosted within a Docker container
• release_files/YOUR_CHALLENGE_FILES
  • All files within release_files will be those which you want shared with the players
  • Files in this directory which are also on the server-side should be symlinked

Deployment

Run python docker_deploy.py to launch all the Docker challenges using docker-compose.