Challenge archive: Google CTF 2024 - IDEA

Challenge: IDEA
Event: Google CTF - 2024 qualifiers
Year: 2024
Category: Cryptography
Authors: deuterium
Mode: interactive
Article: https://deut-erium.github.io/challenges/google-ctf-2024/idea/
Text: https://deut-erium.github.io/challenges/google-ctf-2024/idea/challenge.txt
JSON: https://deut-erium.github.io/challenges/google-ctf-2024/idea/challenge.json

Original description:
We have a new idea about a cipher which we think may provide pretty good privacy
So bruce for impact as we may patent our new proposed encryption standard

Notes:
- The original remote service is retired. Browser practice runs locally with the public dummy reward practice{local_dummy_reward}; it does not award an event solve.
- The original remote service is retired. Browser practice runs locally with the public dummy reward practice{local_dummy_reward}, not an event flag or authoritative score. No TCP endpoint is provided.

Browser practice: https://deut-erium.github.io/challenges/google-ctf-2024/idea/#browser-practice
Runtime: idea
Variants: default (first is default)
Mode describes the original interactive I/O. Start practice from the article, not a TCP client.

Challenge files (primary):
- chall.py (chall.py; handout)
  URL: https://deut-erium.github.io/assets/challenges/google-ctf-2024-idea/chall.py
  Bytes: 4067
  SHA-256: 5fb44f432cffbf19fec715a617be1c373f99d2f3e4a602ebab7c3668b7e040c0
  Upstream provenance: https://raw.githubusercontent.com/google/google-ctf/067421eb7e918c29e39f187fac5a0f0d72a6ab83/2024/quals/crypto-idea/attachments/chall.py

Licenses (local copies):
- Apache-2.0: https://deut-erium.github.io/assets/challenges/licenses/Apache-2.0.txt
  Bytes: 11358
  SHA-256: cfc7749b96f63bd31c3c42b5c471bf756814053e847c10f3eb003417bc523d30
  Upstream provenance: https://raw.githubusercontent.com/google/google-ctf/067421eb7e918c29e39f187fac5a0f0d72a6ab83/LICENSE

SPOILERS - organizer files and solutions
Spoilers: organizer files and upstream source, archive, or solution links may reveal answers. Modified downloads are identified below.
Source: https://github.com/google/google-ctf/blob/067421eb7e918c29e39f187fac5a0f0d72a6ab83/2024/quals/crypto-idea/metadata.yaml
Archive: https://github.com/google/google-ctf/tree/067421eb7e918c29e39f187fac5a0f0d72a6ab83/2024/quals/crypto-idea
Solution: https://github.com/google/google-ctf/blob/067421eb7e918c29e39f187fac5a0f0d72a6ab83/2024/quals/crypto-idea/challenge/solve.py