Challenge archive: SekaiCTF 2023 - RandSubWare

Challenge: RandSubWare
Event: SekaiCTF - 2023
Year: 2023
Category: Cryptography
Authors: deut-erium
Mode: interactive
Article: https://deut-erium.github.io/challenges/sekaictf-2023/randsubware/
Text: https://deut-erium.github.io/challenges/sekaictf-2023/randsubware/challenge.txt
JSON: https://deut-erium.github.io/challenges/sekaictf-2023/randsubware/challenge.json

Description excerpt:
"RandSubWare" - standing for 'Random Substitution Warefare Challenge'. This term encompasses the idea of breaking a substitution permutation network through the use of randomized and strategic attacks on the substituted boxes, engaging in a battle against the complexity and obscurity of the encryption.

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/sekaictf-2023/randsubware/#browser-practice
Runtime: randsubware
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/sekaictf-2023-randsubware/chall.py
  Bytes: 9271
  SHA-256: e8f1adc85143e5213f2992d735383862482da62d1f9356b87fabb63909e50c4f
  Upstream provenance: https://raw.githubusercontent.com/project-sekai-ctf/sekaictf-2023/4dc0f1fb2836c64b3a502e2538ba32530996b8c9/crypto/randsubware/dist/chall.py

Licenses (local copies):
- AGPL-3.0: https://deut-erium.github.io/assets/challenges/licenses/AGPL-3.0.txt
  Bytes: 34523
  SHA-256: 8486a10c4393cee1c25392769ddd3b2d6c242d6ec7928e1414efff7dfb2f07ef
  Upstream provenance: https://raw.githubusercontent.com/project-sekai-ctf/sekaictf-2022/383b16da68c438c5d516e6f00b2716210141f7a4/LICENSE
- CC BY-NC-SA 4.0: https://deut-erium.github.io/assets/challenges/licenses/CC-BY-NC-SA-4.0.txt
  Bytes: 19119
  SHA-256: 14d2138e3a8bd9448254f171b8e17130bf7104d2fd843ab0b924bd105fd00d5a
  Upstream provenance: https://raw.githubusercontent.com/project-sekai-ctf/sekaictf-2022/383b16da68c438c5d516e6f00b2716210141f7a4/LICENSE.content.md

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/project-sekai-ctf/sekaictf-2023/blob/4dc0f1fb2836c64b3a502e2538ba32530996b8c9/crypto/randsubware/README.md
Archive: https://github.com/project-sekai-ctf/sekaictf-2023/tree/4dc0f1fb2836c64b3a502e2538ba32530996b8c9/crypto/randsubware
Solution: https://github.com/project-sekai-ctf/sekaictf-2023/tree/4dc0f1fb2836c64b3a502e2538ba32530996b8c9/crypto/randsubware/solution