Level 05 - Reused Stream Key

Category: Crypto | Difficulty: Medium

A toy XOR stream cipher setup reuses key material across requests.

What participants receive: /api/level05, /api/level05/oracle?plain=... or /api/level05?action=oracle&plain=..., /api/level05/submit or /api/level05?action=submit

Objective: Recover the plaintext behind secretCipherHex and submit it.

curl https://ctf-trpl-wbi.vercel.app/api/level05
curl "https://ctf-trpl-wbi.vercel.app/api/level05?action=oracle&plain=AAAAAAAAAA"
curl -X POST "https://ctf-trpl-wbi.vercel.app/api/level05?action=submit" \
  -H "content-type: application/json" \
  -d '{"secret":"<your-answer>"}'