securityEASYSECURITY DEBUGGING
Warm up with webhook replay window defense
Easy Security Basics arena: HMAC signatures, timestamp tolerance, idempotency, and delivery dedupe
XP reward
125
Coins
10
Target time
33m
Attackers replay old webhook deliveries and the billing system accepts them as fresh events. You are working inside a secure engineering review room, and the arena only clears when the result is safe, deterministic, and explainable.
Learning objective
Learn to apply HMAC signatures, timestamp tolerance, idempotency, and delivery dedupe in a secure engineering review room while explaining the invariant, safety constraints, and hidden edge cases.
Mission order
Headers include timestamp, signature, delivery id, provider id, and raw body hash. Implement the direct solution first, then document the one edge case that can break it. Submit the solution plus enough reasoning to pass hidden edge cases.Visible checks
reproduces the reported failure
Expected: minimal failing case
adds a regression test
Expected: test fails before fix
Clear requirements
- Demonstrates HMAC signatures, timestamp tolerance, idempotency, and delivery dedupe
- Handles the visible sample and hidden edge cases
- Keeps output deterministic and explainable
- Avoids unsafe dynamic execution
Secure validation contract
Judge type
SECURITY DEBUGGING
Complexity target
Minimal reproduction, source-cause fix, and regression test
Workspace
Code editor
typescriptsafe mock judge
Charging editor core
Test Results
Run the visible checks when your first pass is ready.
Clear Protocol
1Read the scenario and restate the expected output shape.
2Run visible checks before chasing hidden edge cases.
3Use Genie for one nudge if stuck, then explain the invariant.
4Submit only when the result is deterministic and safe.
Rewards
XP
125
Coins
10
Mission Route
Hints
Hints are metered and logged for No Hint Hero runs.
Genie Mentor Core
Hint protocol / contextual guardrails active
Progressive hints
Failed-test aware
Solution guarded
Mission: security-easy-webhook-replay-window0 attempts0 failed tests0 hints used
Progressive hint depth
Genie: Genie online. I use your mission, attempts, failed tests, hints, and path context to coach the next rep without dumping answers first.