L-02 Duplicate Allowed-Hash Entry Reduces Circuit Uniqueness
Description
The Noir circuit defines ALLOWED_TREASURE_HASHES as an array of 10 elements, but the final two entries are identical. As a result, the circuit contains only 9 unique allowed treasure hashes.
This weakens the clarity of the intended treasure inventory and creates ambiguity between “10 slots” and “10 unique treasures.”
Risk
This issue does not by itself demonstrate a direct exploit, but it creates correctness and maintenance risk:
reviewers may incorrectly assume there are 10 unique treasure hashes
operators may misunderstand the actual treasure inventory
future changes become riskier because the source does not clearly express the intended unique set
Proof of Concept
The duplicated entries are visible directly in the circuit:
Because is_allowed() only checks whether a hash appears anywhere in the list, the duplicate final entry does not add a new claimable treasure. It only repeats an already-allowed value.
Recommended Mitigation
Replace the duplicate entry with the intended unique treasure hash and regenerate any dependent artifacts.
Lead Judging Commences
unclaimable treasure / bricked withdraw path
The issue stems from a mismatch between the circuit and the contract’s economic assumptions: the Solidity contract is configured for `MAX_TREASURES = 10` and only allows the owner to call `withdraw()` once `claimsCount >= MAX_TREASURES`, while the Noir circuit’s baked-in `ALLOWED_TREASURE_HASHES` array does not actually contain ten distinct treasures because one hash is duplicated and another expected hash is missing. As a result, under the intended one-claim-per-treasure design described in the README, there are only nine uniquely claimable treasures even though the system is funded and accounted as if ten rewards can be legitimately redeemed. That creates two linked consequences from the same root cause: first, one treasure is effectively unclaimable because no valid proof can ever be generated for the missing allowed hash, and second, the normal “hunt over” withdrawal path becomes bricked because honest participants can never reach ten legitimate unique claims, leaving the post-hunt fund recovery logic via `withdraw` function permanently unreachable. The owner can still intervene through the emergency path.
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