The circuit defines 10 allowed treasure hashes baked into ALLOWED_TREASURE_HASHES, matching MAX_TREASURES = 10 in the contract. However, indices 8 and 9 contain identical values. Since each treasure hash corresponds to a unique physical secret, only 9 distinct secrets exist. The 10th reward slot can never be claimed by a unique finder — it is a duplicate of treasure 8.
Likelihood:
Hardcoded in the circuit — present from deployment, affects every hunt instance
Trivially verifiable by inspection
Impact:
Only 9 unique physical treasures exist despite the contract promising 10 rewards
The finder of treasure 8 can claim twice using the same secret (same hash, same proof)
One 10 ETH reward slot is either permanently unclaimable or double-claimable by a single finder
Participants are misled — MAX_TREASURES = 10 and getRemainingTreasures() both suggest 10 prizes
No on-chain PoC needed — the duplicate is directly visible by comparing ALLOWED_TREASURE_HASHES[8] and ALLOWED_TREASURE_HASHES[9] in circuits/src/main.nr:
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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