SNARKeling Treasure Hunt
First Flight #59
Beginner FriendlyGameFiFoundry
100 EXP
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Submission Details
Impact: high
Likelihood: high

`ALLOWED_TREASURE_HASHES[8]` duplicates index 9; treasure 9 is unreachable and residual prize is stranded

Author Revealed upon completion

Description

Indices 8 and 9 of ALLOWED_TREASURE_HASHES in circuits/src/main.nr are byte-identical. Index 8 should be pedersen_hash([9]) per Deploy.s.sol:25, but holds pedersen_hash([10]), duplicating index 9. is_allowed(pedersen_hash([9])) therefore returns false, so no valid proof can be generated for secret 9, and honest play caps at nine distinct claims. With the separate dedup bug patched, withdraw() at line 224 (claimsCount >= MAX_TREASURES) becomes unreachable and 10 ETH plus any donations are stranded.

// circuits/src/main.nr:64-65
-961435057317293580094826482786572873533235701183329831124091847635547871092, // index 8, WRONG
-961435057317293580094826482786572873533235701183329831124091847635547871092 // index 9
// contracts/scripts/Deploy.s.sol:25 (intended index 8)
-4417726114039171734934559783368726413190541565291523767661452385022043124552

The test file already works around the bug: circuits/src/tests.nr:30 uses [1, 2, 3, 4, 5, 6, 7, 8, 10, 10] (no 9), acknowledging that secret 9 cannot be proven.

Risk

Likelihood: certain. Activates whenever the finder of treasure 9 attempts to claim, or the owner attempts non-emergency withdrawal. Impact: (a) finder of treasure 9 receives nothing; (b) 10 ETH of residual prize plus any donations stuck; (c) owner can only recover via pause() + emergencyWithdraw, which cancels the hunt for remaining participants.

Proof of Concept

Noir test proving that secret 9's intended hash is not accepted (add to circuits/src/tests.nr):

#[test(should_fail)]
fn test_secret_9_unreachable() {
let treasure_hash: Field = -4417726114039171734934559783368726413190541565291523767661452385022043124552;
main(9, treasure_hash, 1); // fails because is_allowed(treasure_hash) == false
}

Distinctness check that would fail on current code:

#[test]
fn test_allowed_hashes_are_pairwise_distinct() {
for i in 0..10 {
for j in (i + 1)..10 {
assert(ALLOWED_TREASURE_HASHES[i] != ALLOWED_TREASURE_HASHES[j]);
}
}
}

Solidity-side impact once dedup is patched:

// after nine honest claims (secrets {1..8, 10}):
assertEq(hunt.claimsCount(), 9);
vm.expectRevert(bytes("HUNT_NOT_OVER"));
hunt.withdraw(); // blocked forever; 10 ETH stranded

Recommended Mitigation

Replace the wrong value at circuits/src/main.nr:64:

- -961435057317293580094826482786572873533235701183329831124091847635547871092,
+ -4417726114039171734934559783368726413190541565291523767661452385022043124552,

Regenerate Verifier.sol via circuits/scripts/build.sh and redeploy. Fix the test fixture:

- let treasures: [Field; 10] = [1, 2, 3, 4, 5, 6, 7, 8, 10, 10];
+ let treasures: [Field; 10] = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];

Add the pairwise-distinctness test above so future copy-paste errors fail at nargo test time.

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