SNARKeling Treasure Hunt
First Flight #59
Beginner FriendlyGameFiFoundry
100 EXP
View results
Previous Next
Submission Details
Severity: high
Valid

Duplicate treasure hashes in circuit means only 9 unique treasures exist

mnangatariel27

Root + Impact

Description

The ALLOWED_TREASURE_HASHES array in circuits/src/main.nr lines 55-66
is supposed to contain 10 UNIQUE treasure hashes, but index 8 and index 9
are identical:

global ALLOWED_TREASURE_HASHES: [Field; 10] = [
1505662313093145631275418581390771847921541863527840230091007112166041775502,
-7876059170207639417138377068663245559360606207000570753582208706879316183353,
-5602859741022561807370900516277986970516538128871954257532197637239594541050,
2256689276847399345359792277406644462014723416398290212952821205940959307205,
10311210168613568792124008431580767227982446451742366771285792060556636004770,
-5697637861416433807484703347699404695743570043365849280798663758395067508,
-2009295789879562882359281321158573810642695913475210803991480097462832104806,
8931814952839857299896840311953754931787080333405300398787637512717059406908,
-961435057317293580094826482786572873533235701183329831124091847635547871092, // Index 8
-961435057317293580094826482786572873533235701183329831124091847635547871092 // Index 9 DUPLICATE!
];

Confirmed in test file circuits/src/tests.nr line 30:

let treasures: [Field; 10] = [1, 2, 3, 4, 5, 6, 7, 8, 10, 10];
// ^^ ^^ Both are treasure 10 (same secret)

Treasures[8] and Treasures[9] have identical secret values, meaning
the circuit only has 9 unique treasures despite being designed for 10.

Risk

Likelihood:

  • This is a deployment-time configuration error, present from launch

  • Any participant can generate a valid proof for the duplicate secret

Impact:

  • Only 9 unique treasures exist in the circuit instead of 10

  • 100 ETH is allocated for 10 treasures but only 9 unique ones exist

  • One treasure secret can be used to claim twice, breaking hunt fairness

  • Hunt integrity is compromised — participants cannot trust the design

Proof of Concept

The duplicate is confirmed in two separate files:

  • ALLOWED_TREASURE_HASHES[8] and ALLOWED_TREASURE_HASHES[9] in main.nr are byte-for-byte identical

  • treasures[8] = 10 and treasures[9] = 10 in tests.nr confirm both use the same secret value

Both point to the same secret, creating only 9 unique treasures instead of 10.

Recommended Mitigation

A new unique 10th treasure secret must be generated and the duplicate
replaced. The circuit must then be recompiled to update the verifier.

  1. Generate a new unique 10th treasure secret

  2. Compute its Pedersen hash

  3. Replace duplicate at line 65: ALLOWED_TREASURE_HASHES[9] = NEW_UNIQUE_HASH

  4. Recompile: ./circuits/scripts/build.sh

  5. Regenerate Verifier.sol

  6. Verify all 10 hashes are now unique

Updates

Lead Judging Commences

s3mvl4d Lead Judge 18 days ago
Submission Judgement Published
Validated
Assigned finding tags:

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.

Support

FAQs

Can't find an answer? Chat with us on Discord, Twitter or Linkedin.

Give us feedback!