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

Duplicate hash in ALLOWED_TREASURE_HASHES prevents treasure #9 from ever being claimed

Author Revealed upon completion

Root + Impact

Description

  • The Noir circuit is designed to let a finder prove knowledge of any one of the 10 intended treasures without revealing which one it is. It does this by checking that the public treasure_hash is present in the hardcoded ALLOWED_TREASURE_HASHES array and that it equals pedersen_hash(treasure).

  • The last two entries in ALLOWED_TREASURE_HASHES are identical. The array therefore only contains 9 unique hashes instead of the documented 10. Treasure #9’s hash is missing, so no valid ZK proof can ever be generated for it.

// Baked-in set of 10 allowed treasure hashes (pedersen hashes).
global ALLOWED_TREASURE_HASHES: [Field; 10] = [
1505662313093145631275418581390771847921541863527840230091007112166041775502,
-7876059170207639417138377068663245559360606207000570753582208706879316183353,
-5602859741022561807370900516277986970516538128871954257532197637239594541050,
2256689276847399345359792277406644462014723416398290212952821205940959307205,
10311210168613568792124008431580767227982446451742366771285792060556636004770,
-5697637861416433807484703347699404695743570043365849280798663758395067508,
-2009295789879562882359281321158573810642695913475210803991480097462832104806,
8931814952839857299896840311953754931787080333405300398787637512717059406908,
@> -961435057317293580094826482786572873533235701183329831124091847635547871092,
@> -961435057317293580094826482786572873533235701183329831124091847635547871092 // duplicate of previous entry
];

Risk

Likelihood:

  • The array is statically defined in the circuit source and is baked into the deployed verifier contract.

  • The is_allowed helper and the main function both rely on this exact array; the duplicate is present in every build and every deployment.

Impact:

  • Treasure #9 becomes permanently unclaimable, even a finder who physically locates it and knows the correct secret cannot generate a valid proof.

  • The real-world treasure hunt is left with only 9 working treasures instead of the intended 10, breaking the game design and fairness guarantees.

Proof of Concept

// tests.nr explicitly skips treasure 9 and duplicates treasure 10:
let treasures = [1, 2, 3, 4, 5, 6, 7, 8, 10, 10];
for i in 0..10 {
let treasure = treasures[i];
let treasure_hash = ALLOWED_TREASURE_HASHES[i];
main(treasure, treasure_hash, 2); // passes only because test avoids #9
}

Simply inspecting the array shows ALLOWED_TREASURE_HASHES[8] == ALLOWED_TREASURE_HASHES[9]. Any attempt to claim treasure #9 with its real secret will fail the assert(is_allowed(treasure_hash)) check in main.

Recommended Mitigation

global ALLOWED_TREASURE_HASHES: [Field; 10] = [
1505662313093145631275418581390771847921541863527840230091007112166041775502,
...,
8931814952839857299896840311953754931787080333405300398787637512717059406908,
- -961435057317293580094826482786572873533235701183329831124091847635547871092,
- -961435057317293580094826482786572873533235701183329831124091847635547871092
+ -961435057317293580094826482786572873533235701183329831124091847635547871092, // treasure #9
+ <correct_pedersen_hash_for_treasure_10> // replace with the real hash
];
​
// (or if only 9 treasures were ever intended)
- global ALLOWED_TREASURE_HASHES: [Field; 10] = [
+ global ALLOWED_TREASURE_HASHES: [Field; 9] = [
...
- for i in 0..10 {
+ for i in 0..9 {

Update the array size, loop bounds, all comments that say “10 allowed hashes / 10 treasures”, and the test suite accordingly.

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