ZKWordo

ZK Wordo – simple game of guessing the word. If you've guessed it right – you generate a proof and submit it on-chain. You proof will be verified and the ERC-1155 token will be minted.

There's a new Word every day.

The project uses ZKSnarks and on-chain proof verification.

Snarks

The project utilizes circom zk-circuit.

There're 64 words to form 6-level MerkleTree. Leaves of the tree are hash([word,day]), where day is 0-based day number.

If the word is guessed correctly, prover (backend) generates a proof with the tree path to word.

The proof is then validated on-chain and ERC-1155 token is being issued.

Each proof incorporates a nullifier hash to prevent re-using the proofs.

Bootstrap

Install circom https://docs.circom.io/getting-started/installation/#installing-circom

```sh
cd snarks

# compile the circuit
circom zkwordo.circom --r1cs --wasm --sym

# ptau phases
npx snarkjs powersoftau new bn128 15 pot14_0000.ptau -v
npx snarkjs powersoftau contribute pot14_0000.ptau pot14_0001.ptau --name="ZKWordo" -v
npx snarkjs powersoftau beacon pot14_0001.ptau pot14_beacon.ptau RANDOM_HEX_NUMBER_OF_62_LEN 10 -n="Final"
npx snarkjs powersoftau prepare phase2 pot14_beacon.ptau pot14_final.ptau -v

# export r1cs
npx snarkjs r1cs export json zkwordo.r1cs zkwordo.r1cs.json

# setup plonk verification
npx snarkjs plonk setup zkwordo.r1cs pot14_final.ptau zkwordo_plonk.zkey

# export the verification key
npx snarkjs zkey export verificationkey zkwordo_plonk.zkey verification_key.json

# export the verifier
npx snarkjs zkey export solidityverifier zkwordo_plonk.zkey ../contracts/PlonkVerifier.sol
```

Then proceed normally.

Backend

The backend is a quite simple nest.js project.

Blockchain interactions are based on viem and @wagmi/cli generated ABI definitions.

Dev bootstrap

1. npm install
2. npm run wagmi-generate
3. Intialize your words: cp data/words.json.example data/words.json and then fill in your words and hints.

Then visit backend and webapp to install their deps.

Run backend: cd backend && npm run start:dev.

Run webapp: cd webapp && npm run dev

Check Snarks section to info on snarks bootstrap.