devconVI-workshop

Pre-requisites

• circom
• nodejs

Circuit explanation

get-nft.circom verifies that a certain account in the rollup given a snaphot (state-root) has been done more than 10 transactions. This is a proof of rollup usability and if a user is able to prover that it will receive a NFT as a reward

Constraints

• check nonce provided is greater than 10 with GreaterThan
• build state with HashState
• verify state in the snapshot root with SMTVerifier

Public inputs

• root: snapshot of the hermez rollup state root
• idx: unique identifier of the state-tree. Used as a nullifier to avoid double minting
• ethereumAddress: msg.sender used a a proof of account ownership

Private inputs

• state leaf parameters: tokenID, nonce, sign, balance & ay
• siblings

Resources

• Rollup circuits docs
• Leaf state-tree
• Circom 2.0 installation and tutorial

Create a mock powers of Tau and a zKey:

    circom get-NFT-test.circom --r1cs --wasm --sym --c
    snarkjs powersoftau new bn128 13 pot13_0000.ptau -v
    snarkjs powersoftau contribute pot13_0000.ptau pot13_0001.ptau --name="First contribution" -v
    snarkjs powersoftau prepare phase2 pot13_0001.ptau pot13_final.ptau -v
    snarkjs groth16 setup get-NFT-test.r1cs pot13_final.ptau get-NFT-test_0000.zkey
    snarkjs zkey contribute get-NFT-test_0000.zkey get-NFT-test_0001.zkey --name="1st Contributor Name" -v
    snarkjs zkey export verificationkey get-NFT-test_0001.zkey verification_key.json
    snarkjs zkey export solidityverifier get-NFT-test_0001.zkey verifier.sol

Future work

• Setup different tiers of NFT depending on the nonce
  • nonce should be public then
  • mint NFT depending on nonce selected
• Similar circuit but proving that a certain account has more balance than X