AAVFOP (Automatic Age Verifier For Online Purchases)

Pre-requisites

• circom
• nodejs

Circuit explanation

age-checker.circom verifies that a certain user is older or equal to the minimum age allowed to buy some products.

Constraints

• checks that age provided is greater or equal than 18 with GreaterEqThan
• checks that ethAddr provided is equal than ethAddrPriv.

Public inputs

• ethAddr: msg.sender used a a proof of account ownership

Private inputs

• age, ethAddrPriv

Create a mock powers of Tau and a zKey:

    circom age-checker.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 age-checker.r1cs pot13_final.ptau age-checker_0000.zkey
    snarkjs zkey contribute age-checker_0000.zkey age-checker_0001.zkey --name="1st Contributor Name" -v
    snarkjs zkey export verificationkey age-checker_0001.zkey verification_key.json
    snarkjs zkey export solidityverifier age-checker_0001.zkey verifier.sol

Generate witness.wtns

cd tools/age-checker_js/
node generate_witness.js age-checker.wasm ../input.json witness.wtns

Generate proof

cd tools/age-checker_js/
snarkjs groth16 prove ../age-checker_0001.zkey witness.wtns proof.json public.json
public y proof son ficheros de salida

Verify proof

snarkjs groth16 verify ../verification_key.json public.json proof.json

Run circuit tests

npx hardhat test test/age-checker.test.js

Run Smart contract tests

cd test
npx hardhat test contracts/aavfop.test.js
npx hardhat test contracts/realVerifier.test.js

Deployment on Goerli network:

These smart contracs have been verified in etherscan.

Verifier

0x0452c390556C62C3e2caAb355124F7Bbc945AA6B

Aavfop

0x54a21D33f0e10876F746cAB37Add4Ee494Ab300f