Function to generate solidity parameters

[connorbode]

I had a lot of trouble discovering how to generate parameters to pass to an ethersjs contract function. It's possible that I've gone in the wrong direction, but I wanted to document the steps I took and the suggestions I have.

First, the unstringifyBigInts function is necessary & can be imported as follows:

const ffjavascript = require('ffjavascript')
const unstringifyBigInts = ffjavascript.utils.unstringifyBigInts

Next, here is the code I've used to submit a verifyProof call. Note that verifierContract is an instance of an ethersjs contract.

const { proof, publicSignals } = await snarkjs.plonk.prove(ZKEY_PATH, WITNESS_FILE)
const calldata = await snarkjs.plonk.exportSolidityCallData(unstringifyBigInts(proof), unstringifyBigInts(publicSignals))
const calldataSplit = calldata.split(',')
const proofFormatted = calldataSplit[0]
const publicSignalsFormatted = JSON.parse(values[1]).map(x => BigInt(x).toString())
const output = await verifierContract.verifyProof(proofFormatted, publicSignalsFormatted)

This all took a while for me to put together. A function like snarkjs.plonk.generateSolidityParams(proof, publicSignals) which formats the proof and publicSignals for web3 / ethers would be very useful for people new to snarkjs.

Hopefully this helps someone!

[phated]

You should no longer need to unstringifyBigInts as of #146 - Can you test snarkjs v0.4.17 ?