zkUtil

A tool to work with zkSNARK circuits generated by circom compiler. Based on circom import code by @kobigurk

The generated keys are currently incompatible with upstream Websnark and require using a custom fork

Usage examples:

```shell script

Getting help

zkutil --help zkutil A tool to work with SNARK circuits generated by circom

USAGE: zkutil

FLAGS: -h, --help Prints help information -V, --version Prints version information

SUBCOMMANDS: export-keys Export proving and verifying keys compatible with snarkjs/websnark generate-verifier Generate verifier smart contract help Prints this message or the help of the given subcommand(s) prove Generate a SNARK proof setup Generate trusted setup parameters verify Verify a SNARK proof

Getting help for a subcommand

zkutil prove --help zkutil-prove Generate a SNARK proof

USAGE: zkutil prove [OPTIONS]

FLAGS: -h, --help Prints help information -V, --version Prints version information

OPTIONS: -c, --circuit Circuit JSON file [default: circuit.json] -p, --params Snark trusted setup parameters file [default: params.bin] -r, --proof Output file for proof JSON [default: proof.json] -i, --public Output file for public inputs JSON [default: public.json] -w, --witness Witness JSON file [default: witness.json]

Suppose we have circuit file and a sample inputs

ls circuit.circom input.json

Compile the circuit

circom circuit.circom Constraints: 10000 Constraints: 20000 Constraints: 30000 Constraints: 40000 Constraints: 50000

Generate a local trusted setup

zkutil setup Loading circuit... Generating trusted setup parameters... Has generated 28296 points Writing to file... Done!

Calculate witness from the input.json

At the moment we still need to calculate witness using snarkjs

snarkjs calculatewitness

Generate a snark proof

zkutil prove Loading circuit... Proving... Saved proof.json and public.json

Verify the proof

zkutil verify Proof is correct

Generate a solidity verifier contract

zkutil generate-verifier Created verifier.sol

Export keys to snarkjs/websnark compatible format

zkutil export-keys Exporting params.bin... Created provingkey.json and verificationkey.json

Verify the same proof with snarkjs

snarkjs verify --vk vk.json OK

Here's a list of files that we have after this

ls circuit.circom circuit.json input.json params.bin proof.json public.json verifier.sol vk.json witness.json ```

Also see test.sh for example

Installation

Install Rust

shell script curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh

Install zkutil globally

```shell script cargo install zkutil

Make sure ~/.cargo/bin is in $PATH (should be added automatically during Rust installation)

```

Or alternatively you can compile and run it instead:

shell script git clone https://github.com/poma/zkutil cd zkutil cargo run --release -- prove --help