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

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 vk.json, proving key export skipped because reference key proving_key.json does not exist

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