snarkit

A toolkit to compile and debug circom circuit.

Features

Better support for huge circuits

snarkit supports both wasm witness generator and native(cpp) witness generator. So compared to the snarkjs official tool, snarkit is more friendly for developing huge circuits by using native backend.

Better error detection

snarkit can print very helpful error messages when the circuit code goes wrong. It can display the code line number and the component/signals related to the error, so we can detect the reason for the error quickly and fix it. Example:

# display incorrect component and signals
$ snarkit check ./testdata/num2bits_err/

Invalid constraint:
0 * 0 != ((-1)*signal1 + 1*signal2 + 2*signal3 + 4*signal4 + 8*signal5 + 16*signal6 + 32*signal7 + 64*signal8 + 128*signal9)
Related signals:
signal1: main.num, value: 3
signal2: main.bits[0], value: 1
signal3: main.bits[1], value: 1
signal4: main.bits[2], value: 1
signal5: main.bits[3], value: 0
signal6: main.bits[4], value: 0
signal7: main.bits[5], value: 0
signal8: main.bits[6], value: 0
signal9: main.bits[7], value: 0
please check your circuit and input

# display incorrect code line number
$ snarkit check ./testdata/num2bits_err/ --sanity_check

Constraint doesn't match, /home/ubuntu/repos/snarkit/testdata/num2bits_err/circuit.circom:11:4: 3 != 7circuit: /home/ubuntu/repos/snarkit/testdata/num2bits_err/calcwit.cpp:201: void Circom_CalcWit::checkConstraint(int, PFrElement, PFrElement, const char*): Assertion `false' failed.
Aborted (core dumped)

Example

The following demos how to test a circuit with given inputs/outputs.

$ npm install snarkit

# first, you should prepare the circuit and input/output as the following structure
# all the input.json/output.json pair inside data/*** folder will be tested
# output.json can be an empty json file if you don't need to test against any circuit outputs.
$ find num2bits/
num2bits/
num2bits/data
num2bits/data/case01
num2bits/data/case01/output.json
num2bits/data/case01/input.json
num2bits/circuit.circom

# Snarkit has two backend: wasm and native(cpp). Only native backend can process huge circuits, you have to install some dependencies first before using it.

# use wasm backend
# compile the circuit
$ npx snarkit compile num2bits --backend wasm
# test the circuit
$ npx snarkit check num2bits --backend wasm

# use native backend
# install deps
$ sudo apt install nlohmann-json3-dev nasm g++ libgmp-dev
# compile the circuit
$ npx snarkit compile num2bits --backend native
# test the circuit
$ npx snarkit check num2bits --backend native

Misc

If you encounter FATAL ERROR: Ineffective mark-compacts near heap limit Allocation failed - JavaScript heap out of memory you can try increasing max-old-space-size by setting NODE_ARGS ENV to fully utilize your RAM. For example,

$ export NODE_ARGS='--max-old-space-size=16384'
$ npx snarkit compile num2bits --backend native -f

If still encountering error, then you should try compiling it in a machine with larger RAM.