snarkjs VS tornado-core

git clone https://github.com/iden3/snarkjs cd snarkjs npm ci cd ../simple-zk

The generated wasm and r1cs files are available in the build folder. To generate the proof, we need a proving key file, and to generate this file, we need a ptau file. This ptau file can be generated by snarkjs, or you can download a pregenerated one (you can find the links in the snarkjs repo). For testing, the generated one is good for us, but in your production app, it’s recommended to do the ceremony and generate your own ptau file. (You can read about it in my previous article.)

Their goal was to teach how to use Circom to build zero-knowledge circuits and SnarkJS to compile them into solidity smart contracts.

Oh yeah, this is a known issue with windows; it's perfect on Mac. Do the steps here resolve it: https://github.com/iden3/snarkjs/issues/57 ?

The project mentions that it uses snarkjs and I thought I'd link it directy here. [1] What's interesting in the setup of systems like this one is the "Powers of Tau" ceremony which in decentralized manner (secure multi-party computation) avoid the "trusted setup" problem in non-interactive variants of zero knowledge proof systems like this one. [2]

[1] https://github.com/iden3/snarkjs

[2] https://github.com/ebfull/powersoftau

This is the repo we’re going to look at: Tornado core.

The method that I’m using is the same as what is used by Tornado Cash. Tornado Cash is a non-custodial Ethereum and ERC20 privacy solution based on zkSNARKs.

Tornado Cash is a great learning resource on how to build a real-world zk-app with Circom circuits. I strongly recommend going through the 3-page-long white paper, as well as Gubsheep's breaking down Tornado Cash session from the 0xparc course, plus Porter's overview of the white paper.

This was my very short tutorial on using zk-SNARK in JavaScript. It’s not a full course, and you probably have many questions, but I hope I helped you to start your journey. Circom and snarkjs are well documented, and you can also learn a lot from existing projects like Tornado Cash.

This is the MerkleTree contract, and the problem is on lines 58 and 59, I cannot understand why would you need to veryfy that the hash of a number has to be less than FIELD_SIZE.