logos-storage-proofs-circuits

set the parameters by editing params.sh
run setup.sh to do the circuit-specific setup
run prove.sh to generate input, compute witness and create (and verify) the proof

NOTE: the examples below assume bash. In particular, it won't work with zsh (which is the dafault on newer macOS)! Because, you know, reasons...

Preliminaries

install circom, snarkjs, rapidsnark: https://docs.circom.io/getting-started/installation
install Nim: https://nim-lang.org/

Build the Nim cli proof input generator:

$ cd ../reference/nim/proof_input/
$ nimble build -d:release cli
$ cd ../../../workflow

Powers of tau setup

Either download a ready-to-use "powers of tau" setup file (section 7), or generate one youself using snarkjs (sections 1..7), see the README here: https://github.com/iden3/snarkjs

Size 2^21 (file size about 2GB) should be big enough:

$ cd ..
$ mkdir -p ceremony
$ cd ceremony
$ wget https://storage.googleapis.com/zkevm/ptau/powersOfTau28_hez_final_21.ptau
$ cd ../workflow

Note: generating this yourself will probably take quite a long time.

Set the parameters

There are quite a few parameters (run cli --help too see them), it's probably best to collect them into a parameter file. Check out params.sh and cli_args.sh to see one way to do that.

You can edit params.sh to your taste before running the workflow scripts.

Compile the circuit

First create the main component:

$ mkdir -p build
$ cd build
$ source ./cli_args.sh && ../../reference/nim/proof_input/cli $CLI_ARGS -v --circom="proof_main.circom"

Then compile the circuit:

$ circom --r1cs --O2 -l../../circuit proof_main.circom

Do the circuit-specific setup

See the snarkjs README for an overview of the whole process.

$ snarkjs groth16 setup proof_main.r1cs ../../ceremony/powersOfTau28_hez_final_21.ptau proof_main_0000.zkey
$ snarkjs zkey contribute proof_main_0000.zkey proof_main_0001.zkey --name="1st Contributor Name"

You can add more contributors here if you want.

Finally rename the last contributions result and export the verification key:

$ rm proof_main_0000.zkey
$ mv proof_main_0001.zkey proof_main.zkey

$ snarkjs zkey export verificationkey proof_main.zkey proof_main_verification_key.json

NOTE: You have redo all the above if you change any of the five parameters the circuit depends on (these are: maxdepth, maxslots, cellsize, blocksize, nsamples).

Generate an input to the circuit

$ source ../cli_args.sh && ../../reference/nim/proof_input/cli $CLI_ARGS -v --output=input.json

Generate the witness

$ cd proof_main_js
$ time node generate_witness.js proof_main.wasm ../input.json ../witness.wtns
$ cd ..

Create the proof

Using snarkjs (very slow, but more portable):

$ snarkjs groth16 prove proof_main.zkey witness.wtns proof.json public.json

Or using rapidsnark (fast, but not very portable):

$ rapidsnark proof_main.zkey witness.wtns proof.json public.json

The output of this step will consist of:

proof.json containing the proof itself
public.json containing the public inputs

Verify the proof (on CPU)

$ snarkjs groth16 verify proof_main_verification_key.json public.json proof.json

Generate solidity verifier contract

$ snarkjs zkey export solidityverifier proof_main.zkey verifier.sol