zkConsent

This repository includes the code developed for the dissertation titled:

Privacy-Preserving Solutions for Decentralized Permissionless Blockchains

A dissertation submitted in partial fulfilment of the requirements for an M.Sc. in Blockchain and DLTs, University of Malta.

This code started off from a fork of the Zeth project from Clearmatics. Based on this, five ZKPs were developed for a consent solution for the biobanking sector. Check the dissertation writeup for all design details.

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Setup

Platform	Ubuntu 20.04 LTS
Node.js	12.22.1
Truffle	5.4.17
Web3.js	1.5.3
Boost	1.77.0

libsnark dependency installation

sudo apt install build-essential cmake git libgmp3-dev libprocps-dev \
                   python3-markdown libboost-program-options-dev \
                   libssl-dev python3 pkg-config

For more details on libsnark dependencies refer to:

libsnark: a C++ library for zkSNARK proofs

libsnark-tutorial by Howard Wu

libsnark tutorial by Christian Lundkvist and Sam Mayo

Compiler Installation

sudo apt install gcc-10 g++-10
sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-10 100 \
            --slave /usr/bin/g++ g++ /usr/bin/g++-10 --slave /usr/bin/gcov gcov /usr/bin/gcov-10

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Code Structure

This section describes the repository structure.

ZKP Trusted Setup and Proof Generation

Folder	Description
./snarks	Root folder containing the implementation of libsnark based ZKPs.
./snarks/depends	Git module dependencies for the zkconsenthlp library.
./snarks/zkconsenthlp	A C++ libsnark library implementing the five ZKPs required by the consent system.
./snarks/zkconsent	A C++ command-line tool wrapping the zkconsenthlp library for running the trusted setup and generating proofs.

ZKP Verifiers

Folder	Description
./verifier	Root folder for ZKP verifier implementations.
./verifier/groth16_hlp	Python scripts for pre-processing Groth16 proofs returned by the zkconsent command-line tool. This pre-processing is necessary for submitting the Groth16 proofs to the on-chain verifier smart contracts.
./verifier/verifier_contract	Solidity verifier smart contracts for Groth16 and PGHR13 ZKP schemes.

Miscellaneous

Folder	Description
./eth-gas	A node.js project for retrieving Ethereum Gas fees. This command-line tool takes as input a block range and returns the base gas fees for each block.
./samples	A set of json files containing sample ZKP witnesses that may be used for test generation of proofs.
./tests/blake2s	A node.js project for computing commitments using an independent implementation of Blake2s.
./zeth_tests	Raw data obtained from tests ran against Zeth.
./zkconsentjs	Initial implementation of a C library for allowing integration of the zkconsenthlp library into node.js projects.