GitAnchor

Introduction

With GitAnchor every Git (and GitHub) commit can be made permanent and provable by anchoring it in the blockchain. The smart contract based anchors are immutable and therefore proof that a repository at any given commit state has existed at the time when the anchor was set.

A GitAnchor consist of the commit hash as well as the timestamp when the anchor was set and the wallet address (EOA) of the person who was setting the anchor.

A Git commit hash is a SHA1 hash that among other data itself consists of several different hashes. Those contain the parent hash, which is a pointer to the parent of the current commit, and the tree hash, which is a hash of the whole directory tree including all its files.

GitAnchor therefore provides an easy and convenient way to proof the existence of any kind of files in combination with all the versioning features that regular Git is offering. Its convenience is achieved by a set of seamlessly integrated tools, consisting of a GitHub browser plugin, a command line interface and the GitAnchor webapp.

ETHOnline Hackathon

This is my contribution to the ETHOnline Hackathon taking place from September 2nd to 28th, 2022. For more information visit the GitAnchor ETHOnline Project Page.

Components

GitHub Browser Plugin

Command Line Interface (CLI)

Usage: gitanchor [options] [command]

CLI to create or verify blockchain anchors

Options:
  -V, --version            output the version number
  -d, --debug              output extra debugging in case of errors
  -h, --help               display help for command

Commands:
  verify [options] [hash]  verify anchor for hash
  create [options] [hash]  create anchor for hash
  newwallet                create a new wallet
  help [command]           display help for command

Git Hooks Integration

The CLI can easily be integrated with Git Hooks. Example .git/hooks/post-commit:

#!/bin/sh
gitanchor create --latest

Web Application

A live demo is deployed on GitHub Pages.

Supported Blockchains

Blockchain	Purpose	Type	Contract Address
Ethereum Goerli	Testing	Layer 1	0x65438AaA54141dD923C5F51E81d1aaD11daF3558
Cronos Testnet	Testing	Layer 1	0x65438AaA54141dD923C5F51E81d1aaD11daF3558
Polygon Mumbai	Testing	Layer 2	0x65438AaA54141dD923C5F51E81d1aaD11daF3558
Optimism Goerli	Testing	Layer 2	0x65438AaA54141dD923C5F51E81d1aaD11daF3558

Plan of Action

MVP for the Hackaton

Define project name and project identity (logo, etc.)
Ethereum blockchain anchoring
Seamless GitHub UI integration using Tampermonkey

Possible Features

Polygon blockchain support
Optimism blockchain support
Cronos blockchain support
Web app to set and verify anchors
Commandline tool to set and verify anchors
~~Integrate with The Graph to be able to link the emitted events on Etherscan~~ Not needed, can be accomplished with regular logs and indexes
Git Hooks integration for the commandline tool
~~GitHub Actions integration~~ Not needed, can be accomplished with Git Hooks

Eat Your Own Dogfood

The first version of the contract was deployed on Ethereum Goerli at 0xC3524D9C7bb54929fd7049075Bc2fa05Ba96dF95. The current versions of the contracts are listed above. The commits of this repository are be periodically anchored during development.

luzianscherrer/gitanchor