eth-kvstore: A JavaScript repository from hCaptcha

eth-kvstore

A way to store key-value pairs tied to your ethereum address.

Motivation

We built this smart contract for our own needs in the HUMAN Protocol to allow ethereum addresses to publish and rotate public keys for signing and encrypting arbitrary data.

Separating identity (ETH addr keypair) and signing/encryption (public key published by ETH addr) means we avoid putting the identity key at risk via chosen-plaintext or known-plaintext attacks on the signing/encryption keys, and can easily rotate signing/encryption keys as needed.

Prerequisites

Three environment variables are needed to interact with the contract:

const { MNEMONIC, INFURA_TOKEN, KVSTORE_ADDRESS } = process.env;

MNEMONIC is a list containing 12 to 24 words that ensure certain entropy to our wallet's security. You can get your 12-word mnemonic easily from https://metamask.io/

INFURA_TOKEN is our gateway to the Ethereum blockchain and lets us easily interact with our contract without setting up our own node. You can get your token easily from https://infura.io/

KVSTORE_ADDRESS is the location where KVStore has been deployed. Current location of our Ropsten testnet deployment is in the following address: 0xc1db3c61b47d1f7d6529e435d5b360865a3130bc. You can also deploy your own KVStore by following the Deployment section of the guide.

Once you have setup all the needed prerequisites, setup your local .env file in the root of your project

touch .env

with the following content:

MNEMONIC=<your mnemonic>
INFURA_TOKEN=<your infura token>
KVSTORE_ADDRESS=<your kvstore address>

Get started

Main prerequisites to get going are:

Setup all the env variables in Prerequisites
Copy the KVStore.json to your project's folder.

An example application using eth-kvstore could look something like the following code snippet:

require('dotenv').config();

const HDWalletProvider = require('truffle-hdwallet-provider');
const Web3 = require('web3');
const KVStore = require('./build/contracts/KVStore.json');

const { MNEMONIC, INFURA_TOKEN, KVSTORE_ADDRESS } = process.env;

const provider = new HDWalletProvider(
  MNEMONIC,
  `https://ropsten.infura.io/${INFURA_TOKEN}`,
);
const web3 = new Web3(provider);

const RopstenKVStore = new web3.eth.Contract(KVStore.abi, KVSTORE_ADDRESS);

const set = async (key, value) => {
  const [accountOne] = await web3.eth.getAccounts();
  const receipt = await RopstenKVStore.methods.set(key, value).send({
    from: accountOne,
  });
  console.log(receipt);
  return receipt;
};

const get = async (key) => {
  const [accountOne] = await web3.eth.getAccounts();

  const value = await RopstenKVStore.methods.get(accountOne, key).call({
    from: accountOne,
  });
  console.log(value);
  return value;
};

set('satoshi', 'nakamoto');
get('satoshi');

Docker usage

The built docker image at hcaptcha/eth-kvstore will by default deploy the eth-kvstore contract to whatever is defined by ETH_HOST and ETH_PORT and the provided credentials as described above, if present.

It will drop the address of the deployed contract into the default path ./ethkvstore.address.json that can be used by various other tools by providing a volume mount and reading the contents of that file. The destination can be overridden via the ADDRESS_OUTPUT_FILENAME env var.

To quickly see this in action, run:

docker-compose up
# or
docker run -it --rm -v $(pwd)/deployed:/deployed hcaptcha/eth-kvstore
cat deployed/ethkvstore.address.json

Installation

You need Node as your environmental dependency. At the moment this is guaranteed to work with Node 8.

npm install
npm run compile

Testing

npm run test

Deployment

If you want to deploy your own KVStore to the Ethereum blockchain, you need to install Ganache first. Easiest way to get started is to install it from https://truffleframework.com/ganache

Local deployment

truffle migrate

Testnet deployment

Currently we support the following testnets: Mainnet, Kovan, Ropsten, Rinkeby.

truffle migrate --network ropsten

Contribute

We welcome all pull requests! Please ensure you lint before the commit.

npm run lint

You can inspect more of our linting scripts at package.json. Please submit your pull request against our staging branch. If you find a bug feel free to Click You can reach out to us on telegram

Prior Work

An earlier version of our specification was implemented at: https://github.com/willhay/kvstore.

hCaptcha/eth-kvstore