Client-Side Wallet - Demo

Play with the demo now: https://client-side-wallet-demo.herokuapp.com

This demon example demonstrates how to build a simple DApp (Voting) with client-side Ethereum wallet. Based on Solidity smart contract and client-side UI (JS + jQuery + Ethers.js) + server-side account management (Node.js + Express + simple REST API). The wallet is encrypted in UTC / JSON format (both private key + mnemonics are encrypted with AES-CRT-128 using SCrypt key derivation).

• The app implements register / login / logout / vote.
• Candidates and votes stay in Solidity contract on the Ropsten testnet.
• Users register in the system and get a wallet (private key + address)
  • The wallet JSON is stored after strong encryption at the server side
  • The wallet password / private key never leave the client app
• User login -> download the encrypted wallet JSON from the server
• After login / register, keep the encrypted wallet JSON in the browser session
• Logout -> clear the browser session
• Use different passwords for server login and for the wallet
  • Wallet password (client-side): HMAC(password, username + 'wallet')
  • Server password (wallet id): HMAC(username, password + 'server')
• Lost password cannot be recovered / reset -> use the mnemonics
• Based on the Ethers.js library

Project Structure

This DApp example is based on JavaScript (server-side + client-side)

• public - holds the client-side JS app
• src - holds the server-side Node.js app
• contract - holds the Voting solidity contract, published at https://ropsten.etherscan.io/address/0x121241C506ebb1d04A4d8d355D37aC9fd06361de

Running the Demo

1. Download the demo from GitHub:

git clone https://github.com/nakov/client-side-ethereum-wallet

2. Go to the project directory:

cd client-side-ethereum-wallet

3. Install the NPM packages

npm install

3. Run the server

npm start

4. Open the project URL from your Web browser:

http://localhost:80

Slides and Videos

Slides:

• https://www.slideshare.net/nakov/clientside-wallets-in-dapps-nakov-blockworld-2018-san-jose

Videos:

• https://youtu.be/Wi9nZNUC_B8 (in Bulgarian language, Ethereum meetup, Sofia)
• https://youtu.be/7b3Pr7DMSMc (in English, at Microsoft Singapore)
• https://youtu.be/_E_HPGbDRmk (in English, from BlockWorld 2018, San Jose)