MetaAuth

Express middleware for handling authentication with MetaMask using "eth_signTypedData_v3"

Usage

$ npm install meta-auth --save

Include the middleware in your express routes

const metaAuth = require('meta-auth')();

app.get('/auth/:MetaAddress', metaAuth, (req, res) => {
  // Request a challenge from the server
  res.send(req.metaAuth.challenge)
});

app.get('/auth/:MetaMessage/:MetaSignature', metaAuth, (req, res) => {
  if (req.metaAuth.recovered) {
    // Signature matches the cached address/challenge
    // Authentication is valid, assign JWT, etc.
    res.send(req.metaAuth.recovered);
  } else {
    // Sig did not match, invalid authentication
    res.status(400).send();
  };
});

MetaAuth will check the route parameters for :MetaAddress, :MetaMessage, and :MetaSignature

Parameter names may be changed when passing in an optional config.

const metaAuth = require('meta-auth')({
  message: 'msg',
  signature: 'sig',
  address: 'address'
});

:MetaAddress

If MetaAuth finds req.params.MetaAddress set it will assign a challenge to the address. The challenge is located at req.metaAuth.challenge

:MetaMessage & :MetaSignature

:MetaMessage is the previously issued challenge and :MetaSignature is the user's signature for the provided message. If the recovery address matches the address stored for the given challenge MetaAuth returns the recovery address. In the case of an error or no match false is returned.

Config

const metaAuth = new MetaAuth({
  signature: 'MetaSignature',
  message: 'MetaMessage',
  address: 'MetaAddress',
  banner: 'Example Site Banner'
});

Author of meta-auth original package:

• Alex Sherbuck - I Gave

Author of the fork to use EIP-712

• Henrique Sena