eth-wallet-light

A lightweight, pure JS Ethereum wallet optimized for mobile. Inspired in part by the Consensys eth-lightwallet. This code has not been independently audited, use at your own risk. Features include:

• No dependency on the Node crypto module. This fact makes the library ideal for use in e.g. React Native.
• BIP39 seed words, from a fork of the canonical library that removes dependency on Node crypto.
• Keystores, when stored in-memory or as serialized keystore objects, are always securely encrypted with PBKDF2. All functions accessing sensitive information require a password.
• Keystores can optionally be initialized with a custom RNG for additional randomness. THIS IS HIGHLY RECOMMENDED, as the default RNG used is not a CSPRNG.

Installation

npm install NoahZinsmeister/eth-wallet-light

const wallet = require('eth-wallet-light')

General Functions

wallet.isMnemonicValid(mnemonic)

Checks the validity of the passed mnemonic.

Options

• mnemonic (required): A 12-word BIP39 seed phrase.

wallet.concatSignature(signature)

Concatenates the output of keystore.signMessageHash into a single hex string.

Options

• signature (required): A signature object.

Keystore functions

new wallet.Keystore(rng)

This is the constructor for new keystores. Does not create a keypair.

Options

• rng (optional): A function with one argument (the number of bytes), which must return a random hex string of that many bytes (0x prefix optional). Defaults to a non-secure RNG provided by crypto-js if not passed.

Returns Keystore

keystore.initializeFromEntropy(entropy, password)

This method initializes a keystore with a new random keypair. The password is used to encrypt the initialized keystore.

Options

• entropy (required): A string of entropy. Will be hashed with 32 bytes of output from the keystore’s rng to produce 16 bytes of randomness that is fed to the BIP39 mnemonic generator.
• password (required): A string password that will be fed to PBKDF2 to produce a key that will encrypt the sensitive contents of the keystore.

Returns Promise(Keystore)

keystore.restoreFromMnemonic(mnemonic, password)

This method initializes a keystore, restoring a keypair from a mnemonic. The password is used to encrypt the initialized keystore.

Options

• menemonic (required): 12 BIP39-compliant seed words. Can be used to recover backed-up or new accounts.
• password (required): A string password that will be fed to PBKDF2 to produce a key that will encrypt the sensitive contents of the keystore.

Returns Promise(Keystore)

keystore.restorefromSerialized(serializedKeystore)

This method restores a keystore from serialization. Note that when restoring from a serialized keystore, the rng argument to the keystore constructor is unnecessary, and can safely be left as undefined.

Options

• serializedKeystore (required): The output of keystore.serialize().

Returns Keystore

keystore.serialize()

This method serializes a keystore into a string.

Returns String

keystore.signMessageHash(messageHash, password)

Sign a message with the keystore’s private key.

Options

• messageHash (required): A hex-encoded 32-byte message. The 0x prefix is optional (it is stripped out).
• password (required): The password that encrypts the contents of the keystore.

Returns String

keystore.getMnemonic(password)

Get the mnemonic from the keystore.

Options

• password (required): The password that encrypts the contents of the keystore.

Returns String

keystore.getPrivateKey(password)

Get the private key from the keystore.

Options

• password (required): The password that encrypts the contents of the keystore.

Returns String

keystore.getAddress()

Get the public address from the keystore.

Returns String

Sample Code

Check test/test.js for exhaustive usage examples. Some starter code:

const wallet = require('eth-wallet-light')
const password = 'mypassword' // this should be a real password
var keystore = await new wallet.Keystore().initializeFromEntropy(entropy, password)
console.log('Address: ', keystore.getAddress())
var messageHash = '0x9c22ff5f21f0b81b113e63f7db6da94fedef11b2119b4088b89664fb9a3cb658'
var signature = wallet.concatSignature(keystore.signMessageHash(messageHash, password))
console.log('Signature:', signature)

In Node, here are two example rng functions that are both CSPRNGs. In React Native, this code should instead rely on something like react-native-securerandom.

```javascript
const crypto = require(‘crypto’)

const csprng = (bytes) => { return crypto.randomBytes(bytes).toString(‘hex’) }
const csprngPromise = (bytes) => {
return new Promise(function(resolve, reject) {
crypto.randomBytes(bytes, (err, buf) => {
err ? reject(err) : resolve(buf.toString(‘hex’))
})
})
}