expansejs-wallet

A lightweight wallet implementation. At the moment it supports key creation and conversion between various formats.

It is complemented by the following packages:

• expansejs-tx to sign transactions
• expansejs-icap to manipulate ICAP addresses
• store.js to use browser storage

Motivations are:

• be lightweight
• work in a browser
• use a single, maintained version of crypto library (and that should be in line with expansejs-util and expansejs-tx)
• support import/export between various wallet formats
• support BIP32 HD keys

Features not supported:

• signing transactions
• managing storage (neither in node.js or the browser)

Wallet API

Constructors:

• generate([icap]) - create an instance based on a new random key (setting icap to true will generate an address suitable for the ICAP Direct mode)
• generateVanityAddress(pattern) - create an instance where the address is valid against the supplied pattern (this will be very slow)
• fromPrivateKey(input) - create an instance based on a raw private key
• fromExtendedPrivateKey(input) - create an instance based on a BIP32 extended private key (xprv)
• fromPublicKey(input, [nonStrict]) - create an instance based on a public key (certain methods will not be available)
• fromExtendedPublicKey(input) - create an instance based on a BIP32 extended public key (xpub)
• fromV1(input, password) - import a wallet (Version 1 of the Ethereum wallet format)
• fromV3(input, password, [nonStrict]) - import a wallet (Version 3 of the Ethereum wallet format). Set nonStrict true to accept files with mixed-caps.
• fromEthSale(input, password) - import an Ethereum Pre Sale wallet

For the V1, V3 and EthSale formats the input is a JSON serialized string. All these formats require a password.

Note: fromPublicKey() only accepts uncompressed Ethereum-style public keys, unless the nonStrict flag is set to true.

Instance methods:

• getPrivateKey() - return the private key
• getPublicKey() - return the public key
• getAddress() - return the address
• getChecksumAddressString() - return the address with checksum
• getV3Filename([timestamp]) - return the suggested filename for V3 keystores
• toV3(password, [options]) - return the wallet as a JSON string (Version 3 of the Ethereum wallet format)

All of the above instance methods return a Buffer or JSON. Use the String suffixed versions for a string output, such as getPrivateKeyString().

Note: getPublicKey() only returns uncompressed Ethereum-style public keys.

Thirdparty API

Importing various third party wallets is possible through the thirdparty submodule:

var thirdparty = require('expansejs-wallet/thirdparty')

Constructors:

• fromEtherCamp(passphrase) - import a brain wallet used by Ether.Camp
• fromEtherWallet(input, password) - import a wallet generated by EtherWallet
• fromKryptoKit(seed) - import a wallet from a KryptoKit seed
• fromQuorumWallet(passphrase, userid) - import a brain wallet used by Quorum Wallet

HD Wallet API

To use BIP32 HD wallets, first include the hdkey submodule:

var hdkey = require('expansejs-wallet/hdkey')

Constructors:

• fromMasterSeed(seed) - create an instance based on a seed
• fromExtendedKey(key) - create an instance based on a BIP32 extended private or public key

For the seed we suggest to use bip39 to create one from a BIP39 mnemonic.

Instance methods:

• privateExtendedKey() - return a BIP32 extended private key (xprv)
• publicExtendedKey() - return a BIP32 extended public key (xpub)
• derivePath(path) - derive a node based on a path (e.g. m/44'/0'/0/1)
• deriveChild(index) - derive a node based on a child index
• getWallet() - return a Wallet instance as seen above

Provider Engine

The Wallet can be easily plugged into provider-engine to provide signing:

const WalletSubprovider = require('expansejs-wallet/provider-engine')

<engine>.addProvider(new WalletSubprovider(<wallet instance>))

Note it only supports the basic wallet. With a HD Wallet, call getWallet() first.

Remarks about toV3

The options is an optional object hash, where all the serialization parameters can be fine tuned:

• uuid - UUID. One is randomly generated.
• salt - Random salt for the kdf. Size must match the requirements of the KDF (key derivation function). Random number generated via crypto.getRandomBytes if nothing is supplied.
• iv - Initialization vector for the cipher. Size must match the requirements of the cipher. Random number generated via crypto.getRandomBytes if nothing is supplied.
• kdf - The key derivation function, see below.
• dklen - Derived key length. For certain cipher settings, this must match the block sizes of those.
• cipher - The cipher to use. Names must match those of supported by OpenSSL, e.g. aes-128-ctr or aes-128-cbc.

Depending on the kdf selected, the following options are available too.

For pbkdf2:

• c - Number of iterations. Defaults to 262144.
• prf - The only supported (and default) value is hmac-sha256. So no point changing it.

For scrypt:

• n - Iteration count. Defaults to 262144.
• r - Block size for the underlying hash. Defaults to 8.
• p - Parallelization factor. Defaults to 1.

The following settings are favoured by the Go Ethereum implementation and we default to the same:

• kdf: scrypt
• dklen: 32
• n: 262144
• r: 8
• p: 1
• cipher: aes-128-ctr

License

MIT License

Copyright (C) 2016 Alex Beregszaszi