minimal-ecash-wallet

This is a minimalist eCash (XEC) wallet 'engine' for use with front end web apps. It contains all the core functionality needed by a wallet:

• Create a new eCash wallet, import a mnemonic, or import a private key (WIF)
• Encrypt a wallets mnemonic for safe storage
• Send and receive XEC
• Send and receive SLP tokens
• Get balances and UTXOs
• Retrieve transaction history & transaction details
• Burn tokens
• Price BCH in USD
• Send messages on the blockchain via OP_RETURN data
• Verify that a UTXO is unspent
• Get token icons and other media associated with a token

It is 'token aware' and can work with all SLP tokens, including NFTs. It can interface with Web 2 infrastructure like FullStack.cash or with the Cash Stack Web 3 infrastructure via the bch-consumer library.

This target consumers for this library is:

• bch-wallet-web3-android Bitcoin Cash wallet app that runs on Web and Android.
• psf-bch-wallet command line wallet.

The default derivation path for the wallet keypair is m/44'/245'/0'/0/0. This is the BIP44 standard for SLP token-aware BCH wallets.

Examples

The examples directory shows how to write node.js JavaScript apps that use this library to work with BCH:

• Create a wallet
• Send BCH
• List Tokens
• Send Tokens

How to use it?

Browser

Add to your HTML scripts

<script src="https://unpkg.com/minimal-slp-wallet"></script>

This will load the wallet into window.SlpAddress

Node.js

npm install minimal-slp-wallet --save

// ESM
import BchWallet from 'minimal-slp-wallet'

// CommonJS
const BchWallet = require('minimal-slp-wallet')

Instantiate Library

The wallet has different configuration parameters, that allow it to use web2 or web3 infrastructure. After instantiating a class, two Promises should be awaited:

• await bchWallet.walletInfoPromise will resolve when the BCH has been fully created. It only takes a few microseconds. Once resolves, the object bchWallet.walletInfo will contain all the wallet information.
• await bchWallet.initialize() will reach out to the blockchain and initialize the wallet by fetching its balance, tokens, and UTXO information. This is not necessary to call when creating a new wallet without a transaction history.

Using Web 2 Infrastructure

const BchWallet = require('minimal-slp-wallet')

const bchWallet = new BchWallet(undefined, {
  interface: 'rest-api',
  restURL: 'https://api.fullstack.cash/v5/'
})
await bchWallet.initialize()

Using Web 3 Interface

const BchWallet = require('minimal-slp-wallet')

const bchWallet = new BchWallet(undefined, {
  interface: 'consumer-api',
  restURL: 'https://free-bch.fullstack.cash'
  // Connect to your own instance of ipfs-bch-wallet-consumer:
  // restURL: 'http://localhost:5005'
})
await bchWallet.initialize()

Create new wallets

const bchWallet = new BchWallet()
await bchWallet.walletInfoPromise // Wait for wallet to be created.

// 12 words seed phrase for the wallet
console.log(bchWallet.walletInfo.mnemonic)

// cash address derived from the seed (derivation path: m/44'/245'/0'/0/0)
console.log(bchWallet.walletInfo.cashAddress)

// legacy address derived from the seed (derivation path: m/44'/245'/0'/0/0)
console.log(bchWallet.walletInfo.legacyAddress)

// private key for the BCH address derived from the seed (derivation path: m/44'/245'/0'/0/0)
console.log(bchWallet.walletInfo.privateKey)

Mnemonic encryption

const bchWallet = new BchWallet(null, {
  password: 'myStrongPassword'
})

// 12 words seed phrase for the wallet
console.log(bchWallet.walletInfo.mnemonic)

// encrypted mnemonic
console.log(bchWallet.walletInfo.mnemonicEncrypted)

const bchWallet2 = new BchWallet(bchWallet.walletInfo.mnemonicEncrypted, {
  password: 'myStrongPassword'
})

// decrypted mnemonic
console.log(bchWallet2.walletInfo.mnemonic)

Initialize wallet with mnemonic

// initialize with 12 words seed phrase for the wallet
const bchWallet = new BchWallet(
  'minor bench until split suffer shine series bag avoid cruel orient aunt'
)

// initialize for specific HD derivation path
const bchWallet2 = new BchWallet(
  'minor bench until split suffer shine series bag avoid cruel orient aunt',
  {
    HdPath: "m/44'/245'/0'/1'"
  }
)

Initialize wallet with private key

Private keys are in WIF format, and start with a capital 'K' or 'L'.

const bchWallet = new BchWallet('L3BUek8oq1iijZTkfdRYo8RDxEe3PpB8MyJnh2FSGWAoCjAffQCp')

Send transactions

You can send funds to other BCH wallets. You can distribute funds to N users by simply extending the receiver array.

const bchWallet = new BchWallet()

const receivers = [
  {
    address: 'bitcoincash:qp2rmj8heytjrksxm2xrjs0hncnvl08xwgkweawu9h',
    // amount in satoshis, 1 satoshi = 0.00000001 Bitcoin
    amountSat: 100000
  }
]

const txid = await bchWallet.send(receivers)

// Transaction ID
// you can then see the transaction in one of the explorers
// example: `https://explorer.bitcoin.com/bch/tx/${tx.txid}`;
console.log(txid)

Send Tokens

You can send tokens in a similar way:

const receiver = {
  address: 'simpleledger:qpeq7xx5x3a2jfa0x0w8cjqp4v9cm842vgsjqwzvfk',
  tokenId: 'a4fb5c2da1aa064e25018a43f9165040071d9e984ba190c222a7f59053af84b2',
  qty: 1.25
}

const txid = await bchWallet.sendTokens(receiver)

// Transaction ID
console.log(txid)

Note: Only single token sends are supported at the moment. i.e. One token type per receiver per transaction.

Get Wallet Balance

Gets balance (confirmed + unconfirmed) for an BCH address

// will get a balance for bchWallet.cashAddress
const myBalance = await bchWallet.getBalance()

// will get a balance for any address
const balanceOfOtherAddress = await bchWallet.getBalance(
  'bitcoincash:qp2rmj8heytjrksxm2xrjs0hncnvl08xwgkweawu9h'
)

List Tokens

List the SLP tokens held by an address.

// will get token balance for bchWallet.cashAddress
const myBalance = await bchWallet.listTokens()

// will get a balance for any address
const balanceOfOtherAddress = await bchWallet.listTokens(
  'simpleledger:qpeq7xx5x3a2jfa0x0w8cjqp4v9cm842vgsjqwzvfk'
)

Get Token Data

Given a Token ID for an SLP token, retrieve data about the token. This includes mutable and immutable data using the PS002 specification which controls token icons and other metadata.

const bchWallet = new BchWallet()

const tokenId = '59a62f35b0882b7c0ed80407d9190b460cc566cb6c01ed4817ad64f9d2508702'

const tokenData = await slpWallet.getTokenData(tokenId)

Get Token Media

Given a Token ID for an SLP token, retrieve the token icon URL and other associated media. This includes mutable and immutable data using the PS007 specification which controls token icons and other metadata.

getTokenData() returns much faster, but the client has to lookup the data on IPFS. getTokenData2() has the server lookup the token data. This can sometimes be faster, or sometimes it can take several seconds.

const bchWallet = new BchWallet()

const tokenId = '59a62f35b0882b7c0ed80407d9190b460cc566cb6c01ed4817ad64f9d2508702'

const tokenData = await slpWallet.getTokenData2(tokenId)

Get Wallet Transaction History

Get an array of TXIDs of the transactions involving this wallet.

// will get transaction history for bchWallet.cashAddress
const myTransactions = await bchWallet.getTransactions()

// will get transaction history for any address
const txHistoryOfOtherAddress = await bchWallet.getTransactions(
  'bitcoincash:qp2rmj8heytjrksxm2xrjs0hncnvl08xwgkweawu9h'
)

Get Detailed Transaction Data

Get transactions details for an array of up to 20 TXIDs.

// Input is an array of up to 20 TXIDs.
const txids = [
  '01517ff1587fa5ffe6f5eb91c99cf3f2d22330cd7ee847e928ce90ca95bf781b'
]

const result = await bchWallet.getTxData(txids)

Get the Price of BCH in USD

// Get the current spot price of BCH in USD
const result = await bchWallet.getUsd()

Send Memo.cash TX with OP_RETURN Data

// Write a small amount of text to the blockchain, compatible with memo.cash.
const result = await bchWallet.sendOpReturn('This is a memo.cash post.')

Error Handling

try {
  tx = await bchWallet.send([
    {
      address: 'bitcoincash:qrlhkg4d9z3y88j246a6482xzregxaxnfsagmd2kh3',
      amountSat: 1000
    }
  ])
} catch (err) {
  console.error(err)

  if (err.message && err.message.indexOf('Insufficient') > -1) {
    return alert('Insufficient balance on your BCH account.')
  }

  return alert('Error. Try again later.')
}

Save keys in the browser

While developing BCH apps, remember to never send the private keys / mnemonic / seed phrase to your servers.

1. Your servers can be hacked
2. Depending on your jurisdiction you may not have the allowance to manage the funds of your users

const bchWallet1 = new BchWallet()

// save the mnemonic for later
localStorage.setItem('BCH_MNEMONIC', bchWallet1.walletInfo.mnemonic)

// retrieve mnemonic to initialize the wallet
const bchWallet2 = new BchWallet(localStorage.getItem('BCH_MNEMONIC'))

Validate a UTXO

In BCH applications, it's often necessary to validate if a UTXO is still alive and spendable, or if it's already been spent. This function returns true if the UTXO is still spendable, false if not.

const utxo = {
  txid: 'b94e1ff82eb5781f98296f0af2488ff06202f12ee92b0175963b8dba688d1b40',
  vout: 0
}

const isValid = await bchWallet.utxoIsValid(utxo)

Generate a Key Pair

If a wallet is generated from a 12-word mnemonic, it can generate a key pair from the HD wallet.

const keyPair = await bchWallet.getKeyPair(5)

Licence

MIT