stealth

This module is used for stealth addresses for Bitcoin and other crypto currencies.

Usage

First, you should really read this excellent resource: https://gist.github.com/ryanxcharles/1c0f95d0892b4a92d70a

This module depends upon ecurve and may change to elliptic in the future. However, this is just an implementation detail that shouldn't affect your code.

Example

If you're the payer (sender)

var Stealth = require('stealth')

// you get this from the person you're going to pay (receiver)
var addr = 'vJmtuUb8ysKiM1HtHQF23FGfjGAKu5sM94UyyjknqhJHNdj5CZzwtpGzeyaATQ2HvuzomNVtiwsTJSWzzCBgCTtUZbRFpzKVq9MAUr'
var stealth = Stealth.fromString(addr)

// single-use nonce key pair, works with CoinKey, bitcoinjs-lib, bitcore, etc
var keypair = require('coinkey').createRandom()

// generate payment address
var payToAddress = stealth.genPaymentAddress(keypair.privateKey)

// create transaction with two outputs:
// 1. Regular pay-to-pubkeyhash with `payToAddress` as recipient
// 2. OP_RETURN with `keypair.publicKey`

If you're the payee (recipient)

var Stealth = require('stealth')

// you need to scan every transaction and look for the following:
// 1. does the transaction contain an OP_RETURN?
// 2. if yes, then extract the OP_RETURN
// 3. is the OP_RETURN data a compressed public key (33 bytes)?
// 4. if yes, check if mine

// generate two key pairs, can use CoinKey, bitcoinjs-lib, bitcore, etc
var payloadKeyPair = require('coinkey').createRandom()
var scanKeyPair = require('coinkey').createRandom()

// note, the private keys are NOT encoded in the Stealth address
// you need to save them somewhere
var stealth = new Stealth({
  payloadPrivKey: payloadKeyPair.privateKey,
  payloadPubKey: payloadKeyPair.publicKey,
  scanPrivKey: scanKeyPair.privateKey,
  scanPubKey: scanKeyPair.publicKey
})

var addr = stealth.toString()
// => 'vJmtuUb8ysKiM1HtHQF23FGfjGAKu5sM94UyyjknqhJHNdj5CZzwtpGzeyaATQ2HvuzomNVtiwsTJSWzzCBgCTtUZbRFpzKVq9MAUr'

// publish addr or give it someone
// unlike regular Bitcoin addresses, you can use
// stealth address as much as you like

// scan and decode transactions

var opReturnPubKey = /* */
var pubKeyHashWithPayment = /* */

var keypair = stealth.checkPaymentPubKeyHash(opReturnPubKey, pubKeyHashWithPayment)

// it NOT YOURS, `keypair` will be falsey

if (keypair == null) {
  console.log('payment is not mine')
} else {
  console.log('payment is mine')

  // redeem with `privKey`
  console.log(keypair.privKey)
}

API

(TODO)

+ fromRandom([config])

Class method to create a stealth key from a random entropy. Optionally pass in config with the following:

• rng: A function that should accept a number n and return a Buffer/Array with length n.
• version: Version code for stealth string.

Resources

Credits

The creation of this module owes a lot of credit to the prior work of Ryan X. Charles, specifically the following resources:

• https://github.com/ryanxcharles/fullnode
• https://gist.github.com/ryanxcharles/1c0f95d0892b4a92d70a

Additional Resources

• Dark Wallet description: https://wiki.unsystem.net/en/index.php/DarkWallet/Stealth
• Dark Wallet infographic: https://wiki.unsystem.net/en/images/e/e5/RHhNKL6.jpg
• Stealth Whitepaper: http://sourceforge.net/p/bitcoin/mailman/message/31813471/

License

MIT