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Build Status Coverage Status Go Report Card

spvwallet

Lightweight p2p SPV wallet and library in Go. It connects directly to the bitcoin p2p network to fetch headers, merkle blocks, and transactions.

It uses a number of utilities from btcsuite but natively handles blockchain and wallet.

Library Usage:

// Create a new config
config := spvwallet.NewDefaultConfig()

// Select network
config.Params = &chaincfg.TestNet3Params

// Select wallet datastore
sqliteDatastore, _ := db.Create(config.RepoPath)
config.DB = sqliteDatastore

// Create the wallet
wallet, _ := spvwallet.NewSPVWallet(config)

// Start it!
go wallet.Start()

Easy peasy

The wallet implements the following interface:

type BitcoinWallet interface {

	// Start the wallet
	Start()

	// Return the network parameters
	Params() *chaincfg.Params

	// Returns the type of crytocurrency this wallet implements
	CurrencyCode() string

	// Check if this amount is considered dust
	IsDust(amount int64) bool

	// Get the master private key
	MasterPrivateKey() *hd.ExtendedKey

	// Get the master public key
	MasterPublicKey() *hd.ExtendedKey

	// Get the current address for the given purpose
	CurrentAddress(purpose spvwallet.KeyPurpose) btc.Address

	// Returns a fresh address that has never been returned by this function
	NewAddress(purpose spvwallet.KeyPurpose) btc.Address

	// Parse the address string and return an address interface
	DecodeAddress(addr string) (btc.Address, error)

	// Turn the given output script into an address
	ScriptToAddress(script []byte) (btc.Address, error)

	// Turn the given address into an output script
	AddressToScript(addr btc.Address) ([]byte, error)

	// Returns if the wallet has the key for the given address
	HasKey(addr btc.Address) bool

	// Get the confirmed and unconfirmed balances
	Balance() (confirmed, unconfirmed int64)

	// Returns a list of transactions for this wallet
	Transactions() ([]spvwallet.Txn, error)

	// Get info on a specific transaction
	GetTransaction(txid chainhash.Hash) (spvwallet.Txn, error)

	// Get the height of the blockchain
	ChainTip() uint32

	// Get the current fee per byte
	GetFeePerByte(feeLevel spvwallet.FeeLevel) uint64

	// Send bitcoins to an external wallet
	Spend(amount int64, addr btc.Address, feeLevel spvwallet.FeeLevel) (*chainhash.Hash, error)

	// Bump the fee for the given transaction
	BumpFee(txid chainhash.Hash) (*chainhash.Hash, error)

	// Calculates the estimated size of the transaction and returns the total fee for the given feePerByte
	EstimateFee(ins []spvwallet.TransactionInput, outs []spvwallet.TransactionOutput, feePerByte uint64) uint64

	// Build and broadcast a transaction that sweeps all coins from an address. If it is a p2sh multisig, the redeemScript must be included
	SweepAddress(utxos []spvwallet.Utxo, address *btc.Address, key *hd.ExtendedKey, redeemScript *[]byte, feeLevel spvwallet.FeeLevel) (*chainhash.Hash, error)

	// Create a signature for a multisig transaction
	CreateMultisigSignature(ins []spvwallet.TransactionInput, outs []spvwallet.TransactionOutput, key *hd.ExtendedKey, redeemScript []byte, feePerByte uint64) ([]spvwallet.Signature, error)

	// Combine signatures and optionally broadcast
	Multisign(ins []spvwallet.TransactionInput, outs []spvwallet.TransactionOutput, sigs1 []spvwallet.Signature, sigs2 []spvwallet.Signature, redeemScript []byte, feePerByte uint64, broadcast bool) ([]byte, error)

	// Generate a multisig script from public keys. If a timeout is included the returned script should be a timelocked escrow which releases using the timeoutKey.
	GenerateMultisigScript(keys []hd.ExtendedKey, threshold int, timeout time.Duration, timeoutKey *hd.ExtendedKey) (addr btc.Address, redeemScript []byte, err error)

	// Add a script to the wallet and get notifications back when coins are received or spent from it
	AddWatchedScript(script []byte) error

	// Add a callback for incoming transactions
	AddTransactionListener(func(spvwallet.TransactionCallback))

	// Use this to re-download merkle blocks in case of missed transactions
	ReSyncBlockchain(fromHeight int32)

	// Return the number of confirmations and the height for a transaction
	GetConfirmations(txid chainhash.Hash) (confirms, atHeight uint32, err error)

	// Cleanly disconnect from the wallet
	Close()
}

To create a wallet binary:

make install

Usage:

Usage:
  spvwallet [OPTIONS] <command>

Help Options:
  -h, --help  Show this help message

Available commands:
  addwatchedscript         add a script to watch
  balance                  get the wallet balance
  bumpfee                  bump the tx fee
  chaintip                 return the height of the chain
  createmultisigsignature  create a p2sh multisig signature
  currentaddress           get the current bitcoin address
  dumpheaders              print the header database
  estimatefee              estimate the fee for a tx
  getconfirmations         get the number of confirmations for a tx
  getfeeperbyte            get the current bitcoin fee
  gettransaction           get a specific transaction
  haskey                   does key exist
  masterprivatekey         get the wallet's master private key
  masterpublickey          get the wallet's master public key
  multisign                combine multisig signatures
  newaddress               get a new bitcoin address
  peers                    get info about peers
  resyncblockchain         re-download the chain of headers
  spend                    send bitcoins
  start                    start the wallet
  stop                     stop the wallet
  sweepaddress             sweep all coins from an address
  transactions             get a list of transactions
  version                  print the version number

Finally a gRPC API is available on port 8234. The same interface is exposed via the API plus a streaming wallet notifier which fires when a new transaction (either incoming or outgoing) is recorded then again when it gains its first confirmation.

This library began it's life as a library called uspv written by Thaddeus Dryja for the lnd. Several files still contain the original code.