GOcoin

Overview

This is a library to make bitcoin address and transactions which was initially forked from hellobitcoin, and added some useful features.

GOcoin uses btcec library in btcd instead of https://github.com/toxeus/go-secp256k1 to make it a pure GO program.

Features

1. Normaly Payment(P2PKH) supporting multi TxIns and multi TxOuts.
2. Gethering unspent transaction outputs(UTXO) and send transactions by using Blockr.io WEB API.
3. M of N multisig whose codes were partially ported from https://github.com/soroushjp/go-bitcoin-multisig.
4. Micropayment Channel

Requirements

This requires

• git
• go 1.3+

Installation

$ mkdir tmp
$ cd tmp
$ mkdir src
$ mkdir bin
$ mkdir pkg
$ exoprt GOPATH=`pwd`
$ go get github.com/StorjPlatform/gocoin

Example

(This example omits error handlings for simplicity.)

Key Handling

import gocoin

func main(){
	//make a public and private key pair.
	key, _ := gocoin.GenerateKey(true)
	adr, _ := key.Pub.GetAddress()
	fmt.Println("address=", adr)
	wif := key.Priv.GetWIFAddress()
	fmt.Println("wif=", wif)
	
	//get key from wif
	wif := "928Qr9J5oAC6AYieWJ3fG3dZDjuC7BFVUqgu4GsvRVpoXiTaJJf"
	txKey, _ := gocoin.GetKeyFromWIF(wif)
}

Normal Payment

import gocoin

func main(){
	key, _ := gocoin.GenerateKey(true)

	//get unspent transactions
	service := gocoin.NewBlockrService(true)
	txs, _ := service.GetUTXO(adr,nil)
	
	//Normal Payment
	gocoin.Pay([]*Key{txKey}, []*gocoin.Amounts{&{gocoin.Amounts{"n2eMqTT929pb1RDNuqEnxdaLau1rxy3efi", 0.01*gocoin.BTC}}, service)
}

M of N Multisig

import gocoin

func main(){
	key, _ := gocoin.GenerateKey(true)
	service := gocoin.NewBlockrService(true)

	//2 of 3 multisig
	key1, _ := gocoin.GenerateKey(true)
	key2, _ := gocoin.GenerateKey(true)
	key3, _ := gocoin.GenerateKey(true)
	rs, _:= gocoin.NewRedeemScript(2, []*PublicKey{key1.Pub, key2.Pub, key3.Pub})
	//make a fund
	rs.Pay([]*Key{txKey}, 0.05*gocoin.BTC, service)

    //get a raw transaction for signing.
	rawtx, tx, _:= rs.CreateRawTransactionHashed([]*gocoin.Amounts{&{gocoin.Amounts{"n3Bp1hbgtmwDtjQTpa6BnPPCA8fTymsiZy", 0.05*gocoin.BTC}}, service)

	//spend the fund
	sign1, _:= key2.Priv.Sign(rawtx)
	sign2, _:= key3.Priv.Sign(rawtx)
	rs.Spend(tx, [][]byte{nil, sign1, sign2}, service)
}

Micropayment Channel

import gocoin

func main(){
	service := gocoin.NewBlockrService(true)

	key1, _ := gocoin.GenerateKey(true) //payer
	key2, _ := gocoin.GenerateKey(true) //payee

	payer, _:= gocoin.NewMicropayer(key1, key2.Pub, service)
	payee, _:= gocoin.NewMicropayee(key2, key1.Pub, service)

	txHash, _:= payer.CreateBond([]*Key{key1}, 0.05*BTC)

	locktime := time.Now().Add(time.Hour)
	sign, _:= payee.SignToRefund(txHash, 0.05*gocoin.BTC-gocoin.Fee, uint32(locktime.Unix()))
	payer.SendBond(uint32(locktime.Unix()), sign) //return an error if payee's sig is invalid

	signIP, _:= payer.SignToIncrementedPayment(0.001 * gocoin.BTC)
	payee.IncrementPayment(0.001*gocoin.BTC, signIP) //return an error if payer's sig is invalid
	//more payments

	payee.SendLastPayment()
	//or
	//	payer.SendRefund() after locktime

}

Note:

payer.SendRefund() must be called after locktime.

http://chimera.labs.oreilly.com/books/1234000001802/ch05.html#tx_propagation

Transactions with locktime specifying a future block or time must be held by the originating system and transmitted to the bitcoin network only after they become valid.

Contribution

Improvements to the codebase and pull requests are encouraged.