bip32

This example demonstrates the audits use case in BIP0032.

package main

import (
	"fmt"

	"github.com/sammyne/bip32"
)

func main() {
	// The audits use case described in BIP0032 is:
	//
	// In case an auditor needs full access to the list of incoming and
	// outgoing payments, one can share all account public extended keys.
	// This will allow the auditor to see all transactions from and to the
	// wallet, in all accounts, but not a single secret key.
	//
	//   * N(m/*)
	//   corresponds to the neutered master extended key (also called
	//   the master public extended key)

	// Ordinarily this would either be read from some encrypted source
	// and be decrypted or generated as the NewMasterKey example shows, but
	// for the purposes of this example, the private extended key for the
	// master node is being hard coded here.
	master := "xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jP" +
		"PqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi"

	// Start by getting an extended key instance for the master node.
	// This gives the path:
	//   m
	masterKey, err := bip32.ParsePrivateKey(master)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Neuter the master key to generate a master public extended key.  This
	// gives the path:
	//   N(m/*)
	masterPubKey, err := masterKey.Neuter()
	if err != nil {
		fmt.Println(err)
		return
	}

	// Share the master public extended key with the auditor.
	fmt.Println("Audit key N(m/*):", masterPubKey)

}

Output:

Audit key N(m/*): xpub661MyMwAqRbcFtXgS5sYJABqqG9YLmC4Q1Rdap9gSE8NqtwybGhePY2gZ29ESFjqJoCu1Rupje8YtGqsefD265TMg7usUDFdp6W1EGMcet8

This example demonstrates the default hierarchical deterministic wallet layout as described in BIP0032.

package main

import (
	"fmt"

	"github.com/sammyne/base58"

	"github.com/sammyne/bip32"
)

func main() {
	// The default wallet layout described in BIP0032 is:
	//
	// Each account is composed of two keypair chains: an internal and an
	// external one. The external keychain is used to generate new public
	// addresses, while the internal keychain is used for all other
	// operations (change addresses, generation addresses, ..., anything
	// that doesn't need to be communicated).
	//
	//   * m/iH/0/k
	//     corresponds to the k'th keypair of the external chain of account
	//     number i of the HDW derived from master m.
	//   * m/iH/1/k
	//     corresponds to the k'th keypair of the internal chain of account
	//     number i of the HDW derived from master m.

	// Ordinarily this would either be read from some encrypted source
	// and be decrypted or generated as the NewMasterKey example shows, but
	// for the purposes of this example, the private extended key for the
	// master node is being hard coded here.
	// This is a base58-check encoded private key
	master58 := "xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jP" +
		"PqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi"

	// Start by getting an extended key instance for the master node.
	// This gives the path:
	//   m
	masterKey, err := bip32.ParsePrivateKey(master58)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Derive the extended key for account 0.  This gives the path:
	//   m/0H
	acct0, err := masterKey.Child(bip32.HardenIndex(0))
	if err != nil {
		fmt.Println(err)
		return
	}

	// Derive the extended key for the account 0 external chain.  This
	// gives the path:
	//   m/0H/0
	acct0Ext, err := acct0.Child(0)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Derive the extended key for the account 0 internal chain.  This gives
	// the path:
	//   m/0H/1
	acct0Int, err := acct0.Child(1)
	if err != nil {
		fmt.Println(err)
		return
	}

	// At this point, acct0Ext and acct0Int are ready to derive the keys for
	// the external and internal wallet chains.

	// Derive the 10th extended key for the account 0 external chain.  This
	// gives the path:
	//   m/0H/0/10
	acct0Ext10, err := acct0Ext.Child(10)
	if err != nil {
		fmt.Println(err)
		return
	}

	// Derive the 0th extended key for the account 0 internal chain.  This
	// gives the path:
	//   m/0H/1/0
	acct0Int0, err := acct0Int.Child(0)
	if err != nil {
		fmt.Println(err)
		return
	}

	const mainNetID = 0x00
	// Get and show the address associated with the extended keys for the
	// main bitcoin	network.
	acct0ExtAddr := base58.CheckEncode(acct0Ext10.AddressPubKeyHash(), mainNetID)
	acct0IntAddr := base58.CheckEncode(acct0Int0.AddressPubKeyHash(), mainNetID)

	const format = `
Account %d %s Address %d
  - address: %s
  - depth: %d
  - hardened: %v
  - for main net: %v
`

	fmt.Printf(format, 0, "External", acct0Ext10.Index(), acct0ExtAddr,
		acct0Ext10.Depth(), acct0Ext10.Hardened(),
		acct0Ext10.IsForNet(*bip32.MainNetPrivateKey))
	fmt.Printf(format, 0, "Internal", acct0Int0.Index(), acct0IntAddr,
		acct0Int0.Depth(), acct0Int0.Hardened(),
		acct0Int0.IsForNet(*bip32.MainNetPrivateKey))

}

Output:

Account 0 External Address 10
  - address: 1HVccubUT8iKTapMJ5AnNA4sLRN27xzQ4F
  - depth: 3
  - hardened: false
  - for main net: true

Account 0 Internal Address 0
  - address: 1J5rebbkQaunJTUoNVREDbeB49DqMNFFXk
  - depth: 3
  - hardened: false
  - for main net: true