kmbjz / go-bip32

Golang implementation of the BIP32 HD address spec

go-bip32

An implementation of the BIP32 spec for Hierarchical Deterministic Bitcoin addresses as a simple Go library. The semantics of derived keys are up to the user. BIP43 and BIP44 are good schemes to implement with this library. An additional library for either or both of those on top of this library should be developed.

Example

It's very unlikely, but possible, that a given index does not produce a valid private key. Error checking is skipped in this example for brevity but should be handled in real code. In such a case, a ErrInvalidPrivateKey is returned.

ErrInvalidPrivateKey should be handled by trying the next index for a child key.

Any valid private key will have a valid public key so that Key.PublicKey() method never returns an error.

package main

import (
  "github.com/tyler-smith/go-bip32"
  "fmt"
  "log"
)

// Example address creation for a fictitious company ComputerVoice Inc. where
// each department has their own wallet to manage
func main(){
  // Generate a seed to determine all keys from.
  // This should be persisted, backed up, and secured
  seed, err := bip32.NewSeed()
  if err != nil {
    log.Fatalln("Error generating seed:", err)
  }

  // Create master private key from seed
  computerVoiceMasterKey, _ := bip32.NewMasterKey(seed)

  // Map departments to keys
  // There is a very small chance a given child index is invalid
  // If so your real program should handle this by skipping the index
  departmentKeys := map[string]*bip32.Key{}
  departmentKeys["Sales"], _ = computerVoiceMasterKey.NewChildKey(0)
  departmentKeys["Marketing"], _ = computerVoiceMasterKey.NewChildKey(1)
  departmentKeys["Engineering"], _ = computerVoiceMasterKey.NewChildKey(2)
  departmentKeys["Customer Support"], _ = computerVoiceMasterKey.NewChildKey(3)

  // Create public keys for record keeping, auditors, payroll, etc
  departmentAuditKeys := map[string]*bip32.Key{}
  departmentAuditKeys["Sales"] = departmentKeys["Sales"].PublicKey()
  departmentAuditKeys["Marketing"] = departmentKeys["Marketing"].PublicKey()
  departmentAuditKeys["Engineering"] = departmentKeys["Engineering"].PublicKey()
  departmentAuditKeys["Customer Support"] = departmentKeys["Customer Support"].PublicKey()

  // Print public keys
  for department, pubKey := range departmentAuditKeys {
    fmt.Println(department, pubKey)
  }
}

Thanks

The developers at Factom have contributed a lot to this library and have made many great improvements to it. Please check out their project(s) and give them a thanks if you use this library.

Thanks to bartekn from Stellar for some important bug catches.