bip25519

Documentation

Overview

Package bip25519 deals with BIP32-Ed25519 keys as specified in paper by Khovratovich and Law. Private key generated by this package are in an expanded form and can't be used with most of standard crypto tools and libraries

Example

package main

import (
	"crypto"
	"crypto/ed25519"
	"crypto/rand"
	"crypto/sha256"
	"encoding/hex"
	"fmt"

	"github.com/ecadlabs/hdw"
	"github.com/ecadlabs/hdw/bip25519"
)

var seedData = "fffcf9f6f3f0edeae7e4e1dedbd8d5d2cfccc9c6c3c0bdbab7b4b1aeaba8a5a29f9c999693908d8a8784817e7b7875726f6c696663605d5a5754514e4b484542"

func main() {
	// alternatively use hdw.NewSeedFromMnemonic
	seed, err := hex.DecodeString(seedData)
	if err != nil {
		panic(err)
	}

	// generate the root key
	root := bip25519.NewKeyFromSeed(seed, nil)
	if root == nil {
		panic("unusable seed")
	}

	path := hdw.Path{0, 1, 2}
	// generate the derivative child private key
	priv, err := root.DerivePath(path)
	if err != nil {
		panic(err)
	}

	digest := sha256.Sum256([]byte("text"))
	sig, err := priv.Sign(rand.Reader, digest[:], crypto.Hash(0))
	if err != nil {
		panic(err)
	}

	// get the corresponding public key
	pub := priv.Public()

	// verify the signature
	ok := ed25519.Verify(pub.(ed25519.PublicKey), digest[:], sig)
	fmt.Printf("signature ok: %t\n", ok)

	// derive the public key from the root's public
	pub2, err := root.ExtendedPublic().DerivePath(path)
	if err != nil {
		panic(err)
	}
	// verify the signature
	ok = ed25519.Verify(pub2.Naked().(ed25519.PublicKey), digest[:], sig)
	fmt.Printf("signature ok: %t\n", ok)
}

Output:

signature ok: true
signature ok: true

Index

• Constants
• type Mode
• type Options
• type PrivateKey
  • func NewKeyFromSeed(seed []byte, opt *Options) *PrivateKey
  • func (p *PrivateKey) Chain() []byte
  • func (p *PrivateKey) Derive(index uint32) (hdw.PrivateKey, error)
  • func (s *PrivateKey) DerivePath(path hdw.Path) (hdw.PrivateKey, error)
  • func (p *PrivateKey) ExtendedPublic() hdw.PublicKey
  • func (p *PrivateKey) Naked() crypto.PrivateKey
• type PublicKey
  • func (p *PublicKey) Chain() []byte
  • func (p *PublicKey) Derive(index uint32) (hdw.PublicKey, error)
  • func (s *PublicKey) DerivePath(path hdw.Path) (hdw.PublicKey, error)
  • func (p *PublicKey) Naked() crypto.PublicKey

Examples

• Package

Constants

const (
	// MinSeedSize is the minimal allowed seed byte length
	MinSeedSize = 32
)

Types

type Mode

type Mode int

Mode is the mode of root key generation

const (
	ModeDefault Mode = iota // NewKeyFromSeed will return nil if the seed gave an unusable hash as specified in original paper by Khovratovich and Law
	ModeRetry               // NewKeyFromSeed will rehash the result if the first attempt gave an unusable hash
	ModeForce               // Clear undesired bits of the hash and continue
)

type Options

type Options struct {
	Mode Mode
	HMAC bool // Use HMAC with "ed25519 seed" phrase as a key instead of plain SHA512/SHA256 to generate the root key
}

type PrivateKey

type PrivateKey struct {
	ex25519.PrivateKey
	ChainCode []byte
}

PrivateKey is the extended Ed25519 private key. It implements hdw.PrivateKey

func NewKeyFromSeed

func NewKeyFromSeed(seed []byte, opt *Options) *PrivateKey

NewKeyFromSeed generates the root key from the seed

func (*PrivateKey) Chain

func (p *PrivateKey) Chain() []byte

Chain returns the chain code

func (*PrivateKey) Derive

func (p *PrivateKey) Derive(index uint32) (hdw.PrivateKey, error)

Derive returns a child key of the receiver using a single index

func (*PrivateKey) DerivePath

func (s *PrivateKey) DerivePath(path hdw.Path) (hdw.PrivateKey, error)

Derive returns a child key of the receiver using a full path

func (*PrivateKey) ExtendedPublic

func (p *PrivateKey) ExtendedPublic() hdw.PublicKey

ExtendedPublic returns the extended public key corresponding to the receiver

func (*PrivateKey) Naked

func (p *PrivateKey) Naked() crypto.PrivateKey

Naked returns the naked private key of type ex25519.PrivateKey. This type implements crypto.Signer but it can't be used with the standard crypto library as it keeps the key data in expanded form which is equivalent to the Ed25519 post-hash 512 bit value

type PublicKey

type PublicKey struct {
	ed25519.PublicKey
	ChainCode []byte
}

PublicKey is the extended Ed25519 public key. It implements hdw.PublicKey

func (*PublicKey) Chain

func (p *PublicKey) Chain() []byte

Chain returns the chain code

func (*PublicKey) Derive

func (p *PublicKey) Derive(index uint32) (hdw.PublicKey, error)

Derive returns a child key of the receiver using a single index

func (*PublicKey) DerivePath

func (s *PublicKey) DerivePath(path hdw.Path) (hdw.PublicKey, error)

Derive returns a child key of the receiver using a full path

func (*PublicKey) Naked

func (p *PublicKey) Naked() crypto.PublicKey

Naked returns the naked private key that can be used with the standard Go crypto library