lnd.xprv/watchtower/wtmock/keyring.go
2020-05-20 09:05:15 +02:00

99 lines
2.5 KiB
Go

package wtmock
import (
"sync"
"github.com/btcsuite/btcd/btcec"
"github.com/lightningnetwork/lnd/keychain"
)
// SecretKeyRing is a mock, in-memory implementation for deriving private keys.
type SecretKeyRing struct {
mu sync.Mutex
keys map[keychain.KeyLocator]*btcec.PrivateKey
}
// NewSecretKeyRing creates a new mock SecretKeyRing.
func NewSecretKeyRing() *SecretKeyRing {
return &SecretKeyRing{
keys: make(map[keychain.KeyLocator]*btcec.PrivateKey),
}
}
// DerivePrivKey derives the private key for a given key descriptor. If
// this method is called twice with the same argument, it will return the same
// private key.
func (m *SecretKeyRing) DerivePrivKey(
desc keychain.KeyDescriptor) (*btcec.PrivateKey, error) {
m.mu.Lock()
defer m.mu.Unlock()
if key, ok := m.keys[desc.KeyLocator]; ok {
return key, nil
}
privKey, err := btcec.NewPrivateKey(btcec.S256())
if err != nil {
return nil, err
}
m.keys[desc.KeyLocator] = privKey
return privKey, nil
}
// DeriveKey attempts to derive an arbitrary key specified by the
// passed KeyLocator. This may be used in several recovery scenarios,
// or when manually rotating something like our current default node
// key.
//
// NOTE: This is part of the wtclient.ECDHKeyRing interface.
func (m *SecretKeyRing) DeriveKey(
keyLoc keychain.KeyLocator) (keychain.KeyDescriptor, error) {
m.mu.Lock()
defer m.mu.Unlock()
if key, ok := m.keys[keyLoc]; ok {
return keychain.KeyDescriptor{
KeyLocator: keyLoc,
PubKey: key.PubKey(),
}, nil
}
privKey, err := btcec.NewPrivateKey(btcec.S256())
if err != nil {
return keychain.KeyDescriptor{}, err
}
m.keys[keyLoc] = privKey
return keychain.KeyDescriptor{
KeyLocator: keyLoc,
PubKey: privKey.PubKey(),
}, nil
}
// ECDH performs a scalar multiplication (ECDH-like operation) between the
// target key descriptor and remote public key. The output returned will be the
// sha256 of the resulting shared point serialized in compressed format. If k is
// our private key, and P is the public key, we perform the following operation:
//
// sx := k*P
// s := sha256(sx.SerializeCompressed())
//
// NOTE: This is part of the wtclient.ECDHKeyRing interface.
func (m *SecretKeyRing) ECDH(keyDesc keychain.KeyDescriptor,
pub *btcec.PublicKey) ([32]byte, error) {
_, err := m.DeriveKey(keyDesc.KeyLocator)
if err != nil {
return [32]byte{}, err
}
privKey := m.keys[keyDesc.KeyLocator]
ecdh := &keychain.PrivKeyECDH{PrivKey: privKey}
return ecdh.ECDH(pub)
}