lnd/lnwallet/revocation_producer.go
eugene bb84f0ebc8
multi: store KeyLocator in OpenChannel, use ECDH
This commit adds a RevocationKeyLocator field to the OpenChannel
struct so that the SCB derivation doesn't have to brute-force the
sha chain root key and match the public key. ECDH derivation is now
used to derive the key instead of regular private key derivation a
la DerivePrivKey. The legacy can still be used to recover old
channels.
2021-03-05 12:49:18 -05:00

52 lines
1.5 KiB
Go

// +build !rpctest
package lnwallet
import (
"github.com/lightningnetwork/lnd/keychain"
"github.com/lightningnetwork/lnd/shachain"
)
// nextRevocationProducer creates a new revocation producer, deriving the
// revocation root by applying ECDH to a new key from our revocation root family
// and the multisig key we use for the channel.
func (l *LightningWallet) nextRevocationProducer(res *ChannelReservation,
keyRing keychain.KeyRing) (shachain.Producer, error) {
// Derive the next key in the revocation root family.
nextRevocationKeyDesc, err := keyRing.DeriveNextKey(
keychain.KeyFamilyRevocationRoot,
)
if err != nil {
return nil, err
}
// If the DeriveNextKey call returns the first key with Index 0, we need
// to re-derive the key as the keychain/btcwallet.go DerivePrivKey call
// special-cases Index 0.
if nextRevocationKeyDesc.Index == 0 {
nextRevocationKeyDesc, err = keyRing.DeriveNextKey(
keychain.KeyFamilyRevocationRoot,
)
if err != nil {
return nil, err
}
}
res.nextRevocationKeyLoc = nextRevocationKeyDesc.KeyLocator
// Perform an ECDH operation between the private key described in
// nextRevocationKeyDesc and our public multisig key. The result will be
// used to seed the revocation producer.
revRoot, err := l.ECDH(
nextRevocationKeyDesc, res.ourContribution.MultiSigKey.PubKey,
)
if err != nil {
return nil, err
}
// Once we have the root, we can then generate our shachain producer
// and from that generate the per-commitment point.
return shachain.NewRevocationProducer(revRoot), nil
}