Files
breez-lnd/netann/node_signer.go
Oliver Gugger 8b7c88537c multi: refactor SignDigestCompact into SignMessageCompact
To make it possible to use a remote lnrpc server as a signer for our
wallet, we need to change our main interface to sign the message instead
of the message's digest. Otherwise we'd need to alter the
lnrpc.SignMessage RPC to accept a digest instead of only the message
which has security implications.
2021-10-08 12:06:52 +02:00

59 lines
1.8 KiB
Go

package netann
import (
"fmt"
"github.com/btcsuite/btcd/btcec"
"github.com/lightningnetwork/lnd/input"
"github.com/lightningnetwork/lnd/keychain"
"github.com/lightningnetwork/lnd/lnwallet"
)
// NodeSigner is an implementation of the MessageSigner interface backed by the
// identity private key of running lnd node.
type NodeSigner struct {
keySigner keychain.SingleKeyMessageSigner
}
// NewNodeSigner creates a new instance of the NodeSigner backed by the target
// private key.
func NewNodeSigner(keySigner keychain.SingleKeyMessageSigner) *NodeSigner {
return &NodeSigner{
keySigner: keySigner,
}
}
// SignMessage signs a double-sha256 digest of the passed msg under the
// resident node's private key. If the target public key is _not_ the node's
// private key, then an error will be returned.
func (n *NodeSigner) SignMessage(pubKey *btcec.PublicKey,
msg []byte) (input.Signature, error) {
// If this isn't our identity public key, then we'll exit early with an
// error as we can't sign with this key.
if !pubKey.IsEqual(n.keySigner.PubKey()) {
return nil, fmt.Errorf("unknown public key")
}
// Otherwise, we'll sign the double-sha256 of the target message.
sig, err := n.keySigner.SignMessage(msg, true)
if err != nil {
return nil, fmt.Errorf("can't sign the message: %v", err)
}
return sig, nil
}
// SignMessageCompact signs a single or double sha256 digest of the msg
// parameter under the resident node's private key. The returned signature is a
// pubkey-recoverable signature.
func (n *NodeSigner) SignMessageCompact(msg []byte, doubleHash bool) ([]byte,
error) {
return n.keySigner.SignMessageCompact(msg, doubleHash)
}
// A compile time check to ensure that NodeSigner implements the MessageSigner
// interface.
var _ lnwallet.MessageSigner = (*NodeSigner)(nil)