lnd.xprv/discovery/ann_validation.go

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package discovery
import (
"bytes"
"github.com/davecgh/go-spew/spew"
"github.com/go-errors/errors"
"github.com/lightningnetwork/lnd/lnwire"
"github.com/btcsuite/btcd/btcec"
"github.com/btcsuite/btcd/chaincfg/chainhash"
)
// ValidateChannelAnn validates the channel announcement message and checks
// that node signatures covers the announcement message, and that the bitcoin
// signatures covers the node keys.
func ValidateChannelAnn(a *lnwire.ChannelAnnouncement) error {
// First, we'll compute the digest (h) which is to be signed by each of
// the keys included within the node announcement message. This hash
// digest includes all the keys, so the (up to 4 signatures) will
// attest to the validity of each of the keys.
data, err := a.DataToSign()
if err != nil {
return err
}
dataHash := chainhash.DoubleHashB(data)
// First we'll verify that the passed bitcoin key signature is indeed a
// signature over the computed hash digest.
bitcoinSig1, err := a.BitcoinSig1.ToSignature()
if err != nil {
return err
}
bitcoinKey1, err := btcec.ParsePubKey(a.BitcoinKey1[:], btcec.S256())
if err != nil {
return err
}
if !bitcoinSig1.Verify(dataHash, bitcoinKey1) {
return errors.New("can't verify first bitcoin signature")
}
// If that checks out, then we'll verify that the second bitcoin
// signature is a valid signature of the bitcoin public key over hash
// digest as well.
bitcoinSig2, err := a.BitcoinSig2.ToSignature()
if err != nil {
return err
}
bitcoinKey2, err := btcec.ParsePubKey(a.BitcoinKey2[:], btcec.S256())
if err != nil {
return err
}
if !bitcoinSig2.Verify(dataHash, bitcoinKey2) {
return errors.New("can't verify second bitcoin signature")
}
// Both node signatures attached should indeed be a valid signature
// over the selected digest of the channel announcement signature.
nodeSig1, err := a.NodeSig1.ToSignature()
if err != nil {
return err
}
nodeKey1, err := btcec.ParsePubKey(a.NodeID1[:], btcec.S256())
if err != nil {
return err
}
if !nodeSig1.Verify(dataHash, nodeKey1) {
return errors.New("can't verify data in first node signature")
}
nodeSig2, err := a.NodeSig2.ToSignature()
if err != nil {
return err
}
nodeKey2, err := btcec.ParsePubKey(a.NodeID2[:], btcec.S256())
if err != nil {
return err
}
if !nodeSig2.Verify(dataHash, nodeKey2) {
return errors.New("can't verify data in second node signature")
}
return nil
}
// ValidateNodeAnn validates the node announcement by ensuring that the
// attached signature is needed a signature of the node announcement under the
// specified node public key.
func ValidateNodeAnn(a *lnwire.NodeAnnouncement) error {
// Reconstruct the data of announcement which should be covered by the
// signature so we can verify the signature shortly below
data, err := a.DataToSign()
if err != nil {
return err
}
nodeSig, err := a.Signature.ToSignature()
if err != nil {
return err
}
nodeKey, err := btcec.ParsePubKey(a.NodeID[:], btcec.S256())
if err != nil {
return err
}
// Finally ensure that the passed signature is valid, if not we'll
// return an error so this node announcement can be rejected.
dataHash := chainhash.DoubleHashB(data)
if !nodeSig.Verify(dataHash, nodeKey) {
var msgBuf bytes.Buffer
if _, err := lnwire.WriteMessage(&msgBuf, a, 0); err != nil {
return err
}
return errors.Errorf("signature on NodeAnnouncement(%x) is "+
"invalid: %x", nodeKey.SerializeCompressed(),
msgBuf.Bytes())
}
return nil
}
// ValidateChannelUpdateAnn validates the channel update announcement by
// checking that the included signature covers he announcement and has been
// signed by the node's private key.
func ValidateChannelUpdateAnn(pubKey *btcec.PublicKey,
a *lnwire.ChannelUpdate) error {
data, err := a.DataToSign()
if err != nil {
return errors.Errorf("unable to reconstruct message: %v", err)
}
dataHash := chainhash.DoubleHashB(data)
nodeSig, err := a.Signature.ToSignature()
if err != nil {
return err
}
if !nodeSig.Verify(dataHash, pubKey) {
return errors.Errorf("invalid signature for channel "+
"update %v", spew.Sdump(a))
}
return nil
}