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multi: store KeyLocator in OpenChannel, use ECDH

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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.
This commit is contained in:
eugene
2020-10-21 13:34:05 -04:00
parent 986e69c81b
commit bb84f0ebc8
6 changed files with 183 additions and 58 deletions
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66
chanrestore.go
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@@ -48,20 +48,7 @@ type chanDBRestorer struct {
func (c *chanDBRestorer) openChannelShell(backup chanbackup.Single) (
*channeldb.ChannelShell, error) {
// First, we'll also need to obtain the private key for the shachain
// root from the encoded public key.
//
// TODO(roasbeef): now adds req for hardware signers to impl
// shachain...
privKey, err := c.secretKeys.DerivePrivKey(backup.ShaChainRootDesc)
if err != nil {
return nil, fmt.Errorf("unable to derive shachain root key: %v", err)
}
revRoot, err := chainhash.NewHash(privKey.Serialize())
if err != nil {
return nil, err
}
shaChainProducer := shachain.NewRevocationProducer(*revRoot)
var err error
// Each of the keys in our local channel config only have their
// locators populate, so we'll re-derive the raw key now as we'll need
@@ -97,6 +84,53 @@ func (c *chanDBRestorer) openChannelShell(backup chanbackup.Single) (
return nil, fmt.Errorf("unable to derive htlc key: %v", err)
}
// The shachain root that seeds RevocationProducer for this channel.
// It currently has two possible formats.
var revRoot *chainhash.Hash
// If the PubKey field is non-nil, then this shachain root is using the
// legacy non-ECDH scheme.
if backup.ShaChainRootDesc.PubKey != nil {
ltndLog.Debugf("Using legacy revocation producer format for "+
"channel point %v", backup.FundingOutpoint)
// Obtain the private key for the shachain root from the
// encoded public key.
privKey, err := c.secretKeys.DerivePrivKey(
backup.ShaChainRootDesc,
)
if err != nil {
return nil, fmt.Errorf("could not derive private key "+
"for legacy channel revocation root format: "+
"%v", err)
}
revRoot, err = chainhash.NewHash(privKey.Serialize())
if err != nil {
return nil, err
}
} else {
ltndLog.Debugf("Using new ECDH revocation producer format "+
"for channel point %v", backup.FundingOutpoint)
// This is the scheme in which the shachain root is derived via
// an ECDH operation on the private key of ShaChainRootDesc and
// our public multisig key.
ecdh, err := c.secretKeys.ECDH(
backup.ShaChainRootDesc,
backup.LocalChanCfg.MultiSigKey.PubKey,
)
if err != nil {
return nil, fmt.Errorf("unable to derive shachain "+
"root: %v", err)
}
ch := chainhash.Hash(ecdh)
revRoot = &ch
}
shaChainProducer := shachain.NewRevocationProducer(*revRoot)
var chanType channeldb.ChannelType
switch backup.Version {
@@ -119,8 +153,8 @@ func (c *chanDBRestorer) openChannelShell(backup chanbackup.Single) (
return nil, fmt.Errorf("unknown Single version: %v", err)
}
ltndLog.Infof("SCB Recovery: created channel shell for ChannelPoint(%v), "+
"chan_type=%v", backup.FundingOutpoint, chanType)
ltndLog.Infof("SCB Recovery: created channel shell for ChannelPoint"+
"(%v), chan_type=%v", backup.FundingOutpoint, chanType)
chanShell := channeldb.ChannelShell{
NodeAddrs: backup.Addresses,