lnd: [lncli] unable to restore chan backups: rpc error: code = Unknown desc = unable to unpack chan backup: unable to derive shachain root key: unable to derive private key issue

Background

I had a db corruption issue and trying to recover from my SCB. Using the same seed and recovered the on-chain funds successfully. When attempting to restore off-chain via lncli create or restorechanbackup I get:

[lncli] unable to restore chan backups: rpc error: code = Unknown desc = unable to unpack chan backup: unable to derive shachain root key: unable to derive private key issue.

I found https://github.com/lightningnetwork/lnd/issues/3583 and I seem to be having a similar problem. It starts saving some of the channels back to disk but fails around the 5th one with that error and can’t continue. I’ve noticed that the channel point it fails on is a channel from 2018 - I’m curious if there are some backwards compatibility issues.

Any advice on where to go from here? Is there a way for me to edit my channel.backup and remove the old channels to see if that helps?

Your environment

version of lnd: 0.8.2-beta
which operating system (uname -a on *Nix): Ubuntu 18.04
version of btcd, bitcoind, or other backend: bitcoind 0.19.0.1
any other relevant environment details

Steps to reproduce

Try to recover channels from channel.backup on same seed using lncli create or restorechanbackup.

Expected behaviour

Recover channel.backup successfully.

Actual behaviour

[lncli] unable to restore chan backups: rpc error: code = Unknown desc = unable to unpack chan backup: unable to derive shachain root key: unable to derive private key issue.

2019-12-28 19:22:46.769 [INF] CHBU: Restoring ChannelPoint(removed) to disk: 2019-12-28 19:22:46.827 [INF] LTND: Inserting 1 SCB channel shells into DB 2019-12-28 19:22:46.827 [INF] CHBU: Restoring ChannelPoint(removed) to disk: 2019-12-28 19:22:46.899 [INF] LTND: Inserting 1 SCB channel shells into DB 2019-12-28 19:22:46.899 [INF] CHBU: Restoring ChannelPoint(removed) to disk: 2019-12-28 19:22:46.965 [INF] LTND: Inserting 1 SCB channel shells into DB 2019-12-28 19:22:46.965 [INF] CHBU: Restoring ChannelPoint(removed) to disk: 2019-12-28 19:22:47.023 [INF] LTND: Inserting 1 SCB channel shells into DB 2019-12-28 19:22:47.023 [INF] CHBU: Restoring ChannelPoint(removed) to disk: 2019-12-28 19:22:47.082 [INF] LTND: Inserting 1 SCB channel shells into DB 2019-12-28 19:22:47.083 [INF] CHBU: Restoring ChannelPoint(cb2a5f78d093234b9c3d6b9227b70573bb7cb0b1b2d3c369278c09a4198683cb:0) to disk:

And then I receive the previous error.

About this issue

Original URL
State: closed
Created 5 years ago
Reactions: 1
Comments: 16

Most upvoted comments

I think I found the problem. We changed how the ShaChainRootDesc is created in https://github.com/lightningnetwork/lnd/pull/769, which was released with version v0.4-beta. If you created the channel with version v0.3-beta or earlier, this would explain the behavior.

But as far as I know the SHA chain root is not really used if an SCB is restored since lnd initiates DLP and the remote party force-closes and hands over their per_commit_point. So I’m going to write a command that fixes this old channel by just writing any valid public key into the ShaChainRootDesc.

guggero on Jan 6, 2020

I’ve added a new derivekey command to the channel tool. Could you please run the following command (replace xprv... with your root key):

for i in {1..20000}; do chantools derivekey --neuter --rootkey xprv... --path m/1017\'/0\'/5\'/0/$i | grep Public >> keys.txt; done

This will take a few minutes depending on the speed of your machine. After it finishes, there will be a file keys.txt with the first 20k public keys. Could you check if 02faff90e2d7eb7dcd8c5ca5856179812d100ed25902042706a84c3b32ed6304f6 is in that list? And if so, at what line number? Thank you very much in advance!

guggero on Jan 4, 2020