What are Static Channel Backups?

The initial implementation of static channel backups ("SCB") isn't perfect, but it allows for recovering funds in Lightning channels in case your node hard drive is corrupted.

Each time you open a channel, your node saves that initial data to the backup file. We are currently saving this backup file directly to the Casa Node's SD card, but in the future could offer other forms of backup.

When you restore a node using SCB, your node checks the information for each channel to find the channel partner—the node on the other end of the channel. It then asks each channel partner to force close the channel they had open with you, resulting in the channel funds being deposited to your on-chain BTC wallet.

There are two downsides to this:

  1. To recover your funds in channels, your channels have to close, which can take some time. Then you need to reopen channels to get reconnected to the network.
  2. Your node doesn't know the current balance in each channel, only the opening channel balance. This means you're relying on the partner node to truthfully broadcast the latest balance in the channel. While it's unlikely, the partner could try to steal funds from you, since your node doesn't know the latest balance. This risk will be mitigated when watchtowers are added in a future release of LND.

Static channel backups are still in an early state, and the Lightning Labs team has some improvements in the works. For now, this is a big step forward in keeping your Lightning funds secure.

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