Lightspark

Coinbase will be using Lightspark’s remote-key signing implementation — with the Lightning signing keys entirely held by Coinbase, while Lightspark hosts their Lightning node.

Recovery kit

However, the password/key for your real-money, mainnet Lightning node–which is different from your Lightspark account password–is not recoverable, as Lightspark does not keep and does not have access to an unencrypted copy of this key. You should therefore maintain and store your mainnet Lightning node password securely. If you lose this password, you will not be able to access your funds and Lightspark will not be able to recover this password for you.

Lightspark utilizes operation signing to make the services easier to use, while still providing our customers with full control over their funds.