Key recovery

Generally, validator keystore files are generated alongside a mnemonic. If the keystore and/or the keystore password are lost this mnemonic can regenerate a new, equivalent keystore with a new password.

There are two ways to recover keys using the lighthouse CLI:

  • lighthouse account validator recover: recover one or more EIP-2335 keystores from a mnemonic. These keys can be used directly in a validator client.
  • lighthouse account wallet recover: recover an EIP-2386 wallet from a mnemonic.

⚠️ Warning

Recovering validator keys from a mnemonic should only be used as a last resort. Key recovery entails significant risks:

  • Exposing your mnemonic to a computer at any time puts it at risk of being compromised. Your mnemonic is not encrypted and is a target for theft.
  • It's completely possible to regenerate a validator keypairs that is already active on some other validator client. Running the same keypairs on two different validator clients is very likely to result in slashing.

Recover EIP-2335 validator keystores

A single mnemonic can generate a practically unlimited number of validator keystores using an index. Generally, the first time you generate a keystore you'll use index 0, the next time you'll use index 1, and so on. Using the same index on the same mnemonic always results in the same validator keypair being generated (see EIP-2334 for more detail).

Using the lighthouse account validator recover command you can generate the keystores that correspond to one or more indices in the mnemonic:

  • lighthouse account validator recover: recover only index 0.
  • lighthouse account validator recover --count 2: recover indices 0, 1.
  • lighthouse account validator recover --first-index 1: recover only index 1.
  • lighthouse account validator recover --first-index 1 --count 2: recover indices 1, 2.

For each of the indices recovered in the above commands, a directory will be created in the --validator-dir location (default ~/.lighthouse/{testnet}/validators) which contains all the information necessary to run a validator using the lighthouse vc command. The password to this new keystore will be placed in the --secrets-dir (default ~/.lighthouse/{testnet}/secrets).

where testnet is the name of the testnet passed in the --testnet parameter (default is medalla).

Recover a EIP-2386 wallet

Instead of creating EIP-2335 keystores directly, an EIP-2386 wallet can be generated from the mnemonic. This wallet can then be used to generate validator keystores, if desired. For example, the following command will create an encrypted wallet named wally-recovered from a mnemonic:

lighthouse account wallet recover --name wally-recovered

⚠️ Warning: the wallet will be created with a nextaccount value of 0. This means that if you have already generated n validators, then the next n validators generated by this wallet will be duplicates. As mentioned previously, running duplicate validators is likely to result in slashing.