Teku implements slashing protection to prevent validators from signing blocks or attestations based on what it has already signed.
By default, Teku also locks keystore files listed in the
--validator-keys option to prevent other processes from using it. You can enable and disable this functionality using the
Teku's slashing protection does not provide protection if the same validator key is being used by multiple nodes.
To protect validators from slashable offenses, Teku stores a record of the most recently signed blocks for each validator in the
<data-path>/validator/slashprotection/ directory. One YAML file is stored per validator in the format
<validator-pubkey>.yml (with no
<data-path> using the
--data-path command line option.
Teku also supports doppelganger detection to help prevent slashing. This is an early access feature.
Validator slashing protection file
The slashing protection file records multiple values that protects the validator from incorrectly signing blocks or attestations.
The following rules apply to the file:
- A validator signs a block only if the slot number is greater than
- A validator signs an attestation when the source epoch of the attestation is equal to or exceeds
lastSignedAttestationSourceEpoch, and the target epoch of the attestation is greater than
genesisValidatorsRootis a hash of the validators active at genesis, and is used to differentiate between different chains. Teku does not require this field to be present, but if it is present and differs from the required value, then Teku returns an error.
You can obtain the
genesisValidatorsRoot value by using the
These rules guarantee the validator does not sign anything that is slashable.
Migrate the slashing protection file
Between Teku nodes
If moving a validator from one Teku node to another, you can manually migrate the slashing protection file.
For example, to manually move the file from node A to node B:
- Stop Teku node A and confirm the process has fully exited and won't be restarted.
- Remove the validator key from node A, for example from the
- Copy the file from
- Start node B with the migrated validator key.
- Restart node A if required.
From a non-Teku node
If moving a validator from a different client to Teku, you can either:
- Manually create a new slashing protection file by setting the values based on the validator's last signing details.
- Import the slashing protection file.
To manually create the file, stop the other client to ensure it isn't signing, then set
lastSignedBlockSlot to the current chain head slot + 1,
lastSignedAttestationSourceEpoch to the current justified checkpoint, and set
lastSignedAttestationTargetEpoch to the current epoch + 1.
Start the Teku node with the validator key.