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Key Assignment

Key Assignment (aka. as key delegation) allows validator operators to use different consensus keys for each consumer chain validator node that they operate. There are various reasons to use different consensus keys on different chains, but the main benefit is that validator's provider chain consensus key cannot be compromised if their consumer chain node (or other infrastructure) gets compromised. Interchain security module adds queries and transactions for assigning keys on consumer chains.

The feature is outlined in this ADR-001

By sending an AssignConsumerKey transaction, validators are able to indicate which consensus key they will be using to validate a consumer chain. On receiving the transaction, if the key assignment is valid, the provider will use the assigned consensus key when it sends future voting power updates to the consumer that involve the validator.

tip

Key assignment is handled only by the provider chain - the consumer chains are not aware of the fact that different consensus keys represent the same validator entity.

Rules

  • a key can be assigned as soon as the consumer addition proposal is submitted to the provider
  • validator A cannot assign consumer key K to consumer chain X if there is already a validator B (B!=A) using K on the provider
  • validator A cannot assign consumer key K to consumer chain X if there is already a validator B using K on X
  • a new validator on the provider cannot use a consensus key K if K is already used by any validator on any consumer chain
tip

Validators can use a different key for each consumer chain.

Adding a key

First, create a new node on the consumer chain using the equivalent:

consumerd init <moniker>

Then query your node for the consensus key.

consumerd tendermint show-validator # {"@type":"/cosmos.crypto.ed25519.PubKey","key":"<key>"}

Then, make an assign-consensus-key transaction on the provider chain in order to inform the provider chain about the consensus key you will be using for a specific consumer chain.

gaiad tx provider assign-consensus-key <consumer-chain-id> '<pubkey>' --from <tx-signer> --home <home_dir> --gas 900000 -b sync -y -o json
  • consumer-chain-id is the string identifier of the consumer chain, as assigned on the provider chain
  • consumer-pub-key has the following format {"@type":"/cosmos.crypto.ed25519.PubKey","key":"<key>"}

Check that the key was assigned correctly by querying the provider:

gaiad query provider validator-consumer-key <consumer-chain-id> cosmosvalcons1e....3xsj3ayzf4uv6

You must use a valcons address. You can obtain it by querying your node on the provider gaiad tendermint show-address

OR

gaiad query provider validator-provider-key <consumer-chain-id> consumervalcons1e....123asdnoaisdao

You must use a valcons address. You can obtain it by querying your node on the consumer consumerd tendermint show-address

OR

gaiad query provider all-pairs-valconsensus-address <consumer-chain-id>

You just need to use the chainId of consumer to query all pairs valconsensus address with consumer-pub-key for each of pair

Changing a key

To change your key, simply repeat all of the steps listed above. Take note that your old key will be remembered for at least the unbonding period of the consumer chain so any slashes can be correctly applied

Removing a key

To remove a key, simply switch it back to the consensus key you have assigned on the provider chain by following steps in the Adding a key section and using your provider consensus key.

warning

Validators are strongly recommended to assign a separate key for each consumer chain and not reuse the provider key across consumer chains for security reasons.

Querying proposed consumer chains

To query the consumer addition proposals that are in the voting period, you can use the following command on the provider:

gaiad query provider list-proposed-consumer-chains

This query is valuable for staying informed about when keys can be assigned to newly proposed consumer chains.