How to rotate Ethereum keys

Ethereum key rotation is a safety feature that allows validator nodes to manage their Ethereum keys. Every validator node in the network needs three keys: Ethereum, Tendermint and Vega. This section described to how to dynamically rotate a node's Ethereum key.

Key rotation is a cryptographic best practise that allows a current in-use key to be replaced by a new, different key. It is an activity that should be performed regularly to guard against an in-use key being unknowingly compromised.

Rotating a Node's Ethereum Key can be done by following the below steps:

1. Generate a new Ethereum key
2. Submit an Ethereum key rotation transaction to the network
3. Reload the node's Ethereum wallet
4. Confirm the key rotation with a data node
5. Resolve the key rotation on the MultisigControl Bridge

Prerequisites:

• An installed Vega binary ↗
• A running validator node with its admin server enabled
• The node wallet passphrases

Terminology:

• ETH_ADDR - The Ethereum address being rotated from
• ETH_NEW_ADDR - The Ethereum address being rotated to
• TARGET_BLOCK - The block in which the Ethereum key rotation will take place
• SUBMITTER_ADDR - An Ethereum address that will submit signatures to the MultisigControl Bridge
• DATA_NODE_REST_ADDR - The REST API address of any data node
• CLEF_ADDR - If rotating to a Clef Wallet, the address of the custom Clef instance

Generate a new Ethereum key

Vega supports both local key-store wallets and Clef Wallets. Ethereum key rotation can be performed between wallets of any type. For example you can rotate from an key in a local key-store wallet, to a key generated in a Clef wallet.

Using the nodewallet local key-store

The below command will generate a new Ethereum key in the local key-store:

vega nodewallet generate --chain ethereum --force

It will prompt for both the nodewallet's passphrase and the blockchain wallet's passphrase. The output from this command will look as follows:

ethereumAddress:
0xf0Ace753655495304d5e9794A96eD9791C51e091
walletFilePath:
VEGA_HOME/node/wallets/ethereum/UTC--2022-09-30T13-38-37.768971000Z--f0ace753655495304d5e9794a96ed9791c51e091
registryFilePath:
VEGA_HOME/node/wallets.encrypted

In this case ETH_NEW_ADDR will be 0xf0Ace753655495304d5e9794A96eD9791C51e091.

Using a Clef Wallet

The below command will generate a new Ethereum key inside a clef instance:

clef newaccount

The output of the command will print ETH_NEW_ADDR. This wallet and key can then be imported into the nodewallet using the below command:

vega nodewallet import -c ethereum --ethereum-clef-address http://$CLEF_ADDR  --ethereum-clef-account $ETH_NEW_ADDR --force

Submit Ethereum key rotation transaction to the network

The below command will send an Ethereum Key Rotation transaction into the network:

vega rotate_eth_key --target-block=$TARGET_BLOCK --submitter=$SUBMITTER_ADDR --rotate-from=$ETH_ADDR

TARGET_BLOCK is the block-height at which the key-rotation will occur in the Vega network and must be a block in the future. It is advised to choose a block-height that will be at a time where the below steps can be completed, and one that will not be close to an epoch boundary.

Reload Ethereum wallet in Vega validator node

Once the network reaches TARGET_BLOCK it will rotate the keys associating ETH_NEW_ADDR with the node. It is at this time that the following command needs to be run to rotate the key on the node itself:

vega nodewallet reload -c ethereum

danger

Whereas it is not necessary to reload the nodewallet exactly at TARGET_BLOCK doing so significantly early or significantly late may affect the node's performance scores and therefore the reward payout to that node.

Confirm a successful key rotation

To confirm that the key rotation occurred and to see that ETH_NEW_ADDR is now acknowledged by the network as the node's new Ethereum key, there are two end-points on a data node that can be used:

# this will show the details of all key rotations that have happened
$DATA_NODE_REST_ADDR/api/v2/vega/keys/ethereum/rotations`

# this will show the Ethereum key of each node and should now show ETH_NEW_ADDR
$DATA_NODE_REST_ADDR/api/v2/nodes`

Now that the Ethereuem key rotation is complete the node will produce signature bundles using the new Ethereum key from the new Ethereum nodewallet.

Resolve the key-rotation on the MultisigControl bridge

This section only applies if you are a consensus validator and your original Ethereum key is listed as a signer on the MultisigControl contract.

As a result of the key rotation process the network emits signature bundles that can be used to update the keys on the MultisigControl bridge. You need to notify the MultisigControl Bridge about the change by submitting signature bundles to remove ETH_ADDR and add ETH_NEW_ADDR

danger

Failure to remove ETH_ADDR or add ETH_NEW_ADDR before the end of the epoch will result in no reward payout for the node.

Retrieving the signature bundles from a datanode

The below two commands will return a signature bundle that will remove ETH_ADDR from the bridge and add NEW_ETH_ADDR, respectively:

curl -s $DATA_NODE_REST_ADDR/api/v2/erc20/multisigcontrol/signer/removed/bundles?submitter=$SUBMITTER_ADDR

curl -s $DATA_NODE_REST_ADDR/api/v2/erc20/multisigcontrol/signer/added/bundles?submitter=$SUBMITTER_ADDR

These signature bundles must be submitted to the MultisigControl bridge, and are cryptographically tied to SUBMITTER_ADDR. They can only be submitted to the contract using SUBMITTER_ADDR.

Requesting new signature bundles

If there is a reason that the signature bundles emitted for SUBMITTER_ADDR cannot be used, for example the wallet containing SUBMITTER_ADDR has been lost, it is possible to request from the network more signature bundles for a different SUBMITTER_ADDR.

Using the node's Vega wallet, the below command can be sent to the network to prompt the generation of new signature bundles:

{
    "issueSignatures": 
        {
            "submitter": "'$SUBMITTER_ADDR'", 
            "validatorNodeId": "'$NODE_ID'", 
            "kind": "REMOVE"
        }
}

These can then also be retrieved from a datanode.