eth-staking-smith

Introduction

Command-line tool to facilitate key and deposit data generation for ethereum proof-of-stake validators.

Why we need yet another keystore / deposit tool:

1. eth-staking-smith is written in Rust
2. ability to use as a library to automate key and deposit data generation
3. opt-out of writing to filesystem for better security
4. defer entropy collection to operating system by using getrandom
5. ability to overwrite withdrawal credentials for new and existing mnemonic
6. ability to generate a SignedBLSToExecutionChange message to convert your BLS withdrawal address 0x00 to an execution 0x01 address

Blog post

Performant Ethereum validator key management

Usage

cargo build

New mnemonic

Generate key and deposit data with a new mnemonic:

./target/debug/eth-staking-smith new-mnemonic --help

Example command:

./target/debug/eth-staking-smith new-mnemonic --chain mainnet --keystore_password testtest --num_validators 1

Existing mnemonic

Regenerate key and deposit data with existing mnemonic:

./target/debug/eth-staking-smith existing-mnemonic --help

Example command:

./target/debug/eth-staking-smith existing-mnemonic --chain mainnet --keystore_password testtest --mnemonic "entire habit bottom mention spoil clown finger wheat motion fox axis mechanic country make garment bar blind stadium sugar water scissors canyon often ketchup" --num_validators 1 --withdrawal_credentials "0x0100000000000000000000000000000000000000000000000000000000000001"

Using custom testnet config

Both existing-mnemonic and new-mnemonic commands support generating validators for custom testnets. To reference custom testnet config yaml file, pass --testnet_config parameter with that config as value, and omit --chain parameter:

Example command

./target/debug/eth-staking-smith new-mnemonic --testnet_config /etc/privatenet/config.yaml --keystore_password testtest --num_validators 1 --withdrawal_credentials "0x0100000000000000000000000000000000000000000000000000000000000001"

Converting your BLS 0x00 withdrawal address

Ethereum will be implementing a push-based approach for withdrawals, see EIP-4895 docs.

Those who have configured a BLS withdrawal address (0x00) in the validators deposit contract, will have to undergo the following steps:

1. generate a signed message to trigger BLS to execution address
2. send the signed message to the beacon node

You can use eth-staking-smith as follows to convert your address:

Command to generate SignedBLSToExecutionChange

./target/debug/eth-staking-smith bls-to-execution-change --chain mainnet --mnemonic "entire habit bottom mention spoil clown finger wheat motion fox axis mechanic country make garment bar blind stadium sugar water scissors canyon often ketchup" --validator_start_index 0 --validator_index 100 --withdrawal_credentials "0x0045b91b2f60b88e7392d49ae1364b55e713d06f30e563f9f99e10994b26221d"
--execution_address "0x71C7656EC7ab88b098defB751B7401B5f6d8976F"

Note that --validator-index and --validator-start-index are two distinct parameter, the former being index of validator on Beacon chain, and the latter is the index of validator private key derived from the seed

Exporting CLI standard output into common keystores folder format

Most validator clients recognize the keystore folder format, produced by upstream Python deposit CLI. While eth-staking-smith outputs all validator data into standard output, allowing for better security in enterprise setups, for small and individual stakers this is not convenient, as they need to be able to import validator keys directly into validator client.

To address such needs, eth-staking-smith provides convenience Python3 script to export JSON validator output into common keystore folder format. It should work on any box with Python 3.10+ installed.

mkdir validator_keys/
./target/debug/eth-staking-smith new-mnemonic --chain holesky --num_validators 2 \
  --keystore_password test > validator_secrets.json
cat validator_secrets.json | python3 scripts/generate_keys_folder.py
cat validator_secrets.json | jq .mnemonic.seed > mnemonic.txt
rm validator_secrets.json
echo "MAKE SURE TO BACK UP mnemonic.text IN THE SAFE PLACE"

ls validator_keys/
deposit_data-1720014619.json  keystore-m_12381_3600_0_0_0-1720014619.json  keystore-m_12381_3600_1_0_0-1720014619.json

The contents of validator_keys/ folder might be imported into most validator clients, for example Lighthouse import command will look like that:

echo "test" > ./password.txt
lighthouse account validator import \
  --network holesky --reuse-password
  --directory validator_keys/ --password-file ./password.txt

Command to send SignedBLSToExecutionChange request to Beacon node

curl -H "Content-Type: application/json" -d '{
  "message": {
    "validator_index": 100,
    "from_bls_pubkey": "0x0045b91b2f60b88e7392d49ae1364b55e713d06f30e563f9f99e10994b26221d",
    "to_execution_address": "0x71C7656EC7ab88b098defB751B7401B5f6d8976F"
  },
  "signature": "0x9220e5badefdfe8abc36cae01af29b981edeb940ff88c438f72c8af876fbd6416138c85f5348c5ace92a081fa15291aa0ffb856141b871dc807f3ec2fe9c8415cac3d76579c61455ab3938bc162e139d060c8aa13fcd670febe46bf0bb579c5a"
}' http://localhost:3500/eth/v1/beacon/pool/bls_to_execution_change

Implementation Details

To avoid heavy lifting, we're interfacing Lighthouse account manager, but optimizing it in a way so all operations are done in memory and key material is never written to filesystem during the generation to cater for our use case.

Entropy gathering

When you run the command new-mnemonic a new mnemonic is generated from a seed. Entropy collection for the given seed is done by using the platform dependent getrandom(2) system call. On Linux, getrandom(2) pulls entropy from cryptographically secure RNG provided by Linux kernel, which implements ChaCha based PRNG algorithm that reseeds itself from multiple hardware TRNG sources with 300Hz frequency. If you're running on anything other than Linux, look up target platform implementation in https://github.com/rust-random/getrandom for details.

Ability to tweak performance parameters

Specifically, we have two arguments you may use for improving performance during key generation:

1. You can opt-out of generating keystores by omitting the optional --keystore_password argument. Depending on how you manage your keys you would either store them as keystore files or simply store the private keys in vault. If you're doing the latter it would be more optimal for you to bypass the keystore generation and only retrieve the private keys such that you can store them in vault.
2. To speed up the process of keystore generation, you may want to choose your key derivation function depending on your use case with scrypt with higher security parameters and slower performance vs pbkdf2 achieving better performance with lower security parameters compared to scrypt.

Testing

cargo test

E2E Tests

To test our code e2e, we've generated files using the staking deposit cli v2.3.0 and are comparing the outputs during our tests. This is to guarantee that we're meeting the same criteria. Further error cases are checked in unit tests within the dedicated modules.

Glossary

Term	Description
Wallet	Interface to manage accounts
Account	public/private keypair that points to your funds
keystore file	encrypted version of your private key in JSON funds
key derviation function (kdf)	A Key Derivation Function lets you encrypt your keystore file with a password that you chose when running the cli. Eth staking smith supports scrypt or pbkdf2 and will run the latter by default for improved performance.
decryption key	used to encrypt/decrypt keystore file
mnemonic phrase / seed phrase / seed words	12 or 24 word phrase to access infinite number of accounts, used to derive multiple private keys
seed	secret value used to derive HD wallet addresses from a mnemonic phrase (BIP39 standard)
withdrawal credentials	Withdrawal Credentials is a 32-byte field in the deposit data, for verifying the destination of valid withdrawals. Currently, there are two types of withdrawals: BLS withdrawal (with a 00 prefix) and Ethereum withdrawals (with a 01 prefix). By default the former will be generated, however Ethereum is planning to fully move to 01 credentials once withdrawals become available
withdrawal address	Address for which withdrawal credentials should be generated. Eth staking smith allows execution addresses with the format ^(0x[a-fA-F0-9]{40})$