Skip to content

Latest commit

 

History

History
77 lines (51 loc) · 4.26 KB

deposit-contract.md

File metadata and controls

77 lines (51 loc) · 4.26 KB
Raw

Ethereum 2.0 Phase 0 -- Deposit Contract

Table of contents

Introduction

This document represents the specification for the beacon chain deposit contract, part of Ethereum 2.0 Phase 0.

Constants

The following values are (non-configurable) constants used throughout the specification.

Name Value
DEPOSIT_CONTRACT_TREE_DEPTH 2**5 (= 32)

Configuration

Note: The default mainnet configuration values are included here for spec-design purposes. The different configurations for mainnet, testnets, and YAML-based testing can be found in the configs/constant_presets directory. These configurations are updated for releases and may be out of sync during dev changes.

Name Value
DEPOSIT_CHAIN_ID 1
DEPOSIT_NETWORK_ID 1
DEPOSIT_CONTRACT_ADDRESS 0x00000000219ab540356cBB839Cbe05303d7705Fa

Ethereum 1.0 deposit contract

The initial deployment phases of Ethereum 2.0 are implemented without consensus changes to Ethereum 1.0. A deposit contract at address DEPOSIT_CONTRACT_ADDRESS is added to the Ethereum 1.0 chain defined by the chain-id -- DEPOSIT_CHAIN_ID -- and the network-id -- DEPOSIT_NETWORK_ID -- for deposits of ETH to the beacon chain. Validator balances will be withdrawable to the shards in Phase 2.

Note: See here for a comprehensive list of public Ethereum chain chain-id's and network-id's.

deposit function

The deposit contract has a public deposit function to make deposits. It takes as arguments bytes calldata pubkey, bytes calldata withdrawal_credentials, bytes calldata signature, bytes32 deposit_data_root. The first three arguments populate a DepositData object, and deposit_data_root is the expected DepositData root as a protection against malformatted calldata.

Deposit amount

The amount of ETH (rounded down to the closest Gwei) sent to the deposit contract is the deposit amount, which must be of size at least MIN_DEPOSIT_AMOUNT Gwei. Note that ETH consumed by the deposit contract is no longer usable on Ethereum 1.0.

Withdrawal credentials

One of the DepositData fields is withdrawal_credentials which constrains validator withdrawals. The first byte of this 32-byte field is a withdrawal prefix which defines the semantics of the remaining 31 bytes. The withdrawal prefixes currently supported are BLS_WITHDRAWAL_PREFIX and ETH1_ADDRESS_WITHDRAWAL_PREFIX. Read more in the validator guide.

Note: The deposit contract does not validate the withdrawal_credentials field. Support for new withdrawal prefixes can be added without modifying the deposit contract.

DepositEvent log

Every Ethereum 1.0 deposit emits a DepositEvent log for consumption by the beacon chain. The deposit contract does little validation, pushing most of the validator onboarding logic to the beacon chain. In particular, the proof of possession (a BLS12-381 signature) is not verified by the deposit contract.

Solidity code

The deposit contract source code, written in Solidity, is available here.

Note: To save on gas, the deposit contract uses a progressive Merkle root calculation algorithm that requires only O(log(n)) storage. See here for a Python implementation, and here for a formal correctness proof.