diff --git a/specs/phase0/beacon-chain.md b/specs/phase0/beacon-chain.md index b475584849..c0e026e971 100644 --- a/specs/phase0/beacon-chain.md +++ b/specs/phase0/beacon-chain.md @@ -13,6 +13,7 @@ - [Misc](#misc) - [Gwei values](#gwei-values) - [Initial values](#initial-values) + - [Withdrawal prefixes](#withdrawal-prefixes) - [Time parameters](#time-parameters) - [State list lengths](#state-list-lengths) - [Rewards and penalties](#rewards-and-penalties) @@ -209,7 +210,13 @@ The following values are (non-configurable) constants used throughout the specif | Name | Value | | - | - | | `GENESIS_FORK_VERSION` | `Version('0x00000000')` | + +### Withdrawal prefixes + +| Name | Value | +| - | - | | `BLS_WITHDRAWAL_PREFIX` | `Bytes1('0x00')` | +| `ETH1_ADDRESS_WITHDRAWAL_PREFIX` | `Bytes1('0x01')` | ### Time parameters diff --git a/specs/phase0/deposit-contract.md b/specs/phase0/deposit-contract.md index 23d831917f..02e762daef 100644 --- a/specs/phase0/deposit-contract.md +++ b/specs/phase0/deposit-contract.md @@ -58,12 +58,13 @@ The amount of ETH (rounded down to the closest Gwei) sent to the deposit contrac #### Withdrawal credentials -One of the `DepositData` fields is `withdrawal_credentials`. It is a commitment to credentials for withdrawing validator balance (e.g. to another validator, or to shards). The first byte of `withdrawal_credentials` is a version number. As of now, the only expected format is as follows: +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](./validator.md#withdrawal-credentials). -* `withdrawal_credentials[:1] == BLS_WITHDRAWAL_PREFIX` -* `withdrawal_credentials[1:] == hash(withdrawal_pubkey)[1:]` where `withdrawal_pubkey` is a BLS pubkey - -The private key corresponding to `withdrawal_pubkey` will be required to initiate a withdrawal. It can be stored separately until a withdrawal is required, e.g. in cold storage. +*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 diff --git a/specs/phase0/validator.md b/specs/phase0/validator.md index cb45e65e80..9e2ee7b1f0 100644 --- a/specs/phase0/validator.md +++ b/specs/phase0/validator.md @@ -15,7 +15,9 @@ This is an accompanying document to [Ethereum 2.0 Phase 0 -- The Beacon Chain](. - [Becoming a validator](#becoming-a-validator) - [Initialization](#initialization) - [BLS public key](#bls-public-key) - - [BLS withdrawal key](#bls-withdrawal-key) + - [Withdrawal credentials](#withdrawal-credentials) + - [`BLS_WITHDRAWAL_PREFIX`](#bls_withdrawal_prefix) + - [`ETH1_ADDRESS_WITHDRAWAL_PREFIX`](#eth1_address_withdrawal_prefix) - [Submit deposit](#submit-deposit) - [Process deposit](#process-deposit) - [Validator index](#validator-index) @@ -100,14 +102,41 @@ A validator must initialize many parameters locally before submitting a deposit Validator public keys are [G1 points](beacon-chain.md#bls-signatures) on the [BLS12-381 curve](https://z.cash/blog/new-snark-curve). A private key, `privkey`, must be securely generated along with the resultant `pubkey`. This `privkey` must be "hot", that is, constantly available to sign data throughout the lifetime of the validator. -#### BLS withdrawal key +#### Withdrawal credentials -A secondary withdrawal private key, `withdrawal_privkey`, must also be securely generated along with the resultant `withdrawal_pubkey`. This `withdrawal_privkey` does not have to be available for signing during the normal lifetime of a validator and can live in "cold storage". +The `withdrawal_credentials` field 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 validator constructs their `withdrawal_credentials` via the following: +The following withdrawal prefixes are currently supported. -* Set `withdrawal_credentials[:1] == BLS_WITHDRAWAL_PREFIX`. -* Set `withdrawal_credentials[1:] == hash(withdrawal_pubkey)[1:]`. +##### `BLS_WITHDRAWAL_PREFIX` + +Withdrawal credentials with the BLS withdrawal prefix allow a BLS key pair +`(bls_withdrawal_privkey, bls_withdrawal_pubkey)` to trigger withdrawals. +The `withdrawal_credentials` field must be such that: + +* `withdrawal_credentials[:1] == BLS_WITHDRAWAL_PREFIX` +* `withdrawal_credentials[1:] == hash(bls_withdrawal_pubkey)[1:]` + +*Note*: The `bls_withdrawal_privkey` is not required for validating and can be kept in cold storage. + +##### `ETH1_ADDRESS_WITHDRAWAL_PREFIX` + +Withdrawal credentials with the Eth1 address withdrawal prefix specify +a 20-byte Eth1 address `eth1_withdrawal_address` as the recipient for all withdrawals. +The `eth1_withdrawal_address` can be the address of either an externally owned account or of a contract. + +The `withdrawal_credentials` field must be such that: + +* `withdrawal_credentials[:1] == ETH1_ADDRESS_WITHDRAWAL_PREFIX` +* `withdrawal_credentials[1:12] == b'\x00' * 11` +* `withdrawal_credentials[12:] == eth1_withdrawal_address` + +After the merge of eth1 into eth2, +withdrawals to `eth1_withdrawal_address` will be normal ETH transfers (with no payload other than the validator's ETH) +triggered by a user transaction that will set the gas price and gas limit as well pay fees. +As long as the account or contract with address `eth1_withdrawal_address` can receive ETH transfers +the future withdrawal protocol is agnostic to all other implementation details. ### Submit deposit diff --git a/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_deposit.py b/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_deposit.py index b7a0de6c87..36e76f46c8 100644 --- a/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_deposit.py +++ b/tests/core/pyspec/eth2spec/test/phase0/block_processing/test_process_deposit.py @@ -94,6 +94,49 @@ def test_new_deposit_over_max(spec, state): yield from run_deposit_processing(spec, state, deposit, validator_index) +@with_all_phases +@spec_state_test +def test_new_deposit_eth1_withdrawal_credentials(spec, state): + # fresh deposit = next validator index = validator appended to registry + validator_index = len(state.validators) + withdrawal_credentials = ( + spec.ETH1_ADDRESS_WITHDRAWAL_PREFIX + + b'\x00' * 11 # specified 0s + + b'\x59' * 20 # a 20-byte eth1 address + ) + amount = spec.MAX_EFFECTIVE_BALANCE + deposit = prepare_state_and_deposit( + spec, state, + validator_index, + amount, + withdrawal_credentials=withdrawal_credentials, + signed=True, + ) + + yield from run_deposit_processing(spec, state, deposit, validator_index) + + +@with_all_phases +@spec_state_test +def test_new_deposit_non_versioned_withdrawal_credentials(spec, state): + # fresh deposit = next validator index = validator appended to registry + validator_index = len(state.validators) + withdrawal_credentials = ( + b'\xFF' # Non specified withdrawal credentials version + + b'\x02' * 31 # Garabage bytes + ) + amount = spec.MAX_EFFECTIVE_BALANCE + deposit = prepare_state_and_deposit( + spec, state, + validator_index, + amount, + withdrawal_credentials=withdrawal_credentials, + signed=True, + ) + + yield from run_deposit_processing(spec, state, deposit, validator_index) + + @with_all_phases @spec_state_test @always_bls