#1244 without "5 slots is a Slot"

configs/constant_presets/mainnet.yaml

@@ -44,7 +44,7 @@ EFFECTIVE_BALANCE_INCREMENT: 1000000000
 GENESIS_FORK_VERSION: 0x00000000
 # 0, GENESIS_EPOCH is derived from this constant
 GENESIS_SLOT: 0
-BLS_WITHDRAWAL_PREFIX: 0
+BLS_WITHDRAWAL_PREFIX: 0x00
 
 
 # Time parameters

configs/constant_presets/minimal.yaml

@@ -43,7 +43,7 @@ EFFECTIVE_BALANCE_INCREMENT: 1000000000
 GENESIS_FORK_VERSION: 0x00000000
 # 0, GENESIS_EPOCH is derived from this constant
 GENESIS_SLOT: 0
-BLS_WITHDRAWAL_PREFIX: 0
+BLS_WITHDRAWAL_PREFIX: 0x00
 
 
 # Time parameters

scripts/build_spec.py

@@ -25,7 +25,7 @@
 )
 from eth2spec.utils.ssz.ssz_typing import (
     bit, boolean, Container, List, Vector, uint64,
-    Bytes4, Bytes8, Bytes32, Bytes48, Bytes96, Bitlist, Bitvector,
+    Bytes1, Bytes4, Bytes8, Bytes32, Bytes48, Bytes96, Bitlist, Bitvector,
 )
 from eth2spec.utils.bls import (
     bls_aggregate_pubkeys,
@@ -53,7 +53,7 @@
 )
 from eth2spec.utils.ssz.ssz_typing import (
     bit, boolean, Container, List, Vector, Bytes, uint64,
-    Bytes4, Bytes8, Bytes32, Bytes48, Bytes96, Bitlist, Bitvector,
+    Bytes1, Bytes4, Bytes8, Bytes32, Bytes48, Bytes96, Bitlist, Bitvector,
 )
 from eth2spec.utils.bls import (
     bls_aggregate_pubkeys,
@@ -185,7 +185,7 @@ def combine_constants(old_constants: Dict[str, str], new_constants: Dict[str, st
 
 ignored_dependencies = [
     'bit', 'boolean', 'Vector', 'List', 'Container', 'Hash', 'BLSPubkey', 'BLSSignature', 'Bytes', 'BytesN'
-    'Bytes4', 'Bytes32', 'Bytes48', 'Bytes96', 'Bitlist', 'Bitvector',
+    'Bytes1', 'Bytes4', 'Bytes32', 'Bytes48', 'Bytes96', 'Bitlist', 'Bitvector',
     'uint8', 'uint16', 'uint32', 'uint64', 'uint128', 'uint256',
     'bytes'  # to be removed after updating spec doc
 ]

scripts/function_puller.py

@@ -74,15 +74,14 @@ def get_spec(file_name: str) -> SpecObject:
                         row[i] = row[i].strip().strip('`')
                         if '`' in row[i]:
                             row[i] = row[i][:row[i].find('`')]
-                    if row[1].startswith('uint') or row[1].startswith('Bytes'):
+                    is_constant_def = True
+                    if row[0][0] not in 'ABCDEFGHIJKLMNOPQRSTUVWXYZ_':
+                        is_constant_def = False
+                    for c in row[0]:
+                        if c not in 'ABCDEFGHIJKLMNOPQRSTUVWXYZ_0123456789':
+                            is_constant_def = False
+                    if is_constant_def:
+                        constants[row[0]] = row[1].replace('**TBD**', '0x1234567890123456789012345678901234567890')
+                    elif row[1].startswith('uint') or row[1].startswith('Bytes'):
                         custom_types[row[0]] = row[1]
-                    else:
-                        eligible = True
-                        if row[0][0] not in 'ABCDEFGHIJKLMNOPQRSTUVWXYZ_':
-                            eligible = False
-                        for c in row[0]:
-                            if c not in 'ABCDEFGHIJKLMNOPQRSTUVWXYZ_0123456789':
-                                eligible = False
-                        if eligible:
-                            constants[row[0]] = row[1].replace('**TBD**', '0x1234567890123456789012345678901234567890')
     return functions, custom_types, constants, ssz_objects, inserts

specs/core/0_beacon-chain.md

@@ -19,7 +19,7 @@
         - [State list lengths](#state-list-lengths)
         - [Rewards and penalties](#rewards-and-penalties)
         - [Max operations per block](#max-operations-per-block)
-        - [Signature domains](#signature-domains)
+        - [Signature domain types](#signature-domain-types)
     - [Containers](#containers)
         - [Misc dependencies](#misc-dependencies)
             - [`Fork`](#fork)
@@ -164,6 +164,8 @@ The following values are (non-configurable) constants used throughout the specif
 | `BASE_REWARDS_PER_EPOCH` | `5` |
 | `DEPOSIT_CONTRACT_TREE_DEPTH` | `2**5` (= 32) |
 | `SECONDS_PER_DAY` | `86400` |
+| `JUSTIFICATION_BITS_LENGTH` | `4` |
+| `ENDIANNESS` | `'little'` |
 
 ## Configuration
 
@@ -181,8 +183,6 @@ The following values are (non-configurable) constants used throughout the specif
 | `SHUFFLE_ROUND_COUNT` | `90` |
 | `MIN_GENESIS_ACTIVE_VALIDATOR_COUNT` | `2**16` (= 65,536) |
 | `MIN_GENESIS_TIME` | `1578009600` (Jan 3, 2020) |
-| `JUSTIFICATION_BITS_LENGTH` | `4` |
-| `ENDIANNESS` | `'little'` |
 
 - For the safety of crosslinks, `TARGET_COMMITTEE_SIZE` exceeds [the recommended minimum committee size of 111](https://vitalik.ca/files/Ithaca201807_Sharding.pdf); with sufficient active validators (at least `SLOTS_PER_EPOCH * TARGET_COMMITTEE_SIZE`), the shuffling algorithm ensures committee sizes of at least `TARGET_COMMITTEE_SIZE`. (Unbiasable randomness with a Verifiable Delay Function (VDF) will improve committee robustness and lower the safe minimum committee size.)
 
@@ -201,7 +201,7 @@ The following values are (non-configurable) constants used throughout the specif
 | - | - |
 | `GENESIS_SLOT` | `Slot(0)` |
 | `GENESIS_EPOCH` | `Epoch(0)` |
-| `BLS_WITHDRAWAL_PREFIX` | `0` |
+| `BLS_WITHDRAWAL_PREFIX` | `Bytes1(b'\x00')` |
 
 ### Time parameters
 
@@ -214,20 +214,18 @@ The following values are (non-configurable) constants used throughout the specif
 | `SLOTS_PER_ETH1_VOTING_PERIOD` | `2**10` (= 1,024) | slots | ~1.7 hours |
 | `SLOTS_PER_HISTORICAL_ROOT` | `2**13` (= 8,192) | slots | ~13 hours |
 | `MIN_VALIDATOR_WITHDRAWABILITY_DELAY` | `2**8` (= 256) | epochs | ~27 hours |
-| `PERSISTENT_COMMITTEE_PERIOD` | `2**11` (= 2,048)  | epochs | 9 days  |
+| `PERSISTENT_COMMITTEE_PERIOD` | `2**11` (= 2,048) | epochs | 9 days |
 | `MAX_EPOCHS_PER_CROSSLINK` | `2**6` (= 64) | epochs | ~7 hours |
 | `MIN_EPOCHS_TO_INACTIVITY_PENALTY` | `2**2` (= 4) | epochs | 25.6 minutes |
 
-- `MAX_EPOCHS_PER_CROSSLINK` should be a small constant times `SHARD_COUNT // SLOTS_PER_EPOCH`.
-
 ### State list lengths
 
 | Name | Value | Unit | Duration |
 | - | - | :-: | :-: |
 | `EPOCHS_PER_HISTORICAL_VECTOR` | `2**16` (= 65,536) | epochs | ~0.8 years |
 | `EPOCHS_PER_SLASHINGS_VECTOR` | `2**13` (= 8,192) | epochs | ~36 days |
 | `HISTORICAL_ROOTS_LIMIT` | `2**24` (= 16,777,216) | historical roots | ~26,131 years |
-| `VALIDATOR_REGISTRY_LIMIT` | `2**40` (= 1,099,511,627,776) | validator spots | |
+| `VALIDATOR_REGISTRY_LIMIT` | `2**40` (= 1,099,511,627,776) | validator spots |
 
 ### Rewards and penalties
 
@@ -547,7 +545,7 @@ class BeaconState(Container):
 #### `integer_squareroot`
 
 ```python
-def integer_squareroot(n: uint64) -> int:
+def integer_squareroot(n: uint64) -> uint64:
     """
     Return the largest integer ``x`` such that ``x**2 <= n``.
     """
@@ -570,17 +568,17 @@ def xor(bytes1: Bytes32, bytes2: Bytes32) -> Bytes32:
 ```
 
 ```python
-def int_to_bytes(integer: uint64, length: uint64) -> bytes:
+def int_to_bytes(n: uint64, length: uint64) -> bytes:
     """
-    Return the ``length``-byte serialization of ``integer``.
+    Return the ``length``-byte serialization of ``n``.
     """
-    return integer.to_bytes(length, ENDIANNESS)
+    return n.to_bytes(length, ENDIANNESS)
 ```
 
 #### `bytes_to_int`
 
 ```python
-def bytes_to_int(data: bytes) -> int:
+def bytes_to_int(data: bytes) -> uint64:
     """
     Return the integer deserialization of ``data``.
     """
@@ -715,7 +713,6 @@ def compute_shuffled_index(index: ValidatorIndex, index_count: uint64, seed: Has
     Return the shuffled validator index corresponding to ``seed`` (and ``index_count``).
     """
     assert index < index_count
-    assert index_count <= 2**40
 
     # Swap or not (https://link.springer.com/content/pdf/10.1007%2F978-3-642-32009-5_1.pdf)
     # See the 'generalized domain' algorithm on page 3
@@ -853,7 +850,7 @@ def get_active_validator_indices(state: BeaconState, epoch: Epoch) -> Sequence[V
 #### `get_validator_churn_limit`
 
 ```python
-def get_validator_churn_limit(state: BeaconState) -> int:
+def get_validator_churn_limit(state: BeaconState) -> uint64:
     """
     Return the validator churn limit for the current epoch.
     """
@@ -876,7 +873,7 @@ def get_seed(state: BeaconState, epoch: Epoch) -> Hash:
 #### `get_committee_count`
 
 ```python
-def get_committee_count(state: BeaconState, epoch: Epoch) -> int:
+def get_committee_count(state: BeaconState, epoch: Epoch) -> uint64:
     """
     Return the number of committees at ``epoch``.
     """
@@ -921,7 +918,7 @@ def get_start_shard(state: BeaconState, epoch: Epoch) -> Shard:
 #### `get_shard_delta`
 
 ```python
-def get_shard_delta(state: BeaconState, epoch: Epoch) -> int:
+def get_shard_delta(state: BeaconState, epoch: Epoch) -> uint64:
     """
     Return the number of shards to increment ``state.start_shard`` at ``epoch``.
     """
@@ -1699,7 +1696,7 @@ def process_deposit(state: BeaconState, deposit: Deposit) -> None:
     if pubkey not in validator_pubkeys:
         # Verify the deposit signature (proof of possession) for new validators.
         # Note: The deposit contract does not check signatures.
-        # Note: Deposits are valid across forks, thus the deposit domain is retrieved directly from `compute_domain`
+        # Note: Deposits are valid across forks, thus the deposit domain is retrieved directly from `compute_domain`.
         domain = compute_domain(DOMAIN_DEPOSIT)
         if not bls_verify(pubkey, signing_root(deposit.data), deposit.data.signature, domain):
             return
@@ -1759,10 +1756,7 @@ def process_transfer(state: BeaconState, transfer: Transfer) -> None:
         state.balances[transfer.sender] >= transfer.amount + transfer.fee + MAX_EFFECTIVE_BALANCE
     )
     # Verify that the pubkey is valid
-    assert (
-        state.validators[transfer.sender].withdrawal_credentials ==
-        int_to_bytes(BLS_WITHDRAWAL_PREFIX, length=1) + hash(transfer.pubkey)[1:]
-    )
+    assert state.validators[transfer.sender].withdrawal_credentials == BLS_WITHDRAWAL_PREFIX + hash(transfer.pubkey)[1:]
     # Verify that the signature is valid
     assert bls_verify(transfer.pubkey, signing_root(transfer), transfer.signature, get_domain(state, DOMAIN_TRANSFER))
     # Process the transfer

specs/core/0_deposit-contract.md

@@ -48,8 +48,8 @@ The amount of ETH (rounded down to the closest Gwei) sent to the deposit contrac
 
 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:
 
-- `withdrawal_credentials[:1] == BLS_WITHDRAWAL_PREFIX_BYTE`
-- `withdrawal_credentials[1:] == hash(withdrawal_pubkey)[1:]` where `withdrawal_pubkey` is a BLS pubkey
+* `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.
 

specs/validator/0_beacon-chain-validator.md

@@ -87,8 +87,8 @@ A secondary withdrawal private key, `withdrawal_privkey`, must also be securely
 
 The validator constructs their `withdrawal_credentials` via the following:
 
-- Set `withdrawal_credentials[:1] == BLS_WITHDRAWAL_PREFIX_BYTE`.
-- Set `withdrawal_credentials[1:] == hash(withdrawal_pubkey)[1:]`.
+* Set `withdrawal_credentials[:1] == BLS_WITHDRAWAL_PREFIX`.
+* Set `withdrawal_credentials[1:] == hash(withdrawal_pubkey)[1:]`.
 
 ### Submit deposit
 

test_libs/pyspec/eth2spec/test/helpers/deposits.py

@@ -62,7 +62,7 @@ def prepare_genesis_deposits(spec, genesis_validator_count, amount, signed=False
         pubkey = pubkeys[validator_index]
         privkey = privkeys[validator_index]
         # insecurely use pubkey as withdrawal key if no credentials provided
-        withdrawal_credentials = spec.int_to_bytes(spec.BLS_WITHDRAWAL_PREFIX, length=1) + spec.hash(pubkey)[1:]
+        withdrawal_credentials = spec.BLS_WITHDRAWAL_PREFIX + spec.hash(pubkey)[1:]
         deposit, root, deposit_data_list = build_deposit(
             spec,
             None,
@@ -89,7 +89,7 @@ def prepare_state_and_deposit(spec, state, validator_index, amount, withdrawal_c
 
     # insecurely use pubkey as withdrawal key if no credentials provided
     if withdrawal_credentials is None:
-        withdrawal_credentials = spec.int_to_bytes(spec.BLS_WITHDRAWAL_PREFIX, length=1) + spec.hash(pubkey)[1:]
+        withdrawal_credentials = spec.BLS_WITHDRAWAL_PREFIX + spec.hash(pubkey)[1:]
 
     deposit, root, deposit_data_list = build_deposit(
         spec,

test_libs/pyspec/eth2spec/test/helpers/genesis.py

@@ -6,7 +6,7 @@
 def build_mock_validator(spec, i: int, balance: int):
     pubkey = pubkeys[i]
     # insecurely use pubkey as withdrawal key as well
-    withdrawal_credentials = spec.int_to_bytes(spec.BLS_WITHDRAWAL_PREFIX, length=1) + spec.hash(pubkey)[1:]
+    withdrawal_credentials = spec.BLS_WITHDRAWAL_PREFIX + spec.hash(pubkey)[1:]
     return spec.Validator(
         pubkey=pubkeys[i],
         withdrawal_credentials=withdrawal_credentials,

test_libs/pyspec/eth2spec/test/helpers/transfers.py

@@ -34,7 +34,7 @@ def get_valid_transfer(spec, state, slot=None, sender_index=None,
 
     # ensure withdrawal_credentials reproducible
     state.validators[transfer.sender].withdrawal_credentials = (
-        spec.int_to_bytes(spec.BLS_WITHDRAWAL_PREFIX, length=1) + spec.hash(transfer.pubkey)[1:]
+        spec.BLS_WITHDRAWAL_PREFIX + spec.hash(transfer.pubkey)[1:]
     )
 
     return transfer

test_libs/pyspec/eth2spec/test/phase_0/block_processing/test_process_deposit.py

@@ -131,7 +131,7 @@ def test_invalid_sig_top_up(spec, state):
 def test_invalid_withdrawal_credentials_top_up(spec, state):
     validator_index = 0
     amount = spec.MAX_EFFECTIVE_BALANCE // 4
-    withdrawal_credentials = spec.int_to_bytes(spec.BLS_WITHDRAWAL_PREFIX, length=1) + spec.hash(b"junk")[1:]
+    withdrawal_credentials = spec.BLS_WITHDRAWAL_PREFIX + spec.hash(b"junk")[1:]
     deposit = prepare_state_and_deposit(
         spec,
         state,

test_libs/pyspec/eth2spec/utils/ssz/ssz_typing.py

@@ -495,7 +495,8 @@ def is_fixed_size(cls):
         return True
 
 
-# Helpers for common BytesN types.
+# Helpers for common BytesN types
+Bytes1: BytesType = BytesN[1]
 Bytes4: BytesType = BytesN[4]
 Bytes8: BytesType = BytesN[8]
 Bytes32: BytesType = BytesN[32]