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Remove `fork_version` from `LightClientUpdate` 

The `fork_version` field in `LightClientUpdate` can be derived from the
`update.signature_slot` value by consulting the locally configured fork
schedule. The light client already needs access to the fork schedule to
determine the `GeneralizedIndex` values used for merkle proofs, and the
memory layouts of the structures (including `LightClientUpdate`). The
`fork_version` itself is network dependent and doesn't reveal that info.
This commit is contained in:
Etan Kissling 2022-04-27 09:50:27 +02:00
parent 8cc008d11c
commit 0b8ab23bd4
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GPG Key ID: B21DA824C5A3D03D
6 changed files with 107 additions and 13 deletions
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13
specs/altair/beacon-chain.md
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@ -28,6 +28,7 @@
- [Helper functions](#helper-functions)
- [Crypto](#crypto)
- [Misc](#misc-1)
- [`compute_fork_version`](#compute_fork_version)
- [`add_flag`](#add_flag)
- [`has_flag`](#has_flag)
- [Beacon state accessors](#beacon-state-accessors)
@ -226,6 +227,18 @@ the functionality described in those documents.
### Misc
#### `compute_fork_version`
```python
def compute_fork_version(epoch: Epoch) -> Version:
"""
Return the fork version at the given ``epoch``.
"""
if epoch >= ALTAIR_FORK_EPOCH:
return ALTAIR_FORK_VERSION
return GENESIS_FORK_VERSION
```
#### `add_flag`
```python

5
specs/altair/sync-protocol.md
View File

@ -71,8 +71,6 @@ class LightClientUpdate(Container):
finality_branch: Vector[Bytes32, floorlog2(FINALIZED_ROOT_INDEX)]
# Sync committee aggregate signature
sync_aggregate: SyncAggregate
# Fork version for the aggregate signature
fork_version: Version
# Slot at which the aggregate signature was created (untrusted)
signature_slot: Slot
```
@ -211,7 +209,8 @@ def validate_light_client_update(store: LightClientStore,
pubkey for (bit, pubkey) in zip(sync_aggregate.sync_committee_bits, sync_committee.pubkeys)
if bit
]
domain = compute_domain(DOMAIN_SYNC_COMMITTEE, update.fork_version, genesis_validators_root)
fork_version = compute_fork_version(compute_epoch_at_slot(update.signature_slot))
domain = compute_domain(DOMAIN_SYNC_COMMITTEE, fork_version, genesis_validators_root)
signing_root = compute_signing_root(update.attested_header, domain)
assert bls.FastAggregateVerify(participant_pubkeys, signing_root, sync_aggregate.sync_committee_signature)
```

15
specs/bellatrix/beacon-chain.md
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@ -29,6 +29,7 @@
- [`is_execution_enabled`](#is_execution_enabled)
- [Misc](#misc)
- [`compute_timestamp_at_slot`](#compute_timestamp_at_slot)
- [Modified `compute_fork_version`](#modified-compute_fork_version)
- [Beacon state accessors](#beacon-state-accessors)
- [Modified `get_inactivity_penalty_deltas`](#modified-get_inactivity_penalty_deltas)
- [Beacon state mutators](#beacon-state-mutators)
@ -242,6 +243,20 @@ def compute_timestamp_at_slot(state: BeaconState, slot: Slot) -> uint64:
return uint64(state.genesis_time + slots_since_genesis * SECONDS_PER_SLOT)
```
#### Modified `compute_fork_version`
```python
def compute_fork_version(epoch: Epoch) -> Version:
"""
Return the fork version at the given ``epoch``.
"""
if epoch >= BELLATRIX_FORK_EPOCH:
return BELLATRIX_FORK_VERSION
if epoch >= ALTAIR_FORK_EPOCH:
return ALTAIR_FORK_VERSION
return GENESIS_FORK_VERSION
```
### Beacon state accessors
#### Modified `get_inactivity_penalty_deltas`

20
specs/capella/beacon-chain.md
View File

@ -34,6 +34,8 @@
- [`has_eth1_withdrawal_credential`](#has_eth1_withdrawal_credential)
- [`is_fully_withdrawable_validator`](#is_fully_withdrawable_validator)
- [`is_partially_withdrawable_validator`](#is_partially_withdrawable_validator)
- [Misc](#misc-1)
- [Modified `compute_fork_version`](#modified-compute_fork_version)
- [Beacon chain state transition function](#beacon-chain-state-transition-function)
- [Epoch processing](#epoch-processing)
- [Full withdrawals](#full-withdrawals)
@ -318,6 +320,24 @@ def is_partially_withdrawable_validator(validator: Validator, balance: Gwei) ->
return has_eth1_withdrawal_credential(validator) and has_max_effective_balance and has_excess_balance
```
### Misc
#### Modified `compute_fork_version`
```python
def compute_fork_version(epoch: Epoch) -> Version:
"""
Return the fork version at the given ``epoch``.
"""
if epoch >= CAPELLA_FORK_EPOCH:
return CAPELLA_FORK_VERSION
if epoch >= BELLATRIX_FORK_EPOCH:
return BELLATRIX_FORK_VERSION
if epoch >= ALTAIR_FORK_EPOCH:
return ALTAIR_FORK_VERSION
return GENESIS_FORK_VERSION
```
## Beacon chain state transition function
### Epoch processing

33
tests/core/pyspec/eth2spec/test/altair/unittests/test_sync_protocol.py
View File

@ -16,6 +16,7 @@ from eth2spec.test.helpers.constants import MINIMAL
from eth2spec.test.helpers.light_client import (
get_sync_aggregate,
initialize_light_client_store,
override_config_fork_epochs,
)
from eth2spec.test.helpers.state import (
next_slots,
@ -27,6 +28,9 @@ from eth2spec.test.helpers.merkle import build_proof
@with_altair_and_later
@spec_state_test
def test_process_light_client_update_not_timeout(spec, state):
old_config = spec.config
override_config_fork_epochs(spec, state)
store = initialize_light_client_store(spec, state)
# Block at slot 1 doesn't increase sync committee period, so it won't force update store.finalized_header
@ -41,7 +45,7 @@ def test_process_light_client_update_not_timeout(spec, state):
)
# Sync committee signing the block_header
sync_aggregate, fork_version, signature_slot = get_sync_aggregate(spec, state, block_header)
sync_aggregate, signature_slot = get_sync_aggregate(spec, state, block_header)
next_sync_committee_branch = [spec.Bytes32() for _ in range(spec.floorlog2(spec.NEXT_SYNC_COMMITTEE_INDEX))]
# Ensure that finality checkpoint is genesis
@ -57,7 +61,6 @@ def test_process_light_client_update_not_timeout(spec, state):
finalized_header=finality_header,
finality_branch=finality_branch,
sync_aggregate=sync_aggregate,
fork_version=fork_version,
signature_slot=signature_slot,
)
@ -70,11 +73,16 @@ def test_process_light_client_update_not_timeout(spec, state):
assert store.finalized_header == pre_store.finalized_header
assert store.best_valid_update == update
spec.config = old_config
@with_altair_and_later
@spec_state_test
@with_presets([MINIMAL], reason="too slow")
def test_process_light_client_update_at_period_boundary(spec, state):
old_config = spec.config
override_config_fork_epochs(spec, state)
store = initialize_light_client_store(spec, state)
# Forward to slot before next sync committee period so that next block is final one in period
@ -94,7 +102,7 @@ def test_process_light_client_update_at_period_boundary(spec, state):
)
# Sync committee signing the block_header
sync_aggregate, fork_version, signature_slot = get_sync_aggregate(spec, state, block_header)
sync_aggregate, signature_slot = get_sync_aggregate(spec, state, block_header)
next_sync_committee_branch = [spec.Bytes32() for _ in range(spec.floorlog2(spec.NEXT_SYNC_COMMITTEE_INDEX))]
# Finality is unchanged
@ -108,7 +116,6 @@ def test_process_light_client_update_at_period_boundary(spec, state):
finalized_header=finality_header,
finality_branch=finality_branch,
sync_aggregate=sync_aggregate,
fork_version=fork_version,
signature_slot=signature_slot,
)
@ -121,11 +128,16 @@ def test_process_light_client_update_at_period_boundary(spec, state):
assert store.best_valid_update == update
assert store.finalized_header == pre_store.finalized_header
spec.config = old_config
@with_altair_and_later
@spec_state_test
@with_presets([MINIMAL], reason="too slow")
def test_process_light_client_update_timeout(spec, state):
old_config = spec.config
override_config_fork_epochs(spec, state)
store = initialize_light_client_store(spec, state)
# Forward to next sync committee period
@ -145,7 +157,7 @@ def test_process_light_client_update_timeout(spec, state):
)
# Sync committee signing the block_header
sync_aggregate, fork_version, signature_slot = get_sync_aggregate(spec, state, block_header)
sync_aggregate, signature_slot = get_sync_aggregate(spec, state, block_header)
# Sync committee is updated
next_sync_committee_branch = build_proof(state.get_backing(), spec.NEXT_SYNC_COMMITTEE_INDEX)
@ -160,7 +172,6 @@ def test_process_light_client_update_timeout(spec, state):
finalized_header=finality_header,
finality_branch=finality_branch,
sync_aggregate=sync_aggregate,
fork_version=fork_version,
signature_slot=signature_slot,
)
@ -173,11 +184,16 @@ def test_process_light_client_update_timeout(spec, state):
assert store.best_valid_update == update
assert store.finalized_header == pre_store.finalized_header
spec.config = old_config
@with_altair_and_later
@spec_state_test
@with_presets([MINIMAL], reason="too slow")
def test_process_light_client_update_finality_updated(spec, state):
old_config = spec.config
override_config_fork_epochs(spec, state)
store = initialize_light_client_store(spec, state)
# Change finality
@ -211,7 +227,7 @@ def test_process_light_client_update_finality_updated(spec, state):
)
# Sync committee signing the block_header
sync_aggregate, fork_version, signature_slot = get_sync_aggregate(spec, state, block_header)
sync_aggregate, signature_slot = get_sync_aggregate(spec, state, block_header)
update = spec.LightClientUpdate(
attested_header=block_header,
@ -220,7 +236,6 @@ def test_process_light_client_update_finality_updated(spec, state):
finalized_header=finalized_block_header,
finality_branch=finality_branch,
sync_aggregate=sync_aggregate,
fork_version=fork_version,
signature_slot=signature_slot,
)
@ -230,3 +245,5 @@ def test_process_light_client_update_finality_updated(spec, state):
assert store.optimistic_header == update.attested_header
assert store.finalized_header == update.finalized_header
assert store.best_valid_update is None
spec.config = old_config

34
tests/core/pyspec/eth2spec/test/helpers/light_client.py
View File

@ -1,3 +1,5 @@
from copy import deepcopy
from eth2spec.test.helpers.state import (
transition_to,
)
@ -7,6 +9,35 @@ from eth2spec.test.helpers.sync_committee import (
)
def override_config_fork_epochs(spec, state):
# Test framework adjusts state fork but leaves spec config constants inconsistent
config_overrides = {}
if state.fork.current_version == spec.config.GENESIS_FORK_VERSION:
pass
elif state.fork.current_version == spec.config.ALTAIR_FORK_VERSION:
config_overrides['ALTAIR_FORK_EPOCH'] = spec.GENESIS_EPOCH
elif state.fork.current_version == spec.config.BELLATRIX_FORK_VERSION:
config_overrides['ALTAIR_FORK_EPOCH'] = spec.GENESIS_EPOCH
config_overrides['BELLATRIX_FORK_EPOCH'] = spec.GENESIS_EPOCH
elif state.fork.current_version == spec.config.CAPELLA_FORK_VERSION:
config_overrides['ALTAIR_FORK_EPOCH'] = spec.GENESIS_EPOCH
config_overrides['BELLATRIX_FORK_EPOCH'] = spec.GENESIS_EPOCH
config_overrides['CAPELLA_FORK_EPOCH'] = spec.GENESIS_EPOCH
elif state.fork.current_version == spec.config.SHARDING_FORK_VERSION:
config_overrides['ALTAIR_FORK_EPOCH'] = spec.GENESIS_EPOCH
config_overrides['BELLATRIX_FORK_EPOCH'] = spec.GENESIS_EPOCH
config_overrides['CAPELLA_FORK_EPOCH'] = spec.GENESIS_EPOCH
config_overrides['SHARDING_FORK_EPOCH'] = spec.GENESIS_EPOCH
else:
assert False
tmp_config = deepcopy(spec.config._asdict())
tmp_config.update(config_overrides)
config_types = spec.Configuration.__annotations__
test_config = {k: config_types[k](v) for k, v in tmp_config.items()}
spec.config = spec.Configuration(**test_config)
def initialize_light_client_store(spec, state):
return spec.LightClientStore(
finalized_header=spec.BeaconBlockHeader(),
@ -45,5 +76,4 @@ def get_sync_aggregate(spec, state, block_header, signature_slot=None):
sync_committee_bits=sync_committee_bits,
sync_committee_signature=sync_committee_signature,
)
fork_version = signature_state.fork.current_version
return sync_aggregate, fork_version, signature_slot
return sync_aggregate, signature_slot