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Refactor is_valid_indexed_attestation: extract verify_attestation_custody

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Hsiao-Wei Wang 2020-05-29 01:24:17 +08:00
parent 7509ecb742
commit 8ae7f5b6fa
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1 changed files with 36 additions and 21 deletions
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57
specs/phase1/beacon-chain.md
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@ -52,6 +52,7 @@
- [`get_latest_slot_for_shard`](#get_latest_slot_for_shard)
- [`get_offset_slots`](#get_offset_slots)
- [Predicates](#predicates)
- [`verify_attestation_custody`](#verify_attestation_custody)
- [Updated `is_valid_indexed_attestation`](#updated-is_valid_indexed_attestation)
- [`is_shard_attestation`](#is_shard_attestation)
- [`is_winning_attestation`](#is_winning_attestation)
@ -414,7 +415,7 @@ def unpack_compact_validator(compact_validator: uint64) -> Tuple[ValidatorIndex,
```python
def committee_to_compact_committee(state: BeaconState, committee: Sequence[ValidatorIndex]) -> CompactCommittee:
"""
Given a state and a list of validator indices, outputs the CompactCommittee representing them.
Given a state and a list of validator indices, outputs the ``CompactCommittee`` representing them.
"""
validators = [state.validators[i] for i in committee]
compact_validators = [
@ -569,6 +570,37 @@ def get_offset_slots(state: BeaconState, shard: Shard) -> Sequence[Slot]:
### Predicates
#### `verify_attestation_custody`
```python
def verify_attestation_custody(state: BeaconState, indexed_attestation: IndexedAttestation) -> bool:
"""
Check if ``indexed_attestation`` has valid signature against non-empty custody bits.
"""
attestation = indexed_attestation.attestation
aggregation_bits = attestation.aggregation_bits
domain = get_domain(state, DOMAIN_BEACON_ATTESTER, attestation.data.target.epoch)
all_pubkeys = []
all_signing_roots = []
for block_index, custody_bits in enumerate(attestation.custody_bits_blocks):
assert len(custody_bits) == len(indexed_attestation.committee)
for participant, aggregation_bit, custody_bit in zip(
indexed_attestation.committee, aggregation_bits, custody_bits
):
if aggregation_bit:
all_pubkeys.append(state.validators[participant].pubkey)
# Note: only 2N distinct message hashes
attestation_wrapper = AttestationCustodyBitWrapper(
attestation_data_root=hash_tree_root(attestation.data),
block_index=block_index,
bit=custody_bit,
)
all_signing_roots.append(compute_signing_root(attestation_wrapper, domain))
else:
assert not custody_bit
return bls.AggregateVerify(all_pubkeys, all_signing_roots, signature=attestation.signature)
```
#### Updated `is_valid_indexed_attestation`
Note that this replaces the Phase 0 `is_valid_indexed_attestation`.
@ -584,34 +616,17 @@ def is_valid_indexed_attestation(state: BeaconState, indexed_attestation: Indexe
if not any(aggregation_bits) or len(aggregation_bits) != len(indexed_attestation.committee):
return False
domain = get_domain(state, DOMAIN_BEACON_ATTESTER, attestation.data.target.epoch)
all_pubkeys = []
all_signing_roots = []
if len(attestation.custody_bits_blocks) == 0:
# fall back on phase0 behavior if there is no shard data.
domain = get_domain(state, DOMAIN_BEACON_ATTESTER, attestation.data.target.epoch)
all_pubkeys = []
for participant, aggregation_bit in zip(indexed_attestation.committee, aggregation_bits):
if aggregation_bit:
all_pubkeys.append(state.validators[participant].pubkey)
signing_root = compute_signing_root(indexed_attestation.attestation.data, domain)
return bls.FastAggregateVerify(all_pubkeys, signing_root, signature=attestation.signature)
else:
for block_index, custody_bits in enumerate(attestation.custody_bits_blocks):
assert len(custody_bits) == len(indexed_attestation.committee)
for participant, aggregation_bit, custody_bit in zip(
indexed_attestation.committee, aggregation_bits, custody_bits
):
if aggregation_bit:
all_pubkeys.append(state.validators[participant].pubkey)
# Note: only 2N distinct message hashes
attestation_wrapper = AttestationCustodyBitWrapper(
attestation_data_root=hash_tree_root(attestation.data),
block_index=block_index,
bit=custody_bit
)
all_signing_roots.append(compute_signing_root(attestation_wrapper, domain))
else:
assert not custody_bit
return bls.AggregateVerify(all_pubkeys, all_signing_roots, signature=attestation.signature)
return verify_attestation_custody(state, indexed_attestation)
```
#### `is_shard_attestation`