Remove custody_bits and AttestationDataAndCustodyBit

README.md

@@ -62,7 +62,6 @@ The following are the broad design goals for Ethereum 2.0:
 
 ## For spec contributors
 
-
 Documentation on the different components used during spec writing can be found here:
 * [YAML Test Generators](test_generators/README.md)
 * [Executable Python Spec, with Py-tests](test_libs/pyspec/README.md)

scripts/build_spec.py

@@ -24,14 +24,13 @@
     signing_root,
 )
 from eth2spec.utils.ssz.ssz_typing import (
-    bit, boolean, Container, List, Vector, uint64,
+    boolean, Container, List, Vector, uint64,
     Bytes1, Bytes4, Bytes8, Bytes32, Bytes48, Bytes96, Bitlist, Bitvector,
 )
 from eth2spec.utils.bls import (
     bls_aggregate_signatures,
     bls_aggregate_pubkeys,
     bls_verify,
-    bls_verify_multiple,
     bls_sign,
 )
 

specs/core/0_beacon-chain.md

@@ -26,7 +26,6 @@
             - [`Checkpoint`](#checkpoint)
             - [`Validator`](#validator)
             - [`AttestationData`](#attestationdata)
-            - [`AttestationDataAndCustodyBit`](#attestationdataandcustodybit)
             - [`IndexedAttestation`](#indexedattestation)
             - [`PendingAttestation`](#pendingattestation)
             - [`Eth1Data`](#eth1data)
@@ -55,7 +54,6 @@
             - [`hash_tree_root`](#hash_tree_root)
             - [`signing_root`](#signing_root)
             - [`bls_verify`](#bls_verify)
-            - [`bls_verify_multiple`](#bls_verify_multiple)
             - [`bls_aggregate_pubkeys`](#bls_aggregate_pubkeys)
         - [Predicates](#predicates)
             - [`is_active_validator`](#is_active_validator)
@@ -308,20 +306,11 @@ class AttestationData(Container):
     target: Checkpoint
 ```
 
-#### `AttestationDataAndCustodyBit`
-
-```python
-class AttestationDataAndCustodyBit(Container):
-    data: AttestationData
-    custody_bit: bit  # Challengeable bit (SSZ-bool, 1 byte) for the custody of shard data
-```
-
 #### `IndexedAttestation`
 
 ```python
 class IndexedAttestation(Container):
-    custody_bit_0_indices: List[ValidatorIndex, MAX_VALIDATORS_PER_COMMITTEE]  # Indices with custody bit equal to 0
-    custody_bit_1_indices: List[ValidatorIndex, MAX_VALIDATORS_PER_COMMITTEE]  # Indices with custody bit equal to 1
+    attesting_indices: List[ValidatorIndex, MAX_VALIDATORS_PER_COMMITTEE]
     data: AttestationData
     signature: BLSSignature
 ```
@@ -399,7 +388,6 @@ class AttesterSlashing(Container):
 class Attestation(Container):
     aggregation_bits: Bitlist[MAX_VALIDATORS_PER_COMMITTEE]
     data: AttestationData
-    custody_bits: Bitlist[MAX_VALIDATORS_PER_COMMITTEE]
     signature: BLSSignature
 ```
 
@@ -553,10 +541,6 @@ def bytes_to_int(data: bytes) -> uint64:
 
 `bls_verify` is a function for verifying a BLS signature, as defined in the [BLS Signature spec](../bls_signature.md#bls_verify).
 
-#### `bls_verify_multiple`
-
-`bls_verify_multiple` is a function for verifying a BLS signature constructed from multiple messages, as defined in the [BLS Signature spec](../bls_signature.md#bls_verify_multiple).
-
 #### `bls_aggregate_pubkeys`
 
 `bls_aggregate_pubkeys` is a function for aggregating multiple BLS public keys into a single aggregate key, as defined in the [BLS Signature spec](../bls_signature.md#bls_aggregate_pubkeys).
@@ -605,31 +589,18 @@ def is_valid_indexed_attestation(state: BeaconState, indexed_attestation: Indexe
     """
     Check if ``indexed_attestation`` has valid indices and signature.
     """
-    bit_0_indices = indexed_attestation.custody_bit_0_indices
-    bit_1_indices = indexed_attestation.custody_bit_1_indices
+    indices = indexed_attestation.attesting_indices
 
-    # Verify no index has custody bit equal to 1 [to be removed in phase 1]
-    if not len(bit_1_indices) == 0:  # [to be removed in phase 1]
-        return False                 # [to be removed in phase 1]
     # Verify max number of indices
-    if not len(bit_0_indices) + len(bit_1_indices) <= MAX_VALIDATORS_PER_COMMITTEE:
-        return False
-    # Verify index sets are disjoint
-    if not len(set(bit_0_indices).intersection(bit_1_indices)) == 0:
+    if not len(indices) <= MAX_VALIDATORS_PER_COMMITTEE:
         return False
     # Verify indices are sorted
-    if not (bit_0_indices == sorted(bit_0_indices) and bit_1_indices == sorted(bit_1_indices)):
+    if not indices == sorted(indices):
         return False
     # Verify aggregate signature
-    if not bls_verify_multiple(
-        pubkeys=[
-            bls_aggregate_pubkeys([state.validators[i].pubkey for i in bit_0_indices]),
-            bls_aggregate_pubkeys([state.validators[i].pubkey for i in bit_1_indices]),
-        ],
-        message_hashes=[
-            hash_tree_root(AttestationDataAndCustodyBit(data=indexed_attestation.data, custody_bit=0b0)),
-            hash_tree_root(AttestationDataAndCustodyBit(data=indexed_attestation.data, custody_bit=0b1)),
-        ],
+    if not bls_verify(
+        pubkey=bls_aggregate_pubkeys([state.validators[i].pubkey for i in indices]),
+        message_hash=hash_tree_root(indexed_attestation.data),
         signature=indexed_attestation.signature,
         domain=get_domain(state, DOMAIN_BEACON_ATTESTER, indexed_attestation.data.target.epoch),
     ):
@@ -922,13 +893,9 @@ def get_indexed_attestation(state: BeaconState, attestation: Attestation) -> Ind
     Return the indexed attestation corresponding to ``attestation``.
     """
     attesting_indices = get_attesting_indices(state, attestation.data, attestation.aggregation_bits)
-    custody_bit_1_indices = get_attesting_indices(state, attestation.data, attestation.custody_bits)
-    assert custody_bit_1_indices.issubset(attesting_indices)
-    custody_bit_0_indices = attesting_indices.difference(custody_bit_1_indices)
 
     return IndexedAttestation(
-        custody_bit_0_indices=sorted(custody_bit_0_indices),
-        custody_bit_1_indices=sorted(custody_bit_1_indices),
+        attesting_indices=sorted(attesting_indices),
         data=attestation.data,
         signature=attestation.signature,
     )
@@ -1460,9 +1427,8 @@ def process_attester_slashing(state: BeaconState, attester_slashing: AttesterSla
     assert is_valid_indexed_attestation(state, attestation_2)
 
     slashed_any = False
-    attesting_indices_1 = attestation_1.custody_bit_0_indices + attestation_1.custody_bit_1_indices
-    attesting_indices_2 = attestation_2.custody_bit_0_indices + attestation_2.custody_bit_1_indices
-    for index in sorted(set(attesting_indices_1).intersection(attesting_indices_2)):
+    indices = set(attestation_1.attesting_indices).intersection(attestation_2.attesting_indices)
+    for index in sorted(indices):
         if is_slashable_validator(state.validators[index], get_current_epoch(state)):
             slash_validator(state, index)
             slashed_any = True
@@ -1479,7 +1445,7 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
     assert data.slot + MIN_ATTESTATION_INCLUSION_DELAY <= state.slot <= data.slot + SLOTS_PER_EPOCH
 
     committee = get_beacon_committee(state, data.slot, data.index)
-    assert len(attestation.aggregation_bits) == len(attestation.custody_bits) == len(committee)
+    assert len(attestation.aggregation_bits) == len(committee)
 
     pending_attestation = PendingAttestation(
         data=data,

specs/core/0_fork-choice.md

@@ -199,7 +199,7 @@ def on_attestation(store: Store, attestation: Attestation) -> None:
     assert is_valid_indexed_attestation(target_state, indexed_attestation)
 
     # Update latest messages
-    for i in indexed_attestation.custody_bit_0_indices + indexed_attestation.custody_bit_1_indices:
+    for i in indexed_attestation.attesting_indices:
         if i not in store.latest_messages or target.epoch > store.latest_messages[i].epoch:
             store.latest_messages[i] = LatestMessage(epoch=target.epoch, root=attestation.data.beacon_block_root)
 ```

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

@@ -45,15 +45,13 @@
             - [Construct attestation](#construct-attestation)
                 - [Data](#data)
                 - [Aggregation bits](#aggregation-bits)
-                - [Custody bits](#custody-bits)
                 - [Aggregate signature](#aggregate-signature)
             - [Broadcast attestation](#broadcast-attestation)
         - [Attestation aggregation](#attestation-aggregation)
             - [Aggregation selection](#aggregation-selection)
             - [Construct aggregate](#construct-aggregate)
                 - [Data](#data-1)
                 - [Aggregation bits](#aggregation-bits-1)
-                - [Custody bits](#custody-bits-1)
                 - [Aggregate signature](#aggregate-signature-1)
             - [Broadcast aggregate](#broadcast-aggregate)
                 - [`AggregateAndProof`](#aggregateandproof)
@@ -331,25 +329,14 @@ Set `attestation.data = attestation_data` where `attestation_data` is the `Attes
 
 *Note*: Calling `get_attesting_indices(state, attestation.data, attestation.aggregation_bits)` should return a list of length equal to 1, containing `validator_index`.
 
-##### Custody bits
-
-- Let `attestation.custody_bits` be a `Bitlist[MAX_VALIDATORS_PER_COMMITTEE]` filled with zeros of length `len(committee)`.
-
-*Note*: This is a stub for Phase 0.
-
 ##### Aggregate signature
 
 Set `attestation.signature = signed_attestation_data` where `signed_attestation_data` is obtained from:
 
 ```python
 def get_signed_attestation_data(state: BeaconState, attestation: IndexedAttestation, privkey: int) -> BLSSignature:
-    attestation_data_and_custody_bit = AttestationDataAndCustodyBit(
-        data=attestation.data,
-        custody_bit=0b0,
-    )
-
     domain = get_domain(state, DOMAIN_BEACON_ATTESTER, attestation.data.target.epoch)
-    return bls_sign(privkey, hash_tree_root(attestation_data_and_custody_bit), domain)
+    return bls_sign(privkey, hash_tree_root(attestation.data), domain)
 ```
 
 #### Broadcast attestation
@@ -391,12 +378,6 @@ Set `aggregate_attestation.data = attestation_data` where `attestation_data` is
 
 Let `aggregate_attestation.aggregation_bits` be a `Bitlist[MAX_VALIDATORS_PER_COMMITTEE]` of length `len(committee)`, where each bit set from each individual attestation is set to `0b1`.
 
-##### Custody bits
-
-- Let `aggregate_attestation.custody_bits` be a `Bitlist[MAX_VALIDATORS_PER_COMMITTEE]` filled with zeros of length `len(committee)`.
-
-*Note*: This is a stub for Phase 0.
-
 ##### Aggregate signature
 
 Set `aggregate_attestation.signature = aggregate_signature` where `aggregate_signature` is obtained from:

test_libs/pyspec/eth2spec/fuzzing/test_decoder.py

@@ -9,7 +9,7 @@ def test_decoder():
     rng = Random(123)
 
     # check these types only, Block covers a lot of operation types already.
-    for typ in [spec.AttestationDataAndCustodyBit, spec.BeaconState, spec.BeaconBlock]:
+    for typ in [spec.Attestation, spec.BeaconState, spec.BeaconBlock]:
         # create a random pyspec value
         original = random_value.get_random_ssz_object(rng, typ, 100, 10,
                                                       mode=random_value.RandomizationMode.mode_random,

test_libs/pyspec/eth2spec/test/fork_choice/test_on_attestation.py

@@ -1,7 +1,5 @@
 
-from eth2spec.test.context import with_all_phases, spec_state_test, with_phases
-
-
+from eth2spec.test.context import with_all_phases, spec_state_test
 from eth2spec.test.helpers.block import build_empty_block_for_next_slot
 from eth2spec.test.helpers.attestations import get_valid_attestation
 from eth2spec.test.helpers.state import state_transition_and_sign_block
@@ -19,7 +17,7 @@ def run_on_attestation(spec, state, store, attestation, valid=True):
     indexed_attestation = spec.get_indexed_attestation(state, attestation)
     spec.on_attestation(store, attestation)
     assert (
-        store.latest_messages[indexed_attestation.custody_bit_0_indices[0]] ==
+        store.latest_messages[indexed_attestation.attesting_indices[0]] ==
         spec.LatestMessage(
             epoch=attestation.data.target.epoch,
             root=attestation.data.beacon_block_root,
@@ -100,7 +98,7 @@ def test_on_attestation_same_slot(spec, state):
     run_on_attestation(spec, state, store, attestation, False)
 
 
-@with_phases(['phase0'])
+@with_all_phases
 @spec_state_test
 def test_on_attestation_invalid_attestation(spec, state):
     store = spec.get_genesis_store(state)
@@ -113,6 +111,7 @@ def test_on_attestation_invalid_attestation(spec, state):
     spec.on_block(store, block)
 
     attestation = get_valid_attestation(spec, state, slot=block.slot)
-    # make attestation invalid by setting a phase1-only custody bit
-    attestation.custody_bits[0] = 1
+    # make invalid by using an invalid committee index
+    attestation.data.index = spec.MAX_COMMITTEES_PER_SLOT * spec.SLOTS_PER_EPOCH
+
     run_on_attestation(spec, state, store, attestation, False)

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

@@ -54,11 +54,9 @@ def get_valid_attestation(spec, state, slot=None, index=None, signed=False):
 
     committee_size = len(beacon_committee)
     aggregation_bits = Bitlist[spec.MAX_VALIDATORS_PER_COMMITTEE](*([0] * committee_size))
-    custody_bits = Bitlist[spec.MAX_VALIDATORS_PER_COMMITTEE](*([0] * committee_size))
     attestation = spec.Attestation(
         aggregation_bits=aggregation_bits,
         data=attestation_data,
-        custody_bits=custody_bits,
     )
     fill_aggregate_attestation(spec, state, attestation)
     if signed:
@@ -83,7 +81,7 @@ def sign_aggregate_attestation(spec, state, attestation_data, participants: List
 
 
 def sign_indexed_attestation(spec, state, indexed_attestation):
-    participants = indexed_attestation.custody_bit_0_indices + indexed_attestation.custody_bit_1_indices
+    participants = indexed_attestation.attesting_indices
     indexed_attestation.signature = sign_aggregate_attestation(spec, state, indexed_attestation.data, participants)
 
 
@@ -97,14 +95,9 @@ def sign_attestation(spec, state, attestation):
     attestation.signature = sign_aggregate_attestation(spec, state, attestation.data, participants)
 
 
-def get_attestation_signature(spec, state, attestation_data, privkey, custody_bit=0b0):
-    message_hash = spec.AttestationDataAndCustodyBit(
-        data=attestation_data,
-        custody_bit=custody_bit,
-    ).hash_tree_root()
-
+def get_attestation_signature(spec, state, attestation_data, privkey):
     return bls_sign(
-        message_hash=message_hash,
+        message_hash=attestation_data.hash_tree_root(),
         privkey=privkey,
         domain=spec.get_domain(
             state=state,

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

@@ -2,7 +2,7 @@
     spec_state_test,
     expect_assertion_error,
     always_bls, never_bls,
-    with_all_phases, with_phases,
+    with_all_phases,
     spec_test,
     low_balances,
     with_custom_state,
@@ -274,35 +274,6 @@ def test_bad_source_root(spec, state):
     yield from run_attestation_processing(spec, state, attestation, False)
 
 
-@with_all_phases
-@spec_state_test
-def test_inconsistent_bits(spec, state):
-    attestation = get_valid_attestation(spec, state)
-    state.slot += spec.MIN_ATTESTATION_INCLUSION_DELAY
-
-    custody_bits = attestation.custody_bits[:]
-    custody_bits.append(False)
-
-    attestation.custody_bits = custody_bits
-
-    sign_attestation(spec, state, attestation)
-
-    yield from run_attestation_processing(spec, state, attestation, False)
-
-
-@with_phases(['phase0'])
-@spec_state_test
-def test_non_empty_custody_bits(spec, state):
-    attestation = get_valid_attestation(spec, state)
-    state.slot += spec.MIN_ATTESTATION_INCLUSION_DELAY
-
-    attestation.custody_bits = attestation.aggregation_bits[:]
-
-    sign_attestation(spec, state, attestation)
-
-    yield from run_attestation_processing(spec, state, attestation, False)
-
-
 @with_all_phases
 @spec_state_test
 def test_empty_aggregation_bits(spec, state):
@@ -344,32 +315,3 @@ def test_too_few_aggregation_bits(spec, state):
     attestation.aggregation_bits = attestation.aggregation_bits[:-1]
 
     yield from run_attestation_processing(spec, state, attestation, False)
-
-
-@with_all_phases
-@spec_state_test
-def test_too_many_custody_bits(spec, state):
-    attestation = get_valid_attestation(spec, state, signed=True)
-    state.slot += spec.MIN_ATTESTATION_INCLUSION_DELAY
-
-    # one too many bits
-    attestation.custody_bits.append(0b0)
-
-    yield from run_attestation_processing(spec, state, attestation, False)
-
-
-@with_all_phases
-@spec_state_test
-def test_too_few_custody_bits(spec, state):
-    attestation = get_valid_attestation(spec, state)
-    state.slot += spec.MIN_ATTESTATION_INCLUSION_DELAY
-
-    attestation.custody_bits = Bitlist[spec.MAX_VALIDATORS_PER_COMMITTEE](
-        *([0b1] + [0b0] * (len(attestation.custody_bits) - 1)))
-
-    sign_attestation(spec, state, attestation)
-
-    # one too few bits
-    attestation.custody_bits = attestation.custody_bits[:-1]
-
-    yield from run_attestation_processing(spec, state, attestation, False)