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Update 0_beacon-chain.md

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Justin 2019-01-23 13:24:35 +00:00 committed by GitHub
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specs/core/0_beacon-chain.md
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@ -302,10 +302,10 @@ Code snippets appearing in `this style` are to be interpreted as Python code. Be
```python
{
# Validator indices with custody bit equal to 0
'custody_bit_0_indices': ['uint24'],
# Validator indices with custody bit equal to 1
'custody_bit_1_indices': ['uint24'],
# Validator indices
'validator_indices': '[uint24]',
# Custody bitfield
'custody_bitfield': 'bytes',
# Attestation data
'data': AttestationData,
# Aggregate signature
@ -1110,16 +1110,34 @@ def verify_bitfield(bitfield: bytes, size: int) -> bool:
```python
def verify_slashable_vote_data(state: BeaconState, slashable_vote_data: SlashableVoteData) -> bool:
if len(slashable_vote_data.custody_bit_1_indices) > 0: # [TO BE REMOVED IN PHASE 1]
if slashable_vote_data.custody_bitfield != 0: # [TO BE REMOVED IN PHASE 1]
return False
if len(indices(slashable_vote_data)) > MAX_CASPER_VOTES:
if len(slashable_vote_data.validator_indices) == 0:
return False
for i in range(len(slashable_vote_data.validator_indices) - 1):
if slashable_vote_data.validator_indices[i] >= slashable_vote_data.validator_indices[i + 1]:
return False
if not verify_bitfield(slashable_vote_data.custody_bitfield, len(slashable_vote_data.validator_indices)):
return False
if len(slashable_vote_data.validator_indices) > MAX_CASPER_VOTES:
return False
custody_bit_0_indices = []
custody_bit_1_indices = []
for i, validator_index in enumerate(slashable_vote_data.validator_indices):
if get_bitfield_bit(slashable_vote_data.custody_bitfield, i) == 0:
custody_bit_0_indices.append(validator_index)
else:
custody_bit_1_indices.append(validator_index)
return bls_verify(
pubkeys=[
bls_aggregate_pubkeys([state.validator_registry[i].pubkey for i in slashable_vote_data.custody_bit_0_indices]),
bls_aggregate_pubkeys([state.validator_registry[i].pubkey for i in slashable_vote_data.custody_bit_1_indices]),
bls_aggregate_pubkeys([state.validator_registry[i].pubkey for i in custody_bit_0_indices]),
bls_aggregate_pubkeys([state.validator_registry[i].pubkey for i in custody_bit_1_indices]),
],
messages=[
hash_tree_root(AttestationDataAndCustodyBit(slashable_vote_data.data, CUSTODY_BIT_ZERO)),
@ -1184,16 +1202,6 @@ def integer_squareroot(n: int) -> int:
return x
```
#### `indices`
```python
def indices(slashable_vote_data: SlashableVoteData) -> List[int]:
"""
Return all indicies in ``slashable_vote_data``.
"""
return slashable_vote_data.custody_bit_0_indices + slashable_vote_data.custody_bit_1_indices
```
#### `bls_verify`
`bls_verify` is a function for verifying a BLS signature, defined in the [BLS Signature spec](https://github.com/ethereum/eth2.0-specs/blob/master/specs/bls_signature.md#bls_verify).
@ -1507,7 +1515,7 @@ For each `casper_slashing` in `block.body.casper_slashings`:
* Let `slashable_vote_data_1 = casper_slashing.slashable_vote_data_1`.
* Let `slashable_vote_data_2 = casper_slashing.slashable_vote_data_2`.
* Let `intersection = [x for x in indices(slashable_vote_data_1) if x in indices(slashable_vote_data_2)]`.
* Let `intersection = [x for x in slashable_vote_data_1.validator_indices if x in slashable_vote_data_2.validator_indices]`.
* Verify that `len(intersection) >= 1`.
* Verify that `slashable_vote_data_1.data != slashable_vote_data_2.data`.
* Verify that `is_double_vote(slashable_vote_data_1.data, slashable_vote_data_2.data)` or `is_surround_vote(slashable_vote_data_1.data, slashable_vote_data_2.data)`.