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Made trace a commitment separate from state roots

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Vitalik Buterin 2019-10-14 23:55:41 +08:00 committed by Danny Ryan
parent 9abfc6276a
commit e5544d055b
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1 changed files with 9 additions and 15 deletions
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specs/core/1_new_shards.md
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@ -91,13 +91,6 @@ def get_online_indices(state: BeaconState) -> Set[ValidatorIndex]:
return set([i for i in active_validators if state.online_countdown[i] != 0])
```
### `get_shard_state_root`
```python
def get_shard_state_root(state: BeaconState, shard: Shard) -> Hash:
return state.shard_state_roots[shard][-1]
```
### `pack_compact_validator`
```python
@ -141,7 +134,8 @@ def committee_to_compact_committee(state: BeaconState, committee: Sequence[Valid
### New state variables
```python
shard_state_roots: Vector[List[Hash, MAX_CATCHUP_RATIO * MAX_SHARDS], MAX_SHARDS]
shard_state_roots: Vector[Hash, MAX_SHARDS]
shard_trace_commitments: Vector[Hash, MAX_SHARDS]
shard_next_slots: Vector[Slot, MAX_SHARDS]
online_countdown: Bytes[VALIDATOR_REGISTRY_LIMIT]
current_light_committee: CompactCommittee
@ -184,7 +178,13 @@ def process_attestation(state: BeaconState, attestation: Attestation) -> None:
# Apply
online_indices = get_online_indices(state)
if get_total_balance(state, online_indices.intersection(attesting_indices)) * 3 >= get_total_balance(state, online_indices) * 2:
state.shard_state_roots[shard] = data.shard_state_roots
# Save trace commitment (used for fraud proofs)
trace = List[Hash, MAX_CATCHUP_RATIO * MAX_SHARDS * 2 + 1]([state.shard_state_roots[shard]])
for data, state in zip(data.shard_data_roots, data.shard_state_roots):
trace.extend([data, state])
state.shard_trace_commitments[shard] = hash_tree_root(trace)
# Save state root and next slot
state.shard_state_roots[shard] = data.shard_state_roots[-1]
state.shard_next_slots[shard] += len(data.shard_data_roots)
# Type 2: delayed attestations
@ -256,12 +256,6 @@ TODO. The intent is to have a single universal fraud proof type, which contains
* `custody_bits[i][j] != generate_custody_bit(subkey, block_contents)` for any `j`
* `execute_state_transition(shard, slot, attestation.shard_state_roots[i-1], hash_tree_root(parent), get_shard_proposer(state, shard, slot), block_contents) != shard_state_roots[i]` (if `i=0` then instead use `parent.shard_state_roots[s][-1]`)
For phase 1, we will use a simple state transition function:
* Check that `data[:32] == prev_state_root`
* Check that `bls_verify(get_shard_proposer(state, slot, shard), hash_tree_root(data[-96:]), BLSSignature(data[-96:]), BLOCK_SIGNATURE_DOMAIN)`
* Output the new state root: `hash_tree_root(prev_state_root, other_prev_state_roots, data)`
## Shard state transition function
```python