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Merge pull request #165 from ethereum/vbuterin-patch-13 

Addressed Justin's 16, 17, 18
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vbuterin 2018-11-26 06:24:47 -05:00 committed by GitHub
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38
specs/core/0_beacon-chain.md
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@ -43,7 +43,6 @@ The primary source of load on the beacon chain are "attestations". Attestations
| `MIN_VALIDATOR_SET_CHANGE_INTERVAL` | 2**8 (= 256) | slots | ~25 minutes |
| `SHARD_PERSISTENT_COMMITTEE_CHANGE_PERIOD` | 2**17 (= 131,072) | slots | ~9 days |
| `MIN_ATTESTATION_INCLUSION_DELAY` | 2**2 (= 4) | slots | ~24 seconds |
| `RANDAO_SLOTS_PER_LAYER` | 2**12 (= 4,096) | slots | ~7 hours |
| `SQRT_E_DROP_TIME` | 2**18 (= 262,144) | slots | ~18 days |
| `WITHDRAWALS_PER_CYCLE` | 2**2 (=4) | validators | 5.2m ETH in ~6 months |
| `MIN_WITHDRAWAL_PERIOD` | 2**13 (= 8,192) | slots | ~14 hours |
@ -54,6 +53,8 @@ The primary source of load on the beacon chain are "attestations". Attestations
| `BASE_REWARD_QUOTIENT` | 2**15 (= 32,768) | — |
| `MAX_VALIDATOR_CHURN_QUOTIENT` | 2**5 (= 32) | — |
| `POW_CONTRACT_MERKLE_TREE_DEPTH` | 2**5 (= 32) | - |
| `MAX_ATTESTATION_COUNT` | 2**7 (= 128) | - |
| `LOGOUT_MESSAGE` | `"LOGOUT"` | — |
| `INITIAL_FORK_VERSION` | 0 | — |
**Notes**
@ -266,8 +267,8 @@ A `ValidatorRecord` has the following fields:
'withdrawal_credentials': 'hash32',
# RANDAO commitment
'randao_commitment': 'hash32',
# Slot the RANDAO commitment was last changed
'randao_last_change': 'uint64',
# Slot the proposer has skipped (ie. layers of RANDAO expected)
'randao_skips': 'uint64',
# Balance in Gwei
'balance': 'uint64',
# Status code
@ -581,6 +582,9 @@ def int_sqrt(n: int) -> int:
The beacon chain is initialized when a condition is met inside a contract on the existing PoW chain. This contract's code in Vyper is as follows:
```python
SECONDS_PER_DAY: constant(uint256) = 86400
POW_CONTRACT_MERKLE_TREE_DEPTH: constant(int128) = 32
HashChainValue: event({previous_receipt_root: bytes32, data: bytes[2064], total_deposit_count: int128})
ChainStart: event({receipt_root: bytes32, time: bytes[8]})
@ -591,19 +595,21 @@ total_deposit_count: int128
@public
def deposit(deposit_params: bytes[2048]):
index:int128 = self.total_deposit_count + 2**POW_CONTRACT_MERKLE_TREE_DEPTH
msg_gwei_bytes8: bytes[8] = slice(convert(msg.value / 10**9, 'bytes32'), 24, 8)
timestamp_bytes8: bytes[8] = slice(convert(block.timestamp, 'bytes32'), 24, 8)
msg_gwei_bytes8: bytes[8] = slice(concat("", convert(msg.value / 10**9, bytes32)), start=24, len=8)
timestamp_bytes8: bytes[8] = slice(concat("", convert(block.timestamp, bytes32)), start=24, len=8)
deposit_data: bytes[2064] = concat(deposit_params, msg_gwei_bytes8, timestamp_bytes8)
log.HashChainValue(self.receipt_tree[1], deposit_data, self.total_deposit_count)
self.receipt_tree[index] = sha3(deposit_data)
for i in range(POW_CONTRACT_MERKLE_TREE_DEPTH):
index //= 2
index /= 2
self.receipt_tree[index] = sha3(concat(self.receipt_tree[index * 2], self.receipt_tree[index * 2 + 1]))
self.total_deposit_count += 1
if self.total_deposit_count == 16384:
log.ChainStart(self.receipt_tree[1], timestamp_bytes8)
timestamp_day_boundary: uint256 = as_unitless_number(block.timestamp) - as_unitless_number(block.timestamp) % SECONDS_PER_DAY + SECONDS_PER_DAY
timestamp_day_boundary_bytes8: bytes[8] = slice(concat("", convert(timestamp_day_boundary, bytes32)), start=24, len=8)
log.ChainStart(self.receipt_tree[1], timestamp_day_boundary_bytes8)
@public
@constant
@ -748,7 +754,7 @@ def add_validator(state: State,
pubkey=pubkey,
withdrawal_credentials=withdrawal_credentials,
randao_commitment=randao_commitment,
randao_last_change=current_slot,
randao_skips=0,
balance=DEPOSIT_SIZE * GWEI_PER_ETH,
status=status,
last_status_change_slot=current_slot,
@ -817,7 +823,7 @@ def update_ancestor_hashes(parent_ancestor_hashes: List[Hash32],
### Verify attestations
For each `AttestationRecord` object:
Verify that there are at most `MAX_ATTESTATION_COUNT` `AttestationRecord` objects. For each `AttestationRecord` object:
* Verify that `slot <= block.slot - MIN_ATTESTATION_INCLUSION_DELAY` and `slot >= max(parent.slot - CYCLE_LENGTH + 1, 0)`.
* Verify that `justified_slot` is equal to or earlier than `last_justified_slot`.
@ -841,10 +847,20 @@ Verify that `BLSVerify(pubkey=get_beacon_proposer(state, block.slot).pubkey, dat
### Verify and process RANDAO reveal
First run the following state transition to update `randao_skips` variables for the missing slots.
```python
for slot in range(parent.slot + 1, block.slot):
proposer = get_beacon_proposer(state, slot)
proposer.randao_skips += 1
```
Then:
* Let `repeat_hash(x, n) = x if n == 0 else repeat_hash(hash(x), n-1)`.
* Let `V = get_beacon_proposer(state, block.slot)`.
* Verify that `repeat_hash(block.randao_reveal, (block.slot - V.randao_last_change) // RANDAO_SLOTS_PER_LAYER + 1) == V.randao_commitment`
* Set `state.randao_mix = xor(state.randao_mix, block.randao_reveal)`, `V.randao_commitment = block.randao_reveal`, `V.randao_last_change = block.slot`
* Verify that `repeat_hash(block.randao_reveal, V.randao_skips + 1) == V.randao_commitment`
* Set `state.randao_mix = xor(state.randao_mix, block.randao_reveal)`, `V.randao_commitment = block.randao_reveal`, `V.randao_skips = 0`
### Process PoW receipt root