Fix deposit root, add min_genesis_time, per-block processing

specs/core/0_beacon-chain.md

@@ -126,7 +126,7 @@
 
 This document represents the specification for Phase 0 of Ethereum 2.0 -- The Beacon Chain.
 
-At the core of Ethereum 2.0 is a system chain called the "beacon chain". The beacon chain stores and manages the registry of [validators](#dfn-validator). In the initial deployment phases of Ethereum 2.0, the only mechanism to become a [validator](#dfn-validator) is to make a one-way ETH transaction to a deposit contract on Ethereum 1.0. Activation as a [validator](#dfn-validator) happens when Ethereum 1.0 deposit receipts are processed by the beacon chain, the activation balance is reached, and a queuing process is completed. Exit is either voluntary or done forcibly as a penalty for misbehavior.
+At the core of Ethereum 2.0 is a system chain called the "beacon chain". The beacon chain stores and manages the registry of [validators](#dfn-validator). In the initial deployment phases of Ethereum 2.0, the only mechanism to become a [validator](#dfn-validator) is to make a one-way ETH transaction to a deposit contract on Eth 1.0. Activation as a [validator](#dfn-validator) happens when Eth 1.0 deposit receipts are processed by the beacon chain, the activation balance is reached, and a queuing process is completed. Exit is either voluntary or done forcibly as a penalty for misbehavior.
 
 The primary source of load on the beacon chain is "attestations". Attestations are simultaneously availability votes for a shard block and proof-of-stake votes for a beacon block. A sufficient number of attestations for the same shard block create a "crosslink", confirming the shard segment up to that shard block into the beacon chain. Crosslinks also serve as infrastructure for asynchronous cross-shard communication.
 
@@ -136,7 +136,7 @@ Code snippets appearing in `this style` are to be interpreted as Python code.
 
 ## Terminology
 
-* **Validator**<a id="dfn-validator"></a>—a registered participant in the beacon chain. You can become one by sending ether into the Ethereum 1.0 deposit contract.
+* **Validator**<a id="dfn-validator"></a>—a registered participant in the beacon chain. You can become one by sending ether into the Eth 1.0 deposit contract.
 * **Active validator**<a id="dfn-active-validator"></a>—an active participant in the Ethereum 2.0 consensus invited to, among other things, propose and attest to blocks and vote for crosslinks.
 * **Committee**—a (pseudo-) randomly sampled subset of [active validators](#dfn-active-validator). When a committee is referred to collectively, as in "this committee attests to X", this is assumed to mean "some subset of that committee that contains enough [validators](#dfn-validator) that the protocol recognizes it as representing the committee".
 * **Proposer**—the [validator](#dfn-validator) that creates a beacon chain block.
@@ -195,6 +195,7 @@ These configurations are updated for releases, but may be out of sync during `de
 | `CHURN_LIMIT_QUOTIENT` | `2**16` (= 65,536) |
 | `SHUFFLE_ROUND_COUNT` | `90` |
 | `GENESIS_ACTIVE_VALIDATOR_COUNT` | `2**16` (= 65,536) |
+| `MIN_GENESIS_TIME` | `1578009600` (Jan 3, 2020) |
 
 * For the safety of crosslinks `TARGET_COMMITTEE_SIZE` exceeds [the recommended minimum committee size of 111](https://vitalik.ca/files/Ithaca201807_Sharding.pdf); with sufficient active validators (at least `SLOTS_PER_EPOCH * TARGET_COMMITTEE_SIZE`), the shuffling algorithm ensures committee sizes of at least `TARGET_COMMITTEE_SIZE`. (Unbiasable randomness with a Verifiable Delay Function (VDF) will improve committee robustness and lower the safe minimum committee size.)
 
@@ -1130,31 +1131,34 @@ def slash_validator(state: BeaconState,
 
 ### Genesis trigger
 
-Before genesis has been triggered and whenever the deposit contract emits a `Deposit` log, call the function `is_genesis_trigger(deposits: List[Deposit], timestamp: uint64) -> bool` where:
+Before genesis has been triggered and for every Eth 1.0 block call `is_genesis_trigger(deposits, time)` where:
 
-* `deposits` is the list of all deposits, ordered chronologically, up to and including the deposit triggering the latest `Deposit` log
-* `timestamp` is the Unix timestamp in the Ethereum 1.0 block that emitted the latest `Deposit` log
+* `deposits` is the list of all deposits up to the Eth 1.0 block, ordered chronologically
+* `time` is the Unix time of the Eth 1.0 block
 
-When `is_genesis_trigger(deposits, timestamp) is True` for the first time let:
+When `is_genesis_trigger(deposits, time) is True` for the first time let:
 
 * `genesis_deposits = deposits`
-* `genesis_time = timestamp - timestamp % SECONDS_PER_DAY + 2 * SECONDS_PER_DAY` where `SECONDS_PER_DAY = 86400`
+* `genesis_time = time - time % SECONDS_PER_DAY + 2 * SECONDS_PER_DAY` where `SECONDS_PER_DAY = 86400`
 * `genesis_eth1_data` be the object of type `Eth1Data` where:
     * `genesis_eth1_data.deposit_root` is the deposit root for the last deposit in `deposits`
     * `genesis_eth1_data.deposit_count = len(genesis_deposits)`
-    * `genesis_eth1_data.block_hash` is the Ethereum 1.0 block hash that emitted the log for the last deposit in `deposits`
+    * `genesis_eth1_data.block_hash` is the Eth 1.0 block hash that emitted the log for the last deposit in `deposits`
 
 *Note*: The function `is_genesis_trigger` has yet to be agreed by the community, and can be updated as necessary. We define the following testing placeholder:
 
 ```python
-def is_genesis_trigger(deposits: List[Deposit], timestamp: uint64) -> bool:
+def is_genesis_trigger(deposits: List[Deposit, 2**DEPOSIT_CONTRACT_TREE_DEPTH], time: uint64) -> bool:
+    # Do not deploy too early
+    if time - time % SECONDS_PER_DAY + 2 * SECONDS_PER_DAY < MIN_GENESIS_TIME:
+        return False
+
     # Initialize deposit root
     state = BeaconState()
-    for i in range(DEPOSIT_CONTRACT_TREE_DEPTH - 1):
-        state.eth1_data.deposit_root = hash(state.eth1_data.deposit_root + state.eth1_data.deposit_root)
+    state.eth1_data.deposit_root = hash_tree_root(map(deposits, lambda deposit: deposit.data))
 
     # Process deposits
-    for deposit in deposits:
+    for deposit in deposits
         process_deposit(state, deposit)
 
     # Count active validators at genesis