Revamp per block processing / state transition
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mratsim
parent
0b560f7307
commit
14bb9b6efd
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@ -11,22 +11,21 @@ import intsets, eth_common, math
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# ⚠ Spec is updated very often, implementation might quickly be outdated
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type
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Keccak256_Digest* = Hash256 # TODO, previously Keccak256 fields used the "bytes" type
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Blake2_256_Digest* = Hash256 # while Blake2 used hash32, but latest spec changed everything to hash32
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Blake2_256_Digest* = Hash256 # TODO change to Blake2b-512[0 ..< 32] see https://github.com/status-im/nim-beacon-chain/issues/3
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Uint24* = range[0'u32 .. 0xFFFFFF'u32] # TODO: wrap-around
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BeaconBlock* = object
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parent_hash*: Keccak256_Digest # Hash of the parent block
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parent_hash*: Blake2_256_Digest # Hash of the parent block
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slot_number*: int64 # Slot number (for the PoS mechanism)
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randao_reveal*: Keccak256_Digest # Randao commitment reveal
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randao_reveal*: Blake2_256_Digest # Randao commitment reveal
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attestations*: seq[AttestationRecord] # Attestation votes
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pow_chain_ref*: Keccak256_Digest # Reference to main chain block
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pow_chain_ref*: Blake2_256_Digest # Reference to main chain block
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active_state_root*: Blake2_256_Digest # Hash of the active state
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crystallized_state_root*: Blake2_256_Digest # Hash of the crystallized state
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ActiveState* = object
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pending_attestations*: seq[AttestationRecord] # Attestations that have not yet been processed
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recent_block_hashes*: seq[Keccak256_Digest] # Most recent 2 * CYCLE_LENGTH block hashes, older to newer
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recent_block_hashes*: seq[Blake2_256_Digest] # Most recent 2 * CYCLE_LENGTH block hashes, older to newer
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CrystallizedState* = object
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validators*: seq[ValidatorRecord] # List of active validators
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@ -42,7 +41,7 @@ type
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crosslinking_start_shard*: int16 # The next shard that cross-linking assignment will start from
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crosslink_records*: seq[CrosslinkRecord] # Records about the most recent crosslink for each shard
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total_deposits*: Int256 # Total balance of deposits
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dynasty_seed*: Keccak256_Digest # Used to select the committees for each shard
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dynasty_seed*: Blake2_256_Digest # Used to select the committees for each shard
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dynasty_seed_last_reset*: int64 # Last epoch the crosslink seed was reset
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ShardAndCommittee* = object
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@ -53,14 +52,14 @@ type
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pubkey*: BLSPublicKey # The validator's public key
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withdrawal_shard*: int16 # What shard the validator's balance will be sent to after withdrawal
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withdrawal_address*: EthAddress # And what address
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randao_commitment*: Keccak256_Digest # The validator's current RANDAO beacon commitment
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randao_commitment*: Blake2_256_Digest # The validator's current RANDAO beacon commitment
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balance*: int64 # Current balance
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start_dynasty*: int64 # Dynasty where the validator is inducted
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end_dynasty*: int64 # Dynasty where the validator leaves
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CrosslinkRecord* = object
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dynasty: int64 # What dynasty the crosslink was submitted in
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hash: Keccak256_Digest # The block hash
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hash: Blake2_256_Digest # The block hash
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BLSPublicKey = object
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# Stub for BLS signature
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@ -69,10 +68,10 @@ type
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AttestationRecord* = object
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slot*: int64 # Slot number
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shard_id*: int16 # Shard ID
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oblique_parent_hashes*: seq[Keccak256_Digest]
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oblique_parent_hashes*: seq[Blake2_256_Digest]
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# List of block hashes that this signature is signing over that
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# are NOT part of the current chain, in order of oldest to newest
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shard_block_hash*: Keccak256_Digest # Block hash in the in the shard that we are attesting to
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shard_block_hash*: Blake2_256_Digest # Block hash in the shard that we are attesting to
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attester_bitfield*: IntSet # Who is participating
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aggregateSig*: seq[BLSPublicKey] # The actual signature
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# Note:
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@ -21,7 +21,7 @@ func checkPartialCrosslinkRecords*(beaconBlock: BeaconBlock, crystalState: Cryst
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if heightInEpoch < EpochLength - EndEpochGracePeriod:
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assert heightCutoffs[height_in_epoch] <= int(shardCutoffs[si] < heightCutoffs[heightInEpoch + 1]) # TODO Spec unclear
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else:
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assert vote.shardId == 65535 and vote.shardBlockHash == Keccak256_Digest()
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assert vote.shardId == 65535 and vote.shardBlockHash == Blake2_256_Digest()
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var shard_start, shard_end: int
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if heightInEpoch < EpochLength - 8:
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@ -91,13 +91,23 @@ func get_indices_for_slot*(crystallized_state: CrystallizedState,
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# Clarify with EF if light clients will need the beacon chain
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func get_block_hash*(active_state: ActiveState,
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beacon_block: BeaconBlock, slot: int64): Keccak256_Digest =
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# TODO: Spec uses crystallized_state as arg and activ_state.slot_number
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# which doesn't exist
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beacon_block: BeaconBlock, slot: int64): Blake2_256_Digest =
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let sback = beacon_block.slot_number - CYCLE_LENGTH * 2
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assert sback <= slot
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assert slot < sback + CYCLE_LENGTH * 2
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result = active_state.recent_block_hashes[int slot - sback]
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func get_new_recent_block_hashes*(
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old_block_hashes: seq[Blake2_256_Digest],
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parent_slot, current_slot: int64,
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parent_hash: Blake2_256_Digest
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): seq[Blake2_256_Digest] =
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# Should throw for `current_slot - CYCLE_LENGTH * 2 - 1` according to spec comment
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let d = current_slot - parent_slot
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result = old_block_hashes[d .. ^1]
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for _ in 0 ..< min(d, old_block_hashes.len):
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result.add parent_hash
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@ -0,0 +1,65 @@
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# beacon_chain
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# Copyright (c) 2018 Status Research & Development GmbH
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# Licensed and distributed under either of
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# * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
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# * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
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# at your option. This file may not be copied, modified, or distributed except according to those terms.
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# Note: this is also inspired by https://github.com/ethereum/beacon_chain/blob/master/beacon_chain/state/state_transition.py
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# The official spec at https://notes.ethereum.org/SCIg8AH5SA-O4C1G1LYZHQ# is not fully
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# defining the state transitions.
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#
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# Note that the ethresearch impl is using "block_vote_cache" field, which is a dictionary mapping hashes
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# to the following sub-dictionary:
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# {
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# 'voter_indices': set(),
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# 'total_voter_deposits': 0
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# }
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# It should not be needed anymore with the new AttestationRecord type
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{.warning: "The official spec at https://notes.ethereum.org/SCIg8AH5SA-O4C1G1LYZHQ# is not fully defining state transitions.".}
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import ./datatypes, ./private/helpers
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func process_block(active_state: ActiveState, crystallized_state: CrystallizedState, blck: BeaconBlock, slot: int64) =
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# TODO: unfinished spec
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for attestation in blck.attestations:
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# Verify that slot < block.slot_number and slot >= max(block.slot_number - CYCLE_LENGTH, 0)
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doAssert slot < blck.slot_number
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doAssert slot >= max(blck.slot_number - CYCLE_LENGTH, 0)
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# Compute parent_hashes = [get_block_hash(active_state, block, slot - CYCLE_LENGTH + i) for i in range(CYCLE_LENGTH - len(oblique_parent_hashes))] + oblique_parent_hashes
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# TODO - don't allocate in tight loop
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var parent_hashes = newSeq[Blake2_256_Digest](CYCLE_LENGTH - attestation.oblique_parent_hashes.len)
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for idx, val in parent_hashes.mpairs:
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val = get_block_hash(active_state, blck, slot - CYCLE_LENGTH + idx)
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parent_hashes.add attestation.oblique_parent_hashes
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# Let attestation_indices be get_indices_for_slot(crystallized_state, slot)[x], choosing x so that attestation_indices.shard_id equals the shard_id value provided to find the set of validators that is creating this attestation record.
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let attestation_indices = block:
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let shard_and_committees = get_indices_for_slot(crystallized_state, slot)
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var
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x = 1
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record_creator = shard_and_committees[0]
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while record_creator.shard_id != attestation.shard_id:
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record_creator = shard_and_committees[x]
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inc x
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record_creator
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# Verify that len(attester_bitfield) == ceil_div8(len(attestation_indices)), where ceil_div8 = (x + 7) // 8. Verify that bits len(attestation_indices).... and higher, if present (i.e. len(attestation_indices) is not a multiple of 8), are all zero
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doAssert attestation.attester_bitfield.len == attestation_indices.committee.len
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# Derive a group public key by adding the public keys of all of the attesters in attestation_indices for whom the corresponding bit in attester_bitfield (the ith bit is (attester_bitfield[i // 8] >> (7 - (i %8))) % 2) equals 1
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# TODO
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# Verify that aggregate_sig verifies using the group pubkey generated and hash((slot % CYCLE_LENGTH).to_bytes(8, 'big') + parent_hashes + shard_id + shard_block_hash) as the message.
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# TODO
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# Extend the list of AttestationRecord objects in the active_state, ordering the new additions in the same order as they came in the block.
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# TODO
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# Verify that the slot % len(get_indices_for_slot(crystallized_state, slot-1)[0])'th attester in get_indices_for_slot(crystallized_state, slot-1)[0]is part of at least one of the AttestationRecord objects; this attester can be considered to be the proposer of the block.
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# TODO
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