82 lines
3.9 KiB
Nim
82 lines
3.9 KiB
Nim
# beacon_chain
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# Copyright (c) 2018-2019 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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import
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options, sequtils,
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./spec/[datatypes, crypto, digest, helpers, validator],
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./ssz
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# TODO add tests
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# TODO gossipsub validation lives somewhere, maybe here
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# https://github.com/status-im/nim-beacon-chain/issues/122#issuecomment-562479965
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# it's conceptually separate, sort of, but depends on beaconstate, so isn't a
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# pure libp2p thing.
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# https://github.com/ethereum/eth2.0-specs/blob/v0.9.2/specs/validator/0_beacon-chain-validator.md#aggregation-selection
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func get_slot_signature(state: BeaconState, slot: Slot, privkey: ValidatorPrivKey):
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ValidatorSig =
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# TODO privkey is int in spec, but bls_sign wants a ValidatorPrivKey
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let domain =
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get_domain(state, DOMAIN_BEACON_ATTESTER, compute_epoch_at_slot(slot))
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bls_sign(privkey, hash_tree_root(slot).data, domain)
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# https://github.com/ethereum/eth2.0-specs/blob/v0.9.2/specs/validator/0_beacon-chain-validator.md#aggregation-selection
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func is_aggregator(state: BeaconState, slot: Slot, index: uint64,
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slot_signature: ValidatorSig): bool =
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# TODO index is a CommitteeIndex, aka uint64
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var cache = get_empty_per_epoch_cache()
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let
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committee = get_beacon_committee(state, slot, index, cache)
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modulo = max(1, len(committee) div TARGET_AGGREGATORS_PER_COMMITTEE).uint64
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bytes_to_int(eth2hash(slot_signature.getBytes).data[0..7]) mod modulo == 0
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# https://github.com/ethereum/eth2.0-specs/blob/v0.9.2/specs/validator/0_beacon-chain-validator.md#aggregate-signature-1
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func get_aggregate_signature(attestations: openarray[Attestation]): ValidatorSig =
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let signatures = mapIt(attestations, it.signature)
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bls_aggregate_signatures(signatures)
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func should_aggregate(
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state: BeaconState, index: uint64, privkey: ValidatorPrivKey): bool =
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# https://github.com/ethereum/eth2.0-specs/blob/v0.9.2/specs/validator/0_beacon-chain-validator.md#aggregation-selection
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# A validator is selected to aggregate based upon the return value of
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# is_aggregator().
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let slot = state.slot - 1 # TODO this isn't correct
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# the "Construct aggregate" section seems to suggest it's from a previous
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# slot.
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doAssert slot < state.slot
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is_aggregator(state, slot, index, get_slot_signature(state, slot, privkey))
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func aggregate_attestations_naively*(
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state: BeaconState, index: uint64, privkey: ValidatorPrivKey):
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Option[Attestation] =
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# Keep this code opt-in with clean entry point; if there's a part that
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# mutates state, split that off and keep this separate.
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# TODO alias CommitteeIndex to actual type then convert various uint64's here
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# to it
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# TODO return Option[AggregateAndProof] maybe
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# If the validator is selected to aggregate (`is_aggregator()`), they
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# construct an aggregate attestation
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if not should_aggregate(state, index, privkey):
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return none(Attestation)
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# https://github.com/ethereum/eth2.0-specs/blob/v0.9.2/specs/validator/0_beacon-chain-validator.md#construct-aggregate
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# Collect attestations seen via gossip during the slot that have an
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# equivalent attestation_data to that constructed by the validator,
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# and create an aggregate_attestation: Attestation with the following fields.
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var aggregate_attestation = Attestation(
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)
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# https://github.com/ethereum/eth2.0-specs/blob/v0.9.2/specs/validator/0_beacon-chain-validator.md#aggregate-signature-1
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# Set aggregate_attestation.signature = aggregate_signature where
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# aggregate_signature is obtained from get_aggregate_signature(...).
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aggregate_attestation.signature = get_aggregate_signature([])
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some(aggregate_attestation)
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