more checking that various functions match v0.1; some variable/etc renaming; fix is_double_vote to check epoch, not slot equivalence; finish verify_slashable_attestation; adjust is_surround_vote logic (#100)
This commit is contained in:
Dustin Brody
Jacek Sieka
parent
c567bc410f
commit
4747477160
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@ -10,11 +10,10 @@ import
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../extras, ../ssz,
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./crypto, ./datatypes, ./digest, ./helpers, ./validator
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_effective_balance
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func get_effective_balance*(state: BeaconState, index: ValidatorIndex): uint64 =
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# Validators collect rewards which increases their balance but not their
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# influence. Validators may also lose balance if they fail to do their duty
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# in which case their influence decreases. Once they drop below a certain
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# balance, they're removed from the validator registry.
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## Return the effective balance (also known as "balance at stake") for a
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## validator with the given ``index``.
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min(state.validator_balances[index], MAX_DEPOSIT_AMOUNT)
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func sum_effective_balances*(
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@ -82,6 +81,7 @@ func process_deposit(state: var BeaconState,
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state.validator_balances[index] += amount
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_entry_exit_effect_epoch
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func get_entry_exit_effect_epoch*(epoch: EpochNumber): EpochNumber =
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## An entry or exit triggered in the ``epoch`` given by the input takes effect at
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## the epoch given by the output.
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@ -222,13 +222,15 @@ func get_block_root*(state: BeaconState,
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doAssert slot < state.slot
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state.latest_block_roots[slot mod LATEST_BLOCK_ROOTS_LENGTH]
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_attestation_participants
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func get_attestation_participants*(state: BeaconState,
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attestation_data: AttestationData,
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aggregation_bitfield: seq[byte]): seq[ValidatorIndex] =
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bitfield: seq[byte]): seq[ValidatorIndex] =
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## Attestation participants in the attestation data are called out in a
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## bit field that corresponds to the committee of the shard at the time - this
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## function converts it to list of indices in to BeaconState.validators
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## Returns empty list if the shard is not found
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## Return the participant indices at for the ``attestation_data`` and ``bitfield``.
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# TODO Linear search through shard list? borderline ok, it's a small list
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# TODO bitfield type needed, once bit order settles down
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# TODO iterator candidate
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@ -243,12 +245,13 @@ func get_attestation_participants*(state: BeaconState,
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let crosslink_committee = mapIt(
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filterIt(crosslink_committees, it.shard == attestation_data.shard),
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it.committee)[0]
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assert len(aggregation_bitfield) == (len(crosslink_committee) + 7) div 8
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assert verify_bitfield(bitfield, len(crosslink_committee))
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# Find the participating attesters in the committee
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result = @[]
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for i, validator_index in crosslink_committee:
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let aggregation_bit = (aggregation_bitfield[i div 8] shr (7 - (i mod 8))) mod 2
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let aggregation_bit = get_bitfield_bit(bitfield, i)
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if aggregation_bit == 1:
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result.add(validator_index)
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@ -73,14 +73,25 @@ func bls_aggregate_pubkeys*(keys: openArray[ValidatorPubKey]): ValidatorPubKey =
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else:
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result.combine(key)
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/bls_signature.md#bls_verify
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func bls_verify*(
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pubkey: ValidatorPubKey, msg: openArray[byte], sig: ValidatorSig,
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domain: uint64): bool =
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# name from spec!
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sig.verify(msg, domain, pubkey)
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func bls_sign*(key: ValidatorPrivKey,
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msg: openarray[byte], domain: uint64): ValidatorSig =
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/bls_signature.md#bls_verify_multiple
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func bls_verify_multiple*(
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pubkeys: seq[ValidatorPubKey], messages: seq[array[0..31, byte]],
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sig: ValidatorSig, domain: uint64): bool =
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let L = len(pubkeys)
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assert L == len(messages)
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# TODO calculate product of ate pairings; check how sig.verify works
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true
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func bls_sign*(key: ValidatorPrivKey, msg: openarray[byte],
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domain: uint64): ValidatorSig =
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# name from spec!
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key.sign(domain, msg)
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@ -229,7 +229,7 @@ type
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#attestationdata
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AttestationDataAndCustodyBit* = object
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data*: AttestationData
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custody_bit: bool
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custody_bit*: bool
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#deposit
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Deposit* = object
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@ -14,13 +14,13 @@ import ./datatypes, ./digest, sequtils, math
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func bitSet*(bitfield: var openArray[byte], index: int) =
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bitfield[index div 8] = bitfield[index div 8] or 1'u8 shl (7 - (index mod 8))
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_bitfield_bit
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func get_bitfield_bit*(bitfield: openarray[byte], i: int): byte =
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# https://github.com/ethereum/eth2.0-specs/blob/dev/specs/core/0_beacon-chain.md#get_bitfield_bit
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# Extract the bit in ``bitfield`` at position ``i``.
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(bitfield[i div 8] shr (7 - (i mod 8))) mod 2
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#verify_bitfield
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func verify_bitfield*(bitfield: openarray[byte], committee_size: int): bool =
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# https://github.com/ethereum/eth2.0-specs/blob/dev/specs/core/0_beacon-chain.md#verify_bitfield
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# Verify ``bitfield`` against the ``committee_size``.
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if len(bitfield) != (committee_size + 7) div 8:
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return false
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@ -113,6 +113,7 @@ func repeat_hash*(v: Eth2Digest, n: SomeInteger): Eth2Digest =
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result = eth2hash(result.data)
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dec n
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#integer_squareroot
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func integer_squareroot*(n: SomeInteger): SomeInteger =
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## The largest integer ``x`` such that ``x**2`` is less than ``n``.
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var
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@ -123,12 +124,15 @@ func integer_squareroot*(n: SomeInteger): SomeInteger =
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y = (x + n div x) div 2
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x
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_fork_version
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func get_fork_version*(fork: Fork, epoch: EpochNumber): uint64 =
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## Return the fork version of the given ``epoch``.
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if epoch < fork.epoch:
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fork.previous_version
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else:
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fork.current_version
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#get_domain
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func get_domain*(
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fork: Fork, epoch: EpochNumber, domain_type: SignatureDomain): uint64 =
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# TODO Slot overflow? Or is slot 32 bits for all intents and purposes?
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@ -151,37 +155,31 @@ func merkle_root*(values: openArray[Eth2Digest]): Eth2Digest =
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#TODO
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discard
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proc is_double_vote*(attestation_data_1: AttestationData,
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attestation_data_2: AttestationData): bool =
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## Assumes ``attestation_data_1`` is distinct from ``attestation_data_2``.
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## Returns True if the provided ``AttestationData`` are slashable
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## due to a 'double vote'.
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## A double vote is when a validator votes for two attestations within the
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## same slot - doing so means risking getting slashed.
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attestation_data_1.slot == attestation_data_2.slot
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#slot_to_epoch
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func slot_to_epoch*(slot: SlotNumber): EpochNumber =
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slot div EPOCH_LENGTH
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proc is_surround_vote*(attestation_data_1: AttestationData,
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#is_double_vote
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func is_double_vote*(attestation_data_1: AttestationData,
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attestation_data_2: AttestationData): bool =
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## Check if ``attestation_data_1`` and ``attestation_data_2`` have the same
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## target.
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let
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target_epoch_1 = slot_to_epoch(attestation_data_1.slot)
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target_epoch_2 = slot_to_epoch(attestation_data_2.slot)
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target_epoch_1 == target_epoch_2
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#is_surround_vote
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func is_surround_vote*(attestation_data_1: AttestationData,
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attestation_data_2: AttestationData): bool =
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## Assumes ``attestation_data_1`` is distinct from ``attestation_data_2``.
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## Returns True if the provided ``AttestationData`` are slashable
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## due to a 'surround vote'.
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## Note: parameter order matters as this function only checks
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## that ``attestation_data_1`` surrounds ``attestation_data_2``.
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## Check if ``attestation_data_1`` surrounds ``attestation_data_2``.
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let
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source_epoch_1 = attestation_data_1.justified_epoch
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source_epoch_2 = attestation_data_2.justified_epoch
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target_epoch_1 = slot_to_epoch(attestation_data_1.slot)
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target_epoch_2 = slot_to_epoch(attestation_data_2.slot)
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(
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(source_epoch_1 < source_epoch_2) and
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(source_epoch_2 + 1 == target_epoch_2) and
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(target_epoch_2 < target_epoch_1)
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)
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source_epoch_1 < source_epoch_2 and target_epoch_2 < target_epoch_1
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#is_active_validator
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func is_active_validator*(validator: Validator, epoch: EpochNumber): bool =
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@ -184,8 +184,8 @@ proc processProposerSlashings(
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return true
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# https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#verify_slashable_attestation
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func verify_slashable_attestation(state: BeaconState, slashable_attestation: SlashableAttestation): bool =
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# https://github.com/ethereum/eth2.0-specs/blob/dev/specs/core/0_beacon-chain.md#verify_slashable_attestation
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# Verify validity of ``slashable_attestation`` fields.
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if anyIt(slashable_attestation.custody_bitfield, it != 0): # [TO BE REMOVED IN PHASE 1]
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@ -208,7 +208,31 @@ func verify_slashable_attestation(state: BeaconState, slashable_attestation: Sla
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custody_bit_0_indices: seq[uint64] = @[]
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custody_bit_1_indices: seq[uint64] = @[]
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return true
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for i, validator_index in slashable_attestation.validator_indices:
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if get_bitfield_bit(slashable_attestation.custody_bitfield, i) == 0b0:
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custody_bit_0_indices.add(validator_index)
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else:
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custody_bit_1_indices.add(validator_index)
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# bug in 0.1 version of spec, fixed later; bls_verify is what works
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bls_verify_multiple(
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@[
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bls_aggregate_pubkeys(mapIt(custody_bit_0_indices, state.validator_registry[it.int].pubkey)),
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bls_aggregate_pubkeys(mapIt(custody_bit_1_indices, state.validator_registry[it.int].pubkey)),
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],
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@[
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hash_tree_root(AttestationDataAndCustodyBit(
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data: slashable_attestation.data, custody_bit: false)),
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hash_tree_root(AttestationDataAndCustodyBit(
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data: slashable_attestation.data, custody_bit: true)),
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],
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slashable_attestation.aggregate_signature,
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get_domain(
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state.fork,
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slot_to_epoch(slashable_attestation.data.slot),
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DOMAIN_ATTESTATION,
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),
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)
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proc processAttesterSlashings(state: var BeaconState, blck: BeaconBlock): bool =
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## https://github.com/ethereum/eth2.0-specs/blob/dev/specs/core/0_beacon-chain.md#attester-slashings-1
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