Spec update (#83)
* rm GWEI_PER_ETH * update EJECTION_BALANCE; rm MAX_CASPER_VOTES/replace with MAX_INDICES_PER_SLASHABLE_VOTE; modify GENESIS_SLOT * update various constants from slots to epochs; MAX_CASPER_SLASHINGS -> MAX_ATTESTER_SLASHINGS * AttesterSlashing field renamings; SlashableVote -> SlashableAttestation; add DOMAIN_RANDAO * rm aggregate_signature_poc_[01]_indices * centralize some bitfield functions
This commit is contained in:
Dustin Brody
Jacek Sieka
parent
20e02d5615
commit
d1af069c55
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@ -173,7 +173,7 @@ func getVoteCount(participation_bitfield: openarray[byte]): int =
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# https://github.com/status-im/nim-beacon-chain/issues/19
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for validatorIdx in 0 ..< participation_bitfield.len * 8:
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result += int participation_bitfield.bitIsSet(validatorIdx)
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result += int participation_bitfield.get_bitfield_bit(validatorIdx)
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func getAttestationVoteCount(pool: AttestationPool, current_slot: int): CountTable[Eth2Digest] =
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## Returns all blocks more recent that the current slot
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@ -62,7 +62,7 @@ const
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## with a Verifiable Delay Function (VDF) will improve committee robustness
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## and lower the safe minimum committee size.)
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EJECTION_BALANCE* = 2'u64^4 ##\
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EJECTION_BALANCE* = 2'u64^4 * 10'u64^9 ##\
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## Once the balance of a validator drops below this, it will be ejected from
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## the validator pool
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@ -70,20 +70,20 @@ const
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## At most `1/MAX_BALANCE_CHURN_QUOTIENT` of the validators can change during
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## each validator registry change.
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GWEI_PER_ETH* = 10'u64^9 # Gwei/ETH
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BEACON_CHAIN_SHARD_NUMBER* = not 0'u64 # 2^64 - 1 in spec
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MAX_CASPER_VOTES* = 2^10
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MAX_INDICES_PER_SLASHABLE_VOTE* = 2^12 ##\
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## votes
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MAX_WITHDRAWALS_PER_EPOCH* = 4 # withdrawals
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# Deposit contract
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DEPOSIT_CONTRACT_TREE_DEPTH* = 2^5
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MIN_DEPOSIT_AMOUNT* = 2'u64^0 * GWEI_PER_ETH ##\
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MIN_DEPOSIT_AMOUNT* = 2'u64^0 * 10'u64^9 ##\
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## Minimum amounth of ETH that can be deposited in one call - deposits can
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## be used either to top up an existing validator or commit to a new one
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MAX_DEPOSIT_AMOUNT* = 2'u64^5 * GWEI_PER_ETH ##\
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MAX_DEPOSIT_AMOUNT* = 2'u64^5 * 10'u64^9 ##\
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## Maximum amounth of ETH that can be deposited in one call
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# Time parameter, here so that GENESIS_EPOCH can access it
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@ -93,9 +93,8 @@ const
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## processing is done
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# Initial values
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GENESIS_FORK_VERSION* = 0'u64
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GENESIS_SLOT* = 2'u64^19
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GENESIS_SLOT* = 2'u64^63
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GENESIS_EPOCH* = GENESIS_SLOT div EPOCH_LENGTH # slot_to_epoch(GENESIS_SLOT)
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GENESIS_START_SHARD* = 0'u64
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FAR_FUTURE_EPOCH* = not 0'u64 # 2^64 - 1 in spec
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@ -119,17 +118,17 @@ const
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## wait towards the end of the slot and still have time to publish the
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## attestation.
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SEED_LOOKAHEAD* = 64 ##\
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## slots (~6.4 minutes)
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SEED_LOOKAHEAD* = 1 ##\
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## epochs (~6.4 minutes)
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ENTRY_EXIT_DELAY* = 256 ##\
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## slots (~25.6 minutes)
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ENTRY_EXIT_DELAY* = 4 ##\
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## epochs (~25.6 minutes)
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ETH1_DATA_VOTING_PERIOD* = 2'u64^10 ##\
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## slots (~1.7 hours)
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ETH1_DATA_VOTING_PERIOD* = 2'u64^4 ##\
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## epochs (~1.7 hours)
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MIN_VALIDATOR_WITHDRAWAL_TIME* = 2'u64^14 ##\
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## slots (~27 hours)
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MIN_VALIDATOR_WITHDRAWAL_TIME* = 2'u64^8 ##\
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## epochs (~27 hours)
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# State list lengths
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LATEST_BLOCK_ROOTS_LENGTH* = 2'u64^13
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@ -137,7 +136,8 @@ const
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LATEST_INDEX_ROOTS_LENGTH* = 2'u64^13
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LATEST_PENALIZED_EXIT_LENGTH* = 8192 # epochs
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# Quotients
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# Reward and penalty quotients
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# https://github.com/ethereum/eth2.0-specs/blob/dev/specs/core/0_beacon-chain.md#reward-and-penalty-quotients
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BASE_REWARD_QUOTIENT* = 2'u64^10 ##\
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## The `BASE_REWARD_QUOTIENT` parameter dictates the per-epoch reward. It
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## corresponds to ~2.54% annual interest assuming 10 million participating
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@ -153,7 +153,7 @@ const
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# Max operations per block
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MAX_PROPOSER_SLASHINGS* = 2^4
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MAX_CASPER_SLASHINGS* = 2^4
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MAX_ATTESTER_SLASHINGS* = 2^0
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MAX_ATTESTATIONS* = 2^7
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MAX_DEPOSITS* = 2^4
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MAX_EXITS* = 2^4
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@ -163,7 +163,7 @@ type
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SlotNumber* = uint64
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EpochNumber* = uint64
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# https://github.com/ethereum/eth2.0-specs/blob/master/specs/core/0_beacon-chain.md#data-structures
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# https://github.com/ethereum/eth2.0-specs/blob/dev/specs/core/0_beacon-chain.md#proposerslashing
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ProposerSlashing* = object
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proposer_index*: ValidatorIndex
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proposal_data_1*: ProposalSignedData
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@ -171,26 +171,21 @@ type
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proposal_data_2*: ProposalSignedData
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proposal_signature_2*: ValidatorSig
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# https://github.com/ethereum/eth2.0-specs/blob/dev/specs/core/0_beacon-chain.md#attesterslashing
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AttesterSlashing* = object
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slashable_vote_data_1*: SlashableVote ## \
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slashable_attestation_1*: SlashableAttestation ## \
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## First batch of votes
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slashable_vote_data_2*: SlashableVote ## \
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slashable_attestation_2*: SlashableAttestation ## \
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## Second batch of votes
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SlashableVote* = object
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# https://github.com/ethereum/eth2.0-specs/blob/dev/specs/core/0_beacon-chain.md#slashableattestation
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SlashableAttestation* = object
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validator_indices*: seq[uint64] ##\
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## Validator indices
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custody_bitfield*: seq[byte] ##\
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## Custody bitfield
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# TODO rm aggregate_signature_poc_0_indices, aggregate_signature_poc_1_indices
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aggregate_signature_poc_0_indices*: seq[ValidatorIndex] ##\
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## Proof-of-custody indices (0 bits)
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aggregate_signature_poc_1_indices*: seq[ValidatorIndex] ##\
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## Proof-of-custody indices (1 bits)
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data*: AttestationData ## \
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## Attestation data
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@ -429,11 +424,13 @@ type
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Activation = 0
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Exit = 1
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# https://github.com/ethereum/eth2.0-specs/blob/dev/specs/core/0_beacon-chain.md#signature-domains
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SignatureDomain* {.pure.} = enum
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DOMAIN_DEPOSIT = 0
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DOMAIN_ATTESTATION = 1
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DOMAIN_PROPOSAL = 2
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DOMAIN_EXIT = 3
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DOMAIN_RANDAO = 4
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template epoch*(slot: int|uint64): auto =
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slot div EPOCH_LENGTH
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@ -11,12 +11,26 @@ import ./datatypes, ./digest, sequtils, math
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# TODO spec candidate? there's bits in nim-ranges but that one has some API
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# issues regarding bit endianess that need resolving..
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func bitIsSet*(bitfield: openArray[byte], index: int): bool =
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(bitfield[index div 8] shr byte(7 - (index mod 8))) mod 2 > 0'u8
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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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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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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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for i in committee_size + 1 ..< committee_size - (committee_size mod 8) + 8:
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if get_bitfield_bit(bitfield, i) == 0b1:
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return false
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true
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func mod_get[T](arr: openarray[T], pos: Natural): T =
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arr[pos mod arr.len]
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@ -182,65 +182,73 @@ proc processProposerSlashings(
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return true
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func verify_slashable_vote_data(state: BeaconState, vote_data: SlashableVote): bool =
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if len(vote_data.aggregate_signature_poc_0_indices) +
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len(vote_data.aggregate_signature_poc_1_indices) > MAX_CASPER_VOTES:
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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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return false
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let pubs = [
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bls_aggregate_pubkeys(vote_data.aggregate_signature_poc_0_indices.
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mapIt(state.validator_registry[it].pubkey)),
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bls_aggregate_pubkeys(vote_data.aggregate_signature_poc_1_indices.
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mapIt(state.validator_registry[it].pubkey))]
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if len(slashable_attestation.validator_indices) == 0:
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return false
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# TODO
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# return bls_verify_multiple(pubs, [hash_tree_root(votes)+bytes1(0), hash_tree_root(votes)+bytes1(1), signature=aggregate_signature)
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for i in 0 ..< (len(slashable_attestation.validator_indices) - 1):
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if slashable_attestation.validator_indices[i] >= slashable_attestation.validator_indices[i + 1]:
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return false
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if not verify_bitfield(slashable_attestation.custody_bitfield, len(slashable_attestation.validator_indices)):
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return false
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if len(slashable_attestation.validator_indices) > MAX_INDICES_PER_SLASHABLE_VOTE:
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return false
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var
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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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proc indices(vote: SlashableVote): seq[ValidatorIndex] =
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vote.aggregate_signature_poc_0_indices &
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vote.aggregate_signature_poc_1_indices
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proc processAttesterSlashings(state: var BeaconState, blck: BeaconBlock): bool =
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## https://github.com/ethereum/eth2.0-specs/blob/master/specs/core/0_beacon-chain.md#casper-slashings-1
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if len(blck.body.attester_slashings) > MAX_CASPER_SLASHINGS:
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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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if len(blck.body.attester_slashings) > MAX_ATTESTER_SLASHINGS:
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notice "CaspSlash: too many!"
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return false
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for casper_slashing in blck.body.attester_slashings:
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for attester_slashing in blck.body.attester_slashings:
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let
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slashable_vote_data_1 = casper_slashing.slashable_vote_data_1
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slashable_vote_data_2 = casper_slashing.slashable_vote_data_2
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indices2 = indices(slashable_vote_data_2)
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intersection =
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indices(slashable_vote_data_1).filterIt(it in indices2)
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slashable_attestation_1 = attester_slashing.slashable_attestation_1
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slashable_attestation_2 = attester_slashing.slashable_attestation_2
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if not (slashable_vote_data_1.data != slashable_vote_data_2.data):
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if not (slashable_attestation_1.data != slashable_attestation_2.data):
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notice "CaspSlash: invalid data"
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return false
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if not (len(intersection) >= 1):
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notice "CaspSlash: no intersection"
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return false
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if not (
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is_double_vote(slashable_vote_data_1.data, slashable_vote_data_2.data) or
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is_surround_vote(slashable_vote_data_1.data, slashable_vote_data_2.data)):
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is_double_vote(slashable_attestation_1.data, slashable_attestation_2.data) or
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is_surround_vote(slashable_attestation_1.data, slashable_attestation_2.data)):
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notice "CaspSlash: surround or double vote check failed"
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return false
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if not verify_slashable_vote_data(state, slashable_vote_data_1):
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if not verify_slashable_attestation(state, slashable_attestation_1):
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notice "CaspSlash: invalid votes 1"
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return false
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if not verify_slashable_vote_data(state, slashable_vote_data_2):
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if not verify_slashable_attestation(state, slashable_attestation_2):
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notice "CaspSlash: invalid votes 2"
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return false
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for i in intersection:
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if state.validator_registry[i].penalized_epoch > get_current_epoch(state):
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penalize_validator(state, i)
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let
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indices2 = slashable_attestation_2.validator_indices
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slashable_indices =
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slashable_attestation_1.validator_indices.filterIt(it in indices2)
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if not (len(slashable_indices) >= 1):
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notice "CaspSlash: no intersection"
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return false
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for index in slashable_indices:
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if state.validator_registry[index.int].penalized_epoch > get_current_epoch(state):
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penalize_validator(state, index.ValidatorIndex)
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return true
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@ -451,25 +459,11 @@ func processEpoch(state: var BeaconState) =
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active_validator_indices =
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get_active_validator_indices(state.validator_registry, state.slot)
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total_balance = sum_effective_balances(state, active_validator_indices)
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total_balance_in_eth = total_balance div GWEI_PER_ETH
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# The per-slot maximum interest rate is `2/reward_quotient`.)
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base_reward_quotient =
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BASE_REWARD_QUOTIENT * integer_squareroot(total_balance_in_eth)
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current_epoch = get_current_epoch(state)
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previous_epoch = if current_epoch > GENESIS_EPOCH: current_epoch - 1 else: current_epoch
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next_epoch = (current_epoch + 1).EpochNumber
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func base_reward(state: BeaconState, index: ValidatorIndex): uint64 =
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get_effective_balance(state, index) div base_reward_quotient.uint64 div 4
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func inactivity_penalty(
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state: BeaconState, index: ValidatorIndex, epochs_since_finality: uint64): uint64 =
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base_reward(state, index) +
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get_effective_balance(state, index) *
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epochs_since_finality div INACTIVITY_PENALTY_QUOTIENT div 2
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# TODO doing this with iterators failed:
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# https://github.com/nim-lang/Nim/issues/9827
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let
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@ -640,7 +634,21 @@ func processEpoch(state: var BeaconState) =
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# state.latest_crosslinks[shard] = Crosslink(
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# slot=state.slot, shard_block_root=winning_root(crosslink_committee))
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# TODO Rewards and penalties helpers
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# Rewards and penalties helpers
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# https://github.com/ethereum/eth2.0-specs/blob/dev/specs/core/0_beacon-chain.md#rewards-and-penalties
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let
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base_reward_quotient =
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integer_squareroot(previous_total_balance) div BASE_REWARD_QUOTIENT
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func base_reward(state: BeaconState, index: ValidatorIndex): uint64 =
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get_effective_balance(state, index) div base_reward_quotient.uint64 div 4
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func inactivity_penalty(
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state: BeaconState, index: ValidatorIndex, epochs_since_finality: uint64): uint64 =
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base_reward(state, index) +
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get_effective_balance(state, index) *
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epochs_since_finality div INACTIVITY_PENALTY_QUOTIENT div 2
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block: # Justification and finalization
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let epochs_since_finality = next_epoch - state.finalized_epoch
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