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nimbus-eth2/beacon_chain/spec/signatures_batch.nim

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# beacon_chain
# Copyright (c) 2018-2021 Status Research & Development GmbH
# Licensed and distributed under either of
# * MIT license (license terms in the root directory or at https://opensource.org/licenses/MIT).
# * Apache v2 license (license terms in the root directory or at https://www.apache.org/licenses/LICENSE-2.0).
# at your option. This file may not be copied, modified, or distributed except according to those terms.
{.push raises: [Defect].}
import
# Status lib
blscurve,
stew/[byteutils, results],
taskpools,
bearssl,
# Internal
"."/[helpers, beaconstate, forks],
"."/datatypes/[altair, merge, phase0]
# Otherwise, error.
import chronicles
export altair, phase0, taskpools, bearssl
type
TaskPoolPtr* = TaskPool
BatchVerifier* = object
sigVerifCache*: BatchedBLSVerifierCache ##\
## A cache for batch BLS signature verification contexts
rng*: ref BrHmacDrbgContext ##\
## A reference to the Nimbus application-wide RNG
taskpool*: TaskPoolPtr
func `$`*(s: SignatureSet): string =
"(pubkey: 0x" & s.pubkey.toHex() &
", signing_root: 0x" & s.message.toHex() &
", signature: 0x" & s.signature.toHex() & ')'
# Important:
# - Due to lazy loading, when we do crypto verification
# and only then state-transition verification,
# there is no guarantee that pubkeys and signatures received are valid
# unlike when Nimbus did eager loading which ensured they were correct beforehand
template loadOrExit(signature: ValidatorSig, error: cstring):
untyped =
## Load a BLS signature from a raw signature
## Exits the **caller** with false if the signature is invalid
let sig = signature.load()
if sig.isNone:
return err(error) # this exits the calling scope, as templates are inlined.
sig.unsafeGet()
func addSignatureSet[T](
sigs: var seq[SignatureSet],
pubkey: CookedPubKey,
sszObj: T,
signature: CookedSig,
fork: Fork,
genesis_validators_root: Eth2Digest,
epoch: Epoch,
domain: DomainType) =
## Add a new signature set triplet (pubkey, message, signature)
## to a collection of signature sets for batch verification.
## Can return false if `signature` wasn't deserialized to a valid BLS signature.
let signing_root = compute_signing_root(
sszObj,
get_domain(
fork, domain,
epoch,
genesis_validators_root
)
).data
sigs.add((
blscurve.PublicKey(pubkey),
signing_root,
blscurve.Signature(signature)
))
proc aggregateAttesters(
validatorIndices: openArray[uint64],
validatorKeys: auto,
): Result[CookedPubKey, cstring] =
if validatorIndices.len == 0:
# Aggregation spec requires non-empty collection
# - https://tools.ietf.org/html/draft-irtf-cfrg-bls-signature-04
# Eth2 spec requires at least one attesting index in attestation
# - https://github.com/ethereum/consensus-specs/blob/v1.1.6/specs/phase0/beacon-chain.md#is_valid_indexed_attestation
return err("aggregateAttesters: no attesting indices")
let
firstKey = validatorKeys.load(validatorIndices[0])
if not firstKey.isSome():
return err("aggregateAttesters: invalid attesting index")
var attestersAgg{.noInit.}: AggregatePublicKey
attestersAgg.init(firstKey.get())
for i in 1 ..< validatorIndices.len:
let key = validatorKeys.load(validatorIndices[i])
if not key.isSome():
return err("aggregateAttesters: invalid attesting index")
attestersAgg.aggregate(key.get())
ok(finish(attestersAgg))
proc addIndexedAttestation(
sigs: var seq[SignatureSet],
attestation: IndexedAttestation,
validatorKeys: auto,
state: ForkedHashedBeaconState,
): Result[void, cstring] =
## Add an indexed attestation for batched BLS verification
## purposes
## This only verifies cryptography, checking that
## the indices are sorted and unique is not checked for example.
let aggPk =
? aggregateAttesters(attestation.attesting_indices.asSeq(), validatorKeys)
sigs.addSignatureSet(
aggPK,
attestation.data,
attestation.signature.loadOrExit(
"addIndexedAttestation: cannot load signature"),
getStateField(state, fork),
getStateField(state, genesis_validators_root),
attestation.data.target.epoch,
DOMAIN_BEACON_ATTESTER)
ok()
proc addAttestation(
sigs: var seq[SignatureSet],
attestation: Attestation,
validatorKeys: auto,
state: ForkedHashedBeaconState,
cache: var StateCache
): Result[void, cstring] =
var inited = false
var attestersAgg{.noInit.}: AggregatePublicKey
for valIndex in state.get_attesting_indices(
attestation.data,
attestation.aggregation_bits,
cache
):
if not inited: # first iteration
attestersAgg.init(validatorKeys.load(valIndex).get())
inited = true
else:
attestersAgg.aggregate(validatorKeys.load(valIndex).get())
if not inited:
# There were no attesters
return err("addAttestation: no attesting indices")
let attesters = finish(attestersAgg)
sigs.addSignatureSet(
attesters,
attestation.data,
attestation.signature.loadOrExit(
"addAttestation: cannot load signature"),
getStateField(state, fork),
getStateField(state, genesis_validators_root),
attestation.data.target.epoch,
DOMAIN_BEACON_ATTESTER)
ok()
# Public API
# ------------------------------------------------------
proc addAttestation*(
sigs: var seq[SignatureSet],
fork: Fork, genesis_validators_root: Eth2Digest,
epochRef: auto,
attestation: Attestation
): Result[CookedSig, cstring] =
## Add an attestation for batched BLS verification
## purposes
## This only verifies cryptography
##
## Returns true if the attestation was added to the batching buffer
## Returns false if sanity checks failed (non-empty, keys are valid)
## In that case the seq[SignatureSet] is unmodified
mixin get_attesting_indices, validatorKey
var inited = false
var attestersAgg{.noInit.}: AggregatePublicKey
for valIndex in epochRef.get_attesting_indices(
attestation.data,
attestation.aggregation_bits):
if not inited: # first iteration
attestersAgg.init(epochRef.validatorKey(valIndex).get())
inited = true
else:
attestersAgg.aggregate(epochRef.validatorKey(valIndex).get())
if not inited:
# There were no attesters
return err("addAttestation: no attesting indices")
let
attesters = finish(attestersAgg)
cookedSig = attestation.signature.loadOrExit(
"addAttestation: cannot load signature")
sigs.addSignatureSet(
attesters,
attestation.data,
cookedSig,
fork,
genesis_validators_root,
attestation.data.target.epoch,
DOMAIN_BEACON_ATTESTER)
ok(CookedSig(cookedSig))
proc addSlotSignature*(
sigs: var seq[SignatureSet],
fork: Fork, genesis_validators_root: Eth2Digest,
slot: Slot,
pubkey: CookedPubKey,
signature: ValidatorSig): Result[void, cstring] =
let epoch = compute_epoch_at_slot(slot)
sigs.addSignatureSet(
pubkey,
sszObj = slot,
signature.loadOrExit("addSlotSignature: cannot load signature"),
fork,
genesis_validators_root,
epoch,
DOMAIN_SELECTION_PROOF
)
ok()
proc addAggregateAndProofSignature*(
sigs: var seq[SignatureSet],
fork: Fork, genesis_validators_root: Eth2Digest,
aggregate_and_proof: AggregateAndProof,
pubkey: CookedPubKey,
signature: ValidatorSig
): Result[void, cstring] =
let epoch = compute_epoch_at_slot(aggregate_and_proof.aggregate.data.slot)
sigs.addSignatureSet(
pubkey,
sszObj = aggregate_and_proof,
signature.loadOrExit("addAggregateAndProofSignature: cannot load signature"),
fork,
genesis_validators_root,
epoch,
DOMAIN_AGGREGATE_AND_PROOF
)
ok()
proc collectSignatureSets*(
sigs: var seq[SignatureSet],
signed_block: ForkySignedBeaconBlock,
validatorKeys: auto,
state: ForkedHashedBeaconState,
cache: var StateCache): Result[void, cstring] =
## Collect all signatures in a single signed block.
## This includes
## - Block proposer
## - Randao Reaveal
## - Proposer slashings
## - Attester slashings
## - Attestations
## - VoluntaryExits
##
## We do not include deposits as they can be invalid per protocol
## (secp256k1 signature instead of BLS)
# Metadata
# ----------------------------------------------------
mixin load
let
proposer_index = signed_block.message.proposer_index
proposer_key = validatorKeys.load(proposer_index)
if not proposer_key.isSome():
return err("collectSignatureSets: invalid proposer index")
let epoch = signed_block.message.slot.compute_epoch_at_slot()
# 1. Block proposer
# ----------------------------------------------------
sigs.addSignatureSet(
proposer_key.get(),
signed_block.root,
signed_block.signature.loadOrExit(
"collectSignatureSets: cannot load signature"),
getStateField(state, fork),
getStateField(state, genesis_validators_root),
epoch,
DOMAIN_BEACON_PROPOSER)
# 2. Randao Reveal
# ----------------------------------------------------
sigs.addSignatureSet(
proposer_key.get(),
epoch,
signed_block.message.body.randao_reveal.loadOrExit(
"collectSignatureSets: cannot load randao"),
getStateField(state, fork),
getStateField(state, genesis_validators_root),
epoch,
DOMAIN_RANDAO)
# 3. Proposer slashings
# ----------------------------------------------------
# Denial-of-service:
# SSZ deserialization guarantees that blocks received from random sources
# including peer or RPC
# have at most MAX_PROPOSER_SLASHINGS proposer slashings.
for i in 0 ..< signed_block.message.body.proposer_slashings.len:
# don't use "items" for iterating over large type
# due to https://github.com/nim-lang/Nim/issues/14421
# fixed in 1.4.2
# Alias
template slashing: untyped = signed_block.message.body.proposer_slashings[i]
# Proposed block 1
block:
let
header_1 = slashing.signed_header_1
key_1 = validatorKeys.load(header_1.message.proposer_index)
if not key_1.isSome():
return err("collectSignatureSets: invalid slashing proposer index 1")
let epoch1 = header_1.message.slot.compute_epoch_at_slot()
sigs.addSignatureSet(
key_1.get(),
header_1.message,
header_1.signature.loadOrExit(
"collectSignatureSets: cannot load proposer slashing 1 signature"),
getStateField(state, fork),
getStateField(state, genesis_validators_root),
epoch1,
DOMAIN_BEACON_PROPOSER
)
# Conflicting block 2
block:
let
header_2 = slashing.signed_header_2
key_2 = validatorKeys.load(header_2.message.proposer_index)
if not key_2.isSome():
return err("collectSignatureSets: invalid slashing proposer index 2")
let epoch2 = header_2.message.slot.compute_epoch_at_slot()
sigs.addSignatureSet(
key_2.get(),
header_2.message,
header_2.signature.loadOrExit(
"collectSignatureSets: cannot load proposer slashing 2 signature"),
getStateField(state, fork),
getStateField(state, genesis_validators_root),
epoch2,
DOMAIN_BEACON_PROPOSER
)
# 4. Attester slashings
# ----------------------------------------------------
# Denial-of-service:
# SSZ deserialization guarantees that blocks received from random sources
# including peer or RPC
# have at most MAX_ATTESTER_SLASHINGS attester slashings.
for i in 0 ..< signed_block.message.body.attester_slashings.len:
# don't use "items" for iterating over large type
# due to https://github.com/nim-lang/Nim/issues/14421
# fixed in 1.4.2
# Alias
template slashing: untyped = signed_block.message.body.attester_slashings[i]
# Attestation 1
? sigs.addIndexedAttestation(slashing.attestation_1, validatorKeys, state)
# Conflicting attestation 2
? sigs.addIndexedAttestation(slashing.attestation_2, validatorKeys, state)
# 5. Attestations
# ----------------------------------------------------
# Denial-of-service:
# SSZ deserialization guarantees that blocks received from random sources
# including peer or RPC
# have at most MAX_ATTESTATIONS attestations.
for i in 0 ..< signed_block.message.body.attestations.len:
# don't use "items" for iterating over large type
# due to https://github.com/nim-lang/Nim/issues/14421
# fixed in 1.4.2
? sigs.addAttestation(
signed_block.message.body.attestations[i],
validatorKeys, state, cache)
# 6. VoluntaryExits
# ----------------------------------------------------
# Denial-of-service:
# SSZ deserialization guarantees that blocks received from random sources
# including peer or RPC
# have at most MAX_VOLUNTARY_EXITS voluntary exits.
for i in 0 ..< signed_block.message.body.voluntary_exits.len:
# don't use "items" for iterating over large type
# due to https://github.com/nim-lang/Nim/issues/14421
# fixed in 1.4.2
template volex: untyped = signed_block.message.body.voluntary_exits[i]
let key = validatorKeys.load(volex.message.validator_index)
if not key.isSome():
return err("collectSignatureSets: invalid voluntary exit")
sigs.addSignatureSet(
key.get(),
volex.message,
volex.signature.loadOrExit(
"collectSignatureSets: cannot load voluntary exit signature"),
getStateField(state, fork),
getStateField(state, genesis_validators_root),
volex.message.epoch,
DOMAIN_VOLUNTARY_EXIT)
block:
# 7. SyncAggregate
# ----------------------------------------------------
withState(state):
when stateFork >= BeaconStateFork.Altair and
(signed_block is altair.SignedBeaconBlock or
signed_block is merge.SignedBeaconBlock):
let
current_sync_committee =
state.data.get_sync_committee_cache(cache).current_sync_committee
var inited = false
var attestersAgg{.noInit.}: AggregatePublicKey
for i in 0 ..< current_sync_committee.len:
if signed_block.message.body.sync_aggregate.sync_committee_bits[i]:
let key = validatorKeys.load(current_sync_committee[i])
if not key.isSome():
return err("Invalid key cache")
if not inited: # first iteration
attestersAgg.init(key.get())
inited = true
else:
attestersAgg.aggregate(key.get())
if not inited:
if signed_block.message.body.sync_aggregate.sync_committee_signature !=
default(CookedSig).toValidatorSig():
return err("process_sync_aggregate: empty sync aggregates need signature of point at infinity")
else:
let
attesters = finish(attestersAgg)
previous_slot = max(state.data.slot, Slot(1)) - 1
sigs.addSignatureSet(
attesters,
get_block_root_at_slot(state.data, previous_slot),
signed_block.message.body.sync_aggregate.sync_committee_signature.loadOrExit(
"process_sync_aggregate: cannot load signature"),
state.data.fork,
state.data.genesis_validators_root,
previous_slot.epoch,
DOMAIN_SYNC_COMMITTEE)
ok()
proc batchVerify*(verifier: var BatchVerifier, sigs: openArray[SignatureSet]): bool =
var bytes: array[32, byte]
verifier.rng[].brHmacDrbgGenerate(bytes)
try:
verifier.taskpool.batchVerify(verifier.sigVerifCache, sigs, bytes)
except Exception as exc:
raiseAssert exc.msg # Shouldn't happen
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