nimbus-eth1/fluffy/network/beacon/beacon_chain_historical_sum...

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# fluffy
# Copyright (c) 2023-2024 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.
#
# Implementation of the beacon state historical_summaries provided with a Merkle
# proof that can be verified against the right beacon state root.
#
# As per spec:
# https://github.com/ethereum/portal-network-specs/blob/master/beacon-chain/beacon-network.md#historicalsummaries
#
{.push raises: [].}
import
stew/arrayops,
results,
beacon_chain/spec/forks,
beacon_chain/spec/datatypes/capella,
../../common/common_types
export results
type
HistoricalSummaries* = HashList[HistoricalSummary, Limit HISTORICAL_ROOTS_LIMIT]
HistoricalSummariesProof* = array[5, Digest]
HistoricalSummariesWithProof* = object
epoch*: Epoch
# TODO:
# can epoch instead of slot cause any issues? E.g. to verify with right state?
# To revise when we fully implement this in validateHistoricalSummaries,
# for now follow specification.
# finalized_slot*: Slot
historical_summaries*: HistoricalSummaries
proof*: HistoricalSummariesProof
# TODO: prefixing the summaries with the forkDigest is currently not necessary
# and might never be. Perhaps we should drop this until it is needed. Propose
# spec change?
func encodeSsz*(obj: HistoricalSummariesWithProof, forkDigest: ForkDigest): seq[byte] =
var res: seq[byte]
res.add(distinctBase(forkDigest))
res.add(SSZ.encode(obj))
res
func decodeSsz*(
forkDigests: ForkDigests,
data: openArray[byte],
T: type HistoricalSummariesWithProof,
): Result[HistoricalSummariesWithProof, string] =
if len(data) < 4:
return
Result[HistoricalSummariesWithProof, string].err("Not enough data for forkDigest")
let
forkDigest = ForkDigest(array[4, byte].initCopyFrom(data))
contextFork = forkDigests.consensusForkForDigest(forkDigest).valueOr:
return Result[HistoricalSummariesWithProof, string].err("Unknown fork")
if contextFork > ConsensusFork.Bellatrix:
# There is only one version of HistoricalSummaries starting since Capella
decodeSsz(data.toOpenArray(4, len(data) - 1), HistoricalSummariesWithProof)
else:
Result[HistoricalSummariesWithProof, string].err(
"Invalid Fork for HistoricalSummaries"
)
func buildProof*(
state: ForkedHashedBeaconState
): Result[HistoricalSummariesProof, string] =
let gIndex = GeneralizedIndex(59) # 31 + 28 = 59
var proof: HistoricalSummariesProof
withState(state):
?forkyState.data.build_proof(gIndex, proof)
ok(proof)
func verifyProof*(
historical_summaries: HistoricalSummaries,
proof: HistoricalSummariesProof,
stateRoot: Digest,
): bool =
let
gIndex = GeneralizedIndex(59)
leave = hash_tree_root(historical_summaries)
verify_merkle_multiproof(@[leave], proof, @[gIndex], stateRoot)
func verifyProof*(
summariesWithProof: HistoricalSummariesWithProof, stateRoot: Digest
): bool =
verifyProof(
summariesWithProof.historical_summaries, summariesWithProof.proof, stateRoot
)