182 lines
6.5 KiB
Nim
182 lines
6.5 KiB
Nim
# beacon_chain
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# Copyright (c) 2018-2024 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 https://opensource.org/licenses/MIT).
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# * Apache v2 license (license terms in the root directory or at https://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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{.push raises: [].}
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# Uncategorized helper functions from the spec
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import
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std/algorithm,
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results,
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eth/p2p/discoveryv5/[node],
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./[helpers, digest],
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./datatypes/[eip7594]
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func sortedColumnIndices*(columnsPerSubnet: ColumnIndex,
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subnetIds: HashSet[uint64]):
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seq[ColumnIndex] =
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var res: seq[ColumnIndex] = @[]
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for i in 0'u64 ..< columnsPerSubnet:
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for subnetId in subnetIds:
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let index = DATA_COLUMN_SIDECAR_SUBNET_COUNT * i + subnetId
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res.add(ColumnIndex(index))
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res.sort
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res
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func sortedColumnIndexList*(columnsPerSubnet: ColumnIndex,
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subnetIds: HashSet[uint64]):
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List[ColumnIndex, NUMBER_OF_COLUMNS] =
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var
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res: seq[ColumnIndex]
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for i in 0'u64 ..< columnsPerSubnet:
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for subnetId in subnetIds:
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let index = DATA_COLUMN_SIDECAR_SUBNET_COUNT * i + subnetId
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res.add(ColumnIndex(index))
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res.sort()
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List[ColumnIndex, NUMBER_OF_COLUMNS].init(res)
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func get_custody_column_subnets*(node_id: NodeId,
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custody_subnet_count: uint64):
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HashSet[uint64] =
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# Decouples the custody subnet computation part from
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# `get_custody_columns`, in order to later use this subnet list
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# in order to maintain subscription to specific column subnets.
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var
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subnet_ids: HashSet[uint64]
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current_id = node_id
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while subnet_ids.lenu64 < custody_subnet_count:
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var
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hashed_bytes: array[8, byte]
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let
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current_id_bytes = current_id.toBytesLE()
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hashed_current_id = eth2digest(current_id_bytes)
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hashed_bytes[0..7] = hashed_current_id.data.toOpenArray(0,7)
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let subnet_id = bytes_to_uint64(hashed_bytes) mod
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DATA_COLUMN_SIDECAR_SUBNET_COUNT
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subnet_ids.incl(subnet_id)
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if current_id == UInt256.high.NodeId:
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# Overflow prevention
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current_id = NodeId(StUint[256].zero)
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current_id += NodeId(StUint[256].one)
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subnet_ids
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# https://github.com/ethereum/consensus-specs/blob/v1.5.0-alpha.5/specs/_features/eip7594/das-core.md#get_custody_columns
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func get_custody_columns*(node_id: NodeId,
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custody_subnet_count: uint64):
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seq[ColumnIndex] =
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let
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subnet_ids =
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get_custody_column_subnets(node_id, custody_subnet_count)
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const
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columns_per_subnet =
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NUMBER_OF_COLUMNS div DATA_COLUMN_SIDECAR_SUBNET_COUNT
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sortedColumnIndices(ColumnIndex(columns_per_subnet), subnet_ids)
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func get_custody_column_list*(node_id: NodeId,
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custody_subnet_count: uint64):
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List[ColumnIndex, NUMBER_OF_COLUMNS] =
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# Not in spec in the exact format, but it is useful in sorting custody columns
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# before sending, data_column_sidecars_by_range requests
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let
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subnet_ids =
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get_custody_column_subnets(node_id, custody_subnet_count)
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const
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columns_per_subnet =
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NUMBER_OF_COLUMNS div DATA_COLUMN_SIDECAR_SUBNET_COUNT
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sortedColumnIndexList(ColumnIndex(columns_per_subnet), subnet_ids)
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# https://github.com/ethereum/consensus-specs/blob/v1.5.0-alpha.5/specs/_features/eip7594/das-core.md#compute_matrix
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proc compute_matrix*(blobs: seq[KzgBlob]): Result[seq[MatrixEntry], cstring] =
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## `compute_matrix` helper demonstrates the relationship
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## between blobs and the `MatrixEntries`
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var extended_matrix: seq[MatrixEntry]
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for blbIdx, blob in blobs.pairs:
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let cellsAndProofs = computeCellsAndKzgProofs(blob)
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if cellsAndProofs.isErr:
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return err("Computing Extended Matrix: Issue computing cells and proofs")
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for i in 0..<eip7594.CELLS_PER_EXT_BLOB:
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extended_matrix.add(MatrixEntry(
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cell: cellsAndProofs.get.cells[i],
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kzg_proof: cellsAndProofs.get.proofs[i],
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row_index: blbIdx.uint64,
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column_index: i.uint64
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))
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ok(extended_matrix)
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# https://github.com/ethereum/consensus-specs/blob/v1.5.0-alpha.5/specs/_features/eip7594/das-core.md#recover_matrix
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proc recover_matrix*(partial_matrix: seq[MatrixEntry],
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blobCount: int):
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Result[seq[MatrixEntry], cstring] =
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## This helper demonstrates how to apply recover_cells_and_kzg_proofs
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## The data structure for storing cells is implementation-dependent
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var extended_matrix: seq[MatrixEntry]
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for blob_index in 0..<blobCount:
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var
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cell_indices: seq[CellIndex]
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cells: seq[Cell]
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for e in partial_matrix:
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if e.row_index == uint64(blob_index):
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cell_indices.add(e.column_index)
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cells.add(e.cell)
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let recoveredCellsAndKzgProofs =
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recoverCellsAndKzgProofs(cell_indices, cells)
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if recoveredCellsAndKzgProofs.isErr:
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return err("Issue in recovering cells and proofs")
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for i in 0..<recoveredCellsAndKzgProofs.get.cells.len:
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let
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cell = recoveredCellsAndKzgProofs.get.cells[i]
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proof = recoveredCellsAndKzgProofs.get.proofs[i]
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extended_matrix.add(MatrixEntry(
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cell: cell,
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kzg_proof: proof,
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row_index: blob_index.uint64,
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column_index: i.uint64
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))
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ok(extended_matrix)
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# https://github.com/ethereum/consensus-specs/blob/v1.5.0-alpha.6/specs/_features/eip7594/peer-sampling.md#get_extended_sample_count
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func get_extended_sample_count*(samples_per_slot: int,
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allowed_failures: int):
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int =
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## `get_extended_sample_count` computes the number of samples we
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## should query from peers, given the SAMPLES_PER_SLOT and
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## the number of allowed failures
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# If 50% of the columns are missing, we are able to reconstruct the data
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# If 50% + 1 columns are missing, we cannot reconstruct the data
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const worstCaseConditionCount = (NUMBER_OF_COLUMNS div 2) + 1
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# Compute the false positive threshold
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let falsePositiveThreshold =
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hypergeom_cdf(0, NUMBER_OF_COLUMNS, worstCaseConditionCount, samples_per_slot)
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# Finally, compute the extended sample count
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for i in samples_per_slot .. NUMBER_OF_COLUMNS:
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if hypergeom_cdf(
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allowed_failures,
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NUMBER_OF_COLUMNS,
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worstCaseConditionCount, i) <= falsePositiveThreshold:
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return i
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NUMBER_OF_COLUMNS |