78 lines
3.3 KiB
Python
78 lines
3.3 KiB
Python
from dataclasses import dataclass
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from hashlib import sha3_256
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from typing import List, Optional, Generator, Sequence
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from py_ecc.bls import G2ProofOfPossession as bls_pop
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from da.common import Certificate, NodeId, BLSPublickey
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from da.encoder import EncodedData
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from da.verifier import DABlob, Attestation
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@dataclass
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class DispersalSettings:
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nodes_ids: List[NodeId]
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nodes_pubkey: List[BLSPublickey]
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threshold: int
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class Dispersal:
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def __init__(self, settings: DispersalSettings):
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self.settings = settings
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def _prepare_data(self, encoded_data: EncodedData) -> Generator[DABlob, None, None]:
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assert len(encoded_data.column_commitments) == len(self.settings.nodes_ids)
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assert len(encoded_data.aggregated_column_proofs) == len(self.settings.nodes_ids)
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columns = encoded_data.extended_matrix.columns
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column_commitments = encoded_data.column_commitments
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row_commitments = encoded_data.row_commitments
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rows_proofs = encoded_data.row_proofs
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aggregated_column_commitment = encoded_data.aggregated_column_commitment
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aggregated_column_proofs = encoded_data.aggregated_column_proofs
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blobs_data = enumerate(zip(columns, column_commitments, zip(*rows_proofs), aggregated_column_proofs))
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for index, (column, column_commitment, row_proofs, column_proof) in blobs_data:
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blob = DABlob(
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index,
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column,
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column_commitment,
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aggregated_column_commitment,
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column_proof,
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row_commitments,
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row_proofs
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)
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yield blob
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def _send_and_await_response(self, node: NodeId, blob: DABlob) -> Optional[Attestation]:
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pass
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def _build_certificate(self, encoded_data: EncodedData, attestations: Sequence[Attestation]) -> Certificate:
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assert len(attestations) >= self.settings.threshold
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aggregated = bls_pop.Aggregate([attestation.signature for attestation in attestations])
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return Certificate(
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aggregated_signatures=aggregated,
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aggregated_column_commitment=encoded_data.aggregated_column_commitment,
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row_commitments=encoded_data.row_commitments
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)
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@staticmethod
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def _verify_attestation(public_key: BLSPublickey, attested_message: bytes, attestation: Attestation) -> bool:
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return bls_pop.Verify(public_key, attested_message, attestation.signature)
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@staticmethod
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def _build_attestation_message(encoded_data: EncodedData) -> bytes:
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hasher = sha3_256()
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hasher.update(bytes(encoded_data.aggregated_column_commitment))
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for c in encoded_data.row_commitments:
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hasher.update(bytes(c))
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return hasher.digest()
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def disperse(self, encoded_data: EncodedData) -> Optional[Certificate]:
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attestations = []
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attested_message = self._build_attestation_message(encoded_data)
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for node, pk, blob in zip(self.settings.nodes_ids, self.settings.nodes_pubkey, self._prepare_data(encoded_data)):
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if attestation := self._send_and_await_response(node, blob):
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if self._verify_attestation(pk, attested_message, attestation):
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attestations.append(attestation)
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if len(attestations) >= self.settings.threshold:
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return self._build_certificate(encoded_data, attestations)
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