diff --git a/da/common.py b/da/common.py
index 21f9c62..8d428e3 100644
--- a/da/common.py
+++ b/da/common.py
@@ -2,12 +2,15 @@ from dataclasses import dataclass
 from itertools import chain, zip_longest
 from typing import List, Generator, Self
 
-from eth2spec.eip7594.mainnet import Bytes32
+
+
+from eth2spec.eip7594.mainnet import Bytes32, KZGCommitment as Commitment
 
 
 class NodeId(Bytes32):
     pass
 
+
 class Chunk(Bytes32):
     pass
 
@@ -43,5 +46,7 @@ class Attestation:
 
 @dataclass
 class Certificate:
-    pass
+    aggregated_signatures: BLSSignature
+    aggregated_column_commitment: Commitment
+    row_commitments: List[Commitment]
 
diff --git a/da/dispersal.py b/da/dispersal.py
index 1c8271f..32f05aa 100644
--- a/da/dispersal.py
+++ b/da/dispersal.py
@@ -1,31 +1,41 @@
-from typing import List, Optional, Generator
+from dataclasses import dataclass
+from typing import List, Optional, Generator, Sequence
 
-from da.common import Certificate, NodeId
+from py_ecc.bls import G2ProofOfPossession as bls_pop
+
+from da.common import Certificate, NodeId, BLSPublickey
 from da.encoder import EncodedData
 from da.verifier import DABlob, Attestation
 
 
+@dataclass
+class DispersalSettings:
+    nodes_ids: List[NodeId]
+    nodes_pubkey: List[BLSPublickey]
+    threshold: int
+
+
 class Dispersal:
-    def __init__(self, nodes: List[NodeId], threshold: int):
-        self.nodes = nodes
-        self.threshold = threshold
+    def __init__(self, settings: DispersalSettings):
+        self.settings = settings
 
     def _prepare_data(self, encoded_data: EncodedData) -> Generator[DABlob, None, None]:
-        assert len(encoded_data.row_commitments) == len(self.nodes)
-        assert len(encoded_data.row_proofs) == len(self.nodes)
+        assert len(encoded_data.row_commitments) == len(self.settings.nodes_ids)
+        assert len(encoded_data.row_proofs) == len(self.settings.nodes_ids)
         columns = encoded_data.extended_matrix.columns
         column_commitments = encoded_data.column_commitments
         row_commitments = encoded_data.row_commitments
         rows_proofs = encoded_data.row_proofs
         aggregated_column_commitment = encoded_data.aggregated_column_commitment
-        aggregated_column_proof = encoded_data.aggregated_column_proof
-        for index, (column, column_commitment, row_proofs) in enumerate(zip(columns, column_commitments, rows_proofs)):
+        aggregated_column_proofs = encoded_data.aggregated_column_proofs
+        blobs_data = enumerate(zip(columns, column_commitments, rows_proofs, aggregated_column_proofs))
+        for index, (column, column_commitment, row_proofs, column_proof) in blobs_data:
             blob = DABlob(
                 index,
                 column,
                 column_commitment,
                 aggregated_column_commitment,
-                aggregated_column_proof,
+                column_proof,
                 row_commitments,
                 row_proofs
             )
@@ -34,17 +44,25 @@ class Dispersal:
     def _send_and_await_response(self, node, encoded_data: EncodedData) -> Optional[Attestation]:
         pass
 
-    def _build_certificate(self, attestations: List[Attestation]):
-        pass
+    def _build_certificate(self, encoded_data: EncodedData, attestations: Sequence[Attestation]) -> Certificate:
+        assert len(attestations) >= self.settings.threshold
+        aggregated = bls_pop.Aggregate([attestation.signature for attestation in attestations])
+        return Certificate(
+            aggregated_signatures=aggregated,
+            aggregated_column_commitment=encoded_data.aggregated_column_commitment,
+            row_commitments=encoded_data.row_commitments
+        )
 
-    def _verify_attestation(self, attestation: Attestation) -> bool:
-        pass
+    @staticmethod
+    def _verify_attestation(public_key: BLSPublickey, attested_message: bytes, attestation: Attestation) -> bool:
+        return bls_pop.Verify(public_key, attested_message, attestation.signature)
 
     def disperse(self, encoded_data: EncodedData) -> Optional[Certificate]:
         attestations = []
-        for node, blob in zip(self.nodes, self._prepare_data(encoded_data)):
+
+        for node, blob in zip(self.settings.nodes_ids, self._prepare_data(encoded_data)):
             if attestation := self._send_and_await_response(node, blob):
                 if self._verify_attestation(attestation):
                     attestations.append(attestation)
-            if len(attestations) >= self.threshold:
-                return self._build_certificate(attestations)
+            if len(attestations) >= self.settings.threshold:
+                return self._build_certificate(encoded_data, attestations)