Merge pull request #3579 from asn-d6/peerdas_public_method_bytes

peerDAS: Public methods must accept raw bytes

Author: asn-d6

specs/_features/eip7594/polynomial-commitments-sampling.md

@@ -12,6 +12,8 @@
 - [Preset](#preset)
   - [Cells](#cells)
 - [Helper functions](#helper-functions)
+  - [BLS12-381 helpers](#bls12-381-helpers)
+    - [`bytes_to_cell`](#bytes_to_cell)
   - [Linear combinations](#linear-combinations)
     - [`g2_lincomb`](#g2_lincomb)
   - [FFTs](#ffts)
@@ -81,6 +83,18 @@ Cells are the smallest unit of blob data that can come with their own KZG proofs
 
 ## Helper functions
 
+### BLS12-381 helpers
+
+#### `bytes_to_cell`
+
+```python
+def bytes_to_cell(cell_bytes: Vector[Bytes32, FIELD_ELEMENTS_PER_CELL]) -> Cell:
+    """
+    Convert untrusted bytes into a Cell.
+    """
+    return [bytes_to_bls_field(element) for element in cell_bytes]
+```
+
 ### Linear combinations
 
 #### `g2_lincomb`
@@ -244,7 +258,7 @@ def interpolate_polynomialcoeff(xs: Sequence[BLSFieldElement], ys: Sequence[BLSF
                     summand, [(- int(weight_adjustment) * int(xs[j])) % BLS_MODULUS, weight_adjustment]
                 )
         r = add_polynomialcoeff(r, summand)
-    
+
     return r
 ```
 
@@ -332,7 +346,7 @@ def verify_kzg_proof_multi_impl(commitment: KZGCommitment,
 #### `coset_for_cell`
 
 ```python
-def coset_for_cell(cell_id: int) -> Cell:
+def coset_for_cell(cell_id: CellID) -> Cell:
     """
     Get the coset for a given ``cell_id``
     """
@@ -387,7 +401,7 @@ def compute_cells(blob: Blob) -> Vector[Cell, CELLS_PER_BLOB]:
     polynomial = blob_to_polynomial(blob)
     polynomial_coeff = polynomial_eval_to_coeff(polynomial)
 
-    extended_data = fft_field(polynomial_coeff + [0] * FIELD_ELEMENTS_PER_BLOB, 
+    extended_data = fft_field(polynomial_coeff + [0] * FIELD_ELEMENTS_PER_BLOB,
                               compute_roots_of_unity(2 * FIELD_ELEMENTS_PER_BLOB))
     extended_data_rbo = bit_reversal_permutation(extended_data)
     return [extended_data_rbo[i * FIELD_ELEMENTS_PER_CELL:(i + 1) * FIELD_ELEMENTS_PER_CELL]
@@ -399,30 +413,37 @@ def compute_cells(blob: Blob) -> Vector[Cell, CELLS_PER_BLOB]:
 #### `verify_cell_proof`
 
 ```python
-def verify_cell_proof(commitment: KZGCommitment,
-                      cell_id: int,
-                      cell: Cell,
-                      proof: KZGProof) -> bool:
+def verify_cell_proof(commitment_bytes: Bytes48,
+                      cell_id: CellID,
+                      cell_bytes: Vector[Bytes32, FIELD_ELEMENTS_PER_CELL],
+                      proof_bytes: Bytes48) -> bool:
     """
     Check a cell proof
 
     Public method.
     """
     coset = coset_for_cell(cell_id)
 
-    return verify_kzg_proof_multi_impl(commitment, coset, cell, proof)
+    return verify_kzg_proof_multi_impl(
+        bytes_to_kzg_commitment(commitment_bytes),
+        coset,
+        bytes_to_cell(cell_bytes),
+        bytes_to_kzg_proof(proof_bytes))
 ```
 
 #### `verify_cell_proof_batch`
 
 ```python
-def verify_cell_proof_batch(row_commitments: Sequence[KZGCommitment],
-                            row_ids: Sequence[int],
-                            column_ids: Sequence[int],
-                            cells: Sequence[Cell],
-                            proofs: Sequence[KZGProof]) -> bool:
+def verify_cell_proof_batch(row_commitments_bytes: Sequence[Bytes48],
+                            row_ids: Sequence[uint64],
+                            column_ids: Sequence[uint64],
+                            cells_bytes: Sequence[Vector[Bytes32, FIELD_ELEMENTS_PER_CELL]],
+                            proofs_bytes: Sequence[Bytes48]) -> bool:
     """
-    Check multiple cell proofs. This function implements the naive algorithm of checking every cell
+    Verify a set of cells, given their corresponding proofs and their coordinates (row_id, column_id) in the blob
+    matrix. The list of all commitments is also provided in row_commitments_bytes.
+
+    This function implements the naive algorithm of checking every cell
     individually; an efficient algorithm can be found here:
     https://ethresear.ch/t/a-universal-verification-equation-for-data-availability-sampling/13240
 
@@ -432,10 +453,16 @@ def verify_cell_proof_batch(row_commitments: Sequence[KZGCommitment],
 
     Public method.
     """
+    assert len(cells_bytes) == len(proofs_bytes) == len(row_ids) == len(column_ids)
 
     # Get commitments via row IDs
-    commitments = [row_commitments[row_id] for row_id in row_ids]
-    
+    commitments_bytes = [row_commitments_bytes[row_id] for row_id in row_ids]
+
+    # Get objects from bytes
+    commitments = [bytes_to_kzg_commitment(commitment_bytes) for commitment_bytes in commitments_bytes]
+    cells = [bytes_to_cell(cell_bytes) for cell_bytes in cells_bytes]
+    proofs = [bytes_to_kzg_proof(proof_bytes) for proof_bytes in proofs_bytes]
+
     return all(
         verify_kzg_proof_multi_impl(commitment, coset_for_cell(column_id), cell, proof)
         for commitment, column_id, cell, proof in zip(commitments, column_ids, cells, proofs)
@@ -447,7 +474,8 @@ def verify_cell_proof_batch(row_commitments: Sequence[KZGCommitment],
 ### `recover_polynomial`
 
 ```python
-def recover_polynomial(cell_ids: Sequence[CellID], cells: Sequence[Cell]) -> Polynomial:
+def recover_polynomial(cell_ids: Sequence[CellID],
+                       cells_bytes: Sequence[Vector[Bytes32, FIELD_ELEMENTS_PER_CELL]]) -> Polynomial:
     """
     Recovers a polynomial from 2 * FIELD_ELEMENTS_PER_CELL evaluations, half of which can be missing.
 
@@ -457,7 +485,10 @@ def recover_polynomial(cell_ids: Sequence[CellID], cells: Sequence[Cell]) -> Pol
 
     Public method.
     """
-    assert len(cell_ids) == len(cells)
+    assert len(cell_ids) == len(cells_bytes)
+
+    cells = [bytes_to_cell(cell_bytes) for cell_bytes in cells_bytes]
+
     assert len(cells) >= CELLS_PER_BLOB // 2
     missing_cell_ids = [cell_id for cell_id in range(CELLS_PER_BLOB) if cell_id not in cell_ids]
     roots_of_unity_reduced = compute_roots_of_unity(CELLS_PER_BLOB)
@@ -506,7 +537,7 @@ def recover_polynomial(cell_ids: Sequence[CellID], cells: Sequence[Cell]) -> Pol
 
     eval_shifted_extended_evaluation = fft_field(shifted_extended_evaluation, roots_of_unity_extended)
     eval_shifted_zero_poly = fft_field(shifted_zero_poly, roots_of_unity_extended)
-    
+
     eval_shifted_reconstructed_poly = [
         div(a, b)
         for a, b in zip(eval_shifted_extended_evaluation, eval_shifted_zero_poly)

specs/deneb/polynomial-commitments.md

@@ -578,7 +578,7 @@ def verify_blob_kzg_proof_batch(blobs: Sequence[Blob],
     """
 
     assert len(blobs) == len(commitments_bytes) == len(proofs_bytes)
-    
+
     commitments, evaluation_challenges, ys, proofs = [], [], [], []
     for blob, commitment_bytes, proof_bytes in zip(blobs, commitments_bytes, proofs_bytes):
         assert len(blob) == BYTES_PER_BLOB

tests/core/pyspec/eth2spec/test/eip7594/unittests/polynomial_commitments/test_polynomial_commitments.py

@@ -10,6 +10,10 @@
 from eth2spec.utils.bls import BLS_MODULUS
 
 
+def field_element_bytes(x):
+    return int.to_bytes(x % BLS_MODULUS, 32, "big")
+
+
 @with_eip7594_and_later
 @spec_test
 @single_phase
@@ -34,10 +38,13 @@ def test_verify_cell_proof(spec):
     blob = get_sample_blob(spec)
     commitment = spec.blob_to_kzg_commitment(blob)
     cells, proofs = spec.compute_cells_and_proofs(blob)
+
+    cells_bytes = [[field_element_bytes(element) for element in cell] for cell in cells]
+
     cell_id = 0
-    assert spec.verify_cell_proof(commitment, cell_id, cells[cell_id], proofs[cell_id])
+    assert spec.verify_cell_proof(commitment, cell_id, cells_bytes[cell_id], proofs[cell_id])
     cell_id = 1
-    assert spec.verify_cell_proof(commitment, cell_id, cells[cell_id], proofs[cell_id])
+    assert spec.verify_cell_proof(commitment, cell_id, cells_bytes[cell_id], proofs[cell_id])
 
 
 @with_eip7594_and_later
@@ -47,13 +54,16 @@ def test_verify_cell_proof_batch(spec):
     blob = get_sample_blob(spec)
     commitment = spec.blob_to_kzg_commitment(blob)
     cells, proofs = spec.compute_cells_and_proofs(blob)
+    cells_bytes = [[field_element_bytes(element) for element in cell] for cell in cells]
+
+    assert len(cells) == len(proofs)
 
     assert spec.verify_cell_proof_batch(
-        row_commitments=[commitment],
-        row_ids=[0],
-        column_ids=[0, 1],
-        cells=cells[0:1],
-        proofs=proofs,
+        row_commitments_bytes=[commitment],
+        row_ids=[0, 0],
+        column_ids=[0, 4],
+        cells_bytes=[cells_bytes[0], cells_bytes[4]],
+        proofs_bytes=[proofs[0], proofs[4]],
     )
 
 
@@ -73,21 +83,21 @@ def test_recover_polynomial(spec):
 
     # Extend data with Reed-Solomon and split the extended data in cells
     cells = spec.compute_cells(blob)
+    cells_bytes = [[field_element_bytes(element) for element in cell] for cell in cells]
 
     # Compute the cells we will be recovering from
     cell_ids = []
-    known_cells = []
     # First figure out just the indices of the cells
     for i in range(N_SAMPLES):
         j = rng.randint(0, spec.CELLS_PER_BLOB)
         while j in cell_ids:
             j = rng.randint(0, spec.CELLS_PER_BLOB)
         cell_ids.append(j)
     # Now the cells themselves
-    known_cells = [cells[cell_id] for cell_id in cell_ids]
+    known_cells_bytes = [cells_bytes[cell_id] for cell_id in cell_ids]
 
     # Recover the data
-    recovered_data = spec.recover_polynomial(cell_ids, known_cells)
+    recovered_data = spec.recover_polynomial(cell_ids, known_cells_bytes)
 
     # Check that the original data match the non-extended portion of the recovered data
     assert original_polynomial == recovered_data[:len(recovered_data) // 2]