feat: add method to compute cells

crate-crypto · Feb 21, 2025 · 37673f5 · 37673f5
1 parent 1afb045
commit 37673f5
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Showing 3 changed files with 36 additions and 3 deletions.
diff --git a/api_eip7594.go b/api_eip7594.go
@@ -9,6 +9,24 @@ import (
 	kzgmulti "github.com/crate-crypto/go-eth-kzg/internal/kzg_multi"
 )
 
+func (ctx *Context) ComputeCells(blob *Blob, numGoRoutines int) ([CellsPerExtBlob]*Cell, error) {
+	polynomial, err := DeserializeBlob(blob)
+	if err != nil {
+		return [CellsPerExtBlob]*Cell{}, err
+	}
+
+	// Bit reverse the polynomial representing the Blob so that it is in normal order
+	domain.BitReverse(polynomial)
+
+	// Convert the polynomial in lagrange form to a polynomial in monomial form
+	polyCoeff := ctx.domain.IfftFr(polynomial)
+
+	// Extend the polynomial
+	cosetEvaluations := ctx.fk20.ComputeExtendedPolynomial(polyCoeff)
+
+	return serializeCells(cosetEvaluations)
+}
+
 func (ctx *Context) ComputeCellsAndKZGProofs(blob *Blob, numGoRoutines int) ([CellsPerExtBlob]*Cell, [CellsPerExtBlob]KZGProof, error) {
 	polynomial, err := DeserializeBlob(blob)
 	if err != nil {
@@ -45,17 +63,25 @@ func (ctx *Context) computeCellsAndKZGProofsFromPolyCoeff(polyCoeff []fr.Element
 	}
 
 	// Serialize Cells
+	cells, err := serializeCells(cosetEvaluations)
+	if err != nil {
+		return [CellsPerExtBlob]*Cell{}, [CellsPerExtBlob]KZGProof{}, err
+	}
+	return cells, serializedProofs, nil
+}
+
+func serializeCells(cosetEvaluations [][]fr.Element) ([CellsPerExtBlob]*Cell, error) {
 	var Cells [CellsPerExtBlob]*Cell
 	for i, cosetEval := range cosetEvaluations {
 		if len(cosetEval) != scalarsPerCell {
-			return [CellsPerExtBlob]*Cell{}, [CellsPerExtBlob]KZGProof{}, ErrCosetEvaluationLengthCheck
+			return [CellsPerExtBlob]*Cell{}, ErrCosetEvaluationLengthCheck
 		}
 		cosetEvalArr := (*[scalarsPerCell]fr.Element)(cosetEval)
 
 		Cells[i] = serializeEvaluations(cosetEvalArr)
 	}
 
-	return Cells, serializedProofs, nil
+	return Cells, nil
 }
 
 func (ctx *Context) RecoverCellsAndComputeKZGProofs(cellIDs []uint64, cells []*Cell, numGoRoutines int) ([CellsPerExtBlob]*Cell, [CellsPerExtBlob]KZGProof, error) {

diff --git a/consensus_specs_test.go b/consensus_specs_test.go
@@ -386,12 +386,15 @@ func TestComputeCellsAndKZGProofs(t *testing.T) {
 			}
 
 			cells, proofs, err := ctx.ComputeCellsAndKZGProofs(blob, 0)
+			cells_, err_ := ctx.ComputeCells(blob, 0)
 
 			if err == nil {
 				expectedCellStrs := (*test.Output)[0]
 				expectedCells, err := hexStrArrToCells(expectedCellStrs)
 				require.NoError(t, err)
+				require.NoError(t, err_)
 				require.Equal(t, expectedCells, cells[:])
+				require.Equal(t, cells_[:], cells[:])
 
 				expectedProofStrs := (*test.Output)[1]
 				expectedProofs, err := HexStrArrToProofs(expectedProofStrs)

diff --git a/internal/kzg_multi/fk20/fk20.go b/internal/kzg_multi/fk20/fk20.go
@@ -67,11 +67,15 @@ func (fk *FK20) computeEvaluationSet(polyCoeff []fr.Element) [][]fr.Element {
 	return partition(evaluations, fk.evalSetSize)
 }
 
+func (fk *FK20) ComputeExtendedPolynomial(poly []fr.Element) [][]fr.Element {
+	return fk.computeEvaluationSet(poly)
+}
+
 func (fk *FK20) ComputeMultiOpenProof(poly []fr.Element) ([]bls12381.G1Affine, [][]fr.Element, error) {
 	// Note: `computeEvaluationSet` will create a copy of `poly`
 	// and pad it. Hence, the rest of this method, does not use the padded
 	// version  of `poly`.
-	outputSets := fk.computeEvaluationSet(poly)
+	outputSets := fk.ComputeExtendedPolynomial(poly)
 
 	hComms, err := fk.computeHPolysComm(poly)
 	if err != nil {