PeerDAS: Implement beacon API blob sidecar endpoint for Fulu (#15436)

* `TestGetBlob`: Refactor (no functional change). * `GenerateTestFuluBlockWithSidecars`: Generate commitments consistent with blobs. This is actually not needed for this PR, but it does not hurt. * Beacon API: Implement blob sidecars endpoint for Fulu. * Fix Radek's comment. * Update beacon-chain/rpc/lookup/blocker.go Co-authored-by: Radosław Kapka <rkapka@wp.pl> * Fix Radek's comment. * Update beacon-chain/rpc/lookup/blocker.go Co-authored-by: Radosław Kapka <rkapka@wp.pl> --------- Co-authored-by: Radosław Kapka <rkapka@wp.pl>
2026-01-08 21:08:10 -05:00 · 2025-06-26 12:05:22 +02:00
parent 121914d0d7
commit 1c1e0f38bb
5 changed files with 433 additions and 133 deletions
--- a/beacon-chain/rpc/lookup/BUILD.bazel
+++ b/beacon-chain/rpc/lookup/BUILD.bazel
@@ -10,11 +10,13 @@ go_library(
    visibility = ["//visibility:public"],
    deps = [
        "//beacon-chain/blockchain:go_default_library",
+        "//beacon-chain/core/peerdas:go_default_library",
        "//beacon-chain/db:go_default_library",
        "//beacon-chain/db/filesystem:go_default_library",
        "//beacon-chain/rpc/core:go_default_library",
        "//beacon-chain/state:go_default_library",
        "//beacon-chain/state/stategen:go_default_library",
+        "//cmd/beacon-chain/flags:go_default_library",
        "//config/fieldparams:go_default_library",
        "//config/params:go_default_library",
        "//consensus-types/blocks:go_default_library",
@@ -36,7 +38,9 @@ go_test(
    ],
    embed = [":go_default_library"],
    deps = [
+        "//beacon-chain/blockchain/kzg:go_default_library",
        "//beacon-chain/blockchain/testing:go_default_library",
+        "//beacon-chain/core/peerdas:go_default_library",
        "//beacon-chain/db/filesystem:go_default_library",
        "//beacon-chain/db/testing:go_default_library",
        "//beacon-chain/rpc/core:go_default_library",
@@ -45,6 +49,7 @@ go_test(
        "//beacon-chain/state/stategen:go_default_library",
        "//beacon-chain/state/stategen/mock:go_default_library",
        "//beacon-chain/verification:go_default_library",
+        "//config/fieldparams:go_default_library",
        "//config/params:go_default_library",
        "//consensus-types/blocks:go_default_library",
        "//consensus-types/primitives:go_default_library",
--- a/beacon-chain/rpc/lookup/blocker.go
+++ b/beacon-chain/rpc/lookup/blocker.go
@@ -3,12 +3,15 @@ package lookup
 import (
 	"context"
 	"fmt"
+	"math"
 	"strconv"

 	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/peerdas"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/filesystem"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/core"
+	"github.com/OffchainLabs/prysm/v6/cmd/beacon-chain/flags"
 	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
@@ -49,6 +52,7 @@ type BeaconDbBlocker struct {
 	ChainInfoFetcher   blockchain.ChainInfoFetcher
 	GenesisTimeFetcher blockchain.TimeFetcher
 	BlobStorage        *filesystem.BlobStorage
+	DataColumnStorage  *filesystem.DataColumnStorage
 }

 // Block returns the beacon block for a given identifier. The identifier can be one of:
@@ -212,64 +216,190 @@ func (p *BeaconDbBlocker) Blobs(ctx context.Context, id string, indices []int) (

 	root := bytesutil.ToBytes32(rootSlice)

-	b, err := p.BeaconDB.Block(ctx, root)
+	roSignedBlock, err := p.BeaconDB.Block(ctx, root)
 	if err != nil {
 		return nil, &core.RpcError{Err: errors.Wrapf(err, "failed to retrieve block %#x from db", rootSlice), Reason: core.Internal}
 	}
-	if b == nil {
+
+	if roSignedBlock == nil {
 		return nil, &core.RpcError{Err: fmt.Errorf("block %#x not found in db", rootSlice), Reason: core.NotFound}
 	}

-	// if block is not in the retention window, return 200 w/ empty list
-	if !p.BlobStorage.WithinRetentionPeriod(slots.ToEpoch(b.Block().Slot()), slots.ToEpoch(p.GenesisTimeFetcher.CurrentSlot())) {
+	// If block is not in the retention window, return 200 w/ empty list
+	if !p.BlobStorage.WithinRetentionPeriod(slots.ToEpoch(roSignedBlock.Block().Slot()), slots.ToEpoch(p.GenesisTimeFetcher.CurrentSlot())) {
 		return make([]*blocks.VerifiedROBlob, 0), nil
 	}

-	commitments, err := b.Block().Body().BlobKzgCommitments()
+	roBlock := roSignedBlock.Block()
+
+	commitments, err := roBlock.Body().BlobKzgCommitments()
 	if err != nil {
 		return nil, &core.RpcError{Err: errors.Wrapf(err, "failed to retrieve kzg commitments from block %#x", rootSlice), Reason: core.Internal}
 	}
-	// if there are no commitments return 200 w/ empty list
+
+	// If there are no commitments return 200 w/ empty list
 	if len(commitments) == 0 {
 		return make([]*blocks.VerifiedROBlob, 0), nil
 	}

-	sum := p.BlobStorage.Summary(root)
+	// Compute the first Fulu slot.
+	fuluForkEpoch := params.BeaconConfig().FuluForkEpoch
+	fuluForkSlot := primitives.Slot(math.MaxUint64)
+	if fuluForkEpoch != primitives.Epoch(math.MaxUint64) {
+		fuluForkSlot, err = slots.EpochStart(fuluForkEpoch)
+		if err != nil {
+			return nil, &core.RpcError{Err: errors.Wrap(err, "could not calculate peerDAS start slot"), Reason: core.Internal}
+		}
+	}

-	if len(indices) == 0 {
-		for i := range commitments {
-			if sum.HasIndex(uint64(i)) {
-				indices = append(indices, i)
+	if roBlock.Slot() >= fuluForkSlot {
+		roBlock, err := blocks.NewROBlockWithRoot(roSignedBlock, root)
+		if err != nil {
+			return nil, &core.RpcError{Err: errors.Wrapf(err, "failed to create roBlock with root %#x", root), Reason: core.Internal}
+		}
+
+		return p.blobsFromStoredDataColumns(roBlock, indices)
+	}
+
+	return p.blobsFromStoredBlobs(commitments, root, indices)
+}
+
+// blobsFromStoredBlobs retrieves blob sidercars corresponding to `indices` and `root` from the store.
+// This function expects blob sidecars to be stored (aka. no data column sidecars).
+func (p *BeaconDbBlocker) blobsFromStoredBlobs(commitments [][]byte, root [fieldparams.RootLength]byte, indices []int) ([]*blocks.VerifiedROBlob, *core.RpcError) {
+	summary := p.BlobStorage.Summary(root)
+	maxBlobCount := summary.MaxBlobsForEpoch()
+
+	for _, index := range indices {
+		if uint64(index) >= maxBlobCount {
+			return nil, &core.RpcError{
+				Err:    fmt.Errorf("requested index %d is bigger than the maximum possible blob count %d", index, maxBlobCount),
+				Reason: core.BadRequest,
 			}
 		}
-	} else {
-		for _, ix := range indices {
-			if uint64(ix) >= sum.MaxBlobsForEpoch() {
-				return nil, &core.RpcError{
-					Err:    fmt.Errorf("requested index %d is bigger than the maximum possible blob count %d", ix, sum.MaxBlobsForEpoch()),
-					Reason: core.BadRequest,
-				}
-			}
-			if !sum.HasIndex(uint64(ix)) {
-				return nil, &core.RpcError{
-					Err:    fmt.Errorf("requested index %d not found", ix),
-					Reason: core.NotFound,
-				}
+
+		if !summary.HasIndex(uint64(index)) {
+			return nil, &core.RpcError{
+				Err:    fmt.Errorf("requested index %d not found", index),
+				Reason: core.NotFound,
 			}
 		}
 	}

-	blobs := make([]*blocks.VerifiedROBlob, len(indices))
-	for i, index := range indices {
-		vblob, err := p.BlobStorage.Get(root, uint64(index))
+	// If no indices are provided, use all indices that are available in the summary.
+	if len(indices) == 0 {
+		for index := range commitments {
+			if summary.HasIndex(uint64(index)) {
+				indices = append(indices, index)
+			}
+		}
+	}
+
+	// Retrieve blob sidecars from the store.
+	blobs := make([]*blocks.VerifiedROBlob, 0, len(indices))
+	for _, index := range indices {
+		blobSidecar, err := p.BlobStorage.Get(root, uint64(index))
 		if err != nil {
 			return nil, &core.RpcError{
-				Err:    fmt.Errorf("could not retrieve blob for block root %#x at index %d", rootSlice, index),
+				Err:    fmt.Errorf("could not retrieve blob for block root %#x at index %d", root, index),
 				Reason: core.Internal,
 			}
 		}
-		blobs[i] = &vblob
+
+		blobs = append(blobs, &blobSidecar)
 	}

 	return blobs, nil
 }
+
+// blobsFromStoredDataColumns retrieves data column sidecars from the store,
+// reconstructs the whole matrix if needed, converts the matrix to blobs,
+// and then returns converted blobs corresponding to `indices` and `root`.
+// This function expects data column sidecars to be stored (aka. no blob sidecars).
+// If not enough data column sidecars are available to convert blobs from them
+// (either directly or after reconstruction), an error is returned.
+func (p *BeaconDbBlocker) blobsFromStoredDataColumns(block blocks.ROBlock, indices []int) ([]*blocks.VerifiedROBlob, *core.RpcError) {
+	root := block.Root()
+
+	// Use all indices if none are provided.
+	if len(indices) == 0 {
+		commitments, err := block.Block().Body().BlobKzgCommitments()
+		if err != nil {
+			return nil, &core.RpcError{
+				Err:    errors.Wrap(err, "could not retrieve blob commitments"),
+				Reason: core.Internal,
+			}
+		}
+
+		for index := range commitments {
+			indices = append(indices, index)
+		}
+	}
+
+	// Count how many columns we have in the store.
+	summary := p.DataColumnStorage.Summary(root)
+	stored := summary.Stored()
+	count := uint64(len(stored))
+
+	if count < peerdas.MinimumColumnsCountToReconstruct() {
+		// There is no way to reconstruct the data columns.
+		return nil, &core.RpcError{
+			Err:    errors.Errorf("the node does not custody enough data columns to reconstruct blobs - please start the beacon node with the `--%s` flag to ensure this call to succeed, or retry later if it is already the case", flags.SubscribeAllDataSubnets.Name),
+			Reason: core.NotFound,
+		}
+	}
+
+	// Retrieve from the database needed data columns.
+	verifiedRoDataColumnSidecars, err := p.neededDataColumnSidecars(root, stored)
+	if err != nil {
+		return nil, &core.RpcError{
+			Err:    errors.Wrap(err, "needed data column sidecars"),
+			Reason: core.Internal,
+		}
+	}
+
+	// Reconstruct blob sidecars from data column sidecars.
+	verifiedRoBlobSidecars, err := peerdas.ReconstructBlobs(block, verifiedRoDataColumnSidecars, indices)
+	if err != nil {
+		return nil, &core.RpcError{
+			Err:    errors.Wrap(err, "blobs from data columns"),
+			Reason: core.Internal,
+		}
+	}
+
+	return verifiedRoBlobSidecars, nil
+}
+
+// neededDataColumnSidecars retrieves all data column sidecars corresponding to (non extended) blobs if available,
+// else retrieves all data column sidecars from the store.
+func (p *BeaconDbBlocker) neededDataColumnSidecars(root [fieldparams.RootLength]byte, stored map[uint64]bool) ([]blocks.VerifiedRODataColumn, error) {
+	// Check if we have all the non-extended data columns.
+	cellsPerBlob := fieldparams.CellsPerBlob
+	blobIndices := make([]uint64, 0, cellsPerBlob)
+	hasAllBlobColumns := true
+	for i := range uint64(cellsPerBlob) {
+		if !stored[i] {
+			hasAllBlobColumns = false
+			break
+		}
+		blobIndices = append(blobIndices, i)
+	}
+
+	if hasAllBlobColumns {
+		// Retrieve only the non-extended data columns.
+		verifiedRoSidecars, err := p.DataColumnStorage.Get(root, blobIndices)
+		if err != nil {
+			return nil, errors.Wrap(err, "data columns storage get")
+		}
+
+		return verifiedRoSidecars, nil
+	}
+
+	// Retrieve all the data columns.
+	verifiedRoSidecars, err := p.DataColumnStorage.Get(root, nil)
+	if err != nil {
+		return nil, errors.Wrap(err, "data columns storage get")
+	}
+
+	return verifiedRoSidecars, nil
+}
--- a/beacon-chain/rpc/lookup/blocker_test.go
+++ b/beacon-chain/rpc/lookup/blocker_test.go
@@ -8,12 +8,15 @@ import (
 	"testing"
 	"time"

+	"github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/kzg"
 	mockChain "github.com/OffchainLabs/prysm/v6/beacon-chain/blockchain/testing"
+	"github.com/OffchainLabs/prysm/v6/beacon-chain/core/peerdas"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/db/filesystem"
 	testDB "github.com/OffchainLabs/prysm/v6/beacon-chain/db/testing"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/core"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/rpc/testutil"
 	"github.com/OffchainLabs/prysm/v6/beacon-chain/verification"
+	fieldparams "github.com/OffchainLabs/prysm/v6/config/fieldparams"
 	"github.com/OffchainLabs/prysm/v6/config/params"
 	"github.com/OffchainLabs/prysm/v6/consensus-types/blocks"
 	"github.com/OffchainLabs/prysm/v6/encoding/bytesutil"
@@ -158,172 +161,335 @@ func TestGetBlock(t *testing.T) {
 }

 func TestGetBlob(t *testing.T) {
-	params.SetupTestConfigCleanup(t)
-	cfg := params.BeaconConfig().Copy()
-	cfg.DenebForkEpoch = 1
-	params.OverrideBeaconConfig(cfg)
+	const (
+		slot          = 123
+		blobCount     = 4
+		denebForEpoch = 1
+		fuluForkEpoch = 2
+	)
+
+	setupDeneb := func(t *testing.T) {
+		params.SetupTestConfigCleanup(t)
+		cfg := params.BeaconConfig().Copy()
+		cfg.DenebForkEpoch = denebForEpoch
+		params.OverrideBeaconConfig(cfg)
+	}
+
+	setupFulu := func(t *testing.T) {
+		params.SetupTestConfigCleanup(t)
+		cfg := params.BeaconConfig().Copy()
+		cfg.DenebForkEpoch = denebForEpoch
+		cfg.FuluForkEpoch = fuluForkEpoch
+		params.OverrideBeaconConfig(cfg)
+	}
+
 	ctx := t.Context()
 	db := testDB.SetupDB(t)
-	denebBlock, blobs := util.GenerateTestDenebBlockWithSidecar(t, [32]byte{}, 123, 4)
-	require.NoError(t, db.SaveBlock(t.Context(), denebBlock))
-	_, bs := filesystem.NewEphemeralBlobStorageAndFs(t)
-	testSidecars := verification.FakeVerifySliceForTest(t, blobs)
-	for i := range testSidecars {
-		require.NoError(t, bs.Save(testSidecars[i]))
+
+	// Start the trusted setup.
+	err := kzg.Start()
+	require.NoError(t, err)
+
+	// Create and save Deneb block and blob sidecars.
+	_, blobStorage := filesystem.NewEphemeralBlobStorageAndFs(t)
+
+	denebBlock, storedBlobSidecars := util.GenerateTestDenebBlockWithSidecar(t, [fieldparams.RootLength]byte{}, slot, blobCount)
+	denebBlockRoot := denebBlock.Root()
+
+	verifiedStoredSidecars := verification.FakeVerifySliceForTest(t, storedBlobSidecars)
+	for i := range verifiedStoredSidecars {
+		err := blobStorage.Save(verifiedStoredSidecars[i])
+		require.NoError(t, err)
 	}
-	blockRoot := blobs[0].BlockRoot()
+
+	err = db.SaveBlock(t.Context(), denebBlock)
+	require.NoError(t, err)
+
+	// Create Electra block and blob sidecars. (Electra block = Fulu block),
+	// save the block, convert blob sidecars to data column sidecars and save the block.
+	fuluForkSlot := fuluForkEpoch * params.BeaconConfig().SlotsPerEpoch
+	fuluBlock, fuluBlobSidecars := util.GenerateTestElectraBlockWithSidecar(t, [fieldparams.RootLength]byte{}, fuluForkSlot, blobCount)
+	fuluBlockRoot := fuluBlock.Root()
+
+	cellsAndProofsList := make([]kzg.CellsAndProofs, 0, len(fuluBlobSidecars))
+	for _, blob := range fuluBlobSidecars {
+		var kzgBlob kzg.Blob
+		copy(kzgBlob[:], blob.Blob)
+		cellsAndProogs, err := kzg.ComputeCellsAndKZGProofs(&kzgBlob)
+		require.NoError(t, err)
+		cellsAndProofsList = append(cellsAndProofsList, cellsAndProogs)
+	}
+
+	dataColumnSidecarPb, err := peerdas.DataColumnSidecars(fuluBlock, cellsAndProofsList)
+	require.NoError(t, err)
+
+	verifiedRoDataColumnSidecars := make([]blocks.VerifiedRODataColumn, 0, len(dataColumnSidecarPb))
+	for _, sidecarPb := range dataColumnSidecarPb {
+		roDataColumn, err := blocks.NewRODataColumnWithRoot(sidecarPb, fuluBlockRoot)
+		require.NoError(t, err)
+
+		verifiedRoDataColumn := blocks.NewVerifiedRODataColumn(roDataColumn)
+		verifiedRoDataColumnSidecars = append(verifiedRoDataColumnSidecars, verifiedRoDataColumn)
+	}
+
+	err = db.SaveBlock(t.Context(), fuluBlock)
+	require.NoError(t, err)
+
 	t.Run("genesis", func(t *testing.T) {
+		setupDeneb(t)
+
 		blocker := &BeaconDbBlocker{}
 		_, rpcErr := blocker.Blobs(ctx, "genesis", nil)
-		assert.Equal(t, http.StatusBadRequest, core.ErrorReasonToHTTP(rpcErr.Reason))
-		assert.StringContains(t, "blobs are not supported for Phase 0 fork", rpcErr.Err.Error())
+		require.Equal(t, http.StatusBadRequest, core.ErrorReasonToHTTP(rpcErr.Reason))
+		require.StringContains(t, "blobs are not supported for Phase 0 fork", rpcErr.Err.Error())
 	})
+
 	t.Run("head", func(t *testing.T) {
+		setupDeneb(t)
+
 		blocker := &BeaconDbBlocker{
-			ChainInfoFetcher: &mockChain.ChainService{Root: blockRoot[:]},
+			ChainInfoFetcher: &mockChain.ChainService{Root: denebBlockRoot[:]},
 			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
 				Genesis: time.Now(),
 			},
 			BeaconDB:    db,
-			BlobStorage: bs,
+			BlobStorage: blobStorage,
+		}
+
+		retrievedVerifiedSidecars, rpcErr := blocker.Blobs(ctx, "head", nil)
+		require.IsNil(t, rpcErr)
+		require.Equal(t, blobCount, len(retrievedVerifiedSidecars))
+
+		for i := range blobCount {
+			expected := verifiedStoredSidecars[i]
+
+			actual := retrievedVerifiedSidecars[i].BlobSidecar
+			require.NotNil(t, actual)
+
+			require.Equal(t, expected.Index, actual.Index)
+			require.DeepEqual(t, expected.Blob, actual.Blob)
+			require.DeepEqual(t, expected.KzgCommitment, actual.KzgCommitment)
+			require.DeepEqual(t, expected.KzgProof, actual.KzgProof)
 		}
-		verifiedBlobs, rpcErr := blocker.Blobs(ctx, "head", nil)
-		assert.Equal(t, rpcErr == nil, true)
-		require.Equal(t, 4, len(verifiedBlobs))
-		sidecar := verifiedBlobs[0].BlobSidecar
-		require.NotNil(t, sidecar)
-		assert.Equal(t, uint64(0), sidecar.Index)
-		assert.DeepEqual(t, blobs[0].Blob, sidecar.Blob)
-		assert.DeepEqual(t, blobs[0].KzgCommitment, sidecar.KzgCommitment)
-		assert.DeepEqual(t, blobs[0].KzgProof, sidecar.KzgProof)
-		sidecar = verifiedBlobs[1].BlobSidecar
-		require.NotNil(t, sidecar)
-		assert.Equal(t, uint64(1), sidecar.Index)
-		assert.DeepEqual(t, blobs[1].Blob, sidecar.Blob)
-		assert.DeepEqual(t, blobs[1].KzgCommitment, sidecar.KzgCommitment)
-		assert.DeepEqual(t, blobs[1].KzgProof, sidecar.KzgProof)
-		sidecar = verifiedBlobs[2].BlobSidecar
-		require.NotNil(t, sidecar)
-		assert.Equal(t, uint64(2), sidecar.Index)
-		assert.DeepEqual(t, blobs[2].Blob, sidecar.Blob)
-		assert.DeepEqual(t, blobs[2].KzgCommitment, sidecar.KzgCommitment)
-		assert.DeepEqual(t, blobs[2].KzgProof, sidecar.KzgProof)
-		sidecar = verifiedBlobs[3].BlobSidecar
-		require.NotNil(t, sidecar)
-		assert.Equal(t, uint64(3), sidecar.Index)
-		assert.DeepEqual(t, blobs[3].Blob, sidecar.Blob)
-		assert.DeepEqual(t, blobs[3].KzgCommitment, sidecar.KzgCommitment)
-		assert.DeepEqual(t, blobs[3].KzgProof, sidecar.KzgProof)
 	})
+
 	t.Run("finalized", func(t *testing.T) {
+		setupDeneb(t)
+
 		blocker := &BeaconDbBlocker{
-			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &ethpb.Checkpoint{Root: blockRoot[:]}},
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &ethpb.Checkpoint{Root: denebBlockRoot[:]}},
 			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
 				Genesis: time.Now(),
 			},
 			BeaconDB:    db,
-			BlobStorage: bs,
+			BlobStorage: blobStorage,
 		}

-		verifiedBlobs, rpcErr := blocker.Blobs(ctx, "finalized", nil)
-		assert.Equal(t, rpcErr == nil, true)
-		require.Equal(t, 4, len(verifiedBlobs))
+		verifiedSidecars, rpcErr := blocker.Blobs(ctx, "finalized", nil)
+		require.IsNil(t, rpcErr)
+		require.Equal(t, blobCount, len(verifiedSidecars))
 	})
+
 	t.Run("justified", func(t *testing.T) {
+		setupDeneb(t)
+
 		blocker := &BeaconDbBlocker{
-			ChainInfoFetcher: &mockChain.ChainService{CurrentJustifiedCheckPoint: &ethpb.Checkpoint{Root: blockRoot[:]}},
+			ChainInfoFetcher: &mockChain.ChainService{CurrentJustifiedCheckPoint: &ethpb.Checkpoint{Root: denebBlockRoot[:]}},
 			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
 				Genesis: time.Now(),
 			},
 			BeaconDB:    db,
-			BlobStorage: bs,
+			BlobStorage: blobStorage,
 		}

-		verifiedBlobs, rpcErr := blocker.Blobs(ctx, "justified", nil)
-		assert.Equal(t, rpcErr == nil, true)
-		require.Equal(t, 4, len(verifiedBlobs))
+		verifiedSidecars, rpcErr := blocker.Blobs(ctx, "justified", nil)
+		require.IsNil(t, rpcErr)
+		require.Equal(t, blobCount, len(verifiedSidecars))
 	})
+
 	t.Run("root", func(t *testing.T) {
+		setupDeneb(t)
+
 		blocker := &BeaconDbBlocker{
 			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
 				Genesis: time.Now(),
 			},
 			BeaconDB:    db,
-			BlobStorage: bs,
+			BlobStorage: blobStorage,
 		}
-		verifiedBlobs, rpcErr := blocker.Blobs(ctx, hexutil.Encode(blockRoot[:]), nil)
-		assert.Equal(t, rpcErr == nil, true)
-		require.Equal(t, 4, len(verifiedBlobs))
+
+		verifiedBlobs, rpcErr := blocker.Blobs(ctx, hexutil.Encode(denebBlockRoot[:]), nil)
+		require.IsNil(t, rpcErr)
+		require.Equal(t, blobCount, len(verifiedBlobs))
 	})
+
 	t.Run("slot", func(t *testing.T) {
+		setupDeneb(t)
+
 		blocker := &BeaconDbBlocker{
 			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
 				Genesis: time.Now(),
 			},
 			BeaconDB:    db,
-			BlobStorage: bs,
+			BlobStorage: blobStorage,
 		}
+
 		verifiedBlobs, rpcErr := blocker.Blobs(ctx, "123", nil)
-		assert.Equal(t, rpcErr == nil, true)
-		require.Equal(t, 4, len(verifiedBlobs))
+		require.IsNil(t, rpcErr)
+		require.Equal(t, blobCount, len(verifiedBlobs))
 	})
+
 	t.Run("one blob only", func(t *testing.T) {
+		const index = 2
+
+		setupDeneb(t)
+
 		blocker := &BeaconDbBlocker{
-			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &ethpb.Checkpoint{Root: blockRoot[:]}},
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &ethpb.Checkpoint{Root: denebBlockRoot[:]}},
 			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
 				Genesis: time.Now(),
 			},
 			BeaconDB:    db,
-			BlobStorage: bs,
+			BlobStorage: blobStorage,
 		}
-		verifiedBlobs, rpcErr := blocker.Blobs(ctx, "123", []int{2})
-		assert.Equal(t, rpcErr == nil, true)
-		require.Equal(t, 1, len(verifiedBlobs))
-		sidecar := verifiedBlobs[0].BlobSidecar
-		require.NotNil(t, sidecar)
-		assert.Equal(t, uint64(2), sidecar.Index)
-		assert.DeepEqual(t, blobs[2].Blob, sidecar.Blob)
-		assert.DeepEqual(t, blobs[2].KzgCommitment, sidecar.KzgCommitment)
-		assert.DeepEqual(t, blobs[2].KzgProof, sidecar.KzgProof)
+
+		retrievedVerifiedSidecars, rpcErr := blocker.Blobs(ctx, "123", []int{index})
+		require.IsNil(t, rpcErr)
+		require.Equal(t, 1, len(retrievedVerifiedSidecars))
+
+		expected := verifiedStoredSidecars[index]
+		actual := retrievedVerifiedSidecars[0].BlobSidecar
+		require.NotNil(t, actual)
+
+		require.Equal(t, uint64(index), actual.Index)
+		require.DeepEqual(t, expected.Blob, actual.Blob)
+		require.DeepEqual(t, expected.KzgCommitment, actual.KzgCommitment)
+		require.DeepEqual(t, expected.KzgProof, actual.KzgProof)
 	})
+
 	t.Run("no blobs returns an empty array", func(t *testing.T) {
+		setupDeneb(t)
+
 		blocker := &BeaconDbBlocker{
-			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &ethpb.Checkpoint{Root: blockRoot[:]}},
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &ethpb.Checkpoint{Root: denebBlockRoot[:]}},
 			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
 				Genesis: time.Now(),
 			},
 			BeaconDB:    db,
 			BlobStorage: filesystem.NewEphemeralBlobStorage(t),
 		}
+
 		verifiedBlobs, rpcErr := blocker.Blobs(ctx, "123", nil)
-		assert.Equal(t, rpcErr == nil, true)
+		require.IsNil(t, rpcErr)
 		require.Equal(t, 0, len(verifiedBlobs))
 	})
+
 	t.Run("no blob at index", func(t *testing.T) {
+		setupDeneb(t)
+
 		blocker := &BeaconDbBlocker{
-			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &ethpb.Checkpoint{Root: blockRoot[:]}},
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &ethpb.Checkpoint{Root: denebBlockRoot[:]}},
 			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
 				Genesis: time.Now(),
 			},
 			BeaconDB:    db,
-			BlobStorage: bs,
+			BlobStorage: blobStorage,
 		}
-		noBlobIndex := len(blobs) + 1
+
+		noBlobIndex := len(storedBlobSidecars) + 1
 		_, rpcErr := blocker.Blobs(ctx, "123", []int{0, noBlobIndex})
 		require.NotNil(t, rpcErr)
-		assert.Equal(t, core.ErrorReason(core.NotFound), rpcErr.Reason)
+		require.Equal(t, core.ErrorReason(core.NotFound), rpcErr.Reason)
 	})
+
 	t.Run("index too big", func(t *testing.T) {
+		setupDeneb(t)
+
 		blocker := &BeaconDbBlocker{
-			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &ethpb.Checkpoint{Root: blockRoot[:]}},
+			ChainInfoFetcher: &mockChain.ChainService{FinalizedCheckPoint: &ethpb.Checkpoint{Root: denebBlockRoot[:]}},
 			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
 				Genesis: time.Now(),
 			},
 			BeaconDB:    db,
-			BlobStorage: bs,
+			BlobStorage: blobStorage,
 		}
 		_, rpcErr := blocker.Blobs(ctx, "123", []int{0, math.MaxInt})
 		require.NotNil(t, rpcErr)
-		assert.Equal(t, core.ErrorReason(core.BadRequest), rpcErr.Reason)
+		require.Equal(t, core.ErrorReason(core.BadRequest), rpcErr.Reason)
+	})
+
+	t.Run("not enough stored data column sidecars", func(t *testing.T) {
+		setupFulu(t)
+
+		_, dataColumnStorage := filesystem.NewEphemeralDataColumnStorageAndFs(t)
+		err = dataColumnStorage.Save(verifiedRoDataColumnSidecars[:fieldparams.CellsPerBlob-1])
+		require.NoError(t, err)
+
+		blocker := &BeaconDbBlocker{
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:          db,
+			BlobStorage:       blobStorage,
+			DataColumnStorage: dataColumnStorage,
+		}
+
+		_, rpcErr := blocker.Blobs(ctx, hexutil.Encode(fuluBlockRoot[:]), nil)
+		require.NotNil(t, rpcErr)
+		require.Equal(t, core.ErrorReason(core.NotFound), rpcErr.Reason)
+	})
+
+	t.Run("reconstruction needed", func(t *testing.T) {
+		setupFulu(t)
+
+		_, dataColumnStorage := filesystem.NewEphemeralDataColumnStorageAndFs(t)
+		err = dataColumnStorage.Save(verifiedRoDataColumnSidecars[1 : peerdas.MinimumColumnsCountToReconstruct()+1])
+		require.NoError(t, err)
+
+		blocker := &BeaconDbBlocker{
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:          db,
+			BlobStorage:       blobStorage,
+			DataColumnStorage: dataColumnStorage,
+		}
+
+		retrievedVerifiedRoBlobs, rpcErr := blocker.Blobs(ctx, hexutil.Encode(fuluBlockRoot[:]), nil)
+		require.IsNil(t, rpcErr)
+		require.Equal(t, len(fuluBlobSidecars), len(retrievedVerifiedRoBlobs))
+
+		for i, retrievedVerifiedRoBlob := range retrievedVerifiedRoBlobs {
+			retrievedBlobSidecarPb := retrievedVerifiedRoBlob.BlobSidecar
+			initialBlobSidecarPb := fuluBlobSidecars[i].BlobSidecar
+			require.DeepSSZEqual(t, initialBlobSidecarPb, retrievedBlobSidecarPb)
+		}
+	})
+
+	t.Run("no reconstruction needed", func(t *testing.T) {
+		setupFulu(t)
+
+		_, dataColumnStorage := filesystem.NewEphemeralDataColumnStorageAndFs(t)
+		err = dataColumnStorage.Save(verifiedRoDataColumnSidecars)
+		require.NoError(t, err)
+
+		blocker := &BeaconDbBlocker{
+			GenesisTimeFetcher: &testutil.MockGenesisTimeFetcher{
+				Genesis: time.Now(),
+			},
+			BeaconDB:          db,
+			BlobStorage:       blobStorage,
+			DataColumnStorage: dataColumnStorage,
+		}
+
+		retrievedVerifiedRoBlobs, rpcErr := blocker.Blobs(ctx, hexutil.Encode(fuluBlockRoot[:]), nil)
+		require.IsNil(t, rpcErr)
+		require.Equal(t, len(fuluBlobSidecars), len(retrievedVerifiedRoBlobs))
+
+		for i, retrievedVerifiedRoBlob := range retrievedVerifiedRoBlobs {
+			retrievedBlobSidecarPb := retrievedVerifiedRoBlob.BlobSidecar
+			initialBlobSidecarPb := fuluBlobSidecars[i].BlobSidecar
+			require.DeepSSZEqual(t, initialBlobSidecarPb, retrievedBlobSidecarPb)
+		}
 	})
 }
--- a/changelog/manu-peerdas-beacon-api.md
+++ b/changelog/manu-peerdas-beacon-api.md
@@ -0,0 +1,2 @@
+### Added 
+- Implement beacon API blob sidecar enpoint for Fulu.
--- a/testing/util/fulu.go
+++ b/testing/util/fulu.go
@@ -1,7 +1,6 @@
 package util

 import (
-	"encoding/binary"
 	"math/big"
 	"testing"

@@ -110,14 +109,21 @@ func GenerateTestFuluBlockWithSidecars(t *testing.T, blobCount int, options ...F
 	block.Block.ParentRoot = generator.parent[:]
 	block.Block.ProposerIndex = generator.proposer

-	block.Block.Body.BlobKzgCommitments = make([][]byte, blobCount)
-	for i := range blobCount {
-		var commitment [fieldparams.KzgCommitmentSize]byte
-		binary.LittleEndian.PutUint16(commitment[:16], uint16(i))
-		binary.LittleEndian.PutUint16(commitment[16:32], uint16(generator.slot))
-		block.Block.Body.BlobKzgCommitments[i] = commitment[:]
+	blobs := make([]kzg.Blob, 0, generator.blobCount)
+	commitments := make([][]byte, 0, generator.blobCount)
+
+	for i := range generator.blobCount {
+		blob := kzg.Blob{uint8(i)}
+
+		commitment, err := kzg.BlobToKZGCommitment(&blob)
+		require.NoError(t, err)
+
+		blobs = append(blobs, blob)
+		commitments = append(commitments, commitment[:])
 	}

+	block.Block.Body.BlobKzgCommitments = commitments
+
 	body, err := blocks.NewBeaconBlockBody(block.Block.Body)
 	require.NoError(t, err)

@@ -149,39 +155,30 @@ func GenerateTestFuluBlockWithSidecars(t *testing.T, blobCount int, options ...F
 	root, err := block.Block.HashTreeRoot()
 	require.NoError(t, err)

-	sbb, err := blocks.NewSignedBeaconBlock(block)
+	signedBeaconBlock, err := blocks.NewSignedBeaconBlock(block)
 	require.NoError(t, err)

-	sh, err := sbb.Header()
-	require.NoError(t, err)
-
-	blobs := make([]kzg.Blob, blobCount)
-	for i, commitment := range block.Block.Body.BlobKzgCommitments {
-		roSidecars := GenerateTestDenebBlobSidecar(t, root, sh, i, commitment, inclusion[i])
-		blobs[i] = kzg.Blob(roSidecars.Blob)
-	}
-
 	cellsAndProofs := GenerateCellsAndProofs(t, blobs)

-	dataColumns, err := peerdas.DataColumnSidecars(sbb, cellsAndProofs)
+	sidecars, err := peerdas.DataColumnSidecars(signedBeaconBlock, cellsAndProofs)
 	require.NoError(t, err)

-	roSidecars := make([]blocks.RODataColumn, 0, len(dataColumns))
-	roVerifiedSidecars := make([]blocks.VerifiedRODataColumn, 0, len(dataColumns))
-	for _, dataColumn := range dataColumns {
-		roSidecar, err := blocks.NewRODataColumnWithRoot(dataColumn, root)
+	roSidecars := make([]blocks.RODataColumn, 0, len(sidecars))
+	verifiedRoSidecars := make([]blocks.VerifiedRODataColumn, 0, len(sidecars))
+	for _, sidecar := range sidecars {
+		roSidecar, err := blocks.NewRODataColumnWithRoot(sidecar, root)
 		require.NoError(t, err)

 		roVerifiedSidecar := blocks.NewVerifiedRODataColumn(roSidecar)

 		roSidecars = append(roSidecars, roSidecar)
-		roVerifiedSidecars = append(roVerifiedSidecars, roVerifiedSidecar)
+		verifiedRoSidecars = append(verifiedRoSidecars, roVerifiedSidecar)
 	}

-	rob, err := blocks.NewROBlockWithRoot(sbb, root)
+	roBlock, err := blocks.NewROBlockWithRoot(signedBeaconBlock, root)
 	require.NoError(t, err)

-	return rob, roSidecars, roVerifiedSidecars
+	return roBlock, roSidecars, verifiedRoSidecars
 }

 func GenerateCellsAndProofs(t testing.TB, blobs []kzg.Blob) []kzg.CellsAndProofs {