diff --git a/share/namespace.go b/share/namespace.go
index df4ad74058..2cea574bbc 100644
--- a/share/namespace.go
+++ b/share/namespace.go
@@ -2,7 +2,9 @@ package share
 
 import (
 	"bytes"
+	"encoding/binary"
 	"encoding/hex"
+	"errors"
 	"fmt"
 
 	appns "github.com/celestiaorg/celestia-app/pkg/namespace"
@@ -182,3 +184,49 @@ func (n Namespace) IsGreater(target Namespace) bool {
 func (n Namespace) IsGreaterOrEqualThan(target Namespace) bool {
 	return bytes.Compare(n, target) > -1
 }
+
+// AddInt adds arbitrary int value to namespace, treating namespace as big-endian
+// implementation of int
+func (n Namespace) AddInt(val int) (Namespace, error) {
+	if val == 0 {
+		return n, nil
+	}
+	// Convert the input integer to a byte slice and add it to result slice
+	result := make([]byte, len(n))
+	if val > 0 {
+		binary.BigEndian.PutUint64(result[len(n)-8:], uint64(val))
+	} else {
+		binary.BigEndian.PutUint64(result[len(n)-8:], uint64(-val))
+	}
+
+	// Perform addition byte by byte
+	var carry int
+	for i := len(n) - 1; i >= 0; i-- {
+		var sum int
+		if val > 0 {
+			sum = int(n[i]) + int(result[i]) + carry
+		} else {
+			sum = int(n[i]) - int(result[i]) + carry
+		}
+
+		switch {
+		case sum > 255:
+			carry = 1
+			sum -= 256
+		case sum < 0:
+			carry = -1
+			sum += 256
+		default:
+			carry = 0
+		}
+
+		result[i] = uint8(sum)
+	}
+
+	// Handle any remaining carry
+	if carry != 0 {
+		return nil, errors.New("namespace overflow")
+	}
+
+	return result, nil
+}
diff --git a/share/shwap/namespaced_data.go b/share/shwap/namespaced_data.go
index 558c3c03aa..3f230f2e44 100644
--- a/share/shwap/namespaced_data.go
+++ b/share/shwap/namespaced_data.go
@@ -33,22 +33,17 @@ type RowNamespaceData struct {
 
 // Verify checks the integrity of the NamespacedData against a provided root and namespace.
 func (ns NamespacedData) Verify(root *share.Root, namespace share.Namespace) error {
-	var originalRoots [][]byte
-	for _, rowRoot := range root.RowRoots {
-		if !namespace.IsOutsideRange(rowRoot, rowRoot) {
-			originalRoots = append(originalRoots, rowRoot)
-		}
-	}
+	rowRoots, _, _ := share.FilterRootByNamespace(root, namespace)
 
-	if len(originalRoots) != len(ns) {
-		return fmt.Errorf("expected %d rows, found %d rows", len(originalRoots), len(ns))
+	if len(rowRoots) != len(ns) {
+		return fmt.Errorf("expected %d rows, found %d rows", len(rowRoots), len(ns))
 	}
 
 	for i, row := range ns {
 		if row.Proof == nil || len(row.Shares) == 0 {
 			return fmt.Errorf("row %d is missing proofs or shares", i)
 		}
-		if !row.VerifyInclusion(originalRoots[i], namespace) {
+		if !row.VerifyInclusion(rowRoots[i], namespace) {
 			return fmt.Errorf("failed to verify row %d", i)
 		}
 	}
@@ -156,6 +151,8 @@ func NamespacedRowFromShares(shares []share.Share, namespace share.Namespace, ro
 		}
 	}
 	if count == 0 {
+		// FIXME: This should return Non-inclusion proofs instead. Need support in app wrapper to generate
+		// absence proofs.
 		return RowNamespaceData{}, fmt.Errorf("no shares found in the namespace for row %d", rowIndex)
 	}
 
diff --git a/share/shwap/namespaced_data_test.go b/share/shwap/namespaced_data_test.go
new file mode 100644
index 0000000000..b5765763d5
--- /dev/null
+++ b/share/shwap/namespaced_data_test.go
@@ -0,0 +1,104 @@
+package shwap
+
+import (
+	"bytes"
+	"slices"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/celestiaorg/celestia-node/share"
+	"github.com/celestiaorg/celestia-node/share/eds/edstest"
+	"github.com/celestiaorg/celestia-node/share/sharetest"
+)
+
+func TestNamespacedRowFromShares(t *testing.T) {
+	const odsSize = 8
+
+	minNamespace, err := share.NewBlobNamespaceV0(slices.Concat(bytes.Repeat([]byte{0}, 8), []byte{1, 0}))
+	require.NoError(t, err)
+	err = minNamespace.ValidateForData()
+	require.NoError(t, err)
+
+	for namespacedAmount := 1; namespacedAmount < odsSize; namespacedAmount++ {
+		shares := sharetest.RandSharesWithNamespace(t, minNamespace, namespacedAmount, odsSize)
+		parity, err := share.DefaultRSMT2DCodec().Encode(shares)
+		require.NoError(t, err)
+		extended := slices.Concat(shares, parity)
+
+		nr, err := NamespacedRowFromShares(extended, minNamespace, 0)
+		require.NoError(t, err)
+		require.Equal(t, namespacedAmount, len(nr.Shares))
+	}
+}
+
+func TestNamespacedRowFromSharesNonIncluded(t *testing.T) {
+	// TODO: this will fail until absence proof support is added
+	t.Skip()
+
+	const odsSize = 8
+	// Test absent namespace
+	shares := sharetest.RandShares(t, odsSize)
+	absentNs, err := share.GetNamespace(shares[0]).AddInt(1)
+	require.NoError(t, err)
+
+	parity, err := share.DefaultRSMT2DCodec().Encode(shares)
+	require.NoError(t, err)
+	extended := slices.Concat(shares, parity)
+
+	nr, err := NamespacedRowFromShares(extended, absentNs, 0)
+	require.NoError(t, err)
+	require.Len(t, nr.Shares, 0)
+	require.True(t, nr.Proof.IsOfAbsence())
+}
+
+func TestNamespacedSharesFromEDS(t *testing.T) {
+	const odsSize = 8
+	sharesAmount := odsSize * odsSize
+	namespace := sharetest.RandV0Namespace()
+	for amount := 1; amount < sharesAmount; amount++ {
+		eds, root := edstest.RandEDSWithNamespace(t, namespace, amount, odsSize)
+		nd, err := NewNamespacedSharesFromEDS(eds, namespace)
+		require.NoError(t, err)
+		require.True(t, len(nd) > 0)
+		require.Len(t, nd.Flatten(), amount)
+
+		err = nd.Verify(root, namespace)
+		require.NoError(t, err)
+	}
+}
+
+func TestValidateNamespacedRow(t *testing.T) {
+	const odsSize = 8
+	sharesAmount := odsSize * odsSize
+	namespace := sharetest.RandV0Namespace()
+	for amount := 1; amount < sharesAmount; amount++ {
+		eds, root := edstest.RandEDSWithNamespace(t, namespace, amount, odsSize)
+		nd, err := NewNamespacedSharesFromEDS(eds, namespace)
+		require.NoError(t, err)
+		require.True(t, len(nd) > 0)
+
+		_, from, to := share.FilterRootByNamespace(root, namespace)
+		require.Len(t, nd, to-from)
+		idx := from
+		for _, row := range nd {
+			err = row.Validate(root, namespace, idx)
+			require.NoError(t, err)
+			idx++
+		}
+	}
+}
+
+func TestNamespacedRowProtoEncoding(t *testing.T) {
+	const odsSize = 8
+	namespace := sharetest.RandV0Namespace()
+	eds, _ := edstest.RandEDSWithNamespace(t, namespace, odsSize, odsSize)
+	nd, err := NewNamespacedSharesFromEDS(eds, namespace)
+	require.NoError(t, err)
+	require.True(t, len(nd) > 0)
+
+	expected := nd[0]
+	pb := expected.ToProto()
+	ndOut := NamespacedRowFromProto(pb)
+	require.Equal(t, expected, ndOut)
+}
diff --git a/share/shwap/row.go b/share/shwap/row.go
index 1570756740..423fb5bafe 100644
--- a/share/shwap/row.go
+++ b/share/shwap/row.go
@@ -110,9 +110,9 @@ func RowFromProto(r *pb.Row) Row {
 	}
 }
 
-// NewRowFromEDS constructs a new Row from an Extended Data Square based on the specified index and
+// RowFromEDS constructs a new Row from an Extended Data Square based on the specified index and
 // side.
-func NewRowFromEDS(square *rsmt2d.ExtendedDataSquare, idx int, side RowSide) Row {
+func RowFromEDS(square *rsmt2d.ExtendedDataSquare, idx int, side RowSide) Row {
 	sqrLn := int(square.Width())
 	shares := square.Row(uint(idx))
 	var halfShares []share.Share
diff --git a/share/shwap/row_test.go b/share/shwap/row_test.go
new file mode 100644
index 0000000000..007b191703
--- /dev/null
+++ b/share/shwap/row_test.go
@@ -0,0 +1,114 @@
+package shwap
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/celestiaorg/celestia-node/share"
+	"github.com/celestiaorg/celestia-node/share/eds/edstest"
+)
+
+func TestNewRowFromEDS(t *testing.T) {
+	const odsSize = 8
+	eds := edstest.RandEDS(t, odsSize)
+
+	for rowIdx := 0; rowIdx < odsSize*2; rowIdx++ {
+		for _, side := range []RowSide{Left, Right} {
+			row := RowFromEDS(eds, rowIdx, side)
+
+			want := eds.Row(uint(rowIdx))
+			shares, err := row.Shares()
+			require.NoError(t, err)
+			require.Equal(t, want, shares)
+
+			var half []share.Share
+			if side == Right {
+				half = want[odsSize:]
+			} else {
+				half = want[:odsSize]
+			}
+			require.Equal(t, half, row.halfShares)
+			require.Equal(t, side, row.side)
+		}
+	}
+}
+
+func TestRowValidate(t *testing.T) {
+	const odsSize = 8
+	eds := edstest.RandEDS(t, odsSize)
+	root, err := share.NewRoot(eds)
+	require.NoError(t, err)
+
+	for rowIdx := 0; rowIdx < odsSize*2; rowIdx++ {
+		for _, side := range []RowSide{Left, Right} {
+			row := RowFromEDS(eds, rowIdx, side)
+
+			err := row.VerifyRoot(root, rowIdx)
+			require.NoError(t, err)
+			err = row.Validate(root, rowIdx)
+			require.NoError(t, err)
+		}
+	}
+}
+
+func TestRowValidateNegativeCases(t *testing.T) {
+	eds := edstest.RandEDS(t, 8) // Generate a random Extended Data Square of size 8
+	root, err := share.NewRoot(eds)
+	require.NoError(t, err)
+	row := RowFromEDS(eds, 0, Left)
+
+	// Test with incorrect side specification
+	invalidSideRow := Row{halfShares: row.halfShares, side: RowSide(999)}
+	err = invalidSideRow.Validate(root, 0)
+	require.Error(t, err, "should error on invalid row side")
+
+	// Test with invalid shares (more shares than expected)
+	incorrectShares := make([]share.Share, (eds.Width()/2)+1) // Adding an extra share
+	for i := range incorrectShares {
+		incorrectShares[i] = eds.GetCell(uint(i), 0)
+	}
+	invalidRow := Row{halfShares: incorrectShares, side: Left}
+	err = invalidRow.Validate(root, 0)
+	require.Error(t, err, "should error on incorrect number of shares")
+
+	// Test with empty shares
+	emptyRow := Row{halfShares: []share.Share{}, side: Left}
+	err = emptyRow.Validate(root, 0)
+	require.Error(t, err, "should error on empty halfShares")
+
+	// Doesn't match root. Corrupt root hash
+	root.RowRoots[0][len(root.RowRoots[0])-1] ^= 0xFF
+	err = row.Validate(root, 0)
+	require.Error(t, err, "should error on invalid root hash")
+}
+
+func TestRowProtoEncoding(t *testing.T) {
+	const odsSize = 8
+	eds := edstest.RandEDS(t, odsSize)
+
+	for rowIdx := 0; rowIdx < odsSize*2; rowIdx++ {
+		for _, side := range []RowSide{Left, Right} {
+			row := RowFromEDS(eds, rowIdx, side)
+
+			pb := row.ToProto()
+			rowOut := RowFromProto(pb)
+			require.Equal(t, row, rowOut)
+		}
+	}
+}
+
+// BenchmarkRowValidate benchmarks the performance of row validation.
+// BenchmarkRowValidate-10    	    9591	    121802 ns/op
+func BenchmarkRowValidate(b *testing.B) {
+	const odsSize = 32
+	eds := edstest.RandEDS(b, odsSize)
+	root, err := share.NewRoot(eds)
+	require.NoError(b, err)
+	row := RowFromEDS(eds, 0, Left)
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_ = row.Validate(root, 0)
+	}
+}
diff --git a/share/shwap/sample_test.go b/share/shwap/sample_test.go
new file mode 100644
index 0000000000..39c0e72b41
--- /dev/null
+++ b/share/shwap/sample_test.go
@@ -0,0 +1,127 @@
+package shwap
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	"github.com/celestiaorg/rsmt2d"
+
+	"github.com/celestiaorg/celestia-node/share"
+	"github.com/celestiaorg/celestia-node/share/eds/edstest"
+)
+
+func TestNewSampleFromEDS(t *testing.T) {
+	const odsSize = 8
+	eds := edstest.RandEDS(t, odsSize)
+
+	for _, proofType := range []rsmt2d.Axis{rsmt2d.Row, rsmt2d.Col} {
+		for rowIdx := 0; rowIdx < odsSize*2; rowIdx++ {
+			for colIdx := 0; colIdx < odsSize*2; colIdx++ {
+				sample, err := SampleFromEDS(eds, proofType, rowIdx, colIdx)
+				require.NoError(t, err)
+
+				want := eds.GetCell(uint(rowIdx), uint(colIdx))
+				require.Equal(t, want, sample.Share)
+				require.Equal(t, proofType, sample.ProofType)
+				require.NotNil(t, sample.Proof)
+				require.Equal(t, sample.Proof.End()-sample.Proof.Start(), 1)
+				require.Len(t, sample.Proof.Nodes(), 4)
+			}
+		}
+	}
+}
+
+func TestSampleValidate(t *testing.T) {
+	const odsSize = 8
+	eds := edstest.RandEDS(t, odsSize)
+	root, err := share.NewRoot(eds)
+	require.NoError(t, err)
+
+	for _, proofType := range []rsmt2d.Axis{rsmt2d.Row, rsmt2d.Col} {
+		for rowIdx := 0; rowIdx < odsSize*2; rowIdx++ {
+			for colIdx := 0; colIdx < odsSize*2; colIdx++ {
+				sample, err := SampleFromEDS(eds, proofType, rowIdx, colIdx)
+				require.NoError(t, err)
+
+				require.True(t, sample.VerifyInclusion(root, rowIdx, colIdx))
+				require.NoError(t, sample.Validate(root, rowIdx, colIdx))
+			}
+		}
+	}
+}
+
+// TestSampleNegativeVerifyInclusion checks
+func TestSampleNegativeVerifyInclusion(t *testing.T) {
+	const odsSize = 8
+	eds := edstest.RandEDS(t, odsSize)
+	root, err := share.NewRoot(eds)
+	require.NoError(t, err)
+
+	sample, err := SampleFromEDS(eds, rsmt2d.Row, 0, 0)
+	require.NoError(t, err)
+	included := sample.VerifyInclusion(root, 0, 0)
+	require.True(t, included)
+
+	// incorrect row index
+	included = sample.VerifyInclusion(root, 1, 0)
+	require.False(t, included)
+
+	// incorrect col index is not used in the inclusion proof verification
+	included = sample.VerifyInclusion(root, 0, 1)
+	require.True(t, included)
+
+	// Corrupt the share
+	sample.Share[0] ^= 0xFF
+	included = sample.VerifyInclusion(root, 0, 0)
+	require.False(t, included)
+
+	// incorrect proofType
+	sample, err = SampleFromEDS(eds, rsmt2d.Row, 0, 0)
+	require.NoError(t, err)
+	sample.ProofType = rsmt2d.Col
+	included = sample.VerifyInclusion(root, 0, 0)
+	require.False(t, included)
+
+	// Corrupt the last root hash byte
+	sample, err = SampleFromEDS(eds, rsmt2d.Row, 0, 0)
+	require.NoError(t, err)
+	root.RowRoots[0][len(root.RowRoots[0])-1] ^= 0xFF
+	included = sample.VerifyInclusion(root, 0, 0)
+	require.False(t, included)
+}
+
+func TestSampleProtoEncoding(t *testing.T) {
+	const odsSize = 8
+	eds := edstest.RandEDS(t, odsSize)
+
+	for _, proofType := range []rsmt2d.Axis{rsmt2d.Row, rsmt2d.Col} {
+		for rowIdx := 0; rowIdx < odsSize*2; rowIdx++ {
+			for colIdx := 0; colIdx < odsSize*2; colIdx++ {
+				sample, err := SampleFromEDS(eds, proofType, rowIdx, colIdx)
+				require.NoError(t, err)
+
+				pb := sample.ToProto()
+				sampleOut := SampleFromProto(pb)
+				require.NoError(t, err)
+				require.Equal(t, sample, sampleOut)
+			}
+		}
+	}
+}
+
+// BenchmarkSampleValidate benchmarks the performance of sample validation.
+// BenchmarkSampleValidate-10    	  284829	      3935 ns/op
+func BenchmarkSampleValidate(b *testing.B) {
+	const odsSize = 32
+	eds := edstest.RandEDS(b, odsSize)
+	root, err := share.NewRoot(eds)
+	require.NoError(b, err)
+	sample, err := SampleFromEDS(eds, rsmt2d.Row, 0, 0)
+	require.NoError(b, err)
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		_ = sample.Validate(root, 0, 0)
+	}
+}