diff --git a/cmd/restic/cmd_cat.go b/cmd/restic/cmd_cat.go
index 4e76f8237..ca5c24aed 100644
--- a/cmd/restic/cmd_cat.go
+++ b/cmd/restic/cmd_cat.go
@@ -162,16 +162,16 @@ func (cmd CmdCat) Execute(args []string) error {
 		return err
 
 	case "blob":
-		_, blobType, _, length, err := repo.Index().Lookup(id)
+		blob, err := repo.Index().Lookup(id)
 		if err != nil {
 			return err
 		}
 
-		if blobType != pack.Data {
+		if blob.Type != pack.Data {
 			return errors.New("wrong type for blob")
 		}
 
-		buf := make([]byte, length)
+		buf := make([]byte, blob.Length)
 		data, err := repo.LoadBlob(pack.Data, id, buf)
 		if err != nil {
 			return err
diff --git a/node.go b/node.go
index e79306d5d..eb1ca5f02 100644
--- a/node.go
+++ b/node.go
@@ -212,14 +212,14 @@ func (node Node) createFileAt(path string, repo *repository.Repository) error {
 
 	var buf []byte
 	for _, id := range node.Content {
-		_, _, _, length, err := repo.Index().Lookup(id)
+		blob, err := repo.Index().Lookup(id)
 		if err != nil {
 			return err
 		}
 
 		buf = buf[:cap(buf)]
-		if uint(len(buf)) < length {
-			buf = make([]byte, length)
+		if uint(len(buf)) < blob.Length {
+			buf = make([]byte, blob.Length)
 		}
 
 		buf, err := repo.LoadBlob(pack.Data, id, buf)
diff --git a/repository/index.go b/repository/index.go
index 25e4c5143..2ffac231c 100644
--- a/repository/index.go
+++ b/repository/index.go
@@ -109,24 +109,32 @@ func (idx *Index) Store(t pack.BlobType, id backend.ID, pack backend.ID, offset,
 	idx.store(t, id, pack, offset, length)
 }
 
-// Lookup returns the pack for the id.
-func (idx *Index) Lookup(id backend.ID) (packID backend.ID, tpe pack.BlobType, offset, length uint, err error) {
+// Lookup queries the index for the blob ID and returns a PackedBlob.
+func (idx *Index) Lookup(id backend.ID) (pb PackedBlob, err error) {
 	idx.m.Lock()
 	defer idx.m.Unlock()
 
 	if p, ok := idx.pack[id]; ok {
 		debug.Log("Index.Lookup", "id %v found in pack %v at %d, length %d",
 			id.Str(), p.packID.Str(), p.offset, p.length)
-		return p.packID, p.tpe, p.offset, p.length, nil
+
+		pb := PackedBlob{
+			Type:   p.tpe,
+			Length: p.length,
+			ID:     id,
+			Offset: p.offset,
+			PackID: p.packID,
+		}
+		return pb, nil
 	}
 
 	debug.Log("Index.Lookup", "id %v not found", id.Str())
-	return backend.ID{}, pack.Data, 0, 0, fmt.Errorf("id %v not found in index", id)
+	return PackedBlob{}, fmt.Errorf("id %v not found in index", id)
 }
 
 // Has returns true iff the id is listed in the index.
 func (idx *Index) Has(id backend.ID) bool {
-	_, _, _, _, err := idx.Lookup(id)
+	_, err := idx.Lookup(id)
 	if err == nil {
 		return true
 	}
@@ -137,11 +145,11 @@ func (idx *Index) Has(id backend.ID) bool {
 // LookupSize returns the length of the cleartext content behind the
 // given id
 func (idx *Index) LookupSize(id backend.ID) (cleartextLength uint, err error) {
-	_, _, _, encryptedLength, err := idx.Lookup(id)
+	blob, err := idx.Lookup(id)
 	if err != nil {
 		return 0, err
 	}
-	return encryptedLength - crypto.Extension, nil
+	return blob.PlaintextLength(), nil
 }
 
 // Merge loads all items from other into idx.
@@ -181,10 +189,23 @@ func (idx *Index) AddToSupersedes(ids ...backend.ID) error {
 
 // PackedBlob is a blob already saved within a pack.
 type PackedBlob struct {
-	pack.Blob
+	Type   pack.BlobType
+	Length uint
+	ID     backend.ID
+	Offset uint
 	PackID backend.ID
 }
 
+func (pb PackedBlob) String() string {
+	return fmt.Sprintf("<PackedBlob %v type %v in pack %v: len %v, offset %v",
+		pb.ID.Str(), pb.Type, pb.PackID.Str(), pb.Length, pb.Offset)
+}
+
+// PlaintextLength returns the number of bytes the blob's plaintext occupies.
+func (pb PackedBlob) PlaintextLength() uint {
+	return pb.Length - crypto.Extension
+}
+
 // Each returns a channel that yields all blobs known to the index. If done is
 // closed, the background goroutine terminates. This blocks any modification of
 // the index.
@@ -204,12 +225,10 @@ func (idx *Index) Each(done chan struct{}) <-chan PackedBlob {
 			case <-done:
 				return
 			case ch <- PackedBlob{
-				Blob: pack.Blob{
-					ID:     id,
-					Offset: blob.offset,
-					Type:   blob.tpe,
-					Length: blob.length,
-				},
+				ID:     id,
+				Offset: blob.offset,
+				Type:   blob.tpe,
+				Length: blob.length,
 				PackID: blob.packID,
 			}:
 			}
diff --git a/repository/index_test.go b/repository/index_test.go
index 331ce6a7f..480619fa6 100644
--- a/repository/index_test.go
+++ b/repository/index_test.go
@@ -69,21 +69,21 @@ func TestIndexSerialize(t *testing.T) {
 	OK(t, err)
 
 	for _, testBlob := range tests {
-		packID, tpe, offset, length, err := idx.Lookup(testBlob.id)
+		result, err := idx.Lookup(testBlob.id)
 		OK(t, err)
 
-		Equals(t, testBlob.pack, packID)
-		Equals(t, testBlob.tpe, tpe)
-		Equals(t, testBlob.offset, offset)
-		Equals(t, testBlob.length, length)
+		Equals(t, testBlob.pack, result.PackID)
+		Equals(t, testBlob.tpe, result.Type)
+		Equals(t, testBlob.offset, result.Offset)
+		Equals(t, testBlob.length, result.Length)
 
-		packID, tpe, offset, length, err = idx2.Lookup(testBlob.id)
+		result2, err := idx2.Lookup(testBlob.id)
 		OK(t, err)
 
-		Equals(t, testBlob.pack, packID)
-		Equals(t, testBlob.tpe, tpe)
-		Equals(t, testBlob.offset, offset)
-		Equals(t, testBlob.length, length)
+		Equals(t, testBlob.pack, result2.PackID)
+		Equals(t, testBlob.tpe, result2.Type)
+		Equals(t, testBlob.offset, result2.Offset)
+		Equals(t, testBlob.length, result2.Length)
 	}
 
 	// add more blobs to idx
@@ -126,13 +126,13 @@ func TestIndexSerialize(t *testing.T) {
 
 	// all new blobs must be in the index
 	for _, testBlob := range newtests {
-		packID, tpe, offset, length, err := idx3.Lookup(testBlob.id)
+		blob, err := idx3.Lookup(testBlob.id)
 		OK(t, err)
 
-		Equals(t, testBlob.pack, packID)
-		Equals(t, testBlob.tpe, tpe)
-		Equals(t, testBlob.offset, offset)
-		Equals(t, testBlob.length, length)
+		Equals(t, testBlob.pack, blob.PackID)
+		Equals(t, testBlob.tpe, blob.Type)
+		Equals(t, testBlob.offset, blob.Offset)
+		Equals(t, testBlob.length, blob.Length)
 	}
 }
 
@@ -247,13 +247,13 @@ func TestIndexUnserialize(t *testing.T) {
 	OK(t, err)
 
 	for _, test := range exampleTests {
-		packID, tpe, offset, length, err := idx.Lookup(test.id)
+		blob, err := idx.Lookup(test.id)
 		OK(t, err)
 
-		Equals(t, test.packID, packID)
-		Equals(t, test.tpe, tpe)
-		Equals(t, test.offset, offset)
-		Equals(t, test.length, length)
+		Equals(t, test.packID, blob.PackID)
+		Equals(t, test.tpe, blob.Type)
+		Equals(t, test.offset, blob.Offset)
+		Equals(t, test.length, blob.Length)
 	}
 
 	Equals(t, oldIdx, idx.Supersedes())
@@ -264,13 +264,13 @@ func TestIndexUnserializeOld(t *testing.T) {
 	OK(t, err)
 
 	for _, test := range exampleTests {
-		packID, tpe, offset, length, err := idx.Lookup(test.id)
+		blob, err := idx.Lookup(test.id)
 		OK(t, err)
 
-		Equals(t, test.packID, packID)
-		Equals(t, test.tpe, tpe)
-		Equals(t, test.offset, offset)
-		Equals(t, test.length, length)
+		Equals(t, test.packID, blob.PackID)
+		Equals(t, test.tpe, blob.Type)
+		Equals(t, test.offset, blob.Offset)
+		Equals(t, test.length, blob.Length)
 	}
 
 	Equals(t, 0, len(idx.Supersedes()))
@@ -310,17 +310,17 @@ func TestConvertIndex(t *testing.T) {
 				"Index %v count blobs %v: %v != %v", id.Str(), pack.Tree, idx.Count(pack.Tree), oldIndex.Count(pack.Tree))
 
 			for packedBlob := range idx.Each(nil) {
-				packID, tpe, offset, length, err := oldIndex.Lookup(packedBlob.ID)
+				blob, err := oldIndex.Lookup(packedBlob.ID)
 				OK(t, err)
 
-				Assert(t, packID == packedBlob.PackID,
-					"Check blob %v: pack ID %v != %v", packedBlob.ID, packID, packedBlob.PackID)
-				Assert(t, tpe == packedBlob.Type,
-					"Check blob %v: Type %v != %v", packedBlob.ID, tpe, packedBlob.Type)
-				Assert(t, offset == packedBlob.Offset,
-					"Check blob %v: Type %v != %v", packedBlob.ID, offset, packedBlob.Offset)
-				Assert(t, length == packedBlob.Length,
-					"Check blob %v: Type %v != %v", packedBlob.ID, length, packedBlob.Length)
+				Assert(t, blob.PackID == packedBlob.PackID,
+					"Check blob %v: pack ID %v != %v", packedBlob.ID, blob.PackID, packedBlob.PackID)
+				Assert(t, blob.Type == packedBlob.Type,
+					"Check blob %v: Type %v != %v", packedBlob.ID, blob.Type, packedBlob.Type)
+				Assert(t, blob.Offset == packedBlob.Offset,
+					"Check blob %v: Type %v != %v", packedBlob.ID, blob.Offset, packedBlob.Offset)
+				Assert(t, blob.Length == packedBlob.Length,
+					"Check blob %v: Type %v != %v", packedBlob.ID, blob.Length, packedBlob.Length)
 			}
 		}
 	})
diff --git a/repository/master_index.go b/repository/master_index.go
index 4d52789af..5a5e499e6 100644
--- a/repository/master_index.go
+++ b/repository/master_index.go
@@ -33,24 +33,23 @@ func NewMasterIndex() *MasterIndex {
 }
 
 // Lookup queries all known Indexes for the ID and returns the first match.
-func (mi *MasterIndex) Lookup(id backend.ID) (packID backend.ID, tpe pack.BlobType, offset, length uint, err error) {
+func (mi *MasterIndex) Lookup(id backend.ID) (blob PackedBlob, err error) {
 	mi.idxMutex.RLock()
 	defer mi.idxMutex.RUnlock()
 
 	debug.Log("MasterIndex.Lookup", "looking up id %v", id.Str())
 
 	for _, idx := range mi.idx {
-		packID, tpe, offset, length, err = idx.Lookup(id)
+		blob, err = idx.Lookup(id)
 		if err == nil {
 			debug.Log("MasterIndex.Lookup",
-				"found id %v in pack %v at offset %d with length %d",
-				id.Str(), packID.Str(), offset, length)
+				"found id %v: %v", blob)
 			return
 		}
 	}
 
 	debug.Log("MasterIndex.Lookup", "id %v not found in any index", id.Str())
-	return backend.ID{}, pack.Data, 0, 0, fmt.Errorf("id %v not found in any index", id)
+	return PackedBlob{}, fmt.Errorf("id %v not found in any index", id)
 }
 
 // LookupSize queries all known Indexes for the ID and returns the first match.
diff --git a/repository/repository.go b/repository/repository.go
index e841c692d..51e5613b4 100644
--- a/repository/repository.go
+++ b/repository/repository.go
@@ -92,32 +92,33 @@ func (r *Repository) LoadAndDecrypt(t backend.Type, id backend.ID) ([]byte, erro
 func (r *Repository) LoadBlob(t pack.BlobType, id backend.ID, plaintextBuf []byte) ([]byte, error) {
 	debug.Log("Repo.LoadBlob", "load %v with id %v", t, id.Str())
 	// lookup pack
-	packID, tpe, offset, length, err := r.idx.Lookup(id)
+	blob, err := r.idx.Lookup(id)
 	if err != nil {
 		debug.Log("Repo.LoadBlob", "id %v not found in index: %v", id.Str(), err)
 		return nil, err
 	}
 
-	if length > uint(cap(plaintextBuf))+crypto.Extension {
-		return nil, fmt.Errorf("buf is too small, need %d more bytes", length-uint(cap(plaintextBuf))-crypto.Extension)
+	plaintextBufSize := uint(cap(plaintextBuf))
+	if blob.PlaintextLength() > plaintextBufSize {
+		return nil, fmt.Errorf("buf is too small, need %d more bytes", blob.PlaintextLength()-plaintextBufSize)
 	}
 
-	if tpe != t {
-		debug.Log("Repo.LoadBlob", "wrong type returned for %v: wanted %v, got %v", id.Str(), t, tpe)
-		return nil, fmt.Errorf("blob has wrong type %v (wanted: %v)", tpe, t)
+	if blob.Type != t {
+		debug.Log("Repo.LoadBlob", "wrong type returned for %v: wanted %v, got %v", id.Str(), t, blob.Type)
+		return nil, fmt.Errorf("blob has wrong type %v (wanted: %v)", blob.Type, t)
 	}
 
-	debug.Log("Repo.LoadBlob", "id %v found in pack %v at offset %v (length %d)", id.Str(), packID.Str(), offset, length)
+	debug.Log("Repo.LoadBlob", "id %v found: %v", id.Str(), blob)
 
 	// load blob from pack
-	rd, err := r.be.GetReader(backend.Data, packID.String(), offset, length)
+	rd, err := r.be.GetReader(backend.Data, blob.PackID.String(), blob.Offset, blob.Length)
 	if err != nil {
-		debug.Log("Repo.LoadBlob", "error loading pack %v for %v: %v", packID.Str(), id.Str(), err)
+		debug.Log("Repo.LoadBlob", "error loading blob %v: %v", blob, err)
 		return nil, err
 	}
 
 	// make buffer that is large enough for the complete blob
-	ciphertextBuf := make([]byte, length)
+	ciphertextBuf := make([]byte, blob.Length)
 	_, err = io.ReadFull(rd, ciphertextBuf)
 	if err != nil {
 		return nil, err
@@ -173,13 +174,13 @@ func (r *Repository) LoadJSONUnpacked(t backend.Type, id backend.ID, item interf
 // data and afterwards call json.Unmarshal on the item.
 func (r *Repository) LoadJSONPack(t pack.BlobType, id backend.ID, item interface{}) error {
 	// lookup pack
-	packID, _, offset, length, err := r.idx.Lookup(id)
+	blob, err := r.idx.Lookup(id)
 	if err != nil {
 		return err
 	}
 
 	// load blob from pack
-	rd, err := r.be.GetReader(backend.Data, packID.String(), offset, length)
+	rd, err := r.be.GetReader(backend.Data, blob.PackID.String(), blob.Offset, blob.Length)
 	if err != nil {
 		return err
 	}