diff --git a/src/restic/archiver/archive_reader_test.go b/src/restic/archiver/archive_reader_test.go
index b402bc6d1..e7e88d6cd 100644
--- a/src/restic/archiver/archive_reader_test.go
+++ b/src/restic/archiver/archive_reader_test.go
@@ -11,16 +11,16 @@ import (
 	"github.com/restic/chunker"
 )
 
-func loadBlob(t *testing.T, repo *repository.Repository, id restic.ID, buf []byte) []byte {
-	buf, err := repo.LoadBlob(id, restic.DataBlob, buf)
+func loadBlob(t *testing.T, repo restic.Repository, id restic.ID, buf []byte) []byte {
+	n, err := repo.LoadDataBlob(id, buf)
 	if err != nil {
 		t.Fatalf("LoadBlob(%v) returned error %v", id, err)
 	}
 
-	return buf
+	return buf[:n]
 }
 
-func checkSavedFile(t *testing.T, repo *repository.Repository, treeID restic.ID, name string, rd io.Reader) {
+func checkSavedFile(t *testing.T, repo restic.Repository, treeID restic.ID, name string, rd io.Reader) {
 	tree, err := repo.LoadTree(treeID)
 	if err != nil {
 		t.Fatalf("LoadTree() returned error %v", err)
diff --git a/src/restic/archiver/archiver_test.go b/src/restic/archiver/archiver_test.go
index 1d43254cb..a1fa47683 100644
--- a/src/restic/archiver/archiver_test.go
+++ b/src/restic/archiver/archiver_test.go
@@ -12,8 +12,9 @@ import (
 	"restic/crypto"
 	. "restic/test"
 
-	"github.com/restic/chunker"
 	"restic/errors"
+
+	"github.com/restic/chunker"
 )
 
 var testPol = chunker.Pol(0x3DA3358B4DC173)
@@ -126,6 +127,14 @@ func BenchmarkArchiveDirectory(b *testing.B) {
 	}
 }
 
+func countPacks(repo restic.Repository, t restic.FileType) (n uint) {
+	for _ = range repo.Backend().List(t, nil) {
+		n++
+	}
+
+	return n
+}
+
 func archiveWithDedup(t testing.TB) {
 	repo := SetupRepo()
 	defer TeardownRepo(repo)
@@ -145,7 +154,7 @@ func archiveWithDedup(t testing.TB) {
 	t.Logf("archived snapshot %v", sn.ID().Str())
 
 	// get archive stats
-	cnt.before.packs = repo.Count(restic.DataFile)
+	cnt.before.packs = countPacks(repo, restic.DataFile)
 	cnt.before.dataBlobs = repo.Index().Count(restic.DataBlob)
 	cnt.before.treeBlobs = repo.Index().Count(restic.TreeBlob)
 	t.Logf("packs %v, data blobs %v, tree blobs %v",
@@ -156,7 +165,7 @@ func archiveWithDedup(t testing.TB) {
 	t.Logf("archived snapshot %v", sn2.ID().Str())
 
 	// get archive stats again
-	cnt.after.packs = repo.Count(restic.DataFile)
+	cnt.after.packs = countPacks(repo, restic.DataFile)
 	cnt.after.dataBlobs = repo.Index().Count(restic.DataBlob)
 	cnt.after.treeBlobs = repo.Index().Count(restic.TreeBlob)
 	t.Logf("packs %v, data blobs %v, tree blobs %v",
@@ -173,7 +182,7 @@ func archiveWithDedup(t testing.TB) {
 	t.Logf("archived snapshot %v, parent %v", sn3.ID().Str(), sn2.ID().Str())
 
 	// get archive stats again
-	cnt.after2.packs = repo.Count(restic.DataFile)
+	cnt.after2.packs = countPacks(repo, restic.DataFile)
 	cnt.after2.dataBlobs = repo.Index().Count(restic.DataBlob)
 	cnt.after2.treeBlobs = repo.Index().Count(restic.TreeBlob)
 	t.Logf("packs %v, data blobs %v, tree blobs %v",
diff --git a/src/restic/checker/checker.go b/src/restic/checker/checker.go
index df879fdfd..ebb416938 100644
--- a/src/restic/checker/checker.go
+++ b/src/restic/checker/checker.go
@@ -684,12 +684,13 @@ func checkPack(r restic.Repository, id restic.ID) error {
 		debug.Log("Checker.checkPack", "  check blob %d: %v", i, blob.ID.Str())
 
 		plainBuf := make([]byte, blob.Length)
-		plainBuf, err = crypto.Decrypt(r.Key(), plainBuf, buf[blob.Offset:blob.Offset+blob.Length])
+		n, err := crypto.Decrypt(r.Key(), plainBuf, buf[blob.Offset:blob.Offset+blob.Length])
 		if err != nil {
 			debug.Log("Checker.checkPack", "  error decrypting blob %v: %v", blob.ID.Str(), err)
 			errs = append(errs, errors.Errorf("blob %v: %v", i, err))
 			continue
 		}
+		plainBuf = plainBuf[:n]
 
 		hash := restic.Hash(plainBuf)
 		if !hash.Equal(blob.ID) {
diff --git a/src/restic/checker/checker_test.go b/src/restic/checker/checker_test.go
index 6e9f29d06..0037f0adb 100644
--- a/src/restic/checker/checker_test.go
+++ b/src/restic/checker/checker_test.go
@@ -17,7 +17,7 @@ import (
 
 var checkerTestData = filepath.Join("testdata", "checker-test-repo.tar.gz")
 
-func list(repo *repository.Repository, t restic.FileType) (IDs []string) {
+func list(repo restic.Repository, t restic.FileType) (IDs []string) {
 	done := make(chan struct{})
 	defer close(done)
 
diff --git a/src/restic/checker/testing.go b/src/restic/checker/testing.go
index 3bf9aa2ec..7b642dea1 100644
--- a/src/restic/checker/testing.go
+++ b/src/restic/checker/testing.go
@@ -1,12 +1,12 @@
 package checker
 
 import (
-	"restic/repository"
+	"restic"
 	"testing"
 )
 
 // TestCheckRepo runs the checker on repo.
-func TestCheckRepo(t testing.TB, repo *repository.Repository) {
+func TestCheckRepo(t testing.TB, repo restic.Repository) {
 	chkr := New(repo)
 
 	hints, errs := chkr.LoadIndex()
diff --git a/src/restic/crypto/crypto.go b/src/restic/crypto/crypto.go
index 2ebf5d31b..57fdd6230 100644
--- a/src/restic/crypto/crypto.go
+++ b/src/restic/crypto/crypto.go
@@ -274,9 +274,9 @@ func Encrypt(ks *Key, ciphertext []byte, plaintext []byte) ([]byte, error) {
 // Decrypt verifies and decrypts the ciphertext. Ciphertext must be in the form
 // IV || Ciphertext || MAC. plaintext and ciphertext may point to (exactly) the
 // same slice.
-func Decrypt(ks *Key, plaintext []byte, ciphertextWithMac []byte) ([]byte, error) {
+func Decrypt(ks *Key, plaintext []byte, ciphertextWithMac []byte) (int, error) {
 	if !ks.Valid() {
-		return nil, errors.New("invalid key")
+		return 0, errors.New("invalid key")
 	}
 
 	// check for plausible length
@@ -284,21 +284,26 @@ func Decrypt(ks *Key, plaintext []byte, ciphertextWithMac []byte) ([]byte, error
 		panic("trying to decrypt invalid data: ciphertext too small")
 	}
 
+	// check buffer length for plaintext
+	plaintextLength := len(ciphertextWithMac) - ivSize - macSize
+	if len(plaintext) < plaintextLength {
+		return 0, errors.Errorf("plaintext buffer too small, %d < %d", len(plaintext), plaintextLength)
+	}
+
 	// extract mac
 	l := len(ciphertextWithMac) - macSize
 	ciphertextWithIV, mac := ciphertextWithMac[:l], ciphertextWithMac[l:]
 
 	// verify mac
 	if !poly1305Verify(ciphertextWithIV[ivSize:], ciphertextWithIV[:ivSize], &ks.MAC, mac) {
-		return nil, ErrUnauthenticated
+		return 0, ErrUnauthenticated
 	}
 
 	// extract iv
 	iv, ciphertext := ciphertextWithIV[:ivSize], ciphertextWithIV[ivSize:]
 
-	if cap(plaintext) < len(ciphertext) {
-		// extend plaintext
-		plaintext = append(plaintext, make([]byte, len(ciphertext)-cap(plaintext))...)
+	if len(ciphertext) != plaintextLength {
+		return 0, errors.Errorf("plaintext and ciphertext lengths do not match: %d != %d", len(ciphertext), plaintextLength)
 	}
 
 	// decrypt data
@@ -312,7 +317,7 @@ func Decrypt(ks *Key, plaintext []byte, ciphertextWithMac []byte) ([]byte, error
 	plaintext = plaintext[:len(ciphertext)]
 	e.XORKeyStream(plaintext, ciphertext)
 
-	return plaintext, nil
+	return plaintextLength, nil
 }
 
 // Valid tests if the key is valid.
diff --git a/src/restic/crypto/crypto_int_test.go b/src/restic/crypto/crypto_int_test.go
index 5fed6b54c..1dbc32623 100644
--- a/src/restic/crypto/crypto_int_test.go
+++ b/src/restic/crypto/crypto_int_test.go
@@ -100,15 +100,17 @@ func TestCrypto(t *testing.T) {
 		}
 
 		// decrypt message
-		_, err = Decrypt(k, []byte{}, msg)
+		buf := make([]byte, len(tv.plaintext))
+		n, err := Decrypt(k, buf, msg)
 		if err != nil {
 			t.Fatal(err)
 		}
+		buf = buf[:n]
 
 		// change mac, this must fail
 		msg[len(msg)-8] ^= 0x23
 
-		if _, err = Decrypt(k, []byte{}, msg); err != ErrUnauthenticated {
+		if _, err = Decrypt(k, buf, msg); err != ErrUnauthenticated {
 			t.Fatal("wrong MAC value not detected")
 		}
 
@@ -118,15 +120,17 @@ func TestCrypto(t *testing.T) {
 		// tamper with message, this must fail
 		msg[16+5] ^= 0x85
 
-		if _, err = Decrypt(k, []byte{}, msg); err != ErrUnauthenticated {
+		if _, err = Decrypt(k, buf, msg); err != ErrUnauthenticated {
 			t.Fatal("tampered message not detected")
 		}
 
 		// test decryption
-		p, err := Decrypt(k, []byte{}, tv.ciphertext)
+		p := make([]byte, len(tv.ciphertext))
+		n, err = Decrypt(k, p, tv.ciphertext)
 		if err != nil {
 			t.Fatal(err)
 		}
+		p = p[:n]
 
 		if !bytes.Equal(p, tv.plaintext) {
 			t.Fatalf("wrong plaintext: expected %q but got %q\n", tv.plaintext, p)
diff --git a/src/restic/crypto/crypto_test.go b/src/restic/crypto/crypto_test.go
index fe799da77..39c3cc169 100644
--- a/src/restic/crypto/crypto_test.go
+++ b/src/restic/crypto/crypto_test.go
@@ -32,8 +32,10 @@ func TestEncryptDecrypt(t *testing.T) {
 			"ciphertext length does not match: want %d, got %d",
 			len(data)+crypto.Extension, len(ciphertext))
 
-		plaintext, err := crypto.Decrypt(k, nil, ciphertext)
+		plaintext := make([]byte, len(ciphertext))
+		n, err := crypto.Decrypt(k, plaintext, ciphertext)
 		OK(t, err)
+		plaintext = plaintext[:n]
 		Assert(t, len(plaintext) == len(data),
 			"plaintext length does not match: want %d, got %d",
 			len(data), len(plaintext))
@@ -58,8 +60,10 @@ func TestSmallBuffer(t *testing.T) {
 		cap(ciphertext))
 
 	// check for the correct plaintext
-	plaintext, err := crypto.Decrypt(k, nil, ciphertext)
+	plaintext := make([]byte, len(ciphertext))
+	n, err := crypto.Decrypt(k, plaintext, ciphertext)
 	OK(t, err)
+	plaintext = plaintext[:n]
 	Assert(t, bytes.Equal(plaintext, data),
 		"wrong plaintext returned")
 }
@@ -78,8 +82,9 @@ func TestSameBuffer(t *testing.T) {
 	OK(t, err)
 
 	// use the same buffer for decryption
-	ciphertext, err = crypto.Decrypt(k, ciphertext, ciphertext)
+	n, err := crypto.Decrypt(k, ciphertext, ciphertext)
 	OK(t, err)
+	ciphertext = ciphertext[:n]
 	Assert(t, bytes.Equal(ciphertext, data),
 		"wrong plaintext returned")
 }
@@ -97,9 +102,9 @@ func TestCornerCases(t *testing.T) {
 		len(c))
 
 	// this should decrypt to nil
-	p, err := crypto.Decrypt(k, nil, c)
+	n, err := crypto.Decrypt(k, nil, c)
 	OK(t, err)
-	Equals(t, []byte(nil), p)
+	Equals(t, 0, n)
 
 	// test encryption for same slice, this should return an error
 	_, err = crypto.Encrypt(k, c, c)
@@ -160,7 +165,7 @@ func BenchmarkDecrypt(b *testing.B) {
 	b.SetBytes(int64(size))
 
 	for i := 0; i < b.N; i++ {
-		plaintext, err = crypto.Decrypt(k, plaintext, ciphertext)
+		_, err = crypto.Decrypt(k, plaintext, ciphertext)
 		OK(b, err)
 	}
 }
diff --git a/src/restic/fuse/dir.go b/src/restic/fuse/dir.go
index 14f8c7f21..004d02086 100644
--- a/src/restic/fuse/dir.go
+++ b/src/restic/fuse/dir.go
@@ -12,7 +12,6 @@ import (
 
 	"restic"
 	"restic/debug"
-	"restic/repository"
 )
 
 // Statically ensure that *dir implement those interface
@@ -20,14 +19,14 @@ var _ = fs.HandleReadDirAller(&dir{})
 var _ = fs.NodeStringLookuper(&dir{})
 
 type dir struct {
-	repo        *repository.Repository
+	repo        restic.Repository
 	items       map[string]*restic.Node
 	inode       uint64
 	node        *restic.Node
 	ownerIsRoot bool
 }
 
-func newDir(repo *repository.Repository, node *restic.Node, ownerIsRoot bool) (*dir, error) {
+func newDir(repo restic.Repository, node *restic.Node, ownerIsRoot bool) (*dir, error) {
 	debug.Log("newDir", "new dir for %v (%v)", node.Name, node.Subtree.Str())
 	tree, err := repo.LoadTree(*node.Subtree)
 	if err != nil {
@@ -50,7 +49,7 @@ func newDir(repo *repository.Repository, node *restic.Node, ownerIsRoot bool) (*
 
 // replaceSpecialNodes replaces nodes with name "." and "/" by their contents.
 // Otherwise, the node is returned.
-func replaceSpecialNodes(repo *repository.Repository, node *restic.Node) ([]*restic.Node, error) {
+func replaceSpecialNodes(repo restic.Repository, node *restic.Node) ([]*restic.Node, error) {
 	if node.Type != "dir" || node.Subtree == nil {
 		return []*restic.Node{node}, nil
 	}
@@ -67,7 +66,7 @@ func replaceSpecialNodes(repo *repository.Repository, node *restic.Node) ([]*res
 	return tree.Nodes, nil
 }
 
-func newDirFromSnapshot(repo *repository.Repository, snapshot SnapshotWithId, ownerIsRoot bool) (*dir, error) {
+func newDirFromSnapshot(repo restic.Repository, snapshot SnapshotWithId, ownerIsRoot bool) (*dir, error) {
 	debug.Log("newDirFromSnapshot", "new dir for snapshot %v (%v)", snapshot.ID.Str(), snapshot.Tree.Str())
 	tree, err := repo.LoadTree(*snapshot.Tree)
 	if err != nil {
diff --git a/src/restic/fuse/file.go b/src/restic/fuse/file.go
index d5949ee86..ae1b90124 100644
--- a/src/restic/fuse/file.go
+++ b/src/restic/fuse/file.go
@@ -27,7 +27,7 @@ var _ = fs.HandleReleaser(&file{})
 // for fuse operations.
 type BlobLoader interface {
 	LookupBlobSize(restic.ID, restic.BlobType) (uint, error)
-	LoadBlob(restic.ID, restic.BlobType, []byte) ([]byte, error)
+	LoadDataBlob(restic.ID, []byte) (int, error)
 }
 
 type file struct {
@@ -109,12 +109,12 @@ func (f *file) getBlobAt(i int) (blob []byte, err error) {
 		buf = make([]byte, f.sizes[i])
 	}
 
-	blob, err = f.repo.LoadBlob(f.node.Content[i], restic.DataBlob, buf)
+	n, err := f.repo.LoadDataBlob(f.node.Content[i], buf)
 	if err != nil {
 		debug.Log("file.getBlobAt", "LoadBlob(%v, %v) failed: %v", f.node.Name, f.node.Content[i], err)
 		return nil, err
 	}
-	f.blobs[i] = blob
+	f.blobs[i] = buf[:n]
 
 	return blob, nil
 }
diff --git a/src/restic/fuse/file_test.go b/src/restic/fuse/file_test.go
index 58e6b33ba..0101cadc9 100644
--- a/src/restic/fuse/file_test.go
+++ b/src/restic/fuse/file_test.go
@@ -34,19 +34,19 @@ func (m *MockRepo) LookupBlobSize(id restic.ID, t restic.BlobType) (uint, error)
 	return uint(len(buf)), nil
 }
 
-func (m *MockRepo) LoadBlob(id restic.ID, t restic.BlobType, buf []byte) ([]byte, error) {
-	size, err := m.LookupBlobSize(id, t)
+func (m *MockRepo) LoadDataBlob(id restic.ID, buf []byte) (int, error) {
+	size, err := m.LookupBlobSize(id, restic.DataBlob)
 	if err != nil {
-		return nil, err
+		return 0, err
 	}
 
 	if uint(cap(buf)) < size {
-		return nil, errors.New("buffer too small")
+		return 0, errors.New("buffer too small")
 	}
 
 	buf = buf[:size]
 	copy(buf, m.blobs[id])
-	return buf, nil
+	return int(size), nil
 }
 
 type MockContext struct{}
diff --git a/src/restic/fuse/link.go b/src/restic/fuse/link.go
index 732446a7a..43fb35020 100644
--- a/src/restic/fuse/link.go
+++ b/src/restic/fuse/link.go
@@ -5,7 +5,6 @@ package fuse
 
 import (
 	"restic"
-	"restic/repository"
 
 	"bazil.org/fuse"
 	"bazil.org/fuse/fs"
@@ -20,7 +19,7 @@ type link struct {
 	ownerIsRoot bool
 }
 
-func newLink(repo *repository.Repository, node *restic.Node, ownerIsRoot bool) (*link, error) {
+func newLink(repo restic.Repository, node *restic.Node, ownerIsRoot bool) (*link, error) {
 	return &link{node: node, ownerIsRoot: ownerIsRoot}, nil
 }
 
diff --git a/src/restic/fuse/snapshot.go b/src/restic/fuse/snapshot.go
index 8d14823b0..b97e3ced9 100644
--- a/src/restic/fuse/snapshot.go
+++ b/src/restic/fuse/snapshot.go
@@ -13,7 +13,6 @@ import (
 
 	"restic"
 	"restic/debug"
-	"restic/repository"
 
 	"golang.org/x/net/context"
 )
@@ -30,7 +29,7 @@ var _ = fs.HandleReadDirAller(&SnapshotsDir{})
 var _ = fs.NodeStringLookuper(&SnapshotsDir{})
 
 type SnapshotsDir struct {
-	repo        *repository.Repository
+	repo        restic.Repository
 	ownerIsRoot bool
 
 	// knownSnapshots maps snapshot timestamp to the snapshot
@@ -38,7 +37,7 @@ type SnapshotsDir struct {
 	knownSnapshots map[string]SnapshotWithId
 }
 
-func NewSnapshotsDir(repo *repository.Repository, ownerIsRoot bool) *SnapshotsDir {
+func NewSnapshotsDir(repo restic.Repository, ownerIsRoot bool) *SnapshotsDir {
 	debug.Log("NewSnapshotsDir", "fuse mount initiated")
 	return &SnapshotsDir{
 		repo:           repo,
diff --git a/src/restic/index/index_test.go b/src/restic/index/index_test.go
index 521d0c0b0..f1378531f 100644
--- a/src/restic/index/index_test.go
+++ b/src/restic/index/index_test.go
@@ -15,7 +15,7 @@ var (
 	depth        = 3
 )
 
-func createFilledRepo(t testing.TB, snapshots int, dup float32) (*repository.Repository, func()) {
+func createFilledRepo(t testing.TB, snapshots int, dup float32) (restic.Repository, func()) {
 	repo, cleanup := repository.TestRepository(t)
 
 	for i := 0; i < 3; i++ {
@@ -25,7 +25,7 @@ func createFilledRepo(t testing.TB, snapshots int, dup float32) (*repository.Rep
 	return repo, cleanup
 }
 
-func validateIndex(t testing.TB, repo *repository.Repository, idx *Index) {
+func validateIndex(t testing.TB, repo restic.Repository, idx *Index) {
 	for id := range repo.List(restic.DataFile, nil) {
 		if _, ok := idx.Packs[id]; !ok {
 			t.Errorf("pack %v missing from index", id.Str())
@@ -162,7 +162,7 @@ func TestIndexDuplicateBlobs(t *testing.T) {
 	t.Logf("%d packs with duplicate blobs", len(packs))
 }
 
-func loadIndex(t testing.TB, repo *repository.Repository) *Index {
+func loadIndex(t testing.TB, repo restic.Repository) *Index {
 	idx, err := Load(repo, nil)
 	if err != nil {
 		t.Fatalf("Load() returned error %v", err)
diff --git a/src/restic/pack/pack.go b/src/restic/pack/pack.go
index 40d10839b..17f79b09a 100644
--- a/src/restic/pack/pack.go
+++ b/src/restic/pack/pack.go
@@ -225,12 +225,13 @@ func List(k *crypto.Key, rd io.ReaderAt, size int64) (entries []restic.Blob, err
 		return nil, err
 	}
 
-	hdr, err := crypto.Decrypt(k, buf, buf)
+	n, err := crypto.Decrypt(k, buf, buf)
 	if err != nil {
 		return nil, err
 	}
+	buf = buf[:n]
 
-	hdrRd := bytes.NewReader(hdr)
+	hdrRd := bytes.NewReader(buf)
 
 	pos := uint(0)
 	for {
diff --git a/src/restic/repository.go b/src/restic/repository.go
index 5c1067f7b..c7e8ae170 100644
--- a/src/restic/repository.go
+++ b/src/restic/repository.go
@@ -16,6 +16,7 @@ type Repository interface {
 	Index() Index
 	SaveFullIndex() error
 	SaveIndex() error
+	LoadIndex() error
 
 	Config() Config
 
diff --git a/src/restic/repository/key.go b/src/restic/repository/key.go
index b874dc644..9a0a85c21 100644
--- a/src/restic/repository/key.go
+++ b/src/restic/repository/key.go
@@ -85,10 +85,12 @@ func OpenKey(s *Repository, name string, password string) (*Key, error) {
 	}
 
 	// decrypt master keys
-	buf, err := crypto.Decrypt(k.user, []byte{}, k.Data)
+	buf := make([]byte, len(k.Data))
+	n, err := crypto.Decrypt(k.user, buf, k.Data)
 	if err != nil {
 		return nil, err
 	}
+	buf = buf[:n]
 
 	// restore json
 	k.master = &crypto.Key{}
diff --git a/src/restic/repository/repack.go b/src/restic/repository/repack.go
index 274f2d320..2ce701ad9 100644
--- a/src/restic/repository/repack.go
+++ b/src/restic/repository/repack.go
@@ -15,7 +15,7 @@ import (
 // these packs. Each pack is loaded and the blobs listed in keepBlobs is saved
 // into a new pack. Afterwards, the packs are removed. This operation requires
 // an exclusive lock on the repo.
-func Repack(repo *Repository, packs restic.IDSet, keepBlobs restic.BlobSet) (err error) {
+func Repack(repo restic.Repository, packs restic.IDSet, keepBlobs restic.BlobSet) (err error) {
 	debug.Log("Repack", "repacking %d packs while keeping %d blobs", len(packs), len(keepBlobs))
 
 	buf := make([]byte, 0, maxPackSize)
@@ -48,16 +48,21 @@ func Repack(repo *Repository, packs restic.IDSet, keepBlobs restic.BlobSet) (err
 				continue
 			}
 
-			ciphertext := buf[entry.Offset : entry.Offset+entry.Length]
+			debug.Log("Repack", "  process blob %v", h)
 
-			if cap(plaintext) < len(ciphertext) {
+			ciphertext := buf[entry.Offset : entry.Offset+entry.Length]
+			plaintext = plaintext[:len(plaintext)]
+			if len(plaintext) < len(ciphertext) {
 				plaintext = make([]byte, len(ciphertext))
 			}
 
-			plaintext, err = crypto.Decrypt(repo.Key(), plaintext, ciphertext)
+			debug.Log("Repack", "  ciphertext %d, plaintext %d", len(plaintext), len(ciphertext))
+
+			n, err := crypto.Decrypt(repo.Key(), plaintext, ciphertext)
 			if err != nil {
 				return err
 			}
+			plaintext = plaintext[:n]
 
 			_, err = repo.SaveAndEncrypt(entry.Type, plaintext, &entry.ID)
 			if err != nil {
diff --git a/src/restic/repository/repack_test.go b/src/restic/repository/repack_test.go
index 026e43cbc..9b118d7b4 100644
--- a/src/restic/repository/repack_test.go
+++ b/src/restic/repository/repack_test.go
@@ -23,7 +23,7 @@ func random(t testing.TB, length int) []byte {
 	return buf
 }
 
-func createRandomBlobs(t testing.TB, repo *repository.Repository, blobs int, pData float32) {
+func createRandomBlobs(t testing.TB, repo restic.Repository, blobs int, pData float32) {
 	for i := 0; i < blobs; i++ {
 		var (
 			tpe    restic.BlobType
@@ -65,7 +65,7 @@ func createRandomBlobs(t testing.TB, repo *repository.Repository, blobs int, pDa
 
 // selectBlobs splits the list of all blobs randomly into two lists. A blob
 // will be contained in the firstone ith probability p.
-func selectBlobs(t *testing.T, repo *repository.Repository, p float32) (list1, list2 restic.BlobSet) {
+func selectBlobs(t *testing.T, repo restic.Repository, p float32) (list1, list2 restic.BlobSet) {
 	done := make(chan struct{})
 	defer close(done)
 
@@ -100,7 +100,7 @@ func selectBlobs(t *testing.T, repo *repository.Repository, p float32) (list1, l
 	return list1, list2
 }
 
-func listPacks(t *testing.T, repo *repository.Repository) restic.IDSet {
+func listPacks(t *testing.T, repo restic.Repository) restic.IDSet {
 	done := make(chan struct{})
 	defer close(done)
 
@@ -112,7 +112,7 @@ func listPacks(t *testing.T, repo *repository.Repository) restic.IDSet {
 	return list
 }
 
-func findPacksForBlobs(t *testing.T, repo *repository.Repository, blobs restic.BlobSet) restic.IDSet {
+func findPacksForBlobs(t *testing.T, repo restic.Repository, blobs restic.BlobSet) restic.IDSet {
 	packs := restic.NewIDSet()
 
 	idx := repo.Index()
@@ -130,26 +130,26 @@ func findPacksForBlobs(t *testing.T, repo *repository.Repository, blobs restic.B
 	return packs
 }
 
-func repack(t *testing.T, repo *repository.Repository, packs restic.IDSet, blobs restic.BlobSet) {
+func repack(t *testing.T, repo restic.Repository, packs restic.IDSet, blobs restic.BlobSet) {
 	err := repository.Repack(repo, packs, blobs)
 	if err != nil {
 		t.Fatal(err)
 	}
 }
 
-func saveIndex(t *testing.T, repo *repository.Repository) {
+func saveIndex(t *testing.T, repo restic.Repository) {
 	if err := repo.SaveIndex(); err != nil {
 		t.Fatalf("repo.SaveIndex() %v", err)
 	}
 }
 
-func rebuildIndex(t *testing.T, repo *repository.Repository) {
+func rebuildIndex(t *testing.T, repo restic.Repository) {
 	if err := repository.RebuildIndex(repo); err != nil {
 		t.Fatalf("error rebuilding index: %v", err)
 	}
 }
 
-func reloadIndex(t *testing.T, repo *repository.Repository) {
+func reloadIndex(t *testing.T, repo restic.Repository) {
 	repo.SetIndex(repository.NewMasterIndex())
 	if err := repo.LoadIndex(); err != nil {
 		t.Fatalf("error loading new index: %v", err)
diff --git a/src/restic/repository/repository.go b/src/restic/repository/repository.go
index 87025425d..e0d3659c2 100644
--- a/src/restic/repository/repository.go
+++ b/src/restic/repository/repository.go
@@ -72,20 +72,22 @@ func (r *Repository) LoadAndDecrypt(t restic.FileType, id restic.ID) ([]byte, er
 		return nil, errors.New("invalid data returned")
 	}
 
+	plain := make([]byte, len(buf))
+
 	// decrypt
-	plain, err := r.Decrypt(buf)
+	n, err := r.decryptTo(plain, buf)
 	if err != nil {
 		return nil, err
 	}
 
-	return plain, nil
+	return plain[:n], nil
 }
 
 // LoadBlob tries to load and decrypt content identified by t and id from a
 // pack from the backend, the result is stored in plaintextBuf, which must be
 // large enough to hold the complete blob.
 func (r *Repository) LoadBlob(id restic.ID, t restic.BlobType, plaintextBuf []byte) ([]byte, error) {
-	debug.Log("Repo.LoadBlob", "load %v with id %v", t, id.Str())
+	debug.Log("Repo.LoadBlob", "load %v with id %v (buf %d)", t, id.Str(), len(plaintextBuf))
 
 	// lookup plaintext size of blob
 	size, err := r.idx.LookupSize(id, t)
@@ -94,11 +96,8 @@ func (r *Repository) LoadBlob(id restic.ID, t restic.BlobType, plaintextBuf []by
 	}
 
 	// make sure the plaintext buffer is large enough, extend otherwise
-	plaintextBufSize := uint(cap(plaintextBuf))
-	if size > plaintextBufSize {
-		debug.Log("Repo.LoadBlob", "need to expand buffer: want %d bytes, got %d",
-			size, plaintextBufSize)
-		plaintextBuf = make([]byte, size)
+	if len(plaintextBuf) < int(size) {
+		return nil, errors.Errorf("buffer is too small: %d < %d", len(plaintextBuf), size)
 	}
 
 	// lookup packs
@@ -134,11 +133,12 @@ func (r *Repository) LoadBlob(id restic.ID, t restic.BlobType, plaintextBuf []by
 		}
 
 		// decrypt
-		plaintextBuf, err = r.decryptTo(plaintextBuf, ciphertextBuf)
+		n, err = r.decryptTo(plaintextBuf, ciphertextBuf)
 		if err != nil {
 			lastError = errors.Errorf("decrypting blob %v failed: %v", id, err)
 			continue
 		}
+		plaintextBuf = plaintextBuf[:n]
 
 		// check hash
 		if !restic.Hash(plaintextBuf).Equal(id) {
@@ -403,7 +403,7 @@ func (r *Repository) LoadIndex() error {
 }
 
 // LoadIndex loads the index id from backend and returns it.
-func LoadIndex(repo *Repository, id restic.ID) (*Index, error) {
+func LoadIndex(repo restic.Repository, id restic.ID) (*Index, error) {
 	idx, err := LoadIndexWithDecoder(repo, id, DecodeIndex)
 	if err == nil {
 		return idx, nil
@@ -467,19 +467,14 @@ func (r *Repository) init(password string, cfg restic.Config) error {
 	return err
 }
 
-// Decrypt authenticates and decrypts ciphertext and returns the plaintext.
-func (r *Repository) Decrypt(ciphertext []byte) ([]byte, error) {
-	return r.decryptTo(nil, ciphertext)
-}
-
 // decrypt authenticates and decrypts ciphertext and stores the result in
 // plaintext.
-func (r *Repository) decryptTo(plaintext, ciphertext []byte) ([]byte, error) {
+func (r *Repository) decryptTo(plaintext, ciphertext []byte) (int, error) {
 	if r.key == nil {
-		return nil, errors.New("key for repository not set")
+		return 0, errors.New("key for repository not set")
 	}
 
-	return crypto.Decrypt(r.key, nil, ciphertext)
+	return crypto.Decrypt(r.key, plaintext, ciphertext)
 }
 
 // Encrypt encrypts and authenticates the plaintext and saves the result in
@@ -502,15 +497,6 @@ func (r *Repository) KeyName() string {
 	return r.keyName
 }
 
-// Count returns the number of blobs of a given type in the backend.
-func (r *Repository) Count(t restic.FileType) (n uint) {
-	for _ = range r.be.List(t, nil) {
-		n++
-	}
-
-	return
-}
-
 func (r *Repository) list(t restic.FileType, done <-chan struct{}, out chan<- restic.ID) {
 	defer close(out)
 	in := r.be.List(t, done)
@@ -592,14 +578,17 @@ func (r *Repository) Close() error {
 
 // LoadTree loads a tree from the repository.
 func (r *Repository) LoadTree(id restic.ID) (*restic.Tree, error) {
+	debug.Log("repo.LoadTree", "load tree %v", id.Str())
+
 	size, err := r.idx.LookupSize(id, restic.TreeBlob)
 	if err != nil {
 		return nil, err
 	}
 
+	debug.Log("repo.LoadTree", "size is %d, create buffer", size)
 	buf := make([]byte, size)
 
-	buf, err = r.LoadBlob(id, restic.TreeBlob, nil)
+	buf, err = r.LoadBlob(id, restic.TreeBlob, buf)
 	if err != nil {
 		return nil, err
 	}
@@ -615,6 +604,7 @@ func (r *Repository) LoadTree(id restic.ID) (*restic.Tree, error) {
 
 // LoadDataBlob loads a data blob from the repository to the buffer.
 func (r *Repository) LoadDataBlob(id restic.ID, buf []byte) (int, error) {
+	debug.Log("repo.LoadDataBlob", "load blob %v into buf %p", id.Str(), buf)
 	size, err := r.idx.LookupSize(id, restic.DataBlob)
 	if err != nil {
 		return 0, err
@@ -629,5 +619,7 @@ func (r *Repository) LoadDataBlob(id restic.ID, buf []byte) (int, error) {
 		return 0, err
 	}
 
+	debug.Log("repo.LoadDataBlob", "loaded %d bytes into buf %p", len(buf), buf)
+
 	return len(buf), err
 }
diff --git a/src/restic/repository/repository_test.go b/src/restic/repository/repository_test.go
index 98b8edd84..644650c30 100644
--- a/src/restic/repository/repository_test.go
+++ b/src/restic/repository/repository_test.go
@@ -90,8 +90,10 @@ func TestSave(t *testing.T) {
 		// OK(t, repo.SaveIndex())
 
 		// read back
-		buf, err := repo.LoadBlob(id, restic.DataBlob, make([]byte, size))
+		buf := make([]byte, size)
+		n, err := repo.LoadDataBlob(id, buf)
 		OK(t, err)
+		Equals(t, len(buf), n)
 
 		Assert(t, len(buf) == len(data),
 			"number of bytes read back does not match: expected %d, got %d",
@@ -122,8 +124,10 @@ func TestSaveFrom(t *testing.T) {
 		OK(t, repo.Flush())
 
 		// read back
-		buf, err := repo.LoadBlob(id, restic.DataBlob, make([]byte, size))
+		buf := make([]byte, size)
+		n, err := repo.LoadDataBlob(id, buf)
 		OK(t, err)
+		Equals(t, len(buf), n)
 
 		Assert(t, len(buf) == len(data),
 			"number of bytes read back does not match: expected %d, got %d",
@@ -157,7 +161,7 @@ func BenchmarkSaveAndEncrypt(t *testing.B) {
 	}
 }
 
-func TestLoadJSONPack(t *testing.T) {
+func TestLoadTree(t *testing.T) {
 	repo := SetupRepo()
 	defer TeardownRepo(repo)
 
@@ -169,12 +173,11 @@ func TestLoadJSONPack(t *testing.T) {
 	sn := SnapshotDir(t, repo, BenchArchiveDirectory, nil)
 	OK(t, repo.Flush())
 
-	tree := restic.NewTree()
-	err := repo.LoadJSONPack(restic.TreeBlob, *sn.Tree, &tree)
+	_, err := repo.LoadTree(*sn.Tree)
 	OK(t, err)
 }
 
-func BenchmarkLoadJSONPack(t *testing.B) {
+func BenchmarkLoadTree(t *testing.B) {
 	repo := SetupRepo()
 	defer TeardownRepo(repo)
 
@@ -186,12 +189,10 @@ func BenchmarkLoadJSONPack(t *testing.B) {
 	sn := SnapshotDir(t, repo, BenchArchiveDirectory, nil)
 	OK(t, repo.Flush())
 
-	tree := restic.NewTree()
-
 	t.ResetTimer()
 
 	for i := 0; i < t.N; i++ {
-		err := repo.LoadJSONPack(restic.TreeBlob, *sn.Tree, &tree)
+		_, err := repo.LoadTree(*sn.Tree)
 		OK(t, err)
 	}
 }
@@ -244,7 +245,7 @@ func BenchmarkLoadIndex(b *testing.B) {
 }
 
 // saveRandomDataBlobs generates random data blobs and saves them to the repository.
-func saveRandomDataBlobs(t testing.TB, repo *repository.Repository, num int, sizeMax int) {
+func saveRandomDataBlobs(t testing.TB, repo restic.Repository, num int, sizeMax int) {
 	for i := 0; i < num; i++ {
 		size := mrand.Int() % sizeMax
 
diff --git a/src/restic/test/backend.go b/src/restic/test/backend.go
index d73f0d4fe..e8710b8c8 100644
--- a/src/restic/test/backend.go
+++ b/src/restic/test/backend.go
@@ -49,7 +49,7 @@ func getBoolVar(name string, defaultValue bool) bool {
 	return defaultValue
 }
 
-func SetupRepo() *repository.Repository {
+func SetupRepo() restic.Repository {
 	tempdir, err := ioutil.TempDir(TestTempDir, "restic-test-")
 	if err != nil {
 		panic(err)
@@ -70,27 +70,29 @@ func SetupRepo() *repository.Repository {
 	return repo
 }
 
-func TeardownRepo(repo *repository.Repository) {
+func TeardownRepo(repo restic.Repository) {
 	if !TestCleanupTempDirs {
 		l := repo.Backend().(*local.Local)
 		fmt.Printf("leaving local backend at %s\n", l.Location())
 		return
 	}
 
-	err := repo.Delete()
-	if err != nil {
-		panic(err)
+	if r, ok := repo.(restic.Deleter); ok {
+		err := r.Delete()
+		if err != nil {
+			panic(err)
+		}
 	}
 }
 
-func SnapshotDir(t testing.TB, repo *repository.Repository, path string, parent *restic.ID) *restic.Snapshot {
+func SnapshotDir(t testing.TB, repo restic.Repository, path string, parent *restic.ID) *restic.Snapshot {
 	arch := archiver.New(repo)
 	sn, _, err := arch.Snapshot(nil, []string{path}, parent)
 	OK(t, err)
 	return sn
 }
 
-func WithRepo(t testing.TB, f func(*repository.Repository)) {
+func WithRepo(t testing.TB, f func(restic.Repository)) {
 	repo := SetupRepo()
 	f(repo)
 	TeardownRepo(repo)
diff --git a/src/restic/test/helpers.go b/src/restic/test/helpers.go
index 6c7ee8de1..2fbdb83d6 100644
--- a/src/restic/test/helpers.go
+++ b/src/restic/test/helpers.go
@@ -34,7 +34,7 @@ func Assert(tb testing.TB, condition bool, msg string, v ...interface{}) {
 func OK(tb testing.TB, err error) {
 	if err != nil {
 		_, file, line, _ := runtime.Caller(1)
-		fmt.Printf("\033[31m%s:%d: unexpected error: %s\033[39m\n\n", filepath.Base(file), line, err.Error())
+		fmt.Printf("\033[31m%s:%d: unexpected error: %+v\033[39m\n\n", filepath.Base(file), line, err)
 		tb.FailNow()
 	}
 }
@@ -209,7 +209,7 @@ func WithTestEnvironment(t testing.TB, repoFixture string, f func(repodir string
 }
 
 // OpenLocalRepo opens the local repository located at dir.
-func OpenLocalRepo(t testing.TB, dir string) *repository.Repository {
+func OpenLocalRepo(t testing.TB, dir string) restic.Repository {
 	be, err := local.Open(dir)
 	OK(t, err)
 
diff --git a/src/restic/testing.go b/src/restic/testing.go
index e4fe6ddb3..9b6b627c8 100644
--- a/src/restic/testing.go
+++ b/src/restic/testing.go
@@ -8,8 +8,9 @@ import (
 	"testing"
 	"time"
 
-	"github.com/restic/chunker"
 	"restic/errors"
+
+	"github.com/restic/chunker"
 )
 
 // fakeFile returns a reader which yields deterministic pseudo-random data.
diff --git a/src/restic/walk/walk_test.go b/src/restic/walk/walk_test.go
index 221f5df9c..681c2f1e6 100644
--- a/src/restic/walk/walk_test.go
+++ b/src/restic/walk/walk_test.go
@@ -10,7 +10,6 @@ import (
 	"restic"
 	"restic/archiver"
 	"restic/pipe"
-	"restic/repository"
 	. "restic/test"
 	"restic/walk"
 )
@@ -91,7 +90,7 @@ func TestWalkTree(t *testing.T) {
 }
 
 type delayRepo struct {
-	repo  *repository.Repository
+	repo  restic.Repository
 	delay time.Duration
 }