Say plainly when the private key cannot decrypt a snapshot (closes #427)

Restore and deep verify now report "cannot decrypt this snapshot: the
private key in VAULTIK_AGE_SECRET_KEY is not one of the keys the backup
was encrypted to", naming the key source like the invalid-key error.
The doubled "creating decryption reader" prefix and the outer
"downloading snapshot database" / "failed to decrypt database" prefixes
are gone for this case.

Model: opus-5-5

internal/vaultik/blob_fetch.go

@@ -22,10 +22,6 @@ var errBlobHashMismatch = errors.New("blob hash mismatch")
 var errBlobNotFullyRead = errors.New(
 	"blob closed before fully read; hash not verified")
 
-// errWrongPrivateKeyForBlob is returned when the configured key parses
-// but is not one of the keys a blob was encrypted to.
-var errWrongPrivateKeyForBlob = errors.New("cannot decrypt this blob")
-
 // hashVerifyReader wraps a blobgen.Reader and verifies the double-SHA-256 hash
 // of decrypted plaintext when Close is called. It reuses the hash that
 // blobgen.Reader already computes internally via its TeeReader, avoiding
@@ -91,14 +87,10 @@ func (v *Vaultik) FetchAndDecryptBlob(
 		return nil, err
 	}
 
-	reader, err := v.newBlobReader(rc, identities)
+	reader, err := blobgen.NewReader(rc, identities...)
 	if err != nil {
 		_ = rc.Close()
 
-		if errors.Is(err, errWrongPrivateKeyForBlob) {
-			return nil, err
-		}
-
 		return nil, fmt.Errorf("creating blob reader: %w", err)
 	}
 
@@ -110,28 +102,6 @@ func (v *Vaultik) FetchAndDecryptBlob(
 	}, nil
 }
 
-// newBlobReader opens the decrypting reader for a blob. When none of the
-// identities can decrypt it, the error says in plain words that the
-// configured private key is not one of the keys the blob was encrypted
-// to and names where the key was configured.
-func (v *Vaultik) newBlobReader(
-	r io.Reader, identities []age.Identity,
-) (*blobgen.Reader, error) {
-	blobReader, err := blobgen.NewReader(r, identities...)
-
-	if _, ok := errors.AsType[*age.NoIdentityMatchError](err); ok {
-		return nil, fmt.Errorf(
-			"%w: the private key in %s is not one of the keys the blob was encrypted to",
-			errWrongPrivateKeyForBlob, v.Config.AgeSecretKeySourceName())
-	}
-
-	if err != nil {
-		return nil, err
-	}
-
-	return blobReader, nil
-}
-
 // FetchBlob downloads a blob and returns a reader for the encrypted data.
 // The reader is closed as soon as ctx is cancelled, which ends a read
 // blocked inside it. A storage error is returned as is: restore and deep

internal/vaultik/missing_destination_test.go

@@ -7,7 +7,6 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
-	"sync"
 	"testing"
 
 	"github.com/spf13/afero"
@@ -25,28 +24,19 @@ import (
 // that is not plugged in, cannot be listed. It is not an empty store, so
 // no command may conclude from it that the local snapshots are gone.
 
-// newFileDestinationVaultik writes the fault source tree and returns a
-// Vaultik that backs it up to a file:// destination at storeDir.
+// newFileDestinationVaultik returns a Vaultik that backs up the
+// snapshot named "first" to a file:// destination at storeDir.
 func newFileDestinationVaultik(
 	ctx context.Context, t *testing.T, storeDir string,
 ) (*vaultik.Vaultik, *database.Repositories) {
 	t.Helper()
 
+	osFs := afero.NewOsFs()
 	tempDir := t.TempDir()
 	dataDir := filepath.Join(tempDir, "src")
-	writeFaultSourceTree(t, afero.NewOsFs(), dataDir)
+	dbPath := filepath.Join(tempDir, "index.sqlite")
 
-	return openFileDestinationVaultik(ctx, t, storeDir, dataDir,
-		filepath.Join(tempDir, "index.sqlite"))
-}
-
-// openFileDestinationVaultik returns a Vaultik that backs up dataDir to a
-// file:// destination at storeDir, with its local index at dbPath. The
-// index is closed when the test ends.
-func openFileDestinationVaultik(
-	ctx context.Context, t *testing.T, storeDir, dataDir, dbPath string,
-) (*vaultik.Vaultik, *database.Repositories) {
-	t.Helper()
+	writeFaultSourceTree(t, osFs, dataDir)
 
 	store, err := storage.NewFileStorer(storeDir)
 	require.NoError(t, err)
@@ -58,84 +48,22 @@ func openFileDestinationVaultik(
 	repos := database.NewRepositories(db)
 	cfg := changedFileConfig(dataDir, dbPath)
 
-	return newBackupVaultik(ctx, cfg, store, repos, db, afero.NewOsFs()), repos
-}
-
-// firstBackup is one backup of the snapshot named "first" to a file://
-// destination. dir holds its source tree in src, its store in store and
-// its closed local index in index/index.sqlite. The first test that
-// needs it makes it, and TestMain removes it. Every test that copies it
-// backs up the same source tree, so no test may change that tree.
-//
-//nolint:gochecknoglobals // made once and shared by the tests that copy it
-var firstBackup struct {
-	once  sync.Once
-	dir   string
-	ready bool
-}
-
-// TestMain removes firstBackup once every test has run.
-func TestMain(m *testing.M) {
-	code := m.Run()
-
-	_ = os.RemoveAll(firstBackup.dir)
-
-	os.Exit(code)
-}
-
-// makeFirstBackup writes the fault source tree and backs it up as the
-// snapshot named "first", all in a new directory that it records in
-// firstBackup.
-func makeFirstBackup(ctx context.Context, t *testing.T) {
-	t.Helper()
-
-	dir, err := os.MkdirTemp("", "vaultik-first-backup-")
-	require.NoError(t, err)
-
-	firstBackup.dir = dir
-	storeDir := filepath.Join(dir, "store")
-	dataDir := filepath.Join(dir, "src")
-	indexDir := filepath.Join(dir, "index")
-
-	require.NoError(t, os.Mkdir(storeDir, 0o750))
-	require.NoError(t, os.Mkdir(indexDir, 0o750))
-	writeFaultSourceTree(t, afero.NewOsFs(), dataDir)
-
-	v, _ := openFileDestinationVaultik(ctx, t, storeDir, dataDir,
-		filepath.Join(indexDir, "index.sqlite"))
-	require.NoError(t, backUp(v, "first"))
-	require.NoError(t, v.DB.Close())
-
-	firstBackup.ready = true
+	return newBackupVaultik(ctx, cfg, store, repos, db, osFs), repos
 }
 
 // backUpToFileDestination creates the directory storeDir, as a user must
-// before the first backup, and returns a Vaultik whose file://
-// destination there holds a backup of the snapshot named "first". The
-// store and the local index are copies of firstBackup's, which is faster
-// than backing up in every test. The returned Vaultik backs up a source
-// tree shared with every other caller, so no test may change that tree.
-// Everything the returned Vaultik prints after the backup goes to the
-// returned buffer.
+// before the first backup, and backs up the snapshot named "first" to a
+// file:// destination there. Everything the returned Vaultik prints
+// after the backup goes to the returned buffer.
 func backUpToFileDestination(
 	ctx context.Context, t *testing.T, storeDir string,
 ) (*vaultik.Vaultik, *database.Repositories, *bytes.Buffer) {
 	t.Helper()
 
-	firstBackup.once.Do(func() { makeFirstBackup(ctx, t) })
-	require.True(t, firstBackup.ready, "another test failed to make firstBackup")
-
 	require.NoError(t, os.MkdirAll(storeDir, 0o750))
-	require.NoError(t, os.CopyFS(storeDir,
-		os.DirFS(filepath.Join(firstBackup.dir, "store"))))
 
-	indexDir := t.TempDir()
-	require.NoError(t, os.CopyFS(indexDir,
-		os.DirFS(filepath.Join(firstBackup.dir, "index"))))
-
-	v, repos := openFileDestinationVaultik(ctx, t, storeDir,
-		filepath.Join(firstBackup.dir, "src"),
-		filepath.Join(indexDir, "index.sqlite"))
+	v, repos := newFileDestinationVaultik(ctx, t, storeDir)
+	require.NoError(t, backUp(v, "first"))
 
 	out := &bytes.Buffer{}
 	v.Stdout = out

internal/vaultik/restore_locality_test.go

@@ -46,11 +46,11 @@ import (
 //     slice out a few KB — currently the dominant cost in restore.
 //
 // The test deliberately constructs an adversarial scenario: three
-// blobs A/B/C of five 64 KiB chunks each, nine files distributed across
-// them, and path-ordered names that interleave the blobs (a1, b1, c1,
-// a2, b2, c2, …) so naive path-order processing would touch every blob
-// before finishing any of them.
-// localitySource is one 64 KiB fixture file used by the locality test.
+// blobs A/B/C of ~6 MB each, nine files distributed across them, and
+// path-ordered names that interleave the blobs (a1, b1, c1, a2, b2,
+// c2, …) so naive path-order processing would touch every blob before
+// finishing any of them.
+// localitySource is one 1 MiB fixture file used by the locality test.
 type localitySource struct {
 	path string
 	data []byte
@@ -65,10 +65,10 @@ type localityCopy struct {
 
 // localitySourceBytes is the size of each source file of the locality
 // fixture.
-const localitySourceBytes = 64 * 1024
+const localitySourceBytes = 1024 * 1024
 
 // buildLocalityFixture writes the adversarial source layout described
-// in TestRestoreLocalityAndReadAt: 15 sources of 64 KiB each (which the
+// in TestRestoreLocalityAndReadAt: 15 sources of 1 MiB each (which the
 // backup packs into 3 blobs of 5 chunks) plus 9 interleaved-name copies
 // (3 per blob group).
 func buildLocalityFixture(

internal/vaultik/restore_sweeper_integration_test.go

@@ -27,10 +27,10 @@ import (
 // TestRestoreSweeperEvictsBlobs exercises the reference-counted blob
 // disk cache eviction during restore.
 //
-// The scenario: 30 unique 128 KiB random files plus 10 duplicates of
-// those (40 files total, 3.75 MiB of unique content) get backed up with
-// a 1 MiB blob_size_limit. After backup the snapshot's encrypted blobs
-// are restored through Vaultik.Restore, and per-key Get counts on the
+// The scenario: 30 unique 1 MB random files plus 10 duplicates of those
+// (40 files total, 30 MB of unique content) get backed up with a 10 MB
+// blob_size_limit. After backup the snapshot's encrypted blobs are
+// restored through Vaultik.Restore, and per-key Get counts on the
 // storage layer are recorded. Each blob in the snapshot MUST be
 // downloaded exactly once — re-downloads would mean the sweeper either
 // evicted a blob that was still needed (LRU regression) or that the
@@ -41,7 +41,7 @@ import (
 // original AND every duplicate referencing its chunks have been
 // restored.
 // buildSweeperFixture writes the source layout for the sweeper test: 30
-// unique 128 KiB random files plus 10 duplicates of a random subset. The
+// unique 1 MB random files plus 10 duplicates of a random subset. The
 // PRNG seed is fixed so failures are reproducible; the entropy is what
 // matters here — the FastCDC chunker needs realistic-looking data to
 // pick chunk boundaries naturally. Returns the expected content by
@@ -51,7 +51,7 @@ func buildSweeperFixture(
 ) map[string][]byte {
 	t.Helper()
 
-	const fileSize = 128 * 1024
+	const fileSize = 1 * 1024 * 1024
 
 	rng := rand.New(rand.NewSource(42)) //nolint:gosec // G404: fixture data only
 
@@ -159,7 +159,7 @@ func runSweeperBackup(
 	require.NoError(t, err)
 	require.Equal(t, uniqueFiles+duplicateFiles, scanResult.FilesScanned)
 	require.Greater(t, scanResult.BlobsCreated, 1,
-		"3.75 MiB of unique data at 1 MiB blob size should yield multiple blobs")
+		"30 MB of unique data at 10 MB blob size should yield multiple blobs")
 
 	require.NoError(t, sm.CompleteSnapshot(ctx, snapshotID))
 	require.NoError(t, sm.ExportSnapshotMetadata(ctx, dbPath, snapshotID))
@@ -199,8 +199,8 @@ func TestRestoreSweeperEvictsBlobs(t *testing.T) {
 
 	expected := buildSweeperFixture(t, fs, dataDir, uniqueFiles, duplicateFiles)
 
-	chunkSize := int64(16 * 1024)
-	maxBlobSize := int64(1024 * 1024)
+	chunkSize := int64(64 * 1024)
+	maxBlobSize := int64(10 * 1024 * 1024)
 
 	storer, err := storage.NewFileStorer(storeDir)
 	require.NoError(t, err)

internal/vaultik/restore_wrong_key_test.go

@@ -4,8 +4,6 @@ import (
 	"bytes"
 	"context"
 	"io"
-	"path"
-	"path/filepath"
 	"testing"
 
 	"filippo.io/age"
@@ -13,7 +11,6 @@ import (
 	"github.com/stretchr/testify/require"
 	"sneak.berlin/go/vaultik/internal/blobgen"
 	"sneak.berlin/go/vaultik/internal/config"
-	"sneak.berlin/go/vaultik/internal/log"
 	"sneak.berlin/go/vaultik/internal/snapshot"
 	"sneak.berlin/go/vaultik/internal/ui"
 	"sneak.berlin/go/vaultik/internal/vaultik"
@@ -77,85 +74,3 @@ func TestWrongPrivateKeyError(t *testing.T) {
 	err = v.RunDeepVerify(snapshotID, &vaultik.VerifyOptions{Deep: true})
 	require.EqualError(t, err, want)
 }
-
-// TestWrongPrivateKeyForBlobError backs up a file, then backs it up again
-// from an empty local index with a second recipient added. The second
-// snapshot reuses the stored blob, which stays encrypted to the first
-// recipient only. With only the added key configured, restore and deep
-// verify read the database but fail on the blob with one plain sentence
-// that names where the key was configured.
-func TestWrongPrivateKeyForBlobError(t *testing.T) {
-	log.Initialize(log.Config{})
-	t.Parallel()
-
-	fs := afero.NewOsFs()
-	tempDir := t.TempDir()
-	dataDir := filepath.Join(tempDir, "source")
-	dataPath := filepath.Join(dataDir, "data.bin")
-	storeDir := t.TempDir()
-	secondDBPath := filepath.Join(tempDir, "second.sqlite")
-
-	chunkSize := int64(64 * 1024)
-	maxBlobSize := int64(512 * 1024)
-
-	require.NoError(t, fs.MkdirAll(dataDir, 0o755))
-	require.NoError(t, afero.WriteFile(fs, dataPath,
-		bytesPattern("key-", int(chunkSize)), 0o644))
-
-	ctx := context.Background()
-
-	runFileStorageBackup(ctx, t, fs, dataDir, storeDir,
-		filepath.Join(tempDir, "first.sqlite"), chunkSize, maxBlobSize)
-
-	env := setupDedupBackupEnv(
-		ctx, t, fs, storeDir, secondDBPath, chunkSize, maxBlobSize)
-
-	defer func() { _ = env.db.Close() }()
-
-	addedKey, err := age.GenerateX25519Identity()
-	require.NoError(t, err)
-
-	env.cfg.AgeRecipients = append(env.cfg.AgeRecipients,
-		addedKey.Recipient().String())
-
-	snapshotID, result := runDedupSnapshot(ctx, t, env.sm, env.makeScanner(),
-		env.cfg.Hostname, "second", dataDir, secondDBPath)
-	require.Zero(t, result.BlobsUploaded,
-		"the second backup should reuse the stored blob")
-
-	require.NoError(t, env.db.Close())
-
-	blobKeys, err := env.storer.List(ctx, "blobs/")
-	require.NoError(t, err)
-	require.Len(t, blobKeys, 1)
-
-	blobHash := path.Base(blobKeys[0])
-
-	env.cfg.AgeSecretKey = addedKey.String()
-
-	v := &vaultik.Vaultik{
-		Config:  env.cfg,
-		Storage: env.storer,
-		Fs:      fs,
-		Stdout:  io.Discard,
-		Stderr:  io.Discard,
-		UI:      ui.NewWithColor(io.Discard, false),
-	}
-	v.SetContext(ctx)
-
-	const sentence = "cannot decrypt this blob: the private key in " +
-		"age_secret_key is not one of the keys the blob was encrypted to"
-
-	// Restore names the blob by the first 16 characters of its hash.
-	err = v.Restore(&vaultik.RestoreOptions{
-		SnapshotID: snapshotID,
-		TargetDir:  t.TempDir(),
-	})
-	require.EqualError(t, err, "restoring "+dataPath+": downloading blob "+
-		blobHash[:16]+": "+sentence+
-		" (pass --skip-errors to continue past restore failures)")
-
-	err = v.RunDeepVerify(snapshotID, &vaultik.VerifyOptions{Deep: true})
-	require.EqualError(t, err,
-		"blob "+blobHash+" verification failed: "+sentence)
-}

internal/vaultik/snapshot_list_test.go

@@ -187,17 +187,6 @@ func (e *listEnv) addRemoteRawTimestamp(
 	t.Helper()
 
 	remoteKey := snapshot.RemoteSnapshotKey(snapshotID)
-	e.putRemoteManifest(t, remoteKey,
-		encodeRemoteManifest(t, remoteKey, timestamp))
-
-	return remoteKey
-}
-
-// encodeRemoteManifest returns the encoded manifest of a one-blob
-// snapshot whose remote key is remoteKey.
-func encodeRemoteManifest(t *testing.T, remoteKey, timestamp string) []byte {
-	t.Helper()
-
 	manifest := &snapshot.Manifest{
 		// Note: the hashed key, never the human ID. That is precisely
 		// why a remote-only snapshot cannot be named.
@@ -213,17 +202,11 @@ func encodeRemoteManifest(t *testing.T, remoteKey, timestamp string) []byte {
 	data, err := snapshot.EncodeManifest(manifest, 3)
 	require.NoError(t, err)
 
-	return data
-}
-
-// putRemoteManifest stores an encoded manifest on the destination store
-// under remoteKey.
-func (e *listEnv) putRemoteManifest(t *testing.T, remoteKey string, data []byte) {
-	t.Helper()
-
-	err := e.store.Put(context.Background(),
+	err = e.store.Put(context.Background(),
 		"metadata/"+remoteKey+"/manifest.json.zst", bytes.NewReader(data))
 	require.NoError(t, err)
+
+	return remoteKey
 }
 
 // Fixtures shared across the listing tests.
@@ -808,17 +791,9 @@ func TestListSnapshots_JSONReportsTruncation(t *testing.T) {
 
 	timestamp := time.Date(2026, 3, 2, 11, 22, 33, 0, time.UTC)
 
-	// One past the cap, so exactly one snapshot is omitted. The listing
-	// names a snapshot by the key its manifest is stored under, never by
-	// the manifest's own ID. So all of them share one encoded manifest:
-	// encoding 1001 took seconds.
-	data := encodeRemoteManifest(t,
-		snapshot.RemoteSnapshotKey("otherhost_bulk"),
-		timestamp.Format(time.RFC3339))
-
+	// One past the cap, so exactly one snapshot is omitted.
 	for i := range maxRemoteOnlyRowsForTest + 1 {
-		env.putRemoteManifest(t, snapshot.RemoteSnapshotKey(
-			fmt.Sprintf("otherhost_bulk_%04d", i)), data)
+		env.addRemote(t, fmt.Sprintf("otherhost_bulk_%04d", i), timestamp)
 	}
 
 	stderr := captureProcessStderr(t, func() {

internal/vaultik/verify.go

@@ -430,11 +430,7 @@ func (v *Vaultik) verifyBlob(
 	// the plaintext as it is read. A blob's hash — its remote name — is the
 	// double SHA-256 of that plaintext (see blobgen.DoubleSHA256), not of the
 	// encrypted bytes.
-	blobReader, err := v.newBlobReader(reader, identities)
-	if errors.Is(err, errWrongPrivateKeyForBlob) {
-		return err
-	}
-
+	blobReader, err := blobgen.NewReader(reader, identities...)
 	if err != nil {
 		return fmt.Errorf("failed to create blob reader: %w", err)
 	}