Parse the age identity key once and accept every identity in it (closes #165)

Restore and verify --deep now parse the configured age secret key a single time through a new helper that uses age.ParseIdentities and hands every identity to age.Decrypt. A key file with several identities (a whole age-keygen file) is fully accepted, so a blob encrypted to any of its recipients decrypts, not just the first.

The helper is the first step of both commands, so a missing or unparseable key fails before anything is downloaded. Its error names the config source and never echoes the key value. config.extractAgeSecretKey and its silent fallback are removed; the key is stored raw and parsed only where decryption happens. README, the restore help, and the missing-key error now read the key from a file with \$(cat ...) rather than typed literally, keeping it out of shell history.

Model: opus-4-8

internal/vaultik/verify.go

@@ -94,11 +94,10 @@ func (v *Vaultik) RunDeepVerify(snapshotID string, opts *VerifyOptions) error {
 	}
 
 	// Parse the age secret key once, the same way restore does, and reuse
-	// the identity for the database and every blob.
-	identity, err := v.prepareRestoreIdentity()
+	// the identities for the database and every blob.
+	identities, err := v.restoreIdentities()
 	if err != nil {
-		return v.deepVerifyFailure(result, opts,
-			fmt.Sprintf("parsing age secret key: %v", err), err)
+		return v.deepVerifyFailure(result, opts, err.Error(), err)
 	}
 
 	log.Info("Starting snapshot verification", "snapshot_id", snapshotID, "mode", "deep")
@@ -108,7 +107,7 @@ func (v *Vaultik) RunDeepVerify(snapshotID string, opts *VerifyOptions) error {
 	}
 
 	manifest, tempDB, dbBlobs, err := v.loadVerificationData(
-		snapshotID, opts, result, identity)
+		snapshotID, opts, result, identities)
 	if err != nil {
 		return err
 	}
@@ -129,7 +128,7 @@ func (v *Vaultik) RunDeepVerify(snapshotID string, opts *VerifyOptions) error {
 	result.TotalSize = totalSize
 
 	err = v.runVerificationSteps(
-		manifest, dbBlobs, tempDB, opts, result, totalSize, identity)
+		manifest, dbBlobs, tempDB, opts, result, totalSize, identities)
 	if err != nil {
 		return err
 	}
@@ -154,7 +153,7 @@ func (v *Vaultik) RunDeepVerify(snapshotID string, opts *VerifyOptions) error {
 // loadVerificationData downloads manifest, database, and blob list for verification
 func (v *Vaultik) loadVerificationData(
 	snapshotID string, opts *VerifyOptions, result *VerifyResult,
-	identity age.Identity,
+	identities []age.Identity,
 ) (*snapshot.Manifest, *tempDB, []snapshot.BlobInfo, error) {
 	// Resolve the identifier to the snapshot's remote key. A human ID is
 	// hashed; a remote key (or its abbreviation, as printed for a
@@ -191,7 +190,8 @@ func (v *Vaultik) loadVerificationData(
 		v.stdoutf("Downloading and decrypting database...\n")
 	}
 
-	tdb, err := v.downloadVerifiedSnapshotDB(snapshotID, remoteKey, opts, result, identity)
+	tdb, err := v.downloadVerifiedSnapshotDB(
+		snapshotID, remoteKey, opts, result, identities)
 	if err != nil {
 		return nil, nil, nil, err
 	}
@@ -230,7 +230,7 @@ func (v *Vaultik) loadVerificationData(
 // identity so nothing is left on disk.
 func (v *Vaultik) downloadVerifiedSnapshotDB(
 	snapshotID, remoteKey string, opts *VerifyOptions, result *VerifyResult,
-	identity age.Identity,
+	identities []age.Identity,
 ) (*tempDB, error) {
 	dbPath := fmt.Sprintf("metadata/%s/db.zst.age", remoteKey)
 	log.Info("Downloading encrypted database", "path", dbPath)
@@ -244,7 +244,7 @@ func (v *Vaultik) downloadVerifiedSnapshotDB(
 
 	defer func() { _ = dbReader.Close() }()
 
-	tdb, err := v.decryptAndLoadDatabase(dbReader, identity)
+	tdb, err := v.decryptAndLoadDatabase(dbReader, identities)
 	if err != nil {
 		return nil, v.deepVerifyFailure(result, opts,
 			fmt.Sprintf("failed to decrypt database: %v", err),
@@ -270,7 +270,7 @@ func (v *Vaultik) runVerificationSteps(
 	opts *VerifyOptions,
 	result *VerifyResult,
 	totalSize int64,
-	identity age.Identity,
+	identities []age.Identity,
 ) error {
 	if !opts.JSON {
 		v.stdoutf("Verifying manifest against database...\n")
@@ -297,7 +297,7 @@ func (v *Vaultik) runVerificationSteps(
 			len(dbBlobs), ubytes(totalSize))
 	}
 
-	err = v.performDeepVerificationFromDB(dbBlobs, tdb.db.Conn(), opts, identity)
+	err = v.performDeepVerificationFromDB(dbBlobs, tdb.db.Conn(), opts, identities)
 	if err != nil {
 		return v.deepVerifyFailure(result, opts, err.Error(), err)
 	}
@@ -325,10 +325,10 @@ func (t *tempDB) Close() error {
 // from the encrypted stream. It reads through the same blobgen reader restore
 // uses, streaming the decrypted, decompressed database to a temp file.
 func (v *Vaultik) decryptAndLoadDatabase(
-	reader io.ReadCloser, identity age.Identity,
+	reader io.ReadCloser, identities []age.Identity,
 ) (*tempDB, error) {
 	// Decrypt and decompress through the shared blobgen reader.
-	blobReader, err := blobgen.NewReader(reader, identity)
+	blobReader, err := blobgen.NewReader(reader, identities...)
 	if err != nil {
 		return nil, fmt.Errorf("failed to create decryption reader: %w", err)
 	}
@@ -389,7 +389,7 @@ func (v *Vaultik) decryptAndLoadDatabase(
 
 // verifyBlob downloads and verifies a single blob
 func (v *Vaultik) verifyBlob(
-	blobInfo snapshot.BlobInfo, db *sql.DB, identity age.Identity,
+	blobInfo snapshot.BlobInfo, db *sql.DB, identities []age.Identity,
 ) error {
 	// Download blob using shared fetch method
 	reader, _, err := v.FetchBlob(v.ctx, blobInfo.Hash, blobInfo.CompressedSize)
@@ -403,7 +403,7 @@ 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 := blobgen.NewReader(reader, identity)
+	blobReader, err := blobgen.NewReader(reader, identities...)
 	if err != nil {
 		return fmt.Errorf("failed to create blob reader: %w", err)
 	}
@@ -687,7 +687,7 @@ func (v *Vaultik) verifyBlobExistenceFromDB(blobs []snapshot.BlobInfo) error {
 // each blob using the database as source.
 func (v *Vaultik) performDeepVerificationFromDB(
 	blobs []snapshot.BlobInfo, db *sql.DB, opts *VerifyOptions,
-	identity age.Identity,
+	identities []age.Identity,
 ) error {
 	// Calculate total bytes for ETA
 	var totalBytesExpected int64
@@ -705,7 +705,7 @@ func (v *Vaultik) performDeepVerificationFromDB(
 
 	for i, blobInfo := range blobs {
 		// Verify individual blob
-		err := v.verifyBlob(blobInfo, db, identity)
+		err := v.verifyBlob(blobInfo, db, identities)
 		if err != nil {
 			return fmt.Errorf("blob %s verification failed: %w", blobInfo.Hash, err)
 		}