diff --git a/cmds/portmaster-start/main.go b/cmds/portmaster-start/main.go
index e0430ef7..96801174 100644
--- a/cmds/portmaster-start/main.go
+++ b/cmds/portmaster-start/main.go
@@ -34,6 +34,10 @@ var (
 		UpdateURLs: []string{
 			"https://updates.safing.io",
 		},
+		Verification: helper.VerificationConfig,
+		// FIXME: Add:
+		// integrity check: pretty much the same as "jess verify"
+		// integrity fix: same as check, but delete broken stuff and download again
 		DevMode: false,
 		Online:  true, // is disabled later based on command
 	}
diff --git a/cmds/updatemgr/sign.go b/cmds/updatemgr/sign.go
new file mode 100644
index 00000000..e66b8cfd
--- /dev/null
+++ b/cmds/updatemgr/sign.go
@@ -0,0 +1,268 @@
+package main
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/spf13/cobra"
+
+	"github.com/safing/jess"
+	"github.com/safing/jess/filesig"
+	"github.com/safing/jess/truststores"
+	"github.com/safing/portbase/formats/dsd"
+	"github.com/safing/portbase/updater"
+)
+
+const letterFileExtension = ".letter"
+
+func init() {
+	rootCmd.AddCommand(signCmd)
+	signCmd.PersistentFlags().StringVarP(&envelopeName, "envelope", "", "",
+		"specify envelope name used for signing",
+	)
+	_ = signCmd.MarkFlagRequired("envelope")
+	signCmd.PersistentFlags().StringVarP(&trustStoreDir, "tsdir", "", "",
+		"specify a truststore directory (default loaded from JESS_TS_DIR env variable)",
+	)
+	signCmd.PersistentFlags().StringVarP(&trustStoreKeyring, "tskeyring", "", "",
+		"specify a truststore keyring namespace (default loaded from JESS_TS_KEYRING env variable) - lower priority than tsdir",
+	)
+	signCmd.AddCommand(signIndexCmd)
+}
+
+var (
+	signCmd = &cobra.Command{
+		Use:   "sign",
+		Short: "Sign resources",
+		RunE:  sign,
+		Args:  cobra.NoArgs,
+	}
+	signIndexCmd = &cobra.Command{
+		Use:   "index",
+		Short: "Sign indexes",
+		RunE:  signIndex,
+		Args:  cobra.ExactArgs(1),
+	}
+
+	envelopeName string
+)
+
+func sign(cmd *cobra.Command, args []string) error {
+	// Setup trust store.
+	trustStore, err := setupTrustStore()
+	if err != nil {
+		return err
+	}
+
+	// Get envelope.
+	signingEnvelope, err := trustStore.GetEnvelope(envelopeName)
+	if err != nil {
+		return err
+	}
+
+	// Get all resources and iterate over all versions.
+	export := registry.Export()
+	var fails int
+	for _, rv := range export {
+		for _, version := range rv.Versions {
+			file := version.GetFile()
+
+			// Check if there is an existing signature.
+			_, err := os.Stat(file.Path() + filesig.Extension)
+			switch {
+			case err == nil || os.IsExist(err):
+				// If the file exists, just verify.
+				fileData, err := filesig.VerifyFile(
+					file.Path(),
+					file.Path()+filesig.Extension,
+					file.SigningMetadata(),
+					trustStore,
+				)
+				if err != nil {
+					fmt.Printf("[FAIL] signature error for %s: %s\n", file.Path(), err)
+					fails++
+				} else {
+					fmt.Printf("[ OK ] valid signature for %s: signed by %s\n", file.Path(), getSignedByMany(fileData, trustStore))
+				}
+
+			case os.IsNotExist(err):
+				// Attempt to sign file.
+				fileData, err := filesig.SignFile(
+					file.Path(),
+					file.Path()+filesig.Extension,
+					file.SigningMetadata(),
+					signingEnvelope,
+					trustStore,
+				)
+				if err != nil {
+					fmt.Printf("[FAIL] failed to sign %s: %s\n", file.Path(), err)
+					fails++
+				} else {
+					fmt.Printf("[SIGN] signed %s with %s\n", file.Path(), getSignedBySingle(fileData, trustStore))
+				}
+
+			default:
+				// File access error.
+				fmt.Printf("[FAIL] failed to access %s: %s\n", file.Path(), err)
+				fails++
+			}
+		}
+	}
+
+	if fails > 0 {
+		return fmt.Errorf("signing or checking failed on %d files", fails)
+	}
+	return nil
+}
+
+func signIndex(cmd *cobra.Command, args []string) error {
+	// FIXME:
+	// Do not sign embedded, but also as a separate file.
+	// Slightly more complex, but it makes all the other handling easier.
+
+	indexFilePath := args[0]
+
+	// Setup trust store.
+	trustStore, err := setupTrustStore()
+	if err != nil {
+		return err
+	}
+
+	// Get envelope.
+	signingEnvelope, err := trustStore.GetEnvelope(envelopeName)
+	if err != nil {
+		return err
+	}
+
+	// Read index file.
+	indexData, err := ioutil.ReadFile(indexFilePath)
+	if err != nil {
+		return fmt.Errorf("failed to read index file %s: %w", indexFilePath, err)
+	}
+
+	// Load index.
+	resourceVersions := make(map[string]string)
+	err = json.Unmarshal(indexData, &resourceVersions)
+	if err != nil {
+		return fmt.Errorf("failed to parse index file: %w", err)
+	}
+
+	// Create signed index file structure.
+	index := updater.IndexFile{
+		Channel:   strings.TrimSuffix(filepath.Base(indexFilePath), filepath.Ext(indexFilePath)),
+		Published: time.Now(),
+		Expires:   time.Now().Add(3 * 31 * 24 * time.Hour), // Expires in 3 Months.
+		Versions:  resourceVersions,
+	}
+
+	// Serialize index.
+	indexData, err = dsd.Dump(index, dsd.CBOR)
+	if err != nil {
+		return fmt.Errorf("failed to serialize index structure: %w", err)
+	}
+
+	// Sign index.
+	session, err := signingEnvelope.Correspondence(trustStore)
+	if err != nil {
+		return fmt.Errorf("failed to prepare signing: %w", err)
+	}
+	signedIndex, err := session.Close(indexData)
+	if err != nil {
+		return fmt.Errorf("failed to sign: %w", err)
+	}
+
+	// Write new file.
+	signedIndexData, err := signedIndex.ToDSD(dsd.CBOR)
+	if err != nil {
+		return fmt.Errorf("failed to serialize signed index: %w", err)
+	}
+	signedIndexFilePath := strings.TrimSuffix(indexFilePath, filepath.Ext(indexFilePath)) + letterFileExtension
+	err = ioutil.WriteFile(signedIndexFilePath, signedIndexData, 0o644) //nolint:gosec // Permission is ok.
+	if err != nil {
+		return fmt.Errorf("failed to write signed index to %s: %w", signedIndexFilePath, err)
+	}
+
+	return nil
+}
+
+var (
+	trustStoreDir     string
+	trustStoreKeyring string
+)
+
+func setupTrustStore() (trustStore truststores.ExtendedTrustStore, err error) {
+	// Get trust store directory.
+	if trustStoreDir == "" {
+		trustStoreDir, _ = os.LookupEnv("JESS_TS_DIR")
+		if trustStoreDir == "" {
+			trustStoreDir, _ = os.LookupEnv("JESS_TSDIR")
+		}
+	}
+	if trustStoreDir != "" {
+		trustStore, err = truststores.NewDirTrustStore(trustStoreDir)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	// Get trust store keyring.
+	if trustStore == nil {
+		if trustStoreKeyring == "" {
+			trustStoreKeyring, _ = os.LookupEnv("JESS_TS_KEYRING")
+			if trustStoreKeyring == "" {
+				trustStoreKeyring, _ = os.LookupEnv("JESS_TSKEYRING")
+			}
+		}
+		if trustStoreKeyring != "" {
+			trustStore, err = truststores.NewKeyringTrustStore(trustStoreKeyring)
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+
+	// Truststore is mandatory.
+	if trustStore == nil {
+		return nil, errors.New("no truststore configured, please pass arguments or use env variables")
+	}
+
+	return trustStore, nil
+}
+
+func getSignedByMany(fds []*filesig.FileData, trustStore jess.TrustStore) string {
+	signedBy := make([]string, 0, len(fds))
+	for _, fd := range fds {
+		if sig := fd.Signature(); sig != nil {
+			for _, seal := range sig.Signatures {
+				if signet, err := trustStore.GetSignet(seal.ID, true); err == nil {
+					signedBy = append(signedBy, fmt.Sprintf("%s (%s)", signet.Info.Name, seal.ID))
+				} else {
+					signedBy = append(signedBy, seal.ID)
+				}
+			}
+		}
+	}
+	return strings.Join(signedBy, " and ")
+}
+
+func getSignedBySingle(fd *filesig.FileData, trustStore jess.TrustStore) string {
+	if sig := fd.Signature(); sig != nil {
+		signedBy := make([]string, 0, len(sig.Signatures))
+		for _, seal := range sig.Signatures {
+			if signet, err := trustStore.GetSignet(seal.ID, true); err == nil {
+				signedBy = append(signedBy, fmt.Sprintf("%s (%s)", signet.Info.Name, seal.ID))
+			} else {
+				signedBy = append(signedBy, seal.ID)
+			}
+		}
+		return strings.Join(signedBy, " and ")
+	}
+
+	return ""
+}
diff --git a/updates/helper/indexes.go b/updates/helper/indexes.go
index e925be1a..d0722f34 100644
--- a/updates/helper/indexes.go
+++ b/updates/helper/indexes.go
@@ -5,6 +5,7 @@ import (
 	"os"
 	"path/filepath"
 
+	"github.com/safing/jess/filesig"
 	"github.com/safing/portbase/updater"
 )
 
@@ -103,9 +104,17 @@ func indexExists(registry *updater.ResourceRegistry, indexPath string) bool {
 }
 
 func deleteIndex(registry *updater.ResourceRegistry, indexPath string) error {
+	// Remove index itself.
 	err := os.Remove(filepath.Join(registry.StorageDir().Path, indexPath))
 	if err != nil && !os.IsNotExist(err) {
 		return err
 	}
+
+	// Remove any accompanying signature.
+	err = os.Remove(filepath.Join(registry.StorageDir().Path, indexPath+filesig.Extension))
+	if err != nil && !os.IsNotExist(err) {
+		return err
+	}
+
 	return nil
 }
diff --git a/updates/helper/signing.go b/updates/helper/signing.go
new file mode 100644
index 00000000..78ccab47
--- /dev/null
+++ b/updates/helper/signing.go
@@ -0,0 +1,42 @@
+package helper
+
+import (
+	"github.com/safing/jess"
+	"github.com/safing/portbase/updater"
+)
+
+var (
+	// VerificationConfig holds the complete verification configuration for the registry.
+	VerificationConfig = map[string]*updater.VerificationOptions{
+		"": { // Default.
+			TrustStore:     BinarySigningTrustStore,
+			DownloadPolicy: updater.SignaturePolicyRequire,
+			DiskLoadPolicy: updater.SignaturePolicyWarn,
+		},
+		"all/intel/": nil, // Disable until IntelHub supports signing.
+	}
+
+	// BinarySigningKeys holds the signing keys in text format.
+	BinarySigningKeys = []string{
+		// Safing Code Signing Key #1
+		"recipient:public-ed25519-key:safing-code-signing-key-1:92bgBLneQUWrhYLPpBDjqHbpFPuNVCPAaivQ951A4aq72HcTiw7R1QmPJwFM1mdePAvEVDjkeb8S4fp2pmRCsRa8HrCvWQEjd88rfZ6TznJMfY4g7P8ioGFjfpyx2ZJ8WCZJG5Qt4Z9nkabhxo2Nbi3iywBTYDLSbP5CXqi7jryW7BufWWuaRVufFFzhwUC2ryWFWMdkUmsAZcvXwde4KLN9FrkWAy61fGaJ8GCwGnGCSitANnU2cQrsGBXZzxmzxwrYD",
+		// Safing Code Signing Key #2
+		"recipient:public-ed25519-key:safing-code-signing-key-2:92bgBLneQUWrhYLPpBDjqHbPC2d1o5JMyZFdavWBNVtdvbPfzDewLW95ScXfYPHd3QvWHSWCtB4xpthaYWxSkK1kYiGp68DPa2HaU8yQ5dZhaAUuV4Kzv42pJcWkCeVnBYqgGBXobuz52rFqhDJy3rz7soXEmYhJEJWwLwMeioK3VzN3QmGSYXXjosHMMNC76rjufSoLNtUQUWZDSnHmqbuxbKMCCsjFXUGGhtZVyb7bnu7QLTLk6SKHBJDMB6zdL9sw3",
+	}
+
+	// BinarySigningTrustStore is an in-memory trust store with the signing keys.
+	BinarySigningTrustStore = jess.NewMemTrustStore()
+)
+
+func init() {
+	for _, signingKey := range BinarySigningKeys {
+		rcpt, err := jess.RecipientFromTextFormat(signingKey)
+		if err != nil {
+			panic(err)
+		}
+		err = BinarySigningTrustStore.StoreSignet(rcpt)
+		if err != nil {
+			panic(err)
+		}
+	}
+}
diff --git a/updates/main.go b/updates/main.go
index 434256cf..87b63b93 100644
--- a/updates/main.go
+++ b/updates/main.go
@@ -213,6 +213,15 @@ func DisableUpdateSchedule() error {
 var updateFailedCnt = new(atomic.Int32)
 
 func checkForUpdates(ctx context.Context) (err error) {
+	// Set correct error if context was canceled.
+	defer func() {
+		select {
+		case <-ctx.Done():
+			err = context.Canceled
+		default:
+		}
+	}()
+
 	if !forceUpdate.SetToIf(true, false) && !enableUpdates() {
 		log.Warningf("updates: automatic updates are disabled")
 		return nil