feat: Add key generation support for age

cmd/stbak/cmd/keygen.go

@@ -0,0 +1,94 @@
+package cmd
+
+import (
+	"bytes"
+	"io"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+
+	"filippo.io/age"
+	"github.com/spf13/cobra"
+	"github.com/spf13/viper"
+	"github.com/volatiletech/sqlboiler/v4/boil"
+)
+
+var keygenCmd = &cobra.Command{
+	Use:     "keygen",
+	Aliases: []string{"key", "k"},
+	Short:   "Restore a file or directory from tape or tar file",
+	RunE: func(cmd *cobra.Command, args []string) error {
+		if err := viper.BindPFlags(cmd.PersistentFlags()); err != nil {
+			return err
+		}
+
+		if viper.GetBool(verboseFlag) {
+			boil.DebugMode = true
+		}
+
+		pubkey := ""
+		privkey := ""
+
+		switch viper.GetString(encryptionFlag) {
+		case encryptionFormatAgeKey:
+			identity, err := age.GenerateX25519Identity()
+			if err != nil {
+				return err
+			}
+
+			pubkey = identity.Recipient().String()
+			privkey = identity.String()
+
+			if password := viper.GetString(passwordFlag); password != "" {
+				passwordRecipient, err := age.NewScryptRecipient(password)
+				if err != nil {
+					return err
+				}
+
+				out := &bytes.Buffer{}
+				w, err := age.Encrypt(out, passwordRecipient)
+				if err != nil {
+					return err
+				}
+
+				if _, err := io.WriteString(w, privkey); err != nil {
+					return err
+				}
+
+				if err := w.Close(); err != nil {
+					return err
+				}
+
+				privkey = out.String()
+			}
+		default:
+			return errKeygenForEncryptionFormatUnsupported
+		}
+
+		// Write pubkey (read/writable by everyone)
+		if err := os.MkdirAll(filepath.Dir(viper.GetString(recipientFlag)), os.ModePerm); err != nil {
+			return err
+		}
+
+		if err := ioutil.WriteFile(viper.GetString(recipientFlag), []byte(pubkey), os.ModePerm); err != nil {
+			return err
+		}
+
+		// Write privkey (read/writable only by the owner)
+		if err := os.MkdirAll(filepath.Dir(viper.GetString(identityFlag)), 0700); err != nil {
+			return err
+		}
+
+		return ioutil.WriteFile(viper.GetString(identityFlag), []byte(privkey), 0600)
+	},
+}
+
+func init() {
+	keygenCmd.PersistentFlags().StringP(recipientFlag, "r", "", "Path to write the public key to")
+	keygenCmd.PersistentFlags().StringP(identityFlag, "i", "", "Path to write the private key to")
+	keygenCmd.PersistentFlags().StringP(passwordFlag, "p", "", "Password to protect the private key with")
+
+	viper.AutomaticEnv()
+
+	rootCmd.AddCommand(keygenCmd)
+}

cmd/stbak/cmd/root.go

@@ -57,8 +57,9 @@ var (
 
 	knownEncryptionFormats = []string{encryptionFormatNoneKey, encryptionFormatAgeKey, encryptionFormatPGPKey}
 
-	errUnknownEncryptionFormat     = errors.New("unknown encryption format")
-	errUnsupportedEncryptionFormat = errors.New("unsupported encryption format")
+	errUnknownEncryptionFormat              = errors.New("unknown encryption format")
+	errUnsupportedEncryptionFormat          = errors.New("unsupported encryption format")
+	errKeygenForEncryptionFormatUnsupported = errors.New("can not generate keys for this encryption format")
 )
 
 var rootCmd = &cobra.Command{