Add support for unpadded base64 filenames, "-raw64"

Through base64.RawURLEncoding.

New command-line parameter "-raw64".

cli_args.go

@@ -16,7 +16,7 @@ import (
 type argContainer struct {
 	debug, init, zerokey, fusedebug, openssl, passwd, foreground, version,
 	plaintextnames, quiet, nosyslog, wpanic,
-	longnames, allow_other, ro, reverse, aessiv, nonempty bool
+	longnames, allow_other, ro, reverse, aessiv, nonempty, raw64 bool
 	masterkey, mountpoint, cipherdir, cpuprofile, extpass,
 	memprofile, ko, passfile string
 	// Configuration file name override
@@ -103,6 +103,7 @@ func parseCliOpts() (args argContainer) {
 	flagSet.BoolVar(&args.reverse, "reverse", false, "Reverse mode")
 	flagSet.BoolVar(&args.aessiv, "aessiv", false, "AES-SIV encryption")
 	flagSet.BoolVar(&args.nonempty, "nonempty", false, "Allow mounting over non-empty directories")
+	flagSet.BoolVar(&args.raw64, "raw64", false, "Use unpadded base64 for file names")
 	flagSet.StringVar(&args.masterkey, "masterkey", "", "Mount with explicit master key")
 	flagSet.StringVar(&args.cpuprofile, "cpuprofile", "", "Write cpu profile to specified file")
 	flagSet.StringVar(&args.memprofile, "memprofile", "", "Write memory profile to specified file")

init_dir.go

@@ -37,7 +37,7 @@ func initDir(args *argContainer) {
 	}
 	password := readpassword.Twice(args.extpass)
 	creator := tlog.ProgramName + " " + GitVersion
-	err = configfile.CreateConfFile(args.config, password, args.plaintextnames, args.scryptn, creator, args.aessiv)
+	err = configfile.CreateConfFile(args.config, password, args.plaintextnames, args.scryptn, creator, args.aessiv, args.raw64)
 	if err != nil {
 		tlog.Fatal.Println(err)
 		os.Exit(ErrExitInit)

internal/configfile/config_file.go

@@ -49,7 +49,7 @@ type ConfFile struct {
 // CreateConfFile - create a new config with a random key encrypted with
 // "password" and write it to "filename".
 // Uses scrypt with cost parameter logN.
-func CreateConfFile(filename string, password string, plaintextNames bool, logN int, creator string, aessiv bool) error {
+func CreateConfFile(filename string, password string, plaintextNames bool, logN int, creator string, aessiv bool, raw64 bool) error {
 	var cf ConfFile
 	cf.filename = filename
 	cf.Creator = creator
@@ -70,6 +70,9 @@ func CreateConfFile(filename string, password string, plaintextNames bool, logN
 		cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagDirIV])
 		cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagEMENames])
 		cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagLongNames])
+		if raw64 {
+			cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagRaw64])
+		}
 	}
 	if aessiv {
 		cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagAESSIV])

internal/configfile/config_test.go

@@ -60,7 +60,7 @@ func TestLoadV2StrangeFeature(t *testing.T) {
 }
 
 func TestCreateConfFile(t *testing.T) {
-	err := CreateConfFile("config_test/tmp.conf", "test", false, 10, "test", false)
+	err := CreateConfFile("config_test/tmp.conf", "test", false, 10, "test", false, false)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -68,11 +68,10 @@ func TestCreateConfFile(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-
 }
 
 func TestCreateConfFileAESSIV(t *testing.T) {
-	err := CreateConfFile("config_test/tmp.conf", "test", false, 10, "test", true)
+	err := CreateConfFile("config_test/tmp.conf", "test", false, 10, "test", true, false)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -85,6 +84,20 @@ func TestCreateConfFileAESSIV(t *testing.T) {
 	}
 }
 
+func TestCreateConfFileRaw64(t *testing.T) {
+	err := CreateConfFile("config_test/tmp.conf", "test", false, 10, "test", false, true)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, c, err := LoadConfFile("config_test/tmp.conf", "test")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !c.IsFeatureFlagSet(FlagRaw64) {
+		t.Error("FlagRaw64 flag should be set but is not")
+	}
+}
+
 func TestIsFeatureFlagKnown(t *testing.T) {
 	// Test a few hardcoded values
 	testKnownFlags := []string{"DirIV", "PlaintextNames", "EMENames", "GCMIV128", "LongNames", "AESSIV"}

internal/configfile/feature_flags.go

@@ -17,6 +17,8 @@ const (
 	FlagLongNames
 	// FlagAESSIV selects an AES-SIV based crypto backend.
 	FlagAESSIV
+	// FlagRaw64 enables raw (unpadded) base64 encoding for file names
+	FlagRaw64
 )
 
 // knownFlags stores the known feature flags and their string representation
@@ -27,6 +29,7 @@ var knownFlags = map[flagIota]string{
 	FlagGCMIV128:       "GCMIV128",
 	FlagLongNames:      "LongNames",
 	FlagAESSIV:         "AESSIV",
+	FlagRaw64:          "Raw64",
 }
 
 // Filesystems that do not have these feature flags set are deprecated.

internal/fusefrontend/args.go

@@ -18,4 +18,7 @@ type Args struct {
 	// location. If it is false, reverse mode maps ".gocryptfs.reverse.conf"
 	// to "gocryptfs.conf" in the plaintext dir.
 	ConfigCustom bool
+	// Raw64 is true when RawURLEncoding (without padding) should be used for
+	// file names
+	Raw64 bool
 }

internal/fusefrontend/fs.go

@@ -42,7 +42,7 @@ var _ pathfs.FileSystem = &FS{} // Verify that interface is implemented.
 func NewFS(args Args) *FS {
 	cryptoCore := cryptocore.New(args.Masterkey, args.CryptoBackend, contentenc.DefaultIVBits)
 	contentEnc := contentenc.New(cryptoCore, contentenc.DefaultBS)
-	nameTransform := nametransform.New(cryptoCore, args.LongNames)
+	nameTransform := nametransform.New(cryptoCore, args.LongNames, args.Raw64)
 
 	return &FS{
 		FileSystem:    pathfs.NewLoopbackFileSystem(args.Cipherdir),

internal/fusefrontend_reverse/rfs.go

@@ -56,7 +56,7 @@ func NewFS(args fusefrontend.Args) pathfs.FileSystem {
 	initLongnameCache()
 	cryptoCore := cryptocore.New(args.Masterkey, args.CryptoBackend, contentenc.DefaultIVBits)
 	contentEnc := contentenc.New(cryptoCore, contentenc.DefaultBS)
-	nameTransform := nametransform.New(cryptoCore, args.LongNames)
+	nameTransform := nametransform.New(cryptoCore, args.LongNames, args.Raw64)
 
 	return &reverseFS{
 		// pathfs.defaultFileSystem returns ENOSYS for all operations

internal/nametransform/names.go

@@ -17,13 +17,20 @@ type NameTransform struct {
 	cryptoCore *cryptocore.CryptoCore
 	longNames  bool
 	DirIVCache dirIVCache
+	// b64 = either base64.URLEncoding or base64.RawURLEncoding
+	b64 *base64.Encoding
 }
 
 // New returns a new NameTransform instance.
-func New(c *cryptocore.CryptoCore, longNames bool) *NameTransform {
+func New(c *cryptocore.CryptoCore, longNames bool, raw64 bool) *NameTransform {
+	b64 := base64.URLEncoding
+	if raw64 {
+		b64 = base64.RawURLEncoding
+	}
 	return &NameTransform{
 		cryptoCore: c,
 		longNames:  longNames,
+		b64:        b64,
 	}
 }
 
@@ -32,7 +39,7 @@ func New(c *cryptocore.CryptoCore, longNames bool) *NameTransform {
 // This function is exported because it allows for a very efficient readdir
 // implementation (read IV once, decrypt all names using this function).
 func (n *NameTransform) DecryptName(cipherName string, iv []byte) (string, error) {
-	bin, err := base64.URLEncoding.DecodeString(cipherName)
+	bin, err := n.b64.DecodeString(cipherName)
 	if err != nil {
 		return "", err
 	}
@@ -63,6 +70,6 @@ func (n *NameTransform) EncryptName(plainName string, iv []byte) (cipherName64 s
 	bin := []byte(plainName)
 	bin = pad16(bin)
 	bin = eme.Transform(n.cryptoCore.BlockCipher, iv, bin, eme.DirectionEncrypt)
-	cipherName64 = base64.URLEncoding.EncodeToString(bin)
+	cipherName64 = n.b64.EncodeToString(bin)
 	return cipherName64
 }

mount.go

@@ -143,11 +143,13 @@ func initFuseFrontend(key []byte, args *argContainer, confFile *configfile.ConfF
 		LongNames:      args.longnames,
 		CryptoBackend:  cryptoBackend,
 		ConfigCustom:   args._configCustom,
+		Raw64:          args.raw64,
 	}
 	// confFile is nil when "-zerokey" or "-masterkey" was used
 	if confFile != nil {
 		// Settings from the config file override command line args
 		frontendArgs.PlaintextNames = confFile.IsFeatureFlagSet(configfile.FlagPlaintextNames)
+		frontendArgs.Raw64 = confFile.IsFeatureFlagSet(configfile.FlagRaw64)
 		if confFile.IsFeatureFlagSet(configfile.FlagAESSIV) {
 			frontendArgs.CryptoBackend = cryptocore.BackendAESSIV
 		} else if args.reverse {