diff options
Diffstat (limited to 'internal/configfile')
| -rw-r--r-- | internal/configfile/config_file.go | 49 | ||||
| -rw-r--r-- | internal/configfile/feature_flags.go | 2 |
2 files changed, 31 insertions, 20 deletions
diff --git a/internal/configfile/config_file.go b/internal/configfile/config_file.go index 5bb021c..7565c5e 100644 --- a/internal/configfile/config_file.go +++ b/internal/configfile/config_file.go @@ -56,13 +56,6 @@ func CreateConfFile(filename string, password string, plaintextNames bool, logN cf.Creator = creator cf.Version = contentenc.CurrentVersion - // Generate new random master key - key := cryptocore.RandBytes(cryptocore.KeyLen) - - // Encrypt it using the password - // This sets ScryptObject and EncryptedKey - cf.EncryptKey(key, password, logN) - // Set feature flags cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagGCMIV128]) if plaintextNames { @@ -72,11 +65,22 @@ func CreateConfFile(filename string, password string, plaintextNames bool, logN cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagEMENames]) cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagLongNames]) cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagRaw64]) + // TODO enable this and release as v1.3-beta1 once we have enough test + // coverage + //cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagHKDF]) } if aessiv { cf.FeatureFlags = append(cf.FeatureFlags, knownFlags[FlagAESSIV]) } + // Generate new random master key + key := cryptocore.RandBytes(cryptocore.KeyLen) + + // Encrypt it using the password + // This sets ScryptObject and EncryptedKey + // Note: this looks at the FeatureFlags, so call it AFTER setting them. + cf.EncryptKey(key, password, logN) + // Write file to disk return cf.WriteFile() } @@ -148,20 +152,13 @@ func LoadConfFile(filename string, password string) ([]byte, *ConfFile, error) { // decrypt the master key. Return only the parsed config. return nil, &cf, nil } + // Generate derived key from password scryptHash := cf.ScryptObject.DeriveKey(password) // Unlock master key using password-based key - // gocryptfs v1.2 and older used 96-bit IVs for master key encryption. - // v1.3 and up use 128 bits, which makes EncryptedKey longer (64 bytes). - IVLen := contentenc.DefaultIVBits - if len(cf.EncryptedKey) == 60 { - IVLen = 96 - } - // We use stock Go GCM instead of OpenSSL as speed is not - // important and we get better error messages - cc := cryptocore.New(scryptHash, cryptocore.BackendGoGCM, IVLen) - ce := contentenc.New(cc, 4096) + useHKDF := cf.IsFeatureFlagSet(FlagHKDF) + ce := getKeyEncrypter(scryptHash, useHKDF) tlog.Warn.Enabled = false // Silence DecryptBlock() error messages on incorrect password key, err := ce.DecryptBlock(cf.EncryptedKey, 0, nil) @@ -184,8 +181,8 @@ func (cf *ConfFile) EncryptKey(key []byte, password string, logN int) { scryptHash := cf.ScryptObject.DeriveKey(password) // Lock master key using password-based key - cc := cryptocore.New(scryptHash, cryptocore.BackendGoGCM, contentenc.DefaultIVBits) - ce := contentenc.New(cc, 4096) + useHKDF := cf.IsFeatureFlagSet(FlagHKDF) + ce := getKeyEncrypter(scryptHash, useHKDF) cf.EncryptedKey = ce.EncryptBlock(key, 0, nil) } @@ -220,3 +217,17 @@ func (cf *ConfFile) WriteFile() error { err = os.Rename(tmp, cf.filename) return err } + +// getKeyEncrypter is a helper function that returns the right ContentEnc +// instance for the "useHKDF" setting. +func getKeyEncrypter(scryptHash []byte, useHKDF bool) *contentenc.ContentEnc { + IVLen := 96 + // gocryptfs v1.2 and older used 96-bit IVs for master key encryption. + // v1.3 adds the "HKDF" feature flag, which also enables 128-bit nonces. + if useHKDF { + IVLen = contentenc.DefaultIVBits + } + cc := cryptocore.New(scryptHash, cryptocore.BackendGoGCM, IVLen, useHKDF) + ce := contentenc.New(cc, 4096) + return ce +} diff --git a/internal/configfile/feature_flags.go b/internal/configfile/feature_flags.go index deb3a0e..2d609f2 100644 --- a/internal/configfile/feature_flags.go +++ b/internal/configfile/feature_flags.go @@ -36,7 +36,7 @@ var knownFlags = map[flagIota]string{ FlagLongNames: "LongNames", FlagAESSIV: "AESSIV", FlagRaw64: "Raw64", - //FlagHKDF: "HKDF", + FlagHKDF: "HKDF", } // Filesystems that do not have these feature flags set are deprecated. |