From decfc1ab798055234e16a2e9c0782f56ae50669b Mon Sep 17 00:00:00 2001 From: Jakob Unterwurzacher Date: Fri, 27 Nov 2015 00:03:10 +0100 Subject: diriv: Convert filename encryption users to diriv --- cryptfs/cryptfs_names.go | 48 ++++++++++++--------------------- cryptfs/names_diriv.go | 69 ++++++++++++++++++++++++++++++++++++++++++++++++ cryptfs/names_test.go | 4 +-- 3 files changed, 88 insertions(+), 33 deletions(-) create mode 100644 cryptfs/names_diriv.go (limited to 'cryptfs') diff --git a/cryptfs/cryptfs_names.go b/cryptfs/cryptfs_names.go index 1282f53..37a769f 100644 --- a/cryptfs/cryptfs_names.go +++ b/cryptfs/cryptfs_names.go @@ -12,15 +12,15 @@ import ( ) const ( - ENCRYPT = true - DECRYPT = false + OpEncrypt = iota + OpDecrypt ) -// DecryptName - decrypt filename -func (be *CryptFS) decryptName(cipherName string) (string, error) { +// DecryptName - decrypt base64-encoded encrypted filename "cipherName" +func (be *CryptFS) decryptName(cipherName string, iv []byte) (string, error) { // Make sure relative symlinks still work after encryption - // by passing these trough unchanged + // by passing these through unchanged if cipherName == "." || cipherName == ".." { return cipherName, nil } @@ -34,7 +34,6 @@ func (be *CryptFS) decryptName(cipherName string) (string, error) { return "", fmt.Errorf("Decoded length %d is not a multiple of the AES block size", len(bin)) } - iv := make([]byte, aes.BlockSize) // TODO ? cbc := cipher.NewCBCDecrypter(be.blockCipher, iv) cbc.CryptBlocks(bin, bin) @@ -48,7 +47,7 @@ func (be *CryptFS) decryptName(cipherName string) (string, error) { } // EncryptName - encrypt filename -func (be *CryptFS) encryptName(plainName string) string { +func (be *CryptFS) encryptName(plainName string, iv []byte) string { // Make sure relative symlinks still work after encryption // by passing these trough unchanged @@ -59,7 +58,6 @@ func (be *CryptFS) encryptName(plainName string) string { bin := []byte(plainName) bin = be.pad16(bin) - iv := make([]byte, 16) // TODO ? cbc := cipher.NewCBCEncrypter(be.blockCipher, iv) cbc.CryptBlocks(bin, bin) @@ -67,9 +65,10 @@ func (be *CryptFS) encryptName(plainName string) string { return cipherName64 } -// TranslatePath - encrypt or decrypt path. Just splits the string on "/" -// and hands the parts to EncryptName() / DecryptName() -func (be *CryptFS) translatePath(path string, op bool) (string, error) { + +// TranslatePathZeroIV - encrypt or decrypt path using CBC with a constant all-zero IV. +// Just splits the string on "/" and hands the parts to encryptName() / decryptName() +func (be *CryptFS) TranslatePathZeroIV(path string, op int) (string, error) { var err error // Empty string means root directory @@ -77,6 +76,8 @@ func (be *CryptFS) translatePath(path string, op bool) (string, error) { return path, err } + zeroIV := make([]byte, DIRIV_LEN) + // Run operation on each path component var translatedParts []string parts := strings.Split(path, "/") @@ -88,10 +89,10 @@ func (be *CryptFS) translatePath(path string, op bool) (string, error) { continue } var newPart string - if op == ENCRYPT { - newPart = be.encryptName(part) + if op == OpEncrypt { + newPart = be.encryptName(part, zeroIV) } else { - newPart, err = be.decryptName(part) + newPart, err = be.decryptName(part, zeroIV) if err != nil { return "", err } @@ -102,23 +103,6 @@ func (be *CryptFS) translatePath(path string, op bool) (string, error) { return strings.Join(translatedParts, "/"), err } -// EncryptPath - encrypt filename or path. Just hands it to translatePath(). -func (be *CryptFS) EncryptPath(path string) string { - if be.plaintextNames { - return path - } - newPath, _ := be.translatePath(path, ENCRYPT) - return newPath -} - -// DecryptPath - decrypt filename or path. Just hands it to translatePath(). -func (be *CryptFS) DecryptPath(path string) (string, error) { - if be.plaintextNames { - return path, nil - } - return be.translatePath(path, DECRYPT) -} - // pad16 - pad filename to 16 byte blocks using standard PKCS#7 padding // https://tools.ietf.org/html/rfc5652#section-6.3 func (be *CryptFS) pad16(orig []byte) (padded []byte) { @@ -171,3 +155,5 @@ func (be *CryptFS) unPad16(orig []byte) ([]byte, error) { } return orig[0:newLen], nil } + + diff --git a/cryptfs/names_diriv.go b/cryptfs/names_diriv.go new file mode 100644 index 0000000..c9debab --- /dev/null +++ b/cryptfs/names_diriv.go @@ -0,0 +1,69 @@ +package cryptfs + +import ( + "path/filepath" + "io/ioutil" + "fmt" + "strings" +) + +// readDirIV - read the "gocryptfs.diriv" file from "dir" (absolute path) +func (be *CryptFS) readDirIV(dir string) (iv []byte, err error) { + ivfile := filepath.Join(dir, DIRIV_FILENAME) + iv, err = ioutil.ReadFile(ivfile) + if err != nil { + Warn.Printf("readDirIV: %v\n", err) + return nil, err + } + if len(iv) != DIRIV_LEN { + return nil, fmt.Errorf("readDirIV: Invalid length %d\n", len(iv)) + } + return iv, nil +} + +// EncryptPathDirIV - encrypt path using CBC with DirIV +func (be *CryptFS) EncryptPathDirIV(plainPath string, rootDir string) (string, error) { + if be.plaintextNames { + return plainPath, nil + } + // Empty string means root directory + if plainPath == "" { + return plainPath, nil + } + var wd = rootDir + var encryptedNames []string + plainNames := strings.Split(plainPath, "/") + for _, plainName := range plainNames { + iv, err := be.readDirIV(wd) + if err != nil { + return "", err + } + encryptedName := be.encryptName(plainName, iv) + encryptedNames = append(encryptedNames, encryptedName) + wd = filepath.Join(wd, encryptedName) + } + return filepath.Join(encryptedNames...), nil +} + +// DecryptPathDirIV - encrypt path using CBC with DirIV +func (be *CryptFS) DecryptPathDirIV(encryptedPath string, rootDir string) (string, error) { + if be.plaintextNames { + return encryptedPath, nil + } + var wd = rootDir + var plainNames []string + encryptedNames := strings.Split(encryptedPath, "/") + for _, encryptedName := range encryptedNames { + iv, err := be.readDirIV(wd) + if err != nil { + return "", err + } + plainName, err := be.decryptName(encryptedName, iv) + if err != nil { + return "", err + } + plainNames = append(plainNames, plainName) + wd = filepath.Join(wd, encryptedName) + } + return filepath.Join(plainNames...), nil +} diff --git a/cryptfs/names_test.go b/cryptfs/names_test.go index ccf08df..1ad3391 100644 --- a/cryptfs/names_test.go +++ b/cryptfs/names_test.go @@ -15,8 +15,8 @@ func TestTranslatePath(t *testing.T) { fs := NewCryptFS(key, true, false) for _, n := range s { - c := fs.EncryptPath(n) - d, err := fs.DecryptPath(c) + c, err := fs.TranslatePathZeroIV(n, OpEncrypt) + d, err := fs.TranslatePathZeroIV(c, OpDecrypt) if err != nil { t.Errorf("Got error from DecryptName: %s", err) } -- cgit v1.2.3