From 2b8cbd944149afe51fadddbd67ee4499d1d86250 Mon Sep 17 00:00:00 2001
From: Jakob Unterwurzacher
Date: Sat, 6 Feb 2016 19:20:54 +0100
Subject: Major refactoring: Split up "cryptfs" into several internal packages

"git status" for reference:

deleted:    cryptfs/cryptfs.go
deleted:    cryptfs/names_core.go
modified:   integration_tests/cli_test.go
modified:   integration_tests/helpers.go
renamed:    cryptfs/config_file.go -> internal/configfile/config_file.go
renamed:    cryptfs/config_test.go -> internal/configfile/config_test.go
renamed:    cryptfs/config_test/.gitignore -> internal/configfile/config_test/.gitignore
renamed:    cryptfs/config_test/PlaintextNames.conf -> internal/configfile/config_test/PlaintextNames.conf
renamed:    cryptfs/config_test/StrangeFeature.conf -> internal/configfile/config_test/StrangeFeature.conf
renamed:    cryptfs/config_test/v1.conf -> internal/configfile/config_test/v1.conf
renamed:    cryptfs/config_test/v2.conf -> internal/configfile/config_test/v2.conf
renamed:    cryptfs/kdf.go -> internal/configfile/kdf.go
renamed:    cryptfs/kdf_test.go -> internal/configfile/kdf_test.go
renamed:    cryptfs/cryptfs_content.go -> internal/contentenc/content.go
new file:   internal/contentenc/content_api.go
renamed:    cryptfs/content_test.go -> internal/contentenc/content_test.go
renamed:    cryptfs/file_header.go -> internal/contentenc/file_header.go
renamed:    cryptfs/intrablock.go -> internal/contentenc/intrablock.go
renamed:    cryptfs/address_translation.go -> internal/contentenc/offsets.go
new file:   internal/cryptocore/crypto_api.go
renamed:    cryptfs/gcm_go1.4.go -> internal/cryptocore/gcm_go1.4.go
renamed:    cryptfs/gcm_go1.5.go -> internal/cryptocore/gcm_go1.5.go
renamed:    cryptfs/nonce.go -> internal/cryptocore/nonce.go
renamed:    cryptfs/openssl_aead.go -> internal/cryptocore/openssl_aead.go
renamed:    cryptfs/openssl_benchmark.bash -> internal/cryptocore/openssl_benchmark.bash
renamed:    cryptfs/openssl_test.go -> internal/cryptocore/openssl_test.go
new file:   internal/nametransform/name_api.go
new file:   internal/nametransform/names_core.go
renamed:    cryptfs/names_diriv.go -> internal/nametransform/names_diriv.go
renamed:    cryptfs/names_noiv.go -> internal/nametransform/names_noiv.go
renamed:    cryptfs/names_test.go -> internal/nametransform/names_test.go
new file:   internal/nametransform/pad16.go
renamed:    cryptfs/log.go -> internal/toggledlog/log.go
renamed:    cryptfs/log_go1.4.go -> internal/toggledlog/log_go1.4.go
renamed:    cryptfs/log_go1.5.go -> internal/toggledlog/log_go1.5.go
modified:   main.go
modified:   masterkey.go
modified:   pathfs_frontend/file.go
modified:   pathfs_frontend/file_holes.go
modified:   pathfs_frontend/fs.go
modified:   pathfs_frontend/fs_dir.go
modified:   pathfs_frontend/names.go
modified:   test.bash
---
 internal/nametransform/names_core.go | 63 ++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 internal/nametransform/names_core.go

(limited to 'internal/nametransform/names_core.go')

diff --git a/internal/nametransform/names_core.go b/internal/nametransform/names_core.go
new file mode 100644
index 0000000..452ab45
--- /dev/null
+++ b/internal/nametransform/names_core.go
@@ -0,0 +1,63 @@
+package nametransform
+
+// Filename encryption / decryption functions
+
+import (
+	"crypto/aes"
+	"crypto/cipher"
+	"encoding/base64"
+	"fmt"
+
+	"github.com/rfjakob/eme"
+)
+
+// DecryptName - decrypt base64-encoded encrypted filename "cipherName"
+// The used encryption is either CBC or EME, depending on "useEME".
+//
+// 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)
+	if err != nil {
+		return "", err
+	}
+
+	if len(bin)%aes.BlockSize != 0 {
+		return "", fmt.Errorf("Decoded length %d is not a multiple of the AES block size", len(bin))
+	}
+
+	if n.useEME {
+		bin = eme.Transform(n.cryptoCore.BlockCipher, iv, bin, eme.DirectionDecrypt)
+	} else {
+		cbc := cipher.NewCBCDecrypter(n.cryptoCore.BlockCipher, iv)
+		cbc.CryptBlocks(bin, bin)
+	}
+
+	bin, err = unPad16(bin)
+	if err != nil {
+		return "", err
+	}
+
+	plain := string(bin)
+	return plain, err
+}
+
+// encryptName - encrypt "plainName", return base64-encoded "cipherName64"
+// The used encryption is either CBC or EME, depending on "useEME".
+func (n *NameTransform) encryptName(plainName string, iv []byte) (cipherName64 string) {
+
+	bin := []byte(plainName)
+	bin = pad16(bin)
+
+	if n.useEME {
+		bin = eme.Transform(n.cryptoCore.BlockCipher, iv, bin, eme.DirectionEncrypt)
+	} else {
+		cbc := cipher.NewCBCEncrypter(n.cryptoCore.BlockCipher, iv)
+		cbc.CryptBlocks(bin, bin)
+	}
+
+	cipherName64 = base64.URLEncoding.EncodeToString(bin)
+	return cipherName64
+}
+
-- 
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