Add OpenSSL support for file content encryption/decryption

This brings streaming read performance from 30MB/s to 81MB/s
(similar improvement for writes)

cryptfs/cryptfs.go

@@ -20,21 +20,26 @@ type CryptFS struct {
 	cipherBS uint64
 }
 
-func NewCryptFS(key [16]byte) *CryptFS {
+func NewCryptFS(key [16]byte, useOpenssl bool) *CryptFS {
 
 	b, err := aes.NewCipher(key[:])
 	if err != nil {
 		panic(err)
 	}
 
-	g, err := cipher.NewGCM(b)
+	var gcm cipher.AEAD
+	if useOpenssl {
+		gcm = opensslGCM{key}
+	} else {
+		gcm, err = cipher.NewGCM(b)
 		if err != nil {
 			panic(err)
 		}
+	}
 
 	return &CryptFS{
 		blockCipher: b,
-		gcm: g,
+		gcm: gcm,
 		plainBS: DEFAULT_PLAINBS,
 		cipherBS: DEFAULT_PLAINBS + NONCE_LEN + AUTH_TAG_LEN,
 	}

cryptfs/cryptfs_content.go

@@ -49,8 +49,11 @@ func (be *CryptFS) DecryptBlock(ciphertext []byte) ([]byte, error) {
 
 	// Decrypt
 	var plaintext []byte
+
 	plaintext, err := be.gcm.Open(plaintext, nonce, ciphertext, nil)
+
 	if err != nil {
+		Warn.Printf("DecryptBlock: %s\n", err.Error())
 		return nil, err
 	}
 

cryptfs/openssl_aead.go

@@ -0,0 +1,93 @@
+package cryptfs
+
+// Implements cipher.AEAD with OpenSSL backend
+
+import (
+	"bytes"
+	"github.com/spacemonkeygo/openssl"
+)
+
+type opensslGCM struct {
+	key [16]byte
+}
+
+func (be opensslGCM) Overhead() int {
+	return AUTH_TAG_LEN
+}
+
+func (be opensslGCM) NonceSize() int {
+	return NONCE_LEN
+}
+
+// Seal encrypts and authenticates plaintext, authenticates the
+// additional data and appends the result to dst, returning the updated
+// slice. The nonce must be NonceSize() bytes long and unique for all
+// time, for a given key.
+//
+// The plaintext and dst may alias exactly or not at all.
+func (be opensslGCM) Seal(dst, nonce, plaintext, data []byte) []byte {
+
+	cipherBuf := bytes.NewBuffer(dst)
+
+	ectx, err := openssl.NewGCMEncryptionCipherCtx(128, nil, be.key[:], nonce[:])
+	if err != nil {
+		panic(err)
+	}
+	part, err := ectx.EncryptUpdate(plaintext)
+	if err != nil {
+		panic(err)
+	}
+	cipherBuf.Write(part)
+	part, err = ectx.EncryptFinal()
+	if err != nil {
+		panic(err)
+	}
+	cipherBuf.Write(part)
+	part, err = ectx.GetTag()
+	if err != nil {
+		panic(err)
+	}
+	cipherBuf.Write(part)
+
+	return cipherBuf.Bytes()
+}
+
+// Open decrypts and authenticates ciphertext, authenticates the
+// additional data and, if successful, appends the resulting plaintext
+// to dst, returning the updated slice. The nonce must be NonceSize()
+// bytes long and both it and the additional data must match the
+// value passed to Seal.
+//
+// The ciphertext and dst may alias exactly or not at all.
+func (be opensslGCM) Open(dst, nonce, ciphertext, data []byte) ([]byte, error) {
+
+	if len(data) > 0 {
+		panic("Extra data is not supported")
+	}
+
+	l := len(ciphertext)
+	tag := ciphertext[l-AUTH_TAG_LEN:l]
+	ciphertext = ciphertext[0:l-AUTH_TAG_LEN]
+	plainBuf := bytes.NewBuffer(dst)
+
+	dctx, err := openssl.NewGCMDecryptionCipherCtx(128, nil, be.key[:], nonce[:])
+	if err != nil {
+		return nil, err
+	}
+	part, err := dctx.DecryptUpdate(ciphertext)
+	if err != nil {
+		return nil, err
+	}
+	plainBuf.Write(part)
+	err = dctx.SetTag(tag)
+	if err != nil {
+		return nil, err
+	}
+	part, err = dctx.DecryptFinal()
+	if err != nil {
+		return nil, err
+	}
+	plainBuf.Write(part)
+
+	return plainBuf.Bytes(), nil
+}

frontend/fe_fs.go

@@ -27,14 +27,14 @@ type nullTracer struct {}
 
 func (nullTracer) Trace(op cluefs.FsOperTracer) {}
 
-func NewFS(key [16]byte, backing string) *FS {
+func NewFS(key [16]byte, backing string, useOpenssl bool) *FS {
 	var nt nullTracer
 	clfs, err := cluefs.NewClueFS(backing, nt)
 	if err != nil {
 		panic(err)
 	}
 	return &FS {
-		CryptFS: cryptfs.NewCryptFS(key),
+		CryptFS: cryptfs.NewCryptFS(key, useOpenssl),
 		ClueFS: clfs,
 		backing: backing,
 	}

main.go

@@ -11,6 +11,7 @@ import (
 
 const (
 	PROGRAM_NAME = "gocryptfs"
+	USE_OPENSSL = true
 )
 
 func main() {
@@ -22,7 +23,7 @@ func main() {
 
 	// Create the file system object
 	var key [16]byte
-	cfs := frontend.NewFS(key, conf.GetShadowDir())
+	cfs := frontend.NewFS(key, conf.GetShadowDir(), USE_OPENSSL)
 
 	// Mount the file system
 	mountOpts := []fuse.MountOption{