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-rw-r--r--cryptfs/cryptfs.go15
-rw-r--r--cryptfs/cryptfs_content.go3
-rw-r--r--cryptfs/openssl_aead.go93
3 files changed, 106 insertions, 5 deletions
diff --git a/cryptfs/cryptfs.go b/cryptfs/cryptfs.go
index 9ec511a..40a9024 100644
--- a/cryptfs/cryptfs.go
+++ b/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)
- if err != nil {
- panic(err)
+ 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,
}
diff --git a/cryptfs/cryptfs_content.go b/cryptfs/cryptfs_content.go
index 512bca9..4658529 100644
--- a/cryptfs/cryptfs_content.go
+++ b/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
}
diff --git a/cryptfs/openssl_aead.go b/cryptfs/openssl_aead.go
new file mode 100644
index 0000000..02f50d8
--- /dev/null
+++ b/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
+}