vold: Add a versioned superblock to secure containers.

Add an un-encrypted superblock to the end of a secure container to
help identify the crypto cipher used. This is required in order to
provide some semblence of versioning, in case we have cause to
change the crypto type on an update - say for example switching
from software to hardware encryption, or from 128 -> a zillion
bit keys.

NOTE: This format is incompatible with previous secure containers.
After this change they will no longer be mountable.

Signed-off-by: San Mehat <san@google.com>

1 files changed, 42 insertions, 0 deletions

diff --git a/Asec.h b/Asec.h
new file mode 100644
index 0000000..136ad3b
--- /dev/null
+++ b/Asec.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _ASEC_H
+#define _ASEC_H
+
+struct asec_superblock {
+#define ASEC_SB_MAGIC 0xc0def00d
+    unsigned int magic;
+
+#define ASEC_SB_VER 1
+    unsigned char ver;
+
+#define ASEC_SB_C_CIPHER_NONE    0
+#define ASEC_SB_C_CIPHER_TWOFISH 1
+#define ASEC_SB_C_CIPHER_AES     2
+    unsigned char c_cipher;
+
+#define ASEC_SB_C_CHAIN_NONE 0
+    unsigned char c_chain;
+
+#define ASEC_SB_C_OPTS_NONE 0
+    unsigned char c_opts;
+
+#define ASEC_SB_C_MODE_NONE 0
+    unsigned char c_mode;
+} __attribute__((packed));
+
+#endif