Add support for binding storage encryption to a seed
With this change, vold exposes an API that may be used to bind key
storage encryption keys to a given seed value. The seed value passed to
vold must be consistent across reboots, or key storage keys will not be
derived consistently. The seed is expected to be set very early in boot,
prior to the use of any key storage encryption keys.
This feature is intended to be used for embedded applications such as
in autos, where the seed may be provided by some other component of the
system. In such systems, there is a default user that is automatically
signed in without a PIN or other credentials. By binding the file
encryption to a platform-provided seed, the default user's data gains
additional protection against removal of the Android embedded device
from the integrated system.
Bug: 157501579
Test: Set seed at startup via init.rc. Seed changes fail as expected.
Change-Id: I9b048ec5e045b84c45883724ace2356d4ef6244d
diff --git a/KeyStorage.h b/KeyStorage.h
index 1eb26ae..a69dbf7 100644
--- a/KeyStorage.h
+++ b/KeyStorage.h
@@ -19,7 +19,9 @@
#include "KeyBuffer.h"
+#include <cstdint>
#include <string>
+#include <vector>
namespace android {
namespace vold {
@@ -72,6 +74,9 @@
bool generateWrappedStorageKey(KeyBuffer* key);
// Export the per-boot boot wrapped storage key using keymaster.
bool exportWrappedStorageKey(const KeyBuffer& kmKey, KeyBuffer* key);
+
+// Set a seed to be mixed into all key storage encryption keys.
+bool setKeyStorageBindingSeed(const std::vector<uint8_t>& seed);
} // namespace vold
} // namespace android