OBB: use PBKDF2 for key generation.

Switch to using PBKDF2 for the key generation for OBBs. Any previously
generated OBBs will stop being read correctly. A small pbkdf2gen program
is available to allow generation of appropriate keys with the salts.

Bug: 3059950
Change-Id: If4305c989fd692fd1150eb270dbf751e09c37295
diff --git a/tools/obbtool/Android.mk b/tools/obbtool/Android.mk
index b02c1cb..9300bb7 100644
--- a/tools/obbtool/Android.mk
+++ b/tools/obbtool/Android.mk
@@ -13,6 +13,8 @@
 LOCAL_SRC_FILES := \
 	Main.cpp
 
+LOCAL_CFLAGS := -Wall -Werror
+
 #LOCAL_C_INCLUDES +=
 
 LOCAL_STATIC_LIBRARIES := \
@@ -27,4 +29,18 @@
 
 include $(BUILD_HOST_EXECUTABLE)
 
+include $(CLEAR_VARS)
+
+LOCAL_MODULE := pbkdf2gen
+
+LOCAL_MODULE_TAGS := optional
+
+LOCAL_CFLAGS := -Wall -Werror
+
+LOCAL_SRC_FILES := pbkdf2gen.cpp
+
+LOCAL_SHARED_LIBRARIES := libcrypto
+
+include $(BUILD_HOST_EXECUTABLE)
+
 endif # TARGET_BUILD_APPS