diff --git a/Ext4Crypt.h b/Ext4Crypt.h
index e90167b..d0afd85 100644
--- a/Ext4Crypt.h
+++ b/Ext4Crypt.h
@@ -14,29 +14,29 @@
  * limitations under the License.
  */
 
+#include <string>
+
 #include <stdbool.h>
 #include <sys/cdefs.h>
 
 #include <cutils/multiuser.h>
 
-__BEGIN_DECLS
-
 // General functions
-bool e4crypt_is_native();
 bool e4crypt_initialize_global_de();
 
 bool e4crypt_init_user0();
 bool e4crypt_vold_create_user_key(userid_t user_id, int serial, bool ephemeral);
 bool e4crypt_destroy_user_key(userid_t user_id);
-bool e4crypt_add_user_key_auth(userid_t user_id, int serial, const char* token,
-                               const char* secret);
+bool e4crypt_add_user_key_auth(userid_t user_id, int serial, const std::string& token,
+                               const std::string& secret);
 bool e4crypt_fixate_newest_user_key_auth(userid_t user_id);
 
-bool e4crypt_unlock_user_key(userid_t user_id, int serial, const char* token, const char* secret);
+bool e4crypt_unlock_user_key(userid_t user_id, int serial, const std::string& token,
+                             const std::string& secret);
 bool e4crypt_lock_user_key(userid_t user_id);
 
-bool e4crypt_prepare_user_storage(const char* volume_uuid, userid_t user_id, int serial, int flags);
-bool e4crypt_destroy_user_storage(const char* volume_uuid, userid_t user_id, int flags);
+bool e4crypt_prepare_user_storage(const std::string& volume_uuid, userid_t user_id, int serial,
+                                  int flags);
+bool e4crypt_destroy_user_storage(const std::string& volume_uuid, userid_t user_id, int flags);
 
-bool e4crypt_secdiscard(const char* path);
-__END_DECLS
+bool e4crypt_secdiscard(const std::string& path);