ITS: Add support for encrypted ITS

-Adds encryption and authentication support for ITS files
-Encryption is optional and is enabled using a CMake variable
-The encryption implementation is platform dependent,
 the signatures of the APIs are provided in this change

Change-Id: Ifd3a67ac2274fa8d7ceec19482f7cec01b2cac54
Signed-off-by: Markus Swarowsky <markus.swarowsky@nordicsemi.no>
diff --git a/config/config_base.h b/config/config_base.h
index d9caeb9..9879b68 100644
--- a/config/config_base.h
+++ b/config/config_base.h
@@ -192,6 +192,16 @@
 #define ITS_STACK_SIZE                         0x720
 #endif
 
+/* The size of the authentication tag used when authentication/encryption of ITS files is enabled */
+#ifndef TFM_ITS_AUTH_TAG_LENGTH
+#define TFM_ITS_AUTH_TAG_LENGTH                16
+#endif
+
+/* The size of the nonce used when ITS file encryption is enabled */
+#ifndef TFM_ITS_ENC_NONCE_LENGTH
+#define TFM_ITS_ENC_NONCE_LENGTH               12
+#endif
+
 /* PS Partition Configs */
 
 /* Create flash FS if it doesn't exist for Protected Storage partition */