  In this paper we introduced countermeasures against side-channel attacks in
the shared memory of TrustZone. We proposed zero-contention cache memory or
policy between REE and TEE to prevent from TruSpy attacks in TrustZone. And we
suggested that delay time of data path of REE is equal or similar to that of
data path of TEE to prevent timing side-channel attacks. Also, we proposed
security information flow control based on the Clark-Wilson model, and built
the information flow control mechanism using Authentication Tokenization
Program (ATP). Accordingly we can expect the improved integrity of the
information content between REE and TEE on mobile devices.
