Bus Encryption and Authentication Unit for Symmetric Shared Memory Multiprocessor Sytem Using GCM-AES

Abstract

Hardware security mechanisms in uniprocessor and multiprocessor systems have been proposed to safeguard information more efficiently. This work presents a secure architecture model for a symmetric shared memory multiprocessor (SMP) to safeguard the cache-to-cache transfers. This work proposes a hardware security mechanism, which employs Galois Counter Mode (GCM) of advanced encryption standard (AES) and modifies it to work in an SMP environment. The work focuses on why GCM is a better choice over cipher block chaining mode (CBC) which is used in current state of the art systems. It estimates the storage required by the additional hardware unit in both modes of operation. A full system SMP simulation quantifies the performance overhead introduced by the additional hardware unit in both schemes to safeguard the cache-to-cache transfers. The impact of increasing cache line sizes and the effect of varying throughput of the AES units in both the schemes is studied. Results show that a performance gain in the range of 4X-9X over the CBC scheme is achieved by using GCM mode of operation. The work shows that the throughput of the AES design has a greater impact on the performance of the CBC scheme. The performance loss is very high in CBC scheme with a lower throughput of the AES design compared to GCM. The performance in CBC scheme varies according to the authentication interval while authentication interval does not affect the GCM scheme, thus providing higher security. The presented work using GCM consumes less space on chip providing the same level of security as in the CBC scheme.