关键词: 不经意随机访问机, 低性能开销, 片外不可信内存, 安全处理器, 隐私

Abstract: At present, most computer systems are facing the problem of information leakage. On the physical level, the bus between the processor chip and the offchip untrusted memory is a security risk that causes information leakage. Adversaries can snoop the data and address on the memory bus to obtain sensitive information. Data encryption alone is not enough to ensure the security of the system, because each memory access still needs a plaintext memory address. Adversaries can still snoop the address of each memory access through the bus to obtain implicit information. The possible way to solve this problem is to use the oblivious random access machine (ORAM) scheme to hide the access mode. However, the existing ORAM scheme involves a large number of virtual accesses for each real memory access, which significantly increases the performance overhead. This paper proposes a Group ORAM scheme, which hides the real memory access in a specified number of small clusters of virtual accesses. Its performance overhead will not increase with the increase of memory size, and the scheme adopts a parametric design, which can be flexibly configured according to the requirements of different platforms for security and performance. Experiments on Xilinx xc7vx330t FPGA platform show that Group ORAM can significantly reduce the performance overhead compared with the most advanced. Tiny ORAM scheme for one memory access.

Key words: ORAM, low performance overhead, untrusted offchip memory, secure processor, privacy