Pin Tumbler Lock: A shift based encryption mechanism for racetrack memory

As various non-volatile memory (NVM) technologies have been adopted in different levels of memory hierarchy, the security issue of protecting information retained in NVM after power-off has become a new challenge, which results in extensive research on data encryption for NVM. Previous encryption approaches, however, have some limitations, such as high design complexity and non-trivial timing and energy overhead. Recently, an emerging NVM called racetrack memory (RM) has been widely investigated because of its advantages of ultra-high storage density and fast read/write speed. Besides these well-known advantages, we observe that the tape-like structure of RMcell and its unique shift operation can also be leveraged to facilitate NVM data encryption. Base on this observation, we propose an efficient shift based mechanism, named Pin Tumbler Lock (PTL), which completes encryption and decryption by shifting racetracks in several nanoseconds. Experimental results demonstrate that our design can achieve the same security strength of AES-128 with 3.1% performance overhead and 3.7% energy overhead and 1.56% storage cost and 1.6% area cost.