LAUSR

Emerging nonvolatile memories (NVMs) are considered as potential replacements of the traditional DRAM-based main memories. However, the nonvolatility feature of the NVMs may lead to the stealing of sensitive data stored in NVMs due to their prolonged data retention. Memory encryption turns out to be a viable option to provide data security. However, the existing encryption techniques, on account of the diffusion property, increase the number of bit-flips in the NVM cells, thus leading to their early wear out. Therefore, security and lifetime issues of the NVMs are difficult to go hand in hand. In this article, we identify words that are repeated in several memory blocks and term them as popular words. The proposal is to avoid the encryption of the popular words by maintaining them in a reference table. In our proposal, Pop-Crypt, every block to be written to the memory gets partially encrypted in which the popular words are replaced with pointers to the reference table, and other words get encrypted. The partially encrypted blocks (PEBs) reduce the number of bit-flips in PCM, thereby improving its lifetime significantly. Experimental results show that Pop-Crypt considerably improves lifetime, energy consumption, and system performance over baseline and a state-of-the-art technique.