CADEN: Compression-Assisted Adaptive Encoding to Improve Lifetime of Encrypted Nonvolatile Main Memories

Abstract

Nonvolatile memories are widely considered as a potential replacement of DRAM in main memory due to their high density and low-leakage power consumption. The data in these memories are stored in encrypted form to protect them from data stealing. However, the encryption techniques, on account of their diffusion property impose high randomization in the generated encrypted data. It leads to enormous bit-flips in the memory cells, leading to their early wear out. In this letter, we propose a technique called CADEN that combines our compression technique COMF with an adaptive encoding scheme. The compressed data generated by COMF is encoded in finer granularity using an adaptive encoding approach at low storage overhead. Experimental evaluation shows that CADEN reduces bit-flips and improves lifetime in PCM main memory compared to baseline and existing techniques. In particular, CADEN shows 52% and 57% reduction in bit-flips and energy consumption and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2.31\times $ </tex-math></inline-formula> improvement in lifetime over baseline.