For nonvolatile main memory (NVMM), both security and endurance are important. However, the diffusion property of memory encryption renders existing bit-level write reduction techniques ineffective. This paper proposes DeWrite, a line-level write reduction technique to enhance the endurance and performance of secure NVMM. Moreover, DeWrite leverages a new encryption technique, i.e., hash mode encryption, and exploits opportunistic parallelism between encryption and deduplication operations to efficiently synergize deduplication and encryption for space and time savings.