Lest we remember: cold-boot attacks on encryption keys

Abstract Contrary to popular assumption, DRAMs used in most modern,computers,retain their contents for several sec- onds after power is lost, even at room temperature and even if removed,from a motherboard. Although DRAMs become less reliable when they are not refreshed, they are not immediately erased, and their contents persist sufficiently for malicious (or forensic) acquisition of us- able full-system memory,images. We show that this phe- nomenon,limits the ability of an operating system to pro- tect cryptographic,key material from an attacker with physical access. We use cold reboots to mount successful attacks on popular disk encryption systems using no spe- cial devices or materials. We experimentally characterize the extent and predictability of memory,remanence,and report that remanence,times can be increased dramatically with simple cooling techniques. We offer new algorithms for finding cryptographic keys in memory,images and for correcting errors caused by bit decay. Though we discuss several strategies for partially mitigating these risks, we know of no simple remedy that would eliminate them.