COLD BOOT ATTACKS ON ENCRYPTION KEYS

Abstract

Contrary to popular assumption, DRAMs used in most modern computers retain their contents for several seconds 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 usable full-system memory images. This phenomenon limits the ability of an operating system to protect cryptographic key material from an attacker with physical access. We can use cold reboots to mount successful attacks on popular disk encryption systems using no special devices or materials. We can also find cryptographic keys in memory images and correct errors caused by bit decay using algorithms. Here we discuss several strategies for partially mitigating these risks, but there is no simple remedy that would eliminate them.