Lest we remember : cold boot attacks on encryption keys

J.A. Halderman, S.D. Schoen, N. Heninger, W. Clarkson, W. Paul, J.A. Calandrino, A.J. Feldman, Jacob Appelbaum, E.W. Felten

Research output: Chapter in Book/Report/Conference proceedingConference contributionAcademicpeer-review


Contrary to widespread assumption, dynamic RAM (DRAM), the main memory in most modern computers, retains its contents for several seconds after power is lost, even at room temperature and even if removed from a motherboard. Although DRAM becomes less reliable when it is not refreshed, it is not immediately erased, and its contents persist sufficiently for malicious (or forensic) acquisition of usable full-system memory images. We show that this phenomenon limits the ability of an operating system to protect cryptographic key material from an attacker with physical access to a machine. It poses a particular threat to laptop users who rely on disk encryption: we demonstrate that it could be used to compromise several popular disk encryption products without the need for any special devices or materials. We experimentally characterize the extent and predictability of memory retention 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 mitigating these risks, we know of no simple remedy that would eliminate them.
Original languageEnglish
Title of host publicationProceedings of the 17th USENIX Security Symposium, July 28-August 1, 2008, San Jose, CA, USA
Number of pages16
Publication statusPublished - 2008
Externally publishedYes
Event17th USENIX Security Symposium (USENIX Security 2008) - San Jose, United States
Duration: 29 Jul 20082 Aug 2008
Conference number: 17


Conference17th USENIX Security Symposium (USENIX Security 2008)
Abbreviated titleUSENIX Security 2008
Country/TerritoryUnited States
CitySan Jose
Internet address


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