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Lest We Remember: Cold Boot Attacks on Encryption Keys |
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J. Alex Halderman, Seth D. Schoen, Nadia Heninger, William Clarkson, William Paul, Joseph A. Calandrino, Ariel J. Feldman, Jacob Appelbaum, and Edward W. Felten, |
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2008 |
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| Abstract: |
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Contrary to popular assumption, DRAMs used in most modern computers retain their contents for
seconds to minutes after power is lost, even at room temperature and even if removed from a mother-
board. 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. We show that this phenomenon limits the ability of an operating system to protect cryp-
tographic key material from an attacker with physical access. We use cold reboots to mount successful
attacks on popular disk encryption systems using no special devices or materials. We experimentally
characterize the extent and predictability of memory remanence and report that remanence times can be
increased dramatically with simple 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 |
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| Paper Available At: |
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http://citp.princeton.edu.nyud.net/pub/coldboot.pdf |
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