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  1. #1
    Linux Engineer hazel's Avatar
    Join Date
    May 2004
    Harrow, UK

    Worrying behaviour of DRAM chips

    We were always told that when the power goes off, everything in RAM is lost. Well, apparently that isn't true of modern DRAM chips. They retain data for several minutes even at room temperature, and much longer when cooled.

    A lot of people use encryption on their laptops so that if they are stolen, at least no-one can get at your data. The encryption keys are stored in RAM, where the kernel stops anyone from getting hold of them. But someone could take cut the power, then remove the memory and chill it and recover these keys, getting access to everything on your disks.

    You can read about it here.
    "I'm just a little old lady; don't try to dazzle me with jargon!"

  2. #2
    Administrator jayd512's Avatar
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    Feb 2008
    I was under the assumption, just like everybody else, that power loss means content loss. Even on DRAM.
    Nice find, hazel.

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  3. #3
    Linux Guru Rubberman's Avatar
    Join Date
    Apr 2009
    I can be found either 40 miles west of Chicago, in Chicago, or in a galaxy far, far away.
    This has been well known in the hacker and security/forensics community for some time (a few years at least). We use these techniques to access the encryption keys for systems that utilize full-disc encryption techniques, as an example. If you want to secure your system after shutdown, then modify the code to randomize RAM and flash memory on shutdown. Not simple, but doable.
    Sometimes, real fast is almost as good as real time.
    Just remember, Semper Gumbi - always be flexible!

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