Re: the cold-boot attack

[Jacob Appelbaum <jacob@xxxxxxxxxxxxx>]

Richard Zidlicky wrote:
> Hi,
> 
>> As a reaction to this "attack" I wonder if it might be possible to
>> use level 2 cache of the processor to store keys in highly volatile
>> memory space. 2 or more megabytes on the CPU die might be a last
>> resort. As gpg prevents leaking keys from kernel ram to swap
>> partitions, newer disk encryption might prevent keys to be stored
>> in DRAM cells. Of course, elderly processors might not do this
>> stunt due to lack of level 1/2/3 cache but newer architectures
>> offer ever increasing megabytes. Is that a worthwhile option?
> 
> there is aonether option that is well doable with todays technology.
>  On a multi-CPU machine run a dedicated noninterruptible kernel
> thread on one of the cores which keeps essential parts of the key in
> CPU registers at all times.
> 

I'm curious how you would account for the key schedule information and
other sensitive information.

> Using some of the coprocessors would be another interesting idea but
> much less portable.

Yes, it is less portable but it is tamper resistant and specifically
designed to thwart many types of attacks.

Regards,
Jacob Appelbaum




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