[cryptography] Kernel space vs userspace RNG

Kevin kevinsisco61784 at gmail.com
Mon May 9 11:19:19 EDT 2016

That was my original point.  However, I now realize how much of a 
nightmare that would be.

On 5/9/2016 5:37 AM, Luca Testoni wrote:
> On 06/05/2016 19:48, Russell Leidich wrote:
>> But to answer your question, if we assume that the TRNG resides in the
>> kernel, I see no way in which an acoustic attack could defeat it, even
>> if the implementation sourced its randomness exclusively from the
>> microphone, as too much audio precision would be required to create a
>> predictable byte stream of any significant length in a realistic server
>> environment with lots of fan noise and multipath arrival issues. So
>> unless you're trying to attack a purely audio TRNG in a recording studio
>> -- and probably not even then -- this route seems hopeless.
>> Alternatively, you could try to attack a timer-based TRNG by shooting
>> sound at the booting machine in the hopes that the sound device would
>> send incoming sample packets to main memory on a predictable schedule,
>> but this, too, seems hopeless because even ensuring timing correlation
>> between timestamp counters on different cores is a perpetual annoyance
>> to software developers; hoping to sync the audio and core clocks is much
>> harder. The very existence of the RDTSCP instruction, which reads the
>> timestamp on a specified core, is evidence of this difficulty.
> Maybe could be attacked conversely, by an acoustic isolation of the
> entropy noise sound device?
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