[Cryptech Tech] Google's project vault

[Bernd Paysan]

Am 17. Juli 2015 22:08:04 GMT+08:00, schrieb "Joachim Strömbergson" <joachim at secworks.se>:
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>Aloha!
>
>Picking up an old thread, sorry for a slow reply.
>
>Bernd Paysan wrote:
>> However, I think I was the only one who actually did measure the
>> jitter of the ring oscillators, and the current design doesn't allow
>> end users to run that test, so we fail on that, too ;-).
>
>The current design allows you to read out the raw outputs from the
>oscillators. What should we add more to provide measurement of the
>jitter of the oscillators?
>
>- -- 
>Med vänlig hälsning, Yours
>
>Joachim Strömbergson - Alltid i harmonisk svängning.
>========================================================================
> Joachim Strömbergson          Secworks AB          joachim at secworks.se
>========================================================================
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You need a reliable timing base for the sampling. When I measured the jitter, I sampled every 16 cycles with a 50MHz clock, and filled 512 samples into a buffer. That sort of thing needs some hardware support when the frontend CPU is not deterministic enough. 
-- 
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