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SubjectRe: [PATCH] drivers/net: remove network drivers' last few uses of IRQF_SAMPLE_RANDOM
> For systems with high resolution timers, even if an attacker has total
> knowledge/control of the network, it doesn't seem realistically possible
> for them to determine the low order bits of the nanosecond timer of
> disk and network I/O system calls, if those were used as a source of
> entropy.

Around the same time I was working on getting the performance figures
for the RNG in the Infineon TPM in the system I had, I tried, however
briefly, to concoct a test using netperf and pulling the ITC on an
Itanium processor to generate some randomness. I'm not at all sure I
was doing things correctly - I was pulling the bottom one to 4 bits of
the ITC after each call to recv() of a TCP_RR test - but when I tried to
feed the resulting trickle of data through diehard (which I may have
been running poorly) it was giving nothing but a p value of 0.000000
which while I don't grok the p-value itself, I understand that
consistent value of 0.000000 is bad :(
So, I may have had a bad test case. If someone has some suggestions for
a better test of the low-order-bits-of-the-interval-timer hypothesis
I'd love to hear about them.

rick jones


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