On Fri, May 05, 2006 at 01:13:23PM -0400, Kyle Moffett wrote:
> On May 5, 2006, at 12:42:35, Matt Mackall wrote:
> >Remove SA_SAMPLE_RANDOM from network drivers
> >
> >/dev/random wants entropy sources to be both unpredictable and
> >unobservable. Network devices are neither as they may be directly
> >observed and controlled by an attacker. Thus SA_SAMPLE_RANDOM is
> >not appropriate.
>
> I thought I saw an analysis somewhere of why it was actually OK to
> include randomness from network devices (or even basically any
> interrupt source that isn't periodic on a fundamental hardware
> level). It had something to do with investigating interrupt arrival
> time from real-time network traffic; they hooked a logic analyzer of
> sorts up to the physical ethernet cable itself and to the system bus
> of the destination computer (and wrote software that recorded a TSC
> timestamp of every interrupt). Essentially the interaction between
> the occasional ethernet retransmission, variable internal network
> card latencies and queues, variable CPU-dependent interrupt
> latencies, critical sections in the OS, etc, plus the high-resolution
> nature of the TSC used for a seed value made it a chaotic system and
> basically cryptographically impossible to predict the interrupt
> data. It's possible that the analysis I saw was later proven
> incorrect; but I'd be interested if you've seen some paper or
> research on the topic that I haven't, I'd be interested in references.
I haven't seen such an analysis, scholarly or otherwise and my bias
here is to lean towards the paranoid.
Assuming a machine with no TSC and an otherwise quiescent ethernet
(hackers burning the midnight oil), I think most of the
hard-to-analyze bits above get pretty transparent.
--
Mathematics is the supreme nostalgia of our time.
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
[Index of Archives]
[Kernel Newbies]
[Netfilter]
[Bugtraq]
[Photo]
[Stuff]
[Gimp]
[Yosemite News]
[MIPS Linux]
[ARM Linux]
[Linux Security]
[Linux RAID]
[Video 4 Linux]
[Linux for the blind]
[Linux Resources]
