Hi,
AK wrote (01 Jun 2014 22:22:45 GMT) :
> I just did some quick research on my it's important to have a clock
> that doesn't go backwards in time (the monotonic requirement). Other
> than the fact that the C version of htpdate requires this with its
> "adjust" feature (gave example about databases) and NTP has this in
> its design as well, I found a paper by David Mills (inventor of NTP)
> [1] that talks about the monotonic requirement. However, I couldn't
> see a good explanation as to why it's important. So I looked some more
> and found one concrete example [2] of a software system that does rely
> on the monotonic requirement. I know there should be more evidence,
> and I will look, but I think it's always a good security/correctness
> practice to have a monotonically increasing clock.
> [1] http://www.eecis.udel.edu/~mills/database/reports/time/timeb.pdf
> [2] https://www.unidata.ucar.edu/software/ldm/ldm-current/basics/platform.html
I agree in general.
Time sync'ing is run as part of the system initialization in Tails,
not as a continuous process. So, once the system is fully connected to
Tor and the time has been sync'd (which is what matters), time does
increase monotonically.
Also, we're setting the time to UTC, so most systems will have their
clock changed abruptly anyway, and if something breaks due to this,
well, it breaks and likely we'll notice. So I don't see why we should
introduce more complexity, just for the sake of adjusting the clock
more smoothly in case it's not that far from the current correct
UTC one. Did I miss anything?
Cheers,
--
intrigeri
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