Messages in this thread |  | | Subject | Re: [PATCH] (0/4) Entropy accounting fixes | From | Robert Love <> | Date | 18 Aug 2002 12:58:39 -0400 |
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On Sun, 2002-08-18 at 03:31, Bernd Eckenfels wrote:
> A question: what is the denger of the network entropy? is it, that one is a > fraid that snooping could gather knowledge about random source, or is it > more along the line that one fears that specially deviced packages can feed > manufactured, and therefore not randmom bits?
The later. Some believe someone on your local network, who understands the timing of the physical layers and devices, can influence the entropy pool. Further, then, we assume SHA is cracked. Then they know enough state and can presumably determine the output of [u]random.
Of course, this is all theoretical but I would not gamble in certain situations either. In some, like my workstation on my network, I feel safe and enjoy having sshd not block waiting for entropy. So I wrote the netdev-random stuff...
Note the patches work in the converse manner, too: _today_ there are network drivers that contribute entropy. With netdev-random you can stop that if you wish.
> In the first case, how big would be the hardware proccessing variance for an > interrupt be? Is it realy predictable from sniffing the network how that > will result in interrupts?
Possibly.
> How can softinterrupts help here?
Under load the execution of softinterrupts is virtually non-deterministic, so they do help but we do the timing off the interrupt handler itself.
Robert Love
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