Messages in this thread | | | Date | Mon, 19 Aug 2002 17:21:58 +0200 (CEST) | From | Marco Colombo <> | Subject | Re: [PATCH] (0/4) Entropy accounting fixes |
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On Mon, 19 Aug 2002, Oliver Neukum wrote:
> > > > 1. You create a problem for in kernel users of random numbers. > > > 2. You forgo the benefit of randomness by concurrent access to > > > /dev/urandom 3. You will not benefit from hardware random number > > > generators as easily. > > > > You lost me. The kernel of course has "client" access to the internal > > pool. And since the userspace reads from /dev/random, it benefits > > The kernel users of random numbers may be unable to block. > Thus the kernel has to have a PRNG anyway. > You may as well export it. > > > from HRNG just the same way it does now. Point 2 is somewhat obscure > > to me. The kernel has only one observer to deal with, in theory. > > In theory. In practice what goes out through eg. the network is > most important. Additional accesses to a PRNG bitstream unknown > outside make it harder to predict the bitstream.
Not at all. Let me (one process) read 1MB from /dev/urandom, and analyze it. If I can break SHA-1, I'm able to predict *future* /dev/urandom output, expecially if I keep draining bits from /dev/random.
And even if it was not the case, you don't necessary need to read the PRNG output *in order* to be able to guess it. Every N bits you read, you learn more about its internal state.
Despite that, you tells you I'm not able to capture outgoing network packets as well?
.TM. -- ____/ ____/ / / / / Marco Colombo ___/ ___ / / Technical Manager / / / ESI s.r.l. _____/ _____/ _/ Colombo@ESI.it
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