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SubjectRe: kernel security questions
   Date: Mon, 16 Mar 1998 14:31:05 -0500 (EST)
From: Jon Lewis <jlewis@inorganic5.fdt.net>

> /dev/urandom and /dev/random use the same algorithm for generating
> random numbers, and so their speed is the same. The big difference
> between the two is that the random number generator keeps traccxcxcx

If you try to read signifigant amounts of data from both /dev/random and
/dev/urandom, you'll find urandom to be orders of magnitude faster.
Perhaps this is just because /dev/random runs out of random bytes and
makes you wait for more to accumulate.

Sorry, my keyboard malfuctioned while I was sending this (and I had to
wait to get a new Sun type 5 keyboard)....

Yes, the only difference is that /dev/random runs out of random bytes
and it makes you wait for more to be accumulated. Note that on some
systems, it can block for a long time waiting for new user-gneerated
entry to be entered into the system. So you have to use care before
using /dev/random. (Perhaps the best thing to do is to use it when
you're generating sensitive keying information, and you tell the user to
pound on the keyboard repeatedly until you print out "OK, enough".)

- Ted

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