Re: random or urandom???

From:
Date: 09/09/02 

Date: Mon, 09 Sep 2002 21:44:18 +0200

Dragan Cvetkovic wrote:
>
> In other words, /dev/random is more secure but much slower and will most
> certainly block when large number of data is required (I think somebody
> posted that he needed 10 minutes with /dev/random for the same amount of
> data that /dev/urandom could generated within 10sec).

We discussed that back in february: <news:3C6EE1AA.6ECB954E@daimi.au.dk>

The speed of /dev/random is mostly affected by the speed of the user.
While the speed of /dev/urandom is only affected by the speed of the
CPU. So comparing them will give different results depnding on the
speed of your CPU and the speed of your user.

If I move my mouse like if I was mad, I am able to produce 10KB/s
from /dev/random. OTOH /dev/urandom produces 440KB/s with my 350MHz
AMD K6/2.

Others have expirenced larger differences like 1KB/s vs. 1MB/s. The
speed of randomness from the mouse might depend on the type, at
least it seemed to be the case that PS/2 mice gives more randomness
than serial mice.

To wipe a 10GB harddisk with /dev/random, you would have to move the
mouse for 11 days nonstop. And you should repeat that three times.
That is more than one month of nonstop mousemovements. I think if
you do that you will have something else to worry about than if
anybody is able to read your disk. 

-- 
Kasper Dupont -- der bruger for meget tid på usenet.
For sending spam use mailto:aaarep@daimi.au.dk
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