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Re: [vox-tech] random # gen seeds
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Re: [vox-tech] random # gen seeds



On Wed, Mar 13, 2002 at 08:05:13PM -0800, Matt Holland wrote:
> I need to generate more than one random number generator seed per second 
> within a C program (I have a program that runs about 6 times a second, 
> and I need unique seeds for each run).  time(0) only gives me a 
> resolution of 1 second... any suggestions?
> 
> Thanks,
> Matt

Ummm, you don't really say what kind of random numbers you need, true random?
Psuedo random?  Unique?  Just different?  Any reason you couldn't just
once a minute get some bytes from /dev/random to initialize a random()
and generate 6*60 psuedorandom numbers?

Quite a bit of effort has been put into /dev/random to insure it's as
random as possible collecting entropy from as many places as possible,
protection against entropy flooding, support for adding entropy by 
cat my_collection_of_random_stuff > /dev/random etc.  Oh and it's
careful to query information that is not easily visible outside
the kernel.

But the main problem is if you read to quickly from /dev/random you
will block till the generator decides it has enough entropy to output
more.


-- 
Bill Broadley
Mathematics/Institute of Theoretical Dynamics
UC Davis
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