From mboxrd@z Thu Jan  1 00:00:00 1970
From: wudmx@web.de (Andreas Leppert)
Date: Sun, 30 Jan 2011 00:49:10 +0100
Subject: Creating the same random numbers
In-Reply-To: <1041152607-1296331182-cardhu_decombobulator_blackberry.rim.net-897203629-@b27.c7.bise7.blackberry>
References: <20110129140936.GA3225@yoda>
	<AANLkTi=npMrRDt8FQ=EM-dC-jYBts8KC5BY5A9tqx2a-@mail.gmail.com>
	<1041152607-1296331182-cardhu_decombobulator_blackberry.rim.net-897203629-@b27.c7.bise7.blackberry>
Message-ID: <20110129234909.GD3225@yoda>
To: kernelnewbies@lists.kernelnewbies.org
List-Id: kernelnewbies.lists.kernelnewbies.org

On Sat, Jan 29, 2011 at 07:59:34PM +0000, creslin at gmail.com wrote:
> But in short answer yes, if you use the same seed the same answer
> would be generated, assuming no further entropy is used later I.e
> dependent on method employed to expand. Though then the 'randomness'
> is in the seed not the output. Its this capability which allows simple
> access control token devices to operate.
> 
I'm not quite familiar with the number generators in the kernel. Right
now I do this to get a random number betwen min and max:

/* compute the random value within the given min and max wrt to step */
int tmp_bytes, range;

range = max - min + 1;
get_random_bytes(&tmp_bytes, sizeof(tmp_bytes));
if (0 > tmp_bytes)
	tmp_bytes = -tmp_bytes;
new_random_param->curval = tmp_bytes % range + min;

You mentioned the seed value. Is there a way to set a seed value before
I invoke get_random_bytes? Could you direct me to a page / source file
where I can get more information about it?

Thanks for all responses so long!
Andreas Leppert