Wipe function?

Joseph Bruni jbruni@mac.com
Thu Aug 28 07:07:01 2003

Obviously, the better way would be to pull out a number of bytes from 
/dev/random to seed your PRNG and then use the output from that to wipe 
the file in question.

FWIW, the /dev/random and /dev/urandom devices on OS X are identical:

 From the random(4) man page:

	/dev/urandom is a compatibility nod to Linux. On Linux, /dev/urandom 
	produce lower quality output if the entropy pool drains, while
	/dev/random will prefer to block and wait for additional entropy to be
	collected.  With Yarrow, this choice and distinction is not necessary,
	and the two devices behave identically. You may use either.

I noticed that /dev/random is also writable -- allowing one to add 
additional entropy to the pool. That's kinda cool. I could probably hit 
infinite improbability by writing my checking account balance into 
/dev/random!! With my luck my computer would turn into a bowl of 
petunias saying, "Not again!"


On Wednesday, August 27, 2003, at 09:33  PM, Werner Koch wrote:

> On Thu, 28 Aug 2003 00:10:27 +0530, Aditya  said:
>> cat /dev/urrandom on linux this way you wont end up emptying the 
>> system random pool !
> Wrong.  There is just one pool.  /dev/urandom and /dev/random both
> take their numbers from the same pool.  /dev/urandom merely does no
> block but falls back into a pseudo random number mode.  As soon as new
> entropy arrives /dev/urandom will suck it out not leaving anything for
> /dev/random.