Is /dev/random good enough to generate one-time pads?

[Bryan Reece]

   Date: Thu, 28 Nov 1996 15:31:28 +0000 (GMT)
   From: The Deviant <deviant at pooh-corner.com>

   On Wed, 27 Nov 1996, Igor Chudov @ home wrote:

   > Subj sez it all.
   > 
   > Thank you.
   > 
   > 	- Igor.

   Yes, as a matter of fact it is.  /dev/random is based on an entropy pool
   taken from hardware interrupts and such, thus is a RNG, not a PRNG (thats
   right IPG, Linux uses hardware to get random numbers... imagine that!).
   /dev/urandom is, however, a PRNG...

Only if you try to pull out more bits than you can get from /dev/random.

Note that /dev/random on a single-user system doesn't generate bits
fast enough to be practical for OTP generation (try od -tc1
/dev/random sometime; you'll get about 512 bytes if you haven't used
it lately, then reads will block until enough unpredictable things
happen ).  Of course, you can add more randomness sources.

How good a source would a radio or diode noise source connected to the
parallel port's IRQ input be?  It certainly sounds like it would be
cheap enough.