On Thu, Oct 17, 2013 at 02:39:01PM -0700, Jon Callas wrote:
It is certainly true that radioactivity is a random effect, and is quantum in nature. That does not mean that in order for a random sampling to be quantum, it must be based on radioactivity; there are other quantum sources of randomness. Noisy diodes, resister noise, CCD noise, etc. are all quantum. If you want to get picky, *all* physical effects are quantum, even ones that aren't usefully random. There is nothing magic about one physical source or other that makes it more suited for crypto. Thinking that a hardware source should be radioactive is affirming the consequence, as well.
Radioactivity is almost uniquely insensitive to tampering through environmental influences, though, owing to the large energy scale of nuclear processes [1]. Unfortunately, it does not automatically follow that the circuit used to detect it is also similarly robust, and NSA would probably be able to easily develop the capability to eavesdrop on Geiger-counter based RNGs if they become widespread. A high DC voltage, and abrupt current pulses - this is sounding rather similar to a spark-gap transmitter. [1] A handful of exceptions exist involving low-energy beta decays, such as Dy-163 and Re-187. -- Andrea Shepard <andrea@persephoneslair.org> PGP fingerprint (ECC): 2D7F 0064 F6B6 7321 0844 A96D E928 4A60 4B20 2EF3 PGP fingerprint (RSA): 7895 9F53 C6D1 2AFD 6344 AF6D 35F3 6FFA CBEC CA80