+Pouyan & David. -----Original Message----- From: Kalle Valo [mailto:kvalo@xxxxxxxxxxxxxx] Sent: Friday, July 31, 2015 3:09 PM To: Stephan Mueller Cc: Oleksij Rempel; Pan, Miaoqing; linville@xxxxxxxxxxxxx; linux-wireless@xxxxxxxxxxxxxxx; Theodore Ts'o; linux-crypto@xxxxxxxxxxxxxxx; nhorman@xxxxxxxxxxxxx Subject: Re: [PATCH 2/2] ath9k: export HW random number generator Stephan Mueller <smueller@xxxxxxxxxx> writes: >>-rw-rw-r-- 1 lex lex 2564096 Jul 27 11:36 hwrng.out >>-rw-rw-r-- 1 lex lex 2468394 Jul 27 11:36 hwrng.out.bz2 >> >>Do i understand it correctly, in case of hwrng bzip was able to find >>enough pattern to compressed the data? Even with format overhead? >> >>I'm no an expert, help of an expert would be welcome, added some more >>people to CC > > This one does not look good for a claim that the RNG produces white > noise. An RNG that is wired up to /dev/hwrng should produce white > noise. Either by having an appropriate noise source or by conditioning > the output of the noise source. > > When conditioning the output, you have to be careful about the entropy claim. > For example, you cannot state that the data stream from your noise > source has close to one bit of entropy for each obtained bit. Thus, > the conditioner must ensure that the data from the noise source is > collected and its entropy is maintained and accumulated. > > However, the hwrandom framework does not provide any conditioning > logic. And I would say that such conditioner logic should not reside > in a driver either. I would say that the discussed RNG does not seem > fit for hooking it up with the hwrandom framework. Based on the discussion I'm going to revert this patch, at least for now. -- Kalle Valo -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
