Matches for Entropy, 516 total results Sorted by newest | relevance
Tue Jul 15 21:22:37 UTC 2014 <Rassah> asciilifeform: So, if I use an entropy device to generate paper walets, you can bruteforce it by recording the temperature in my room???
Tue Jul 15 21:19:00 UTC 2014 <Rassah> asciilifeform: From Nikita again: Most cells have too much skew to be useful. We suck entropy out of those whose skew is low. That's why there is ~21:1 cell-to-entropy ratio at room temperature on most devices. They had one device from Microchip IIRC, whose entropy was much lower, but the others were very close to the 20–21 ballpark. We analysed data from MRD SoC, which is in the bitcoincard, and got the same 21:1 ratio. Then I
Tue Jul 15 21:19:00 UTC 2014 <Rassah> put it in the freezer in the kitchen and collected data while it was cooling down. There was still plenty at 0ºC, but it smoothly went down to zero entropy around -20º. The cells with high skew are those which effectively constitute device signature.
Tue Jul 15 21:11:35 UTC 2014 <Rassah> Will Atmel know what your seed and other entropy sources are? If not, why does it matter?
Tue Jul 15 21:01:27 UTC 2014 <asciilifeform> Rassah: by what means do you 'collect the entropy' ?
Tue Jul 15 21:00:30 UTC 2014 <Rassah> We don't use hashing as a source of entropy, no. Only to combine ours with a salt
Tue Jul 15 20:59:57 UTC 2014 <asciilifeform> mircea_popescu: yes. some people, somehow, think this adds 'entropy'
Tue Jul 15 20:57:35 UTC 2014 <asciilifeform> Rassah: hashing as an attempt to 'distill' entropy.
Tue Jul 15 20:40:46 UTC 2014 <Rassah> It may reduce entropy, but it inreases he number of attack vectors, doesn't it? Attacker would need both the hardware based RNG and the salt to compromise it
Tue Jul 15 20:39:23 UTC 2014 <asciilifeform> Rassah: do you actually believe that hashing can add (instead of subtracting) entropy?
Tue Jul 15 20:36:49 UTC 2014 <Rassah> key = H(salt||H(entropy)) with H(entropy) on a second sheet of paper so the user can verify it... or something
Tue Jul 15 20:33:54 UTC 2014 <Rassah> Yes. If you plug tis device into your PC while holding down the button, it shows up in "flash mode", where instead of just a USB stick with a JPG on it, you get to see all the system and settings files. One of those files is a user provded sald (like diceware) that will be combined with the rest of the entropy sources to produce the final key
Tue Jul 15 20:32:03 UTC 2014 <Rassah> I mean the chip and the hardware has a lot of stuff in there. The entropy is altready there, but initially we figured the SRAM chip was overkill. The "software adding entropy" meaning we just add more code to grab entropy from more hardware and user sources
Tue Jul 15 20:30:46 UTC 2014 <mircea_popescu> software does not add entropy.
Tue Jul 15 20:30:10 UTC 2014 <Rassah> mircea_popescu: No, the hardware design is finished. Changes are only in software. Initial method of creating keys is done, we are just adding software patches to add more and more entropy sources to this thing.
Tue Jul 15 20:26:54 UTC 2014 <Rassah> Ah, got a eply. Seems we'll be using he Atmel provided SRAM after all. And "We will be doing our own analysis of data from several chips, and provide a raw entropy file for those who want to do their own for their specific device." combined with "option to enter a user-supllied salt"
Tue Jul 15 20:24:38 UTC 2014 <Rassah> We can store part of the raw entropy into non-volatile memory and
Tue Jul 15 20:24:38 UTC 2014 <Rassah> compare it on the next run. Since we have about 30 times more entropy
Tue Jul 15 20:23:09 UTC 2014 <Rassah> In our tests, it still had plenty of entropy at 0ºC, but it smoothly went down to zero entropy around -20º. Maybe we should put warning stickers on these things saying "Caution - Chaotic System. Do not use in low entropy environments above the Arctic or below the Antarctic circle, unless exposed to external sources of energy" :)
Tue Jul 15 20:14:49 UTC 2014 <Rassah> Basically an extremely high level entropy generator that uses that entropy to make secure paper walets