On 3/17/19 2:11 PM, Keith Packard wrote: > Thanks much for reviewing the system; we can change the timestamps to 64 > bits and then go find enough entropy to seed that to a random > value. The latter piece will take a bit of searching; entropy in > deterministic systems is a rare commodity, but we do have ADC pins and a > radio receiver. Time for some research. >
My favorite source of entropy is the user. Run something like a linear feedback shift register (or just run AES over and over) until the user does some randomly timed thing. In other words, shuffle the bits until the user stops it. For bonus points, save the result to nonvolatile memory and use that as the starting point the next time you shuffle bits. It doesn't have to be perfect, just unpredictable. 64 bits? Wow. Heat death of the universe time scales here. :-) The weak point in the system will then probably be the users selection of an AES key. They are unlikely to select a strong key. Perhaps another application for those randomly shuffled bits. -- http://home.earthlink.net/~david.schultz The cheaper the crook, the gaudier the patter. - Sam Spade _______________________________________________ altusmetrum mailing list [email protected] http://lists.gag.com/mailman/listinfo/altusmetrum
