On Mon, Jun 20, 2016 at 09:00:49PM +0200, Stephan Mueller wrote: > > The time stamp maintenance is the exact cause for the correlation: one HID > event triggers: > > - add_interrupt_randomness which takes high-res time stamp, Jiffies and some > pointers > > - add_input_randomness which takes high-res time stamp, Jiffies and HID event > value > > The same applies to disk events. My suggestion is to get rid of the double > counting of time stamps for one event. > > And I guess I do not need to stress that correlation of data that is supposed > to be entropic is not good :-) What is your concern, specifically? If it is in the entropy accounting, there is more entropy in HID event interrupts, so I don't think adding the extra 1/64th bit of entropy is going to be problematic. If it is that there are two timestamps that are closely correleated being added into the pool, the add_interrupt_randomness() path is going to mix that timestamp with the interrupt timings from 63 other interrupts before it is mixed into the input pool, while the add_input_randomness() mixes it directly into the pool. So if you think there is a way this could be leveraged into attack, please give specifics --- but I think we're on pretty solid ground here. Cheers, - Ted -- 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
