05.07.2017 1:31, Bernd Paysan пишет:
> Am Mittwoch, 5. Juli 2017, 00:23:40 CEST schrieb Pavel Shatov:
>> In step 6. block memory R is either overwritten with its own contents
>> (that changes no bits) or with a different value that on average changes
>> half of the bits. I have a feeling that those will have different power
>> consumption.
>
> If you want to avoid that, add one bit per memory cell which means "xor the
> rest with a pattern that has half of the bits set ('h55... 'haa..., 'h33,
> 'hcc, all are equally good). That way, you can achieve true constant-power
> for the memory write at the cost of just one bit per memory word.
Thanks for the excellent tip!
> However, most of the energy going into SRAM writes is precharging the bit
> lines, and discharging them, and since those are all symmetric (you discharge
> either the left or the right bit line for a SRAM write), only the
> flip/non-flip
> of the SRAM cell itself can make a difference. And that difference is small
> compared to the rest.
>
--
With best regards,
Pavel Shatov
_______________________________________________
Tech mailing list
Tech@cryptech.is
https://lists.cryptech.is/listinfo/tech
