I've been thinking about the *power* side-channel: the ability to watch instantaneous power consumption to guess what a computer is computing. Closely related: the chip temperature side-channel: the ability to watch instantaneous temperature distributions across a chip to guess what a computer is computing. Note that simple power supply filtering doesn't work well enough, as one might be able to watch enough computation to still be able to discern some amount of information. Since many computers would like to keep confidential what they are computing, the question is raised: **Are there computer arithmetic circuits which draw the same sequence of instantaneous power draws *regardless* of the numbers being computed or moved?** For example, some computer circuit may draw slightly more power when a "1" appears on a bus instead of a "0". Under these conditions, it might make sense to drive the bus with both the number and its binary complement, in order to keep the power draw the same, no matter what bit pattern is being operated on. Are there particular number representations and arithmetic circuits (or even *boolean circuits*) whose power consumption is indifferent ("oblivious") to the input bit patterns? Note that CMOS typically utilizes both PNP and NPN transistors in a complementary fashion. However, due to semiconductor physics, these transistors are not 100% complementary -- especially at high clock rates -- and therefore they don't provide as much obliviousness as one would like, so assume for this conversation that we might still have to mirror even CMOS gates.