New Year's Resolution: Full Disk Encryption on Every Computer You Own • Hacker News Board

Re: New Year's Resolution: Full Disk Encryption on Every Computer You Own

#181

Post by epochwolf » Tue, Jan 03, 2012, 6:09 PM UTC

pyre wrote: post #180

epochwolf wrote: post #159

Earlier quoted context omitted.

You could just hold down the power button on your computer for 4 seconds and require a password to boot the system.

That depends on how quickly they can get guns pointed at you once the door is kicked in.

Okay, then you can set up your system to do a force shutdown if the power button is hit. If you're on a desktop, have a power strip near your foot so you can kick the toggle switch if the door comes down. (Or have a big red kill switch wired into the power supply on the front of the case.)

The latter option probably won't earn you any favors with the judge or the jury.

Re: New Year's Resolution: Full Disk Encryption on Every Computer You Own

#182

Post by eneveu » Tue, Jan 03, 2012, 11:51 PM UTC

fl3tch wrote: post #111

trotsky wrote: post #76

The feds and other serious folks are pretty careful these days not to turn off anything until they've had forensics evaluate the situation. And not just because of FDE, memory analysis very frequently yields the best evidence due to it's timely and overlooked nature. Since most encryption systems retain their keys during lock and sleep, unless you usually leave your system powered off I wouldn't count on being afford…

If you're worried about a state-level adversary, then yes, you should always turn off your computer when not using it. They could still be spying on you and wait until you turn it on to kick down the door. There are people who have thought about these things, too. One suggestion is a dead man's trap, like a pad that you sit on, so if the door gets kicked down (or they snipe you from outside the window), as soon as yo…

Reminds me of Cryptonomicon.

Re: New Year's Resolution: Full Disk Encryption on Every Computer You Own

#183

Post by sitkack » Wed, Jan 04, 2012, 6:26 PM UTC

thibaut_barrere wrote: post #79

sitkack wrote: post #35

Earlier quoted context omitted.

Knox is a better UI for the bultin in folder encryption on OSX?

see http://help.agilebits.com/Knox/why_knox.html

Cool. I already do something similar with encrypted sparseimages, I will give this a try.

Re: New Year's Resolution: Full Disk Encryption on Every Computer You Own

#184

Post by sitkack » Wed, Jan 04, 2012, 9:32 PM UTC

mikeash wrote: post #123

sitkack wrote: post #34

Earlier quoted context omitted.

An idling CPU and a slightly loaded CPU use about the same amount of energy. I think my Q6600 quad used 190W @ idle and running full tilt cpu (ray tracing) it was using 220W. For FDE it depends on how much IO you are doing. I doubt it will make even a 0.01 difference in your daily power consumption.

I don't think so. On my laptop, fully loading the CPU takes it from silent to screaming fans in about two minutes. That's clearly a big change in heat production and therefore power consumption.

You should use a kill-a-watt and measure it. Probably less than you think. Laptops already on the edge of their thermal envelopes, anything above their low steady state (browsing, listening to music) will cause the fans to spin.

Re: New Year's Resolution: Full Disk Encryption on Every Computer You Own

#185

Post by mikeash » Thu, Jan 05, 2012, 12:18 AM UTC

sitkack wrote: post #184

mikeash wrote: post #123

Earlier quoted context omitted.

I don't think so. On my laptop, fully loading the CPU takes it from silent to screaming fans in about two minutes. That's clearly a big change in heat production and therefore power consumption.

You should use a kill-a-watt and measure it. Probably less than you think. Laptops already on the edge of their thermal envelopes, anything above their low steady state (browsing, listening to music) will cause the fans to spin.

The battery time remaining will also drop by a factor of 4 or more. This is large enough that I don't think a more precise instrument is needed to determine that the effect is significant.

Re: New Year's Resolution: Full Disk Encryption on Every Computer You Own

#186

Post by sitkack » Thu, Jan 05, 2012, 2:00 AM UTC

mikeash wrote: post #185

sitkack wrote: post #184

Earlier quoted context omitted.

You should use a kill-a-watt and measure it. Probably less than you think. Laptops already on the edge of their thermal envelopes, anything above their low steady state (browsing, listening to music) will cause the fans to spin.

The battery time remaining will also drop by a factor of 4 or more. This is large enough that I don't think a more precise instrument is needed to determine that the effect is significant.

If I have time this weekend I will pop the battery on my macbook and do an erlang compile on an encrypted sparse image both on the rotational drive and the ssd. I'll report back on how much energy was consumed for (encrypted,non-encrypted) x (ssd,rotational)

batteries derate rapidly as the current draw goes up. They are not linear. For my own edification it would be nice to know what kind of energy hit encryption takes on both storage mediums.

Re: New Year's Resolution: Full Disk Encryption on Every Computer You Own

#187

Post by mikeash » Thu, Jan 05, 2012, 3:10 AM UTC

sitkack wrote: post #186

mikeash wrote: post #185

Earlier quoted context omitted.

The battery time remaining will also drop by a factor of 4 or more. This is large enough that I don't think a more precise instrument is needed to determine that the effect is significant.

If I have time this weekend I will pop the battery on my macbook and do an erlang compile on an encrypted sparse image both on the rotational drive and the ssd. I'll report back on how much energy was consumed for (encrypted,non-encrypted) x (ssd,rotational) batteries derate rapidly as the current draw goes up. They are not linear. For my own edification it would be nice to know what kind of energy hit encryption tak…

I would definitely be interested in hearing. I don't expect that the overhead of encryption will cause much additional power draw, simply because encryption doesn't require all that much CPU power. The stuff about fully loaded CPUs was wandering off into the theoretical realm about CPU power consumption variance in general.

For whatever it may be worth, I couldn't find idle power consumption for my notebook's CPU, but it is possible to come up with a worst-case estimate by taking the battery capacity and dividing by the runtime. Apple specifies "up to" 7 hours. While that is of course hard to achieve, I think it's fair to use that figure when looking at idle power use. The battery is 50Wh, so we can figure that the computer as a whole is using at most about 7W when idle. The i7-2677M CPU is specced to use up to 17W all by its lonesome when running flat out, so that's a substantial increase, especially when you take into account the fact that the base 7W idle-ish consumption is for everything in the computer, not just the CPU.