51–60 of 74 posts
I built a program that automatically locks my OSX machine when I get far enough away from it. It uses iBeacon ranging and I have the beacon in my pocket. Debated on sharing with others but I never managed to clean it up enough to be proud of sharing it.
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There's a program for Linux that does the same, but using your phone (or other Bluetooth device) called blueproximity. It had a slight tendency for false positives, though - sometimes it locked the screen even with the device less than a meter away.
I had a laptop once that for some reason wouldn't use the battery even on a full charge. So, naturally, as soon as the power cord was pulled out, the laptop crashed. Would make for a pretty good DMS; being deceiving with a battery attached and the OS reporting a full charge. I wonder if there's a way to modify the mainboard (knife a lead or something) to be incapable of using the battery while still charging and the…
Why go the hardware route? The AC adapter state is reported to the operating system; for instance, KDE on my laptop plays a sound when a blackout cuts the power to the AC adapter. It should be simple to have something else monitor the power state and tell logind to lock all screens on AC power loss, or even force a shutdown if you're paranoid.
Not that it would help much; there are devices which can keep the AC power on while a computer is unplugged and transported, even for desktops (which have no internal battery). Nothing prevents these devices from also being used on laptops.
What you want is an RFID keyfob/detector. There used to be a writeup on a homebrew version of this at http://hackaday.com/2013/09/07/hidden-rfid-reader-locks-work... -- but the link that article references is rotten now. A sufficiently motivated person should be able to dig up instructions somewhere. A few years ago there were companies that did this for most operating systems, and fairly inexpensively too, but I'm h…
Anything rfid can easily be duplicated.
[1] http://en.wikipedia.org/wiki/Contactless_smart_card#Security
I built a program that automatically locks my OSX machine when I get far enough away from it. It uses iBeacon ranging and I have the beacon in my pocket. Debated on sharing with others but I never managed to clean it up enough to be proud of sharing it.
Carrying a beacon in your pocket seems like a really impractical solution if you own a smartphone.
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Anything rfid can easily be duplicated.
A simple readonly RFID tag - agreed. But think "smartcard with wireless power transmission" like [1]. These should be able to ensure cryptographically secure communication and identification. At least MitM-attacks without physical access to the card should be unfeasible, right? [1] http://en.wikipedia.org/wiki/Contactless_smart_card#Security
If you're up against an enemy capable of realizing ahead of time that you've RFID-protected your device, and capable of cloning your RFID tag without your knowledge, then you're probably screwed no matter what you do.
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You probably read about it in Cryptonomicon (I know that's where I read about it), but I don't know if Stephenson made it up or not. As to practically It seems quite unfeasible. First of all since magnetic forces fall off according to the inverse square law, you're going to need a seriously large magnet to for it work at say 1 meters distance or so. You're basically going to have seriously retrofit your entire house,…
Unless you can get your hands on a powerful magnetic monopole, the field falls off with the inverse CUBE of distance. (Note: noone has so far managed to get their hands on a magnetic monopole, powerful or otherwise.)
I remember reading about that if HDD can be put in a magnetic field, it will be destroyed. If my door/passage can be set to generate magnetic field enough to destroy HDD, then as soon as authorities take out the computer out of your home, the HDD will be destroyed. But I have no idea how practical is this.
I remember reading about that if HDD can be put in a magnetic field, it will be destroyed. If my door/passage can be set to generate magnetic field enough to destroy HDD, then as soon as authorities take out the computer out of your home, the HDD will be destroyed. But I have no idea how practical is this.
As others have noted: Cryptonomicon. ...but that basic idea did give me another one: electromagnets on a separate circuit inside the drive enclosure or laptop body. Fail to pass a security check on schedule and the circuit is engaged, destroying the HDD. I'm no hardware wizz although I did make a motor out of a nail and copper wire once.
The problem then is false positives. Only 1 mistake and kablooie.
I remember reading about that if HDD can be put in a magnetic field, it will be destroyed. If my door/passage can be set to generate magnetic field enough to destroy HDD, then as soon as authorities take out the computer out of your home, the HDD will be destroyed. But I have no idea how practical is this.
And right next to the magnetic coil, behind a small blast shield, was an old PC... an early 90s beige box looking like a 486 or early pentium, controlling some measurement equipment.
We asked how that worked, and whether there are any problems with "EMP" with the hardware or the hard disk. The answer was, no, the PC works fine. But you have to be extremely careful not to leave any screws or screwdrivers around, because "above xxx T/m field gradient, iron starts to fly", as evidenced by lots of scratches on the concrete.