RFID Kill Switch

[rmcdaniels]

In an effort to make the Civic less stealable, I wanted to install a kill switch. I had some cheap RFID modules that I got off of ebay (I see them there for $10-$20 all the time), so I rigged it up as a kill switch. That way I don't have to have a switch that is visible or even accessible from the interior of the car. As long as the RFID tag is within a few inches of the antenna, it activates the switch. You could put it behind the dash or an interior panel, maybe by the ash tray, just toss the tag in the ashtray to drive the car. I won't go in to what to kill with the switch, just don't make it the fuel pump, kill multiple items necessary to start the car (you will want a manual with a wiring diagram of the car), run your wires inside the OEM wiring harness, physically separate the RFID controller/antenna/relay, and back it up with a paging system. My goal isn't to make the car impossible to steal, just to notify me if someone is trying to steal it and slow them down long enough for me to arm myself and go make their acquaintance. The units that I got didn't have an output section, aside from a TTL output, so I rigged up a transistor to act as a switch for a relay. It appears to be working well, although mine is overheating a bit because my transistor is too small (trying to run a relay that takes 2.5 watts with a transistor that can handle 1.8 watts), but a bigger transistor costs about a dollar, so I'll fix it later. I may also try a smaller relay, the large/heavy-duty automotive relays draw much more than a regular electronics relay, and none of the stuff that I am killing requires anywhere near the 30 amp relay that I am currently using.

For anyone not familiar with RFID, there is a small antenna in the car that constantly looks for a tag, and I have a small tag that looks like a plastic key fob. The tag gets it's power from electromagnetic energy radiated from the antenna (so no batteries for the tag), so when it gets in range of the antenna (about four inches), the tag transmits a code to the RFID controller. If it transmits the correct code, then the RFID controller deactivates my kill switch. Each RFID tag has a unique code, and I can program my controller for which tags I want it to recognize.

I'd include pictures of my antenna mounting and details of how I wired the kill switch, but that would be stupid.

[HONDA GHANDI]

Nice work Mr McD. I had an idea for a kill using the hondata NOS inputs (switch activated) as well. This could make that idea virtually undetectable and impossible to work around short of a tow rope.

[Martian]

Tobi, intrigued by the hondata aspect. I needs some info.

[HONDA GHANDI]

Call me next week. I gots ideas.

[stu]

Very cool Roger.

[rmcdaniels]

I thought about doing something proprietary with an EMS input since I'm using AEM, I could signal it to turn off the injector outputs or something, which would be impossible to detect without logging in to the EMS, but ended up going with something a little more conventional. There are a lot of possibilities though, my last Civic had three kill relays controlled by the alarm system. I think that 90% of the effectiveness is in the installation though, someone smart will figure it out pretty quickly if they can see the wires.

[stu]

They should do that with government laptops with people who have sensitive information on them.

[rmcdaniels]

Actually I sell those now, and they use something similar on the ones used for processing sensitive and classified data. There is a CAC (Common Access Card) that you have to put in the computer to access it; it controls access to the PC and all of your information on the hard drive is encrypted using a key from your CAC, so even if someone hacks it all they have is encrypted data.

[Conrad]

rofl... I have a CAC.... and I stick it in my computer at work... (IBNERD)

[Street_Kings]

They should do that with government laptops with people who have sensitive information on them.

Actually I sell those now, and they use something similar on the ones used for processing sensitive and classified data. There is a CAC (Common Access Card) that you have to put in the computer to access it; it controls access to the PC and all of your information on the hard drive is encrypted using a key from your CAC, so even if someone hacks it all they have is encrypted data.


if you've got vista ultimate or enterprise, you've already got this function in the form of a feature called bitlocker.

[HondaPower]

Sounds good.