sounds like a cool project..
So I just finished the first stage of my project which was to lock and unlock my car based on the proximity of my phone using bluetooth and thought I'd share it with you guys to see if you have any feedback. I used a Raspberry Pi with the cheapest USB bluetooth dongle I could find at MicroCenter as the basis for my system. Essentially the RPi continuously polls my Galaxy S5 for RSSI data, and if the value is within a certain range one of the 3.3v GPIO pins is brought high for .2 seconds. The two GPIO pins are each connected to a transistor which activates a relay which closes off the two wires attached to either the lock or unlock button on the driver's side door (lock or unlock depends on which GPIO pin is activated.) One of the wires attached to the lock button is also connected to a voltage divider which is then connected to another GPIO pin set for input, keeping the pin normally high and bringing it low while the lock button is pressed. This allowed me to use the lock button to deactivate and reactivate the bluetooth unlock system by holding it down for 5 seconds. The RPi was originally $40 when I got it a year ago, however I believe you can get one for $30 nowadays, the bluetooth dongle was $10, the 2 relays were $12, I got a pack of 15 transistors for $3.50 at RadioShack, and the miscellaneous resistors, wire, and 2 diodes for the relays should run about $10, bringing the total cost to about $65. The next step is to install a push button start that's enabled by the RPi when the phone is close enough while retaining the functionality of the stock ignition. If anyone knows a good way to override the Ford PATS system I would really appreciate it. Lemme know if you guys have any suggestions and if anyone wants a full write up to do something similar I'd be more than happy to oblige.
sounds like a cool project..
Be careful. You may want to use a different technology. Blue tooth is very easy to hack and if someone with very basic hacking skills knows you are using blue tooth in such a manner. Anything you give access to through blue tooth can be used by someone else.
So if you use blue tooth to disable any sort of security to start your car or anything you just made your car easy to steal. Or at least break into.
From what I understand blue tooth is not encrypted and I could use a simple program to capture your transmissions and be in your car. If I use am amplified antennae on a device made for doing this (less than $100 for the device) I could likely pick this up a block or more away. So be careful with what you do with this...
Chances of you having a hacker near you might be slight but just be careful...
Yes, at the moment it's not very secure. All that would be required is for someone to spoof my mac address and get close to my car. But this was really just a proof of concept for the door unlock part. I'm developing an android app for this project that will send a rolling code based on the current time, after which someone would need to spoof my mac address and figure out the algorithm used to determine the rolling code. It's pretty much the same concept used in stock keyless entry systems and garage door openers. Bluetooth itself is not encrypted, but its fairly simple to encrypt the data you're sending over it. I appreciate the concern nonetheless though. I'll post the code with an example algorithm for the encryption and rolling code once its finished, and then it's on to getting the push button start implemented.