I have an idea, but i don't know IF it could work, or HOW to do it.
this is the idea: to have an application that has two sub-states:
normal state: the smartphone (nokia n9 in my case) is silent and/because is next to an NFC tag.
alarm state: the smartphone makes a hell of a noise and/because is far from the above tag
the trigger from normal to alarm would be a check of the proximity with the tag (every 5 seconds? don't know), and the trigger from alarm to normal would be a password / facelock / voice check / blood exam / whatever.
the reason i thought of this system is simple: in a subway, in a swimming pool (if you leave the smartphone on sight), or wherever, it's more difficult to steal the smartphone AND the NFC tag than the smartphone alone. this is truer when the tag and the phone are in different pockets of the same jacket for example.
when it's about coding, I am THE IGNORANCE in the flesh
i don't even have an NFC tag, so i really have no idea what i'm talking about
If you want that your N9detects an NFC tag it has to be less than some milimeters away from the phones back. So this is a nice idea but impossible to do.
you can do low power BT hack for example limiting antenna to 1m. and keeping BT device on your other pocked. But cons are that the other device will require power.
- The detection distance for typical tags is only a couple of centimetres at most. You might be able to put a tag onto the other side of pocket lining or something like that, but hardly to different pockets
- You cannot control from applications when or how to poll for tags, the system keeps that to itself. N9 only polls for tags when the phone is not idle (when the display is on). So checking every 5 seconds on an idle device is out of the question.
While you could bring a tag to the RF field while the display is on and keep it there after device goes idle (NFC remains active until tag leaves the RF field), that is quite expensive batterywise.
- You cannot control from applications when or how to poll for tags, the system keeps that to itself. N9 only polls for tags when the phone is not idle (when the display is on). So checking every 5 seconds on an idle device is out of the question.
this is a huge problem i wasnt aware of. thank you all, anyway!
Same idea but with Bluetooth instead of nfc would be cool. The other Bluetooth device could be anything from your headsets (that you keep in a different pocket) to your boyfriend's phone when you'r out together.
The only issue is... What exactly will happen when the Bluetooth connection is lost? Play a loud sound? The thief will simply switch it off. Keep sending text messages? Coordinates? Pictures taken by both cameras? Is the idea patented?
All NFC, BT, WLAN and GSM-cell change, and proximity change alarms could be useful.
NFC-alarm can be replaced with acceleration check, when the device is in stationary place, so no other type of acceleration is happening like if phone would be in a moving car.
@benny: the headset idea is very interesting!! it would remove the problem to carry an ad-hoc BT item.
i thought that alarm mode would trigger an audio alarm and a functionality lock (so that the alarm cannot be muted).
@zimon: i didn't think of the smscon possibility! it would give serious security improvement to the app.
