Electronic Protocol

[paddysteed]

This is a flow diagram of an authentication protocol I designed a few months back. I am happy for it to be used for this project. It would be useful for small device wireless authentication as it does not require the pass-code to be sent nor does it require encryption. There are libraries available for microcontrolers to do the hashing functions and the random number generation (http://www.das-labor.org/wiki/AVR-Crypto-Lib/en).

[paddysteed]

You could have a wireless key inserted into a slot, when turned powered the device and powered the key (through induction, the same method electric toothbrush's use to charge, there would be no need for a battery in either key or lock making the lock suitable for standard doors where there is no power supply. Both key and lock would just have a large capacitor for storing the power needed to unlock and lock.

You could also have a 'Master key' -- connected to a computer or smart phone (bluetooth?) which would be inserted to update the 'allowed key's' in the locks database.

[vov35]

Bluetooth itself is a horribly insecure protocol. Also we discussed in the main thread how exactly the lock itself would be designed, and the vulnerabilities of having giant inductors...

[paddysteed]

Bluetooth+RSA is very secure!

[jonwil]

This is exactly the sort of authentication protocol I suggested in the other thread.

Although I would use SHA-256 (or possibly double SHA-256) to avoid vulnerabilities in SHA1.

[paddysteed]

Great Minds think alike, who said anything about inductors? http://en.wikipedia.org/wiki/Piezoelectric_motor

[mh]

They are nice, you can build systems that can't be influenced by magnets with them.
I don't see how they relate to toothbrushes or induction, though.
And if you want power from a piezo electric generator, I'm afraid you'd have to turn a lot...

Building an electromagnetic generator somewhere into the system would be possible though, I think, and could be designed in a secure way.

Cheers
mh

[paddysteed]

The pizo motor would turn the lock, it is not influenced by magnetic fields, there would be an electromagnetic generator when the key was turned but manipulating that would not cause the door to open, the induction is to power the key

[vov35]

You could have a wireless key inserted into a slot, when turned powered the device and powered the key (through induction, the same method electric toothbrush's use to charge, there would be no need for a battery in either key or lock making the lock suitable for standard doors where there is no power supply. Both key and lock would just have a large capacitor for storing the power needed to unlock and lock.

You could also have a 'Master key' -- connected to a computer or smart phone (bluetooth?) which would be inserted to update the 'allowed key's' in the locks database.

Giant inductors.
I don't really care if it's a piezo or not, it's a question of what happens if one were to expose it to massive RF...

[mh]

"Massive RF" like an open microwave oven can be more easily shielded from, than strong magnets.
I.e. wrapping things in electrically conductive material is easier than in magnetically conductive material.

[jonwil]

IR is the best way IMO. Done right its nigh-impossible for someone to fry an IR system. (well a lot harder than frying RF type systems)

Also, IR isn't vulnerable to the kind of attacks being carried out on car keyfobs by thieves where the attacker jams the signal from the keyfob so the user thinks they locked their car but the car is still unlocked.

The keys could have batteries that charge up over USB (come into the house and plug your keyfob into a USB charger box on the front table and its right there when you want to go and will be fully charged up) or they could just have car key batteries that could be replaced at the same places car keyfob batteries get replaced (car key batteries last long enough so why wouldn't the batteries in these things)

[vov35]

"Massive RF" like an open microwave oven can be more easily shielded from, than strong magnets.
I.e. wrapping things in electrically conductive material is easier than in magnetically conductive material.

Which doesn't work when you need an antenna.

I agree with the IR idea... but I more or less proposed it in this project.

[paddysteed]

I agree, EMPing the lock would probably cause it to break, but it will never open the lock, the problem with inductors in locks is that by manipulating magnetic fields around them one may be able to open the lock, which is exactly why I propose that the motor for the bolt is a pizo motor, they are unaffected by magnetic fields.

[paddysteed]

IR would be very good, at the end of the key inserted into the lock. I see no way to power the lock apart from a dyno although I see no problem with a dyno due to reasons in my previous post.

[vov35]

if you microwave it you're arcing through many semiconductors, causing things to fault open. That's my security concern here...