We all want to keep our bitcoin safe . . .
But how about making a real, physical safe that you can open with bitcoin ?
Here is how I think you will be able to do it. Not now, but in a few months.The overall plan
Imagine you have a bitcoin address (to which you have the private key) called the LockKeeper address. Each physical lock you produce also has a bitcoin address. Call this the Lock address.
Using the Raspberry Pi you run a bitcoin client that is specifically looking for a transaction FROM the LockKeeper TO the Lock. If the lock sees such a transaction it opens the solenoid that a typical electronic lock has and then you can open the safe.Materials
1) First, get a safe. Let's spend £35 on one of these:http://www.diy.com/nav/fix/hardware/security/safes/-specificproducttype-electronic_safes/B-and-Q-Electronic-Safe-Anthracite-Small-9380971
If you have ever dismantled one of these you will know that there is a solenoid in the mechanism which, when active, enables you to turn the handle of the lock and open it. We are going to hack that.
2) Buy a Raspberry Pi. $35. (Ok you cannot buy them yet but Real Soon Now)
3) Install a future version of MultiBit (ok, it is not written yet!) that incorporates the ideas of "the Sound of Bitcoin' from this thread: https://bitcointalk.org/index.php?topic=53371.0
4) Buy a cheap USB microphone, a power switch and an op-amp/ relay (used to power the safe's solenoid)The build
1) You drill through the case of the safe and mount the power switch and microphone so that you can :
+ switch on the power switch from outside
+ the microphone can listen to external noises.
Epoxy these into place.
2) You add the Lock address to the copy of MultiBit which is running on the Raspberry Pi.
3) You hack the MultiBit source code (it is open source after all!) so that when it is notified of a transaction from LockKeeper to Lock it "does something" on the Raspberry Pi to power the opamp/ relay that then opens the solenoid. (I don't know how to breadboard the Raspberry Pi but I am sure it is doable).
4) The Raspberry Pi goes inside the physical safe, with an AA battery power supply.How it works
1) You do a spend from the LockKeeper to the Lock address. Only you can do this as only you have the LockKeeper's private key.
2) The transaction representing the spend you convert to a sound.
3) You switch on the physical safe's Raspberry Pi
4) You playback the sound so that the USB microphone can hear it.
5) The Raspberry Pi hears the sound, decodes the bitcoin transaction, understands it is a transaction from the LockKeeper address to the Lock's bitcoin address and hence powers the solenoid.
6) The physical lock opens.
It is crazy-tech, but in the near future it would be do-able and pretty cheap to build.