Hi,
since this is my first post in this forum, allow me to first introduce myself:
I'm a computer science student interested mainly in P2P and cryptography. Besides that I'm also involved in the "hacking community" in Germany (CCC). These are the two reasons why I got to know about Bitcoin quite early I guess. So far I didn't really participate actively in the community, but I think I've got a good understanding of the technology and I follow the news about Bitcoin all the time. Due to my interest in cryptography I'm also especially interested in this project of the Johns Hopkins University named Zerocoin. :-)
So as this forum requests a substantial first post, I want to share with you my thoughts on using a Smartphone as an Offline-Wallet for Bitcoin. They arose after reading about offline transactions with Armory that work like the following (nothing new of course, but I want to make clear the difference to my idea):
Initialization:
1. Generate Bitcoin Wallet on a computer that is never connected to a network
2. Import the Bitcoin address into your normal wallet (in a way that the private key doesn't leave the offline computer).
Spending:
1. Create unsigned transaction on your normal wallet (since it doesn't have the private key)
2. Put unsigned transaction on a USB stick and transfer it to the offline computer
3. Sign transaction with the offline computer, transfer it back to the normal wallet
4. Upload the transaction to the Bitcoin network
I think this is a better solution than the Trezor, because it allows to make encrypted backups of the private key instead of (as I understand it) unencrypted paper wallets. The problem is that another computer and a USB stick is needed which isn't a very comfortable and mobile solution. If you build a small computer and replace the stick with a cable you again end up with something like the Trezor, so the solutions are of course very similar. By the way, here is a nice talk from the Trezor guys:
https://www.youtube.com/watch?v=151cR4aeGNUMy idea is to use QR-Codes to transfer the transaction from the normal wallet to the offline computer and back. That way you could use an old Smartphone in flight mode as the offline computer, since you only need a camera and a display. There are small and cheap Smartphones available on the market that would fit perfectly for that purpose. You could easily make encrypted backups on the Micro-SD. I think the following two threads are about the same/a similar idea and also show that there are some problems:
https://bitcointalk.org/index.php?topic=278237.0;allhttps://bitcointalk.org/index.php?topic=230010.0;allI'm not yet convinced that the problems can't be solved and I think it would be good when a lot of people think about this, because it's something that affects every Bitcoin owner. So that's the reason for this post, although it may have been discussed before. Let me know what you think, opposing views are welcome. ;-)
Nightwolf
