Topic: DIY Bowser Hardware Wallet - page 2. (Read 594 times)

Hardware wallet is a physical electronic device, built for the sole purpose of securing bitcoins. The core innovation is that the hardware wallet must be connected to your computer, phone, or tablet before bitcoins may be spent. Hardware wallets are a good choice if you’re serious about security and convenient, reliable Bitcoin storage.

Bitcoin hardware wallets keep private keys separate from vulnerable, internet-connected devices. Your all-important private keys are maintained in a secure offline environment on the hardware wallet, fully protected even should the device be plugged into a malware-infected computer. As bitcoins are digital, cybercriminals could, potentially, target your computer’s “software wallet” and steal them by accessing your private key.

This is DIY hardware wallet, and it is NOT for newbies and people like spongebob Ledger shiller.

Let's see what makes a hardware wallet:

https://en.bitcoin.it/wiki/Hardware_wallet

Edit: Please see https://bitcointalksearch.org/topic/m.1327630 for an updated prototype.

Hardware Bitcoin wallet is a project which aims to implement a minimal dedicated Bitcoin wallet. Its main difference with every other Bitcoin client/wallet out there is its low resource requirements: the binary is currently 25 kilobytes large, it uses less than 2 kilobytes of RAM and requires only 160 bytes of non-volatile storage per wallet. With such low requirements, I reckon a production device would be smaller, more robust and cheaper than any other Bitcoin wallet.

The wallet stores private keys (actually, it only stores a seed for the deterministic key generator), parses transactions and signs transactions. It essentially doesn't do anything else. This is by design - simpler means a smaller attack surface. Private keys are generated on the device and never leave the device, except when doing a wallet backup. Even then, the seed is only displayed - it is never sent over the serial port. My intention is that physical access to a device is required in order to obtain private keys or to spend anything. As an additional layer of security, wallets can be encrypted. An encrypted wallet offers pseudo-two-factor authentication: in order to spend BTC, you need to know the wallet passphrase and you need to have the hardware Bitcoin wallet.

Here's a somewhat messy prototype:

The thing on the left is an Arduino clone (though I'm not actually using the Arduino IDE or libraries). The bunch of discretes on the lower part of the breadboard comprise a noise source, which is used to generate random numbers. The input user interface consists of two pushbuttons (bottom-left and bottom-right corners), where the user can approve or disapprove of actions. This gives you an idea of the necessary hardware peripherals required. Of course, a production device would be much more compact than this .


Here's the prototype signing a transaction:

Here's an actual transaction that it signed: http://blockexplorer.com/t/AEhoN6bzjd.

The code is hosted at: https://github.com/someone42/hardware-bitcoin-wallet. Currently, there's only a port for the ATmega328 microcontroller. However, most of the code is platform-independent; porting to another microcontroller "only" involves writing drivers for the microcontroller's peripherals.

I shall commit to being open and transparent, releasing source code and hardware specifications as I produce them. If people are interested, I might even design a production hardware Bitcoin wallet. From simple BOM and assembly cost estimates, such a device would cost 6 to 7 USD per unit to manufacture (for a quantity of 1000). If anyone has questions/suggestions, feel free to ask in this thread.