Here’s what you get…
1. Raspberry Pi Zero (The Pi Zero has no WiFi, bluetooth, or ethernet which is what we want. Less ways to get hacked.)
2. Micro SD card containing Raspbian OS operating system installed, and importantly, Electrum Desktop Wallet installed, Ian Coleman’s BIP 39 seed generator, and the BIP 39 wordlist – all important for generating your own keys, and independently verifying them. You also can independently verify the seeds, xpubs, and addresses generated by your hardware wallet.
Some basic instructions
I have made several of these and can ship them to you fully installed, if you don’t want to go through my guide and make it yourself. The reason this is hard to do is because there are big obstacles to install Linux programs on a computer that never connects to online package managers for installation. THIS IS AN AIR-GAPPED COMPUTER – ie it will never connect to the internet.
If you do want to make them yourself, you can follow my guide, or ask me for mentoring. The simplest way is to buy the completed device. The price is $100 USD, plus shipping from Australia, payment in equivalent bitcoin ONLY. (Spend $100 plus shipping on your exchange, and send bitcoin from there to invoice address).
Contact me at firstname.lastname@example.org or Twitter DM @parman_the, for questions an to order.
What you don’t get:
You need to buy your own low power charger (most phone chargers are fine)
You also need your own USB cable with this type of connector to the Pi (micro USB)
You also need a HDMI monitor. Many people have one lying around. You can even use a TV with HDMI, as long as it is not too smart and can connect to your WiFi.
Make sure you have a HDMI cable. I suggest HDMI male at both ends.
The output to the Pi needs to be MINI HDMI. Note this is different to a Pi 4 which needs micro HDMI (even smaller). I would recommend getting an adaptor (HDMI female to male mini HDMI).
OPTIONAL: You could also buy a separate adaptor for your Pi 4 which you might have or might get one day. (HDMI female to male micro HDMI). This way, you can use the same cable for the Pi 4.
You’ll need a wired keyboard and wired mouse that has no bluetooth capabilities – even though the Pi Zero has no bluetooth, you don’t want your keyboard broadcasting your keystrokes through the air to a clever hacker.
You need a minimum 3 port USB hub, that connects to the Pi through a micro USB connection. If you use a regular hub and add an adapter to make it micro USB, it won’t work. Some come with extra power, but you don’t need that.
Get a USB pen drive for transferring PSBTs
You really don’t need a case, but if your into spending sats for appearances, go for it. Official Raspberry Pi ones are cheap, about 6 dollars.
The device will come with a microSD card inserted. This has the operating system (Raspbian OS with Desktop, which is Debian based Gnu/Linux).
Connect all ther peripherals first, and only then should you connect the power.
On the far left is the HDMI slot. On the far Right is the power. Next to that is the microUSB, to which you add the USB adapter, to which you add the mouse and keyboard.
When the OS loads up, you should be presented with a log-in screen.
The username is Pi, and the password is “raspberry” – this is the default. You absolutely should change it. This is how: Click the black Icon for “Terminal” at the top (It will take a while to load, the Pi Zero is SLOW), and type “sudo passwd Pi”, <enter>, and follow the prompts. Pay attention – it’s “passwd” not “password”
On the desktop you will see an Electrum directory and a BIP39 directory. The latter contains the Ian Coleman Webtool which will be useful to create and verify BIP39 mnemonics. It also has the BIP39 English wordlists – There are a few. They have the same words, in the same order, but the numbering varies – see my article on making keys to make use of these files at some stage.
To run Electrum, open Terminal, and navigate to the Electrum directory (note Terminal remains open while Electrum is running)…
If this makes no sense, it’s good to learn. Watch this video.
Once you are in the Electrum directory, type this to run electrum:
After about 15 seconds, Electrum will load up. This slow speed is normal. You will notice some errors reported in the Terminal window; this is safe to ignore and is normal.
Connect up a USB webcam to one of the USB ports and you will be able to import QR code unsigned transactions for signing from your watching only wallet. Note that the refresh rate will be very slow and laggy because the Pi Zero is not very powerful. Just hold the camera still and wait.