Good guide.
If you don't have a computer available to keep off and disconnected until June, you can also use a TAILS Live system from USB.
TAILS is a well-known and actively updated open source Linux distribution that uses the TOR network. What we're interested in, though, is not TOR but the other security measures it uses to leave no traces behind on your computer.
When you shut down the TAILS system, everything in memory is wiped. (Just RAM, the memory TAILS uses, is wiped; this won't affect or interact with any data on your hard drive.)
To follow this method:
Get TAILS from https://tails.boum.org/install/index.en.html. Make sure you use Firefox or another verification method explained on the download page. The installer will install TAILS to a USB drive, so you'll need a reasonably-sized USB drive available.
Once you've installed TAILS to your USB drive, restart your computer from the USB drive. You might have to press a key as your computer starts to enter a "BIOS Setup," "Boot Options," "Boot Device," or similar screen and set your USB drive to boot first. Most commonly, the steps to do this will be:
(Note: the following steps are for PCs. On Macs, simply hold the Option (⌥) key as the Mac boots and select your USB drive.)
- Start the computer and press ESC, DEL, F1, F2, F8 or F10 during the initial startup screen. These keys differ from computer to computer. If your special key is not displayed, you might need to try several different options – feel free to mash a bunch as the computer boots up. If your Windows/Linux operating system starts up, you've missed your opportunity and will need to reboot again.
- (sometimes) Depending on the BIOS manufacturer, a menu may appear. Choose to enter BIOS setup. The BIOS setup utility page appears.
- Use the arrow keys to select the BOOT tab. Here, system devices will appear in order of priority. Hard Drive, CD Drive, Network, and so on.
- (sometimes) If a "+Hard Drive" option is shown and you don't see USB elsewhere, move the "+Hard Drive" to the top of the boot sequence list. Expand the hard drive device to display all hard drives.
- Move your USB device to the top of the list of boot devices.
- Save and exit the BIOS setup utility. The shortcut key for this is usually F10.
- The computer will restart with the changed settings. You likely don't even have to change these settings back, since the computer will now only start from your USB drive when it is plugged in. Otherwise, it will start from the next device in the boot sequence list.
- Once TAILS has booted up, follow the other steps in Cypherglass's guide as usual.
Note that this means, of course, that there is NO WAY AT ALL to recover your key from the computer should you lose the private key. But that's the point. No one else can recover it, either. Make sure you "securely backup your public / private key pair in a safe location" as noted.
Once that's done, you can turn off the computer running TAILS, yank the USB key (even wipe it if you want), and proceed.