Offline Cold Storage with Raspberry Pi (Raspbian)

Offline Cold Storage Wallet with Raspberry Pi

Offline OS Preparation:
1.) Install Raspbian OS onto your Raspberry Pi SD Card (recommended to download directly from Raspian.org )
2.) Plug in SD Card with Raspbian installed, and boot up
3.) Upon first boot, select “Expand Root Partition” in order to utilize all the space on the SD Card
4.) Log in, connect an ethernet cable, open a Root Terminal window and enter “apt-get update && apt-get upgrade”
5.) Then enter “apt-get install python-qt4 python-pip”
6.) Then install Electrum by entering “pip install https://download.electrum.org/Electrum-1.9.7.tar.gz#md5=5764f38d6e4bc287a577c8d16e797882”
7.) Disconnect Ethernet cable

Electrum setup:
1.) In the terminal, run “electrum -o” (-o designates Offline Mode)
2.) select “create new wallet”
3.) Electrum provides you with a 12-word seed. This seed can be used to recover your wallet if anything happens to your SD Card, or forgetting passwords. Use a text editor such as gedit to copy the seed into. Save the seed in the home directory, for example, as “seed.seed”. OR write down the seed and keep it in a very very safe place. If somebody gets your seed, then they will have access to all of the coins on this wallet.
4.) Electrum will ask you to confirm that you have saved the seed somewhere, so make sure it is in the text editor and paste it into the confirmation window and proceed.
5.) Set a wallet password that you will remember to encrypt your wallet
6.) In Electrum, go to Wallet → Master Public Key. Copy the Master Public Key to a text editor such as gedit and save it in the home directory, for example, as “Master-Public-Key.txt”
7.) Quit Electrum
8.) Open up a Root Terminal window and encrypt your seed: “gpg --symmetric seed.seed” Use a strong password that you will remember.
9.) Delete the original seed file: “shred -u seed.seed”
10.) Put a USB drive into the Raspberry Pi and copy the two files you just created to it: “seed.seed.gpg” and “Master-Public-Key.txt”

Online Computer:
1.) Put the USB Stick into your internet-connected computer and copy the “seed.seed.gpg” file to your filesystem for backup and distribution purposes
2.) Install Electrum onto your internet-connected computer
3.) At first launch, select “Restore wallet from master public key”
4.) When asked, provide the key in “Master-Public-Key.txt” into Electrum
5.) This creates a “Watch Only” wallet that has only public keys of your wallet while keeping your private keys offline forever. You can use this Watch Only wallet to monitor your balances and initiate new transactions

Performing an Offline Transaction:
(https://electrum.org/tutorials.html#offline-mpk)
1.) [Online PC] Go to the send tab and make a transaction. Instead of sending it, Electrum will detect a seedless wallet and query for a location to save the transaction. Select your USB-Key.
2.) [Offline PC] Go to Settings -> Import/Export -> "Load raw transaction". Select your transaction from the USB-Key. It will detect it's not signed and will prompt you to do so now. Fill in your password and sign the transaction. Save the new, signed, transaction to your USB-Key.
3.) [Online PC] Go to Settings -> Import/Export -> "Load raw transaction". Select the signed transaction and it will ask you if you want to broadcast it.