Links to Storage Methods
This page reviews published methods for backing up and storing bitcoin wallets.
Cold Storage Methods
Glacier protocol
The glacier protocol is a cold storage scheme. It teaches how to use multiple computers made by different manufacturers which help resist attacks like malicious firmware. The multiple computers are given the same entropy and the user checks that they result in the same bitcoin addresses and private keys. Users are advised to avoid sidechannels like audio, power, magnetic and radio.
The tutorial teaches users to deal with raw private keys and write them down on paper. Deterministic wallets are not used, nor are full nodes. Users are instructed to look up their balances on a blockchain explorer website which damages the user's privacy and makes them trust the website for verifying the rules of bitcoin.
SmartCustody's Simple Self-Custody Cold Storage
github.com/BlockchainCommons/SmartCustodyWhitePapers
This guide show how to store coins in a cold storage situation with the ability for heirs to recover your funds if you die. The guide is a bit hard to read with many optional steps, and the "basic scenario" uses 2 hardware wallets with the same seed for some reason. It recommends putting information in a safe deposit box that is enough to steal funds, so you're putting a lot of trust in the safe deposit box. There are Alternate scenarios, but they don't make themselves very clear.
Yeticold
This website helps you set up an ubuntu machine that you then can run a utility from to create a wallet. It can create hot, warm, or cold wallets. The project is still in beta, has limited information on how it works and the code isn't clean and comes without a test framework.
Casa
Casa is a multisig system that uses geographically distributed keys on different hardware devices. It is unique in that it recommends against backing up seed phrases, instead offering functionality to easily replace compromised / unusable keys.
Electrum's cold storage guide
https://electrum.readthedocs.io/en/latest/coldstorage.html
The wallet features seed phrases, deterministic wallets, offline signing. Unsigned transactions can be transferred with QR codes and saving to a file (which can be put on a USB flash drive or any other transfer method). The wallet can be backed by a full node if the user connects to their own server, but this is optional and does not happen by default.
The tutorial does not aim to discuss anything about creating a secure offline computer.
Rusty Russell's "Remarkably Unreliable Guide To Bitcoin Storage"
https://github.com/rustyrussell/bitcoin-storage-guide
The tutorial teaches how to use a laptop as the secure offline computer. It uses ubuntu OS, and Bitcoin Core as the bitcoin wallet. The private key material is stored in raw private key format, not seed phrases (which bitcoin core doesn't support) and so the guide does not benefit from deterministic wallets. QR codes are used to transfer transactions between the offline and online computers. As the tutorial uses Bitcoin Core it enjoys the benefits of a full node wallet.
However, it recommends naively splitting keys (without using a secure key-splitting algorithm like Shamir's secret sharing algorithm), and so is insecure and certainly not well vetted.
Alexandr Nellson's Scheme
medium.com/@nellsonx/how-to-properly-store-bitcoins
This method is relatively basic, glossing over important steps like how to properly airgap a machine, how to create and handle a strong passphrase, and how to back up your seed. It uses usb drives to boot the machine and transfer transaction information, which is a significant attack vector. It also isn't open source and is definitely not well vetted.
Cold Wasabi
https://docs.wasabiwallet.io/using-wasabi/ColdWasabi.html
This is a pretty basic guide that focuses on using the Wasabi wallet to mix your coins before sending them to a hardware wallet. There is supplementary information about how to setup a hardware wallet and backup your seed, but this doesn't make for a complete or easy-to-use guide. It is open source, and so might be somewhat vetted.
Coldcard
Coldcard wallet offers several ways for cold storage:
- make backups of the seed on an SD card, delete the seed from the Coldcard device
- create a paper wallet, not related to the seed on the Coldcard
On top of that you can choose to never connect the Coldcard to a computer.
Other Storage Methods
Bitgoldwallet's Storage Methods
https://www.bitgoldwallet.com/how-to-store-bitcoin.html
This site has a number of different storage methods of both the hot and cold variety. The methods are detailed and complex, and somewhat hard to read. It seems to have some odd recommendations, like using password protected PDF files and Zorin OS. More review required.
Storage Method Components
The items in this section are methods that do not outline a complete backup or storage mechanism, and thus must be combined with other techniques in order to create a security backup or storage mechanism.
- A small paper on bitcoin storage best practices - github.com/devrandom/../storage-best-practices.md
- Pamela Morgan's guides to bitcoin inheritance planning - medium.com/@pamelawjd