Glacier is a step-by-step protocol for storing bitcoins in a highly secure manner. It is intended for:
- Personal storage: Glacier does not address institutional security needs such as internal controls, transparent auditing, and preventing access to funds by a single individual.
- Large amounts of money ($100,000+): Glacier thoroughly considers corner cases such as obscure vectors for malware infection, personal estate planning, human error resulting in loss of funds, and so on. Even if your Bitcoin holdings are more modest, it’s worth considering using Glacier. If Bitcoin proves successful as a global currency, it will appreciate 10x (or much more) in the coming years. Security will become increasingly important if your holdings appreciate and Bitcoin becomes a more attractive target for thieves. The “Protocol Overview” section also describes some lower-security, lower-cost approaches to self-managed storage that may be more appropriate for smaller amounts of funds.
- Long-term storage: Glacier not only considers the Bitcoin security landscape today, but also a future world where Bitcoin is much more valuable and attracts many more security threats.
- Infrequently-accessed funds: Accessing highly secure bitcoins is cumbersome and introduces security risk through the possibility of human error, so it is best done infrequently.
- Technically unskilled users: Although the Glacier protocol is long, it is clear and straightforward to follow. No technical expertise is required.
The Glacier protocol covers bitcoin storage, not procurement. It assumes you already possess bitcoins and wish to store them more securely.
If you are already familiar with Bitcoin security concepts and are certain that you want high security cold storage, you may prefer to read Trusting This Protocol and then skip to the section Choosing a Multisignature Withdrawal Policy.
Trusting this protocol
Funds secured using Glacier can only be as secure as its design. Here’s what you can trust about this protocol:
- Expert advisors: The development of Glacier was guided with input from Bitcoin technology and security experts. See our advisor list.
- Open source: GlacierScript, the Glacier companion software, is open source. The code is straightforward and well-commented to facilitate easy review for flaws or vulnerabilities. View it on Github.
- Community review: The protocol has evolved in conjunction with the wider Bitcoin community. Early versions were circulated during development, and community feedback integrated. See our list of contributors.
- Natural selection: All documentation and code related to this protocol is under open licenses (Creative Commons for the document, MIT license for the code), enabling others to publish their own revisions. Inferior alternatives will tend to lose popularity over time.
If you like, you may review the design document for details on the technical design.
Self-Managed Storage vs. Online
Let’s start by assessing whether Glacier is right for you.
There is no such thing as perfect security. There are only degrees of security, and those degrees come at a cost (in time, money, convenience, etc.) So the first question is: How much security are you willing to invest in? For most people, most of the time, the authors recommend storing Bitcoin using a high-quality online storage service. The pros and cons of the various online services are beyond the scope of this document, but most popular ones are fairly secure and easy to use. Some popular options are Blockchain, Coinbase, Gemini, and Kraken.
However, all online storage services still come with some notable risks which self-managed storage does not have:
- Identity spoofing: Your account on the service could be hacked (including through methods such as identity theft, where someone convinces the service they are you).
- Network exposure: Online services still need to transmit security-critical information over the Internet, which creates an opportunity for that information to be stolen. In contrast, self-managed storage can be done with no network exposure.
- Under constant attack: Online services can be hacked by attackers from anywhere in the world. People know these services store lots of funds, which makes them much larger targets. If there’s a flaw in their security, it’s more likely to be found and exploited.
- Internal theft: They have to protect against internal theft from a large group of employees & contractors.
- Intentional seizure: They have the ability (whether of their own volition, or under pressure from governments) to seize your funds. There is historical precedent for this, even if funds are not suspected of criminal involvement. In 2010, Cyprus unilaterally seized many bank depositors’ funds to cope with an economic crisis. In 1933, the US abruptly demanded citizens surrender almost all gold they owned to the government. Regardless of how one views the political desirability of these particular decisions, there is precedent for governments taking such an action, and one cannot necessarily predict the reasons they might do so in the future. Furthermore,Bitcoin still operates in a political and legal grey zone, which increases these political risks.
Some online wallet services have insurance to cover losses, although that insurance doesn’t protect against all of these scenarios, and often has limits on the amount insured.
Recently, some providers are rolling out services which are a hybrid of an online service and self-managed storage. Examples include Coinbase’s multisig vault and Green Address. The design of these services significantly reduces (though does not eliminate) the risks described above.
However, they also require some care and technical competence to securely manage the electronic “keys” which provide access to funds.
Many people do use online or hybrid solutions to store sizeable amounts of money. We recommend self-managed storage for large investments, but ultimately it’s a personal decision based on your risk tolerance and costs you’re willing to pay (in money and time) for security.
Glacier focuses exclusively on self-managed storage.
Glacier vs. Hardware Wallets
Many people who choose self-managed storage (as opposed to an online storage service) use “hardware wallets” such as the Trezor, Ledger, and KeepKey to store their bitcoins. While these are great products that provide strong security, Glacier is intended to offer an even higher level of protection than today’s hardware wallets can provide.
The primary security consideration is that all hardware wallets today operate via a physical USB link to a regular computer. While they employ extensive safeguards to prevent any sensitive data (such as private keys) from being transmitted over this connection, it’s possible that an undiscovered vulnerability could be exploited by malware to steal private keys from the device.
For details on this and other security considerations, see the “No Hardware Wallets” section of the design document As with online multisig vaults, many people do use hardware wallets to store sizeable amounts of money. We personally recommend Glacier for large investments, but ultimately it’s a personal decision based on your risk tolerance and costs you’re willing to pay (in money and time) for security.