One comment I have noticed continually re-appear on social media over the last couple months is roughly the following:
If you’re building a new blockchain you should regularly take a hash of the network state and “anchor” it (write it) into another blockchain, for redundancy purposes.
Part of the current popularity in the anchoring meme is that some cryptocurrency enthusiasts and Bitcoin maximalists in particular want other non-cryptocurrency distributed ledgers to rely on existing cryptocurrency networks — networks that some enthusiasts own tokens to and hope that price appreciation will take place in the event that the network is used.
Ignoring the hypothetical monetary incentives, let’s assume that writing/storing network states externally is useful and it is the goal of every blockchain designers such as Bob and Alice. Are other blockchains the only relevantly secure places that all blockchain designers should look at using?
For instance, if the goal is to publish a hash of a state in a media that is difficult to censor and widespread enough to retrieve over time, then there are several “old school” newspapers and magazines that can be used for such purposes (which is what Guardtime does).
- There are half a dozen Japanese newspapers that each have over 2 million in circulation.
- In the UK, both The Sun and Daily Mirror have a circulation of over 1.5 million
- Similarly, in the US, there are three companies: USA Today, The New York Times and The Wall Street Journal that also have a circulation of over 1.5 million
The question for the paranoid is, what is more likely: someone deliberately destroying and/or replacing 1.5 million newspapers which contain the hash of the network state, or someone knocking out 5,728 network nodes?
While “anchoring” the hash of state into other media may be useful, leaving it in just one blockchain — such as the Bitcoin blockchain — does not fully reduce the risk of a well-funded attacker trying to revise history. Safety in this case comes in numbers and if it is redundancy Bob and Alice are looking for (and paranoid about), it may be worth it to publish hashes in multiple venues and media.
Similarly, if sustainability is a key concern then public goods such as cryptocurrencies have a question mark on them as well. Why? Because there are over 100 dead altcoins now. Convincing users — and more importantly miners — to maintain a network when it is no longer profitable to do so is an uphill challenge.1
Lastly, a well designed network (or distributed ledger in this case) that is robust and mature should not necessarily rely on “anchoring” at all. But this dovetails into a different conversation about how to design a secure network, a topic for another post. Either way, hash-storage-as-service, is probably not the next big trillion dollar idea for 2016.
- It’s a challenge for any public good, not just Bitcoin, that eventually relies solely on altruism and charity. [↩]