Crypto Long & Short: 51% Attacks and Open-Source Value

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Human ingenuity finds a way around limitations. Sometimes these limitations are obstacles in the way of progress and creative thinking comes up with new paths. Sometimes these limitations are a lack of knowledge, and experimentation pushes the boundaries of the possible. And sometimes the limitations are rules, which a few believe don’t apply to them and which some take as a motivating challenge.

We see examples of the above every minute of our daily lives. It’s in the race to find a vaccine, the diplomatic posturing over privacy, the anguish of finding a way around unemployment, even your toddler’s determination to not eat the spinach. We also see it every day in crypto – it’s in the Twitter hack, the rush to develop better payments systems, the scramble to raise funds. The list goes on.

You’re reading Crypto Long & Short, a newsletter that looks closely at the forces driving cryptocurrency markets. Authored by CoinDesk’s head of research, Noelle Acheson, it goes out every Sunday and offers a recap of the week – with insights and analysis – from a professional investor’s point of view. You can subscribe here.

Related: Ethereum Classic's Terrible, Horrible, No Good, Very Bad Week

Last week threw up a couple of examples that not only exhibit increasingly frequent manipulations of protocol rules, they also highlight one of crypto’s core value propositions.

Ethereum Classic is the original Ethereum blockchain maintained by stakeholders that refused to jump over to the fork that corrected for The DAO hack in 2016. Over the past few days it has suffered not one, but two 51% attacks.

A 51% attack happens when enough mining computing power (also known as hashpower) colludes to alter previously processed blocks and determine new ones, allowing attackers to block some transactions and reverse others. In a 51% attack, malicious miners could create a competing blockchain that allows the same coins to be spent twice.

This maneuver is relatively frequent in smaller blockchains such as Ethereum Classic (ETC), which has a market cap of approximately $830 million at time of writing. Ethereum’s (ETH) market cap, for comparison, is currently around $44 billion. The attacks are usually brief, and then business carries on as usual. But two in the space of one week has prompted some commentators to question the blockchain’s survival. 

The amounts lost are not inconsiderable. In the first attack, the malicious miner(s) managed to double-spend a little over 800,000 ETC (about $5.6 million) after paying about $204,000 to acquire the necessary hash power. In the second attack, the double-spend was at least $1.6 million.

This is more than a lesson for investors to be wary of smaller proof-of-work blockchains. It also puts to rest the notion that open-source software, such as the Bitcoin (BTC) blockchain, is vulnerable to copies. And it is a clear example of why network security is a fundamental part of an asset’s value.