The Horizen team carefully evaluated the pros and cons of changing from the existing Equihash Proof of Work mining algorithm. This was caused by two events that happened close together in time. One was the double spend attack that was made against an exchange partner, and the other was the appearance of Equihash ASIC miners for sale to the public. The major concern of the team, as well as much of the Horizen community, was maintaining the security of the project. In order to prevent future attacks that could be accomplished by gaining more than 51% of the mining hashrate, the Horizen development team immediately began working on a change to the consensus algorithm to limit the likelihood of a hidden blockchain fork becoming public and perpetrating a double spend.

Watch Rolf Versluis, Co-founder and Executive Advisor of Horizen, explaining our decision on Horizen mining algorithm

Horizen is a project that is sensitive to the concerns and desires of the community and worked to determine if there was a clear desire to change the mining algorithm. It was difficult to determine, but what was clear was that people did not want further 51% attacks. Because of the possibility that a single company that builds or buys many Equihash ASIC miners could operate them and control the majority of the hashrate on the network, the team also evaluated changing the Equihash mining algorithm to something different. The team provided updates to the community while this was going on in blog posts, in bi-weekly video updates, and in various forms of social media.

Horizen is going to maintain the existing Equihash mining algorithm.

There will not be a change to the algorithm unless there is a security issue that necessitates a change. Longer term, this issue can be revisited by the community after we have our Governance model in place. This will allow a full representative vote by the Horizen Community.

REASONS

The primary reason for not making a change is that the Horizen network continues to get more secure now that ASIC’s have started mining, even though Horizen is not the Equihash category leader.

There are secondary reasons for prioritizing Horizen improvements over algorithm change, and that if an algorithm change were made, there would be a time period of vulnerability while miners switched over.

Furthermore, we are partnered with many exchanges and integrations; Hard forks would force a chain of changes that affect our existing integrations tremendously. At this time, we believe a change of such magnitude would not be necessary.

The team has seen activity of the people who are buying ASIC miners – they appear to be mining Horizen directly, and not pointing their hashrate at Nicehash. This can be shown by watching the statistics at https://www.crypto51.app/ which currently show that it is not possible to perform a 51% attack on Horizen by renting Nicehash hashpower – only about 50% of the hashpower required to perform an attack is available for rent.

Furthermore, Horizen does more than differentiate the project on mining algorithm. We have many ways of differentiation, including:

50 person multidisciplinary team with a track record of accomplishments

A multi-tiered node system: Secure and Supernodes

Active sidechain development for Governance and distributed node tracking and payment

Strong development and operations

Significant development improvements on the roadmap for 2018 and 2019

Yes, there are counterarguments. There is 8x the amount of Equihash hashpower on Zcash as on Horizen right now, and if a single mining farm that has Equihash ASIC’s decided to attack Horizen there would be an issue. This is a short term problem as the 51% attack prevention update will make that attack vector significantly more difficult.

There is also the argument that promoting GPU mining distributes ZEN to more people around the world. Fully 30% of new Horizen is distribute by Treasury and Secure/Super Node payments, which creates a much wider distribution pool than other cryptocurrencies.

The Horizen team determined that the overall security of the Horizen project was best served by continuing with the existing Equihash mining algorithm. This decision was made after careful observation, evaluation, and discussion with people in the community as well as the Horizen team members.

Thanks to everyone for contributing to the discussion and decision!