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A bit over a month ago, Bitmain announced the release of its Equihash miner—the Antminer Z9 Mini—painting a target on cryptocurrencies like Bitcoin Gold, Zcash, Komodo, and a number of others that use this algorithm to verify blocks.

Not long after that, we got a report from Forklog—a Russian cryptocurrency publication—that ASICs have been taking over a large portion of the cryptocurrency’s hashing power.

“During the last 15 days, ASIC miners from Bitmain have aggressively increased their share of extracted blocks in the Zcash network to 40%, undermining the position of the largest pool, Flypool. In the coming week, there may be a fundamental redistribution of control over the network in favor of ASIC miners,” the publication reported.

According to a graph provided by Forklog, the amount of ASIC activity has been rising steadily over the past two weeks and briefly overtaking Flypool’s hashing power. Since last week on Monday, the pool has been locking horns with ASICs, vying for dominance over the network.

Given the proper ingredients, we could see another 51% attack unfolding in the future, much like it already did for ZenCash and Bitcoin Gold—two other Equihash cryptocurrencies.

Such incidents could be catastrophic, allowing attackers to double-spend, profiting immensely off of the vulnerable blockchain. The ZenCash manipulation allowed attackers to make two double-spends of 6,600 and 13,000 ZEN, respectively.

The total sum double-spent sums up to $361,032. That’s not bad for around $7000-worth in effort to manipulate the blockchain.

Forklog’s source, Altpool.pro, points out the fact that Bitmain hasn’t yet shipped out ASICs for Equihash in large measures.

“Representatives of the pool believe that Bitmain will start shipping devices only when the developers of Zcash will offer to change the consensus algorithm, something they’re already working on,” the publication added.

To be fair, there is no evidence at this moment that Bitmain has ever executed a 51% attack or that it intends to do so with Zcash. However, it is disconcerting that the pattern that lead to such an attack in other Equihash networks appears to be repeating.