An application by Matter Labs to register "ZK" as a trademark has been met with a robust response from competitors StarkWare, Algorand, and Polygon.

"We condemn this behavior in the strongest possible terms, as a transparent attempt by a corporation to claim ownership over something that does not belong to it," the group wrote in a statement posted yesterday on GitHub. "We speak as some of the original creators of ZK or Zero-Knowledge cryptography, as academic cartographers, and as ZK researchers and developers from leading projects."

Registering a trademark typically takes at least a year, but applicants can (and do) use proof of an application having been accepted by the U.S. Patent and Trademark Office to do business. Matter Labs, which developed zkSync technology, submitted its application in February.

The group of competitors allege that Matter Labs has used its pending application to approach exchanges and ask that it be allowed to "register a token under the ticker name ZK."

ZK, or zero-knowledge, proofs were first described in a 1985 MIT research paper: "The Knowledge Complexity of Interactive Proof Systems." They've become popular in among cryptocurrency projects because they keep internal datasets private while still leveraging them in of smart contract applications. For example, it allows a protocol to see that a user has enough funds to complete a transaction without the user having to reveal exactly how much they have in their wallet.

For its part, Matter Labs has said it applied for the trademark so it can be "used freely" in relation to ZK Sync, ZK Stack, and other related technologies. "Like it or not," the team wrote on Twitter last night, "trademarks are the only legal tool available for this today."

In its application, Matter Labs states that the signatory (Matter Labs's general counsel, Geoff Thompason) believes the company "is the owner of the trademark" and that "no other person" has the right to use the mark in commerce.

The Twitter post was met with another round of criticism.

"This rings hollow," wrote Idyllic Labs co-founder and CEO Will Chen. And Rebecca Rettig, chief legal officer at Polygon Labs, had scrutiny for the reasons Matter Labs filed the application in the first place.

"If a challenge has forced you to apply for the TM, pls disclose that," she wrote on Twitter. "Otherwise, [this] is baseless. There's no need for a 'framework' to let others use the term b/c this is something everyone can use w/o your supposed permission."

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