Matter Labs Accuses Polygon of Spreading "Untrue Claims" With Code-Copying Allegations

Ethereum scaling firm Polygon said in a tweet on Thursday that Matter Labs, the firm behind the zkSync rollup, copied part of Polygon’s open-source code without providing attribution. Matter Labs denied the allegations in a statement to CoinDesk, arguing that the code was "prominently attributed" in a line atop one of the files in question.

Blockchain projects frequently release their code under open-source software licenses, meaning outside developers are allowed to read, copy, and even (in some cases) contribute to the code should they so desire. However, community norms – and most open-source licenses – generally require that third-party developers acknowledge when they’ve used code that originated elsewhere.

In a blog post, Polygon alleged that Matter Labs recently released a proving system, called Boojum, which included some source code that had been copy-pasted from Polygon’s own “Plonky2” software library. “This code is included without the original copyrights or clear attribution to the original authors,” Polygon said. “Copy-pasting source code without attribution and making misleading claims about the original work is against the open source ethos and hurts the ecosystem.”

A Matter Labs spokesperson said the blog post from Polygon contained "untrue claims." "The new Boojum high-performance proof system leverages 5% from Plonky2, which is prominently attributed in the first line of our module," the spokesperson told CoinDesk in a Telegram message. "Where else, other than the very first line of our library would this have been included if we wanted it to be more prominent?"

In its blog post, Polygon included several screenshots comparing its own code to that of Matter Labs. In a screenshot of a Matter Labs file titled "mod.rs" Polygon captioned that it contained "no attribution for the original authors." Matter Labs CEO Alex Gluchowski linked to that same file in a tweet. The first line of the mod.rs file, which was excluded from Polygon's screenshot, reads, "NOTE: we take a Plonky2 implementation of non-vectorized field as the baseline."

Polygon's blog post included other examples where its code was apparently lifted without attribution by Matter Labs. Gluchowski later addressed some of those examples in an in-depth tweet, acknowledging that they "could have done it better. The community rightfully pointed out that there is a more standard approach to attributions, which we will wholeheartedly apply from now on."

Polygon and Matter Labs build competing zero-knowledge rollups – so-called layer 2 blockchains that offload traffic from the “layer 1” Ethereum chain to offer cheaper and quicker transactions for users. This isn’t the first time tensions have flared up between the two projects as they’ve jostled with one another to attract some of the same users and investors.

This most recent spat between Polygon and Matter Labs highlighted the ongoing tension between two of the leading firms vying to expand Ethereum and lay claim to its next wave of users. It also showed the dark side of open-source culture: making one's code freely available can spur collaboration, earn goodwill and help tech mature – but it can also lead to messiness when there are competing interests at play.

Read more: War of Words Over zkEVMs Might Portend Long Struggle to Tech Maturity

Other members of Ethereum’s layer 2 ecosystem took the occasion of Polygon’s blog post to share their own disappointment with Matter Labs. Starkware co-founder Uri Kolodny tweeted that it wasn’t “the first time” that a company had copied another team’s code without giving credit, adding, “I'll bet an ice-cream it won't be the last time either.” Kolodny didn’t clarify in his tweet whether he was talking about Matter Labs or speaking generally.

Starkware’s Ecosystem Lead, Louis Guthmann, also shared that “These allegations are very serious. Respecting licences and more importantly, honesty and clear attribution is the soul of Open Source.”

UPDATE (August 3, 22:39 UTC): Adds statement from Matter Labs.

UPDATE (August 4, 14:24 UTC): Adds tweet from Alex Gluchowski