Zama and Sunscreen Take Their Encryption Feud to French Court

A patent application the U.S. Patent Office turned down has resurfaced across the Atlantic, where it now anchors a legal fight between two companies building Fully Homomorphic Encryption (FHE) tools. At stake is ownership of "programmable bootstrapping," a technique both firms say is central to making encrypted computation practical.

Zama's CEO, Rand Hindi, publicly accused rival Sunscreen Tech of using Zama's technology without a license. Sunscreen responded by calling the accusation an attempt at patent trolling. Between the two companies sits a foundational piece of privacy infrastructure, and the dispute shows no sign of a quick resolution — leaving developers who rely on either company's tools watching from the sidelines.

01Origins of the technology

The lineage traces back to 2019, when Michael Egorov — then working on NuCypher — found a method for accelerating encrypted computation using GPUs. That work became the seed for Sunscreen Tech, a company built around the goal of privacy-preserving smart contracts.

Roughly four years later, the same underlying technology is the subject of a legal battle that could reshape how open-source cryptography research operates. On December 3, 2023, Sunscreen received a formal notice from Zama's legal counsel, alleging use of patented encryption methods and objecting to what Zama characterized as disparaging technical comparisons made by Sunscreen.

02Why FHE matters

Fully Homomorphic Encryption allows computation to be performed directly on encrypted data, without ever decrypting it — a property that could enable validator-blind smart contracts, medical research that never exposes patient identities, or AI systems that cannot inspect the data they process. The catch is cost: running meaningful computation on encrypted data today is still slow and resource-intensive. Both Zama and Sunscreen have been competing to solve that bottleneck, since whichever company gets there first stands to shape how private computation is built going forward. That race is now being litigated rather than coded.

03Zama's account

According to Hindi's public statement, Zama invested "years and tens of millions" of dollars developing its FHE technology under a business model that made the tools free for research but licensed for commercial use. Hindi says Sunscreen engineers repeatedly showed up in Zama's support channels asking detailed questions about implementation choices and specific code — activity Zama initially read as benchmarking. He alleges that Sunscreen subsequently released its own TFHE implementation that reproduced not only Zama's approach but specific bugs found in Zama's codebase. Hindi states he attempted several paths to resolve the matter, including proposals for a commercial partnership, revenue sharing, and investment, before Sunscreen stopped responding.

04Sunscreen's response

Sunscreen disputes this account and points to a few pieces of documented evidence. First, the U.S. Patent Office rejected Zama's programmable bootstrapping patent application, describing it as "an abstract idea without significantly more." Second, Sunscreen says the "disparaging" comparisons Zama's lawyers referenced are simply benchmark results the company presented publicly at zkSummit12, a presentation that remains available online. Sunscreen also maintains that its TFHE library, published on GitHub, is original work, and that the support-channel interactions Zama flagged as suspicious were ordinary open-source engagement. Sunscreen further notes that Zama pursued a European patent shortly after the U.S. rejection — which it frames as forum shopping. Sunscreen argues that a Zama win in France would extend well past this one dispute, potentially exposing any open-source cryptography project to similar legal risk.

05What the record shows

The documentary trail includes Zama's European filing, patent EP4150852, which underpins its legal claims after the equivalent U.S. application was rejected as an abstract idea. Notably, Zama's own August 2022 blog post had argued that "security by obscurity cannot exist" and that a cryptosystem can only be trusted once the community has had a chance to try to break it — a stance seemingly at odds with the licensing demands and legal threats now being pursued. Meanwhile, Sunscreen's code, benchmark data, and zkSummit12 presentation remain publicly viewable for anyone who wants to check the underlying claims.

06The underlying technical dispute

Set aside the legal framing and the core disagreement is over whether "programmable bootstrapping" is patentable property or simply established mathematics — a question now before French courts despite the U.S. Patent Office's rejection of the equivalent claim. While that plays out, other approaches to privacy-preserving computation continue to advance: Trusted Execution Environments (TEEs) are already deployed in production, though not without their own issues — Intel's SGX has had documented vulnerabilities. Developer henry (hdevalence) has observed that FHE, unlike zero-knowledge proofs — which had a clear product-market fit and no real competing approach — has to compete against TEEs, which already offer working functionality today. Every day the patent dispute continues is a day competing approaches keep improving.

07A parallel from sports gaming

The situation has an echo in an unrelated industry. In the early 2000s, Madden NFL faced genuine competition from titles like Sega's NFL 2K and NFL Gameday, pressure that pushed EA Sports to release some of the best entries in the franchise's history. Once EA acquired exclusive rights to the NFL license, that competitive pressure disappeared — and so did meaningful innovation in the games that followed, which increasingly amounted to roster updates sold as new releases.

The FHE field may be approaching a similar fork. The Zama-Sunscreen dispute isn't only about who owns a specific bootstrapping technique; it's about who gets to keep building in this space at all and who gets locked out. History suggests that removing competition tends to produce stagnation rather than progress, and if this dispute concentrates control of foundational FHE techniques in one company's hands, the risk is that the technology itself loses momentum while the legal process runs its course. Whatever the courts in France decide, developers and users of privacy-preserving technology have the most to lose from a prolonged standoff.