Eli Ben-Sasson, CEO and co-founder of StarkWare, has long championed the potential of zero-knowledge proofs to transform blockchain scalability. While StarkWare has been a key contributor to Ethereum scaling through innovations like Cairo, StarkEx, and StarkNet, the team is now turning its attention to Bitcoin - bringing with it over a decade of ZK research, production-grade cryptographic systems, and a belief that scaling Bitcoin is essential for its future.
In this conversation, @EliBenSasson discusses why Bitcoin needs scaling, what makes STARKs uniquely suited to the task, and how he envisions a future where Bitcoin becomes more than digital gold - transforming into globally accessible, self-custodial digital cash.
The limitations of Bitcoin’s base layer are well known: high fees, slow settlement times, and an upper bound of around 10 transactions per second. This, Eli argues, is incompatible with a global monetary network. “You can’t have a functioning economy if moving value is this expensive and slow,” he says. “Right now, Bitcoin is like trying to pay with a giant stone tablet. It needs to become usable for everyday transactions.”
That usability is central to what Ben-Sasson believes is the original vision of Bitcoin: electronic peer-to-peer cash. Scaling Bitcoin - without compromising its trust-minimized core - is a prerequisite for enabling applications like lending, borrowing, microtransactions, and widespread use in emerging markets.
@StarkWareLtd is uniquely positioned to contribute to this transformation. While the company’s early focus was @ethereum, Ben-Sasson notes that it was a Bitcoin conference in 2013 that first inspired his shift from academia to zero-knowledge cryptography. “I’ve always seen STARKs as the natural fit for Bitcoin. They’re trustless, post-quantum secure, and don’t rely on any hidden assumptions or trusted setups.”
Yet Bitcoin presents a unique technical environment. Unlike Ethereum, Bitcoin lacks a native smart contract platform, and uses a UTXO-based transaction model. This introduces constraints for implementing Layer 2 systems like StarkNet. “There are no accounts or programmable state. To support rollups, you need to introduce covenants - restrictions on how UTXOs can be spent,” he explains.
Recent work by StarkWare’s team, in collaboration with Andrew Poelstra and Ethan Heilman, introduced a way to implement covenants on Bitcoin even under today’s constraints - though at high cost. A more robust path forward involves the proposed opcode OP_CAT, which would enable more expressive covenants at the base layer. This would allow Bitcoin to act as the settlement layer for high-throughput, fully self-custodial STARK-based rollups.
Ben-Sasson acknowledges the conservative nature of Bitcoin development. “It should be slow. That’s part of what makes it secure. But I believe OP_CAT would not compromise Bitcoin’s safety - it would enhance its usefulness.” He also addresses concerns that covenants might harm Bitcoin’s fungibility. In practice, he says, similar restrictions can already be imposed today through multi-signature wallets and centralized custodians.
Scaling Bitcoin with STARKs wouldn’t just improve usability - it could also impact Bitcoin’s long-term sustainability. As mining rewards diminish, fees will need to support the network. More economic activity, enabled by efficient L2s, means more total fees. “The most important thing is growing the economy around Bitcoin. The rest will follow.”
What makes STARKs especially attractive, in his view, is their scalability profile. New proving systems like Circle STARKs use extremely small field sizes, allowing for fast and low-cost batch proof generation. This directly translates into lower transaction fees. “You get the best of both worlds: minimal trust assumptions and maximum scale,” Ben-Sasson says. “And unlike hash-based systems, STARKs are post-quantum secure and inherently more transparent.”
The @Starknet ecosystem has already become home to computationally intensive applications ranging from AI and gaming to advanced DeFi. Connecting those applications to Bitcoin, while preserving its security model, would enable a new class of programmable Bitcoin-native assets. “Imagine real gaming, DeFi, identity systems - secured by Bitcoin, but with the performance of modern compute platforms. That’s what we’re aiming for.”
Asked what the roadmap looks like, Ben-Sasson says users can expect better UX for trading with hBTC and inscription-based assets, and an emerging builder community aligned with Bitcoin’s ethos of self-custody and decentralization. “We want this to become the platform where developers can build applications that go beyond sending BTC - apps that return power and ownership to users, not custodians.”
Looking ahead, he envisions Bitcoin as one node in a broader “Integrity Web” - a global infrastructure layer for verifiable computation. “Just like the internet gave us peer-to-peer information, the Integrity Web will give us peer-to-peer truth. Bitcoin will be one of the central anchors, and STARKs will be a core engine driving it.”
Interview conducted by @alicelingl (House of ZK). Edited for clarity and brevity.
