Starknet can become a single layer that settles on both Bitcoin and Ethereum.
Eli Ben-Sasson
Starknet will become the first network to settle simultaneously on Bitcoin and Ethereum and scale Bitcoin to many thousands of transactions per second. This will happen within six months after the potential Bitcoin upgrade, OP_CAT. This is my proposal for the future of Starknet and, by extension, for blockchain, the global economy, and our individual rights. We are already taking concrete steps towards this vision and are coming forward as public supporters of OP_CAT adoption.
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Many thanks, in no particular order, to Andrew Poelstra (Blockstream), Robin Linus (BitVM/ZeroSync), Weikeng Chen (L2 Iterative), Vitalik Buterin, Zooko (ZCash), Jeremy Rubin, Eric Wall, Lightning Labs, Udi Wertheimer (Taproot Wizards), Sims Gautam (Alpen Lab), Carter Feldman (QED), David Tse (Babylon), Elias Tazartes (Kakarot), Lauren Stephanian (Pantera), Jon Charbonneau, Larry Cermak, Ajit Tripathi and many others across the Bitcoin and Ethereum communities for feedback and discussion.
This post does not necessarily reflect each reviewer’s personal opinion on OP_CAT adoption.
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The moment has finally come for STARKs to step up to their next challenge. The stars are now aligned for STARKs to show their scaling muscle on the most egalitarian money ever created: Bitcoin. Once OP_CAT is adopted on Bitcoin, implementing a STARK verifier in Bitcoin Script becomes a reality. This opens a path to move safely and self-custodially between Bitcoin and Starknet, creating a single Layer 2 to scale both Ethereum and Bitcoin.
Crypto can clean up the digital and financial worlds. It can deliver integrity to money and rebalance power in our society, taking it away from big tech and restoring it to sovereign individuals. It’s a tool to empower humans and grassroots communities. In short, it’s a source of good. Therefore, we need a vision that showcases this and that is relevant for all. I left my calm career in academia to go after this vision.
No such vision is complete without scaling the chain that started this great project. Scale Bitcoin and we unleash blockchain’s power to transform the world. StarkWare is backing this plan with practical steps and the launch of a $1 million fund to support new research which will shed light on the pros and cons of adopting OP_CAT on Bitcoin.
Our strategic partnership with Weikeng Chen of L2 Iterative Ventures (L2IV) through the ZeroSync Foundation has been very productive, culminating in the emergence of the Bitcoin Wildlife Sanctuary. We leveraged their teams’ hands-on approach to engineering and research expertise to push the boundaries in open-source work on OP_CAT-based covenants and STARK verifiers implemented in Bitcoin scripts. We are also grateful to BitVM and the ZeroSync Foundation, who have opened the minds of so many as to what Bitcoin can be. Separately, QED’s Carter Feldman has also been influential, showing us what a fresh perspective and open-minded look at Taproot can discover.
This post will be followed by lots of official updates from StarkWare and Starknet, but for now, I want to take the conversation back to basics and state why we’re all doing what we’re doing.
2008: The rupture
It’s 2008, and global finance has just crashed. In response, Satoshi Nakamoto publishes the revolutionary Bitcoin Whitepaper. At this moment of rupture, Satoshi showed us how we could do things differently. We, the public, could demand and enforce a higher standard of integrity and transparency in the financial realm. Instead of relying on the citadels and skyscrapers of traditional banks, Satoshi introduced an inclusive protocol that invites everyone to join it. This protocol distributes value fairly and transparently to its broad base of contributors through Bitcoin mining and fees. The broader the base of contributors, the better and safer Bitcoin becomes.
Bitcoin gave us far more than a ledger-it gave us faith in change. It did so precisely at the moment when banks screwed up, were busy repossessing homes, and hoping we didn’t all realize that despite all the mortgage lenders’ “trust us” swagger, even houses aren’t “as safe as houses.”
Bitcoin’s impact, fully realized, can go even further than the reality we see today. Its destiny can and should be mass usage as a global reserve. It can form the basis for a global ‘Integrity Web’ that underpins all social functions our free society requires: money, property rights management, and social interactions.
Bitcoin’s Whitepaper foresaw a network that was used practically for payments, large and small, and operated by all, rich and poor. Today, there are 1.5 billion people in the world who don’t even have a bank account. Bitcoin payments would not just be an alternative for these people but actually their first access to financial infrastructure. Bitcoin today offers too little capacity and what capacity is available is too expensive for almost all of these 1.5 billion. It is my motivation to develop the technology that can make Bitcoin, and the free society it sustains, accessible to all.
The elephant in the essay
Some think of StarkWare as Ethereum maxis. Although we align with Ethereum values and remain committed to its success, we are first and foremost STARK maxis. Starknet is deployed as a Layer 2 on Ethereum, and connecting Starknet to Bitcoin as well is a natural extension of its feature set. It aligns with our vision, steadfast since founding StarkWare, that STARKs are a public good needed to scale all truly decentralized blockchain projects. Of course, Ethereum is also the incarnation of the same ambitious mission outlined earlier, despite it taking a different path, with different tradeoffs. And this is great, because overall this increases our likelihood to succeed in building protocols that can resist nation-states. The core values of Ethereum were the reason why we chose it as the settlement layer for Starknet in the first place, and those values still stand. We firmly believe in Ethereum and are committed to its long term success. Bringing ZK-STARKs to Bitcoin would not be a deviation from our path, but rather coming full circle. To date, StarkWare has deployed all its systems solely on Ethereum. But STARK scaling for blockchains is an idea that originated at a Bitcoin conference in the spring of 2013.
I stepped out on stage at the conference to speak about my nascent-and somewhat wonky-research about a type of cryptographic proof later called STARKs, and many of the audience members responded that this cryptographic research was exactly what blockchain needed. In other words, I was orange-pilled by Bitcoin two years before Ethereum was launched.
So, StarkWare has been deeply involved with Bitcoin since its very beginnings and we have continued to observe the network with admiration. I now feel comfortable having this conversation publicly as Taproot, and potentially OP_CAT, shape what is possible on Bitcoin.
We have also backed a number of breakthrough Bitcoin projects such as ZeroSync, which is pioneering the integration of ZK proofs with Bitcoin to enhance privacy and scalability. StarkWare also commissioned the “Validity Rollups on Bitcoin” report by researcher John Light, which reassessed the potential for integrating existing validity rollups with Bitcoin, and concluded that there could be an ideal match. Our next-gen circle-stark prover-verifier, Stwo, works over the finite field M31. This field plays nicely with Bitcoin script, which makes us perfectly suited to provide the next generation of Bitcoin scaling.
What I hope to see
My dream is to see Bitcoin attain the scale it needs to serve everyone, constantly. This involves opening it up to participation for all, without financial barriers to entry. I believe it must happen with steadfast adherence to Satoshi’s insistence on decentralization and security.
The internet started off as a niche playground for nerdy engineers and academics. Scaling it, which took years to do, transformed it into the infrastructure that runs our lives. Blockchain is a tool that rides over the Internet and can democratize it and rebalance power by distributing trust and integrity to large communities of sovereign individuals, rather than entrusting it with a few large corporations. But to truly seize power and bring it back to the masses, it needs to scale.
I am also convinced that the opportunity to scale Bitcoin should be seized to advance a value that is important to many in the Bitcoin community: privacy. The same cryptography that can provide Bitcoin with scalability also offers the raw ingredients to enhance privacy capabilities. In time, we’ll see that you can have it all: your keys, your coins, your confidentiality.
How do we expect to get there?
We, StarkWare, are taking three tangible steps today to get Bitcoin to scale:
- We will propose a new design for Starknet to unify the space by enabling Starknet to become a self-custodial decentralized Layer 2 to simultaneously and synchronously settle on Ethereum and Bitcoin. A single layer that settles on both chains at once. Our team will conduct – or sponsor – all the work needed to achieve this. The architectural details we are researching will be available in the upcoming weeks.
- StarkWare is launching a $1 million fund that will award grants to Bitcoin researchers and developers who research OP_CAT and its impact. These grants will be awarded to individuals and projects working in good faith both in favor and against the upgrade as well as contributing proofs of concept for OP_CAT usage. Details on this fund will be announced next week.
- Finally, we believe that the OP_CAT Bitcoin soft fork is the safest path for Bitcoin to scale, notably enabling STARK verification and rollups. As such, we announce our public support for OP_CAT. OP_CAT makes trustless rollups possible on Bitcoin by enabling recursive covenants that can manage and update their state autonomously, drastically increasing transaction throughput without overloading Bitcoin.
If you want to discuss StarkWare’s expansion to the Bitcoin network, please email us or join the conversation on X.
What does scaling Bitcoin unlock?
By scaling Bitcoin, we will be able to process transactions for millions of users in a single second – in contrast to circa thirteen transactions per second today. Some of the use cases we have envisioned for Bitcoin at scale include:
- Scaling both Bitcoin and Ethereum, together: Blockchain is fragmented today. You can choose between the “digital gold” of Bitcoin, which you can use to hold value but little else, or Ethereum, which aims to be “the world’s computer,” or various smaller chains. By straddling and offering choice over the two biggest chains (dApps can choose either or both), Starknet will defragment them. Without interfering in the independent governance of either chain, it will scale both, together.
- Privacy: STARKs, the cryptographic proofs that will be used for the scaling process, have baked into them massive, and as yet unrealized, potential to deliver privacy. The potential for privacy and the Bitcoin community are a match made in heaven. The “zero-knowledge” side of the technology is well understood but still to be unpacked and translated into practical solutions. Integrating private L2s into the Bitcoin ecosystem, utilizing technologies like Zcash, MimbleWimble, or Noir, can significantly enhance transaction privacy.
- Finance for the excluded: To us, Bitcoin’s mission has always been, in part, about empowering the underprivileged. Approximately 1.5 billion people globally lack access to traditional banking services, a debilitating hurdle to financial upward mobility. Other attempts at scaling Bitcoin have not yet provided a mass-use solution. With a new scaling approach and added tools, Bitcoin has the potential to offer the world’s unbanked an inclusive and global financial system.
- Financial innovation over Bitcoin: Bitcoin today supports digital cash payments, but modern markets need more: better self-custody options with programmable vaults, risk management and hedging tools, credit, lending, derivatives, futures contracts, and more. All these require more functionality that cannot and should not, be built directly on Bitcoin. Making Starknet a Layer 2 on Bitcoin provides the best of both worlds: tremendous financial innovation backed by the security of Bitcoin serving as digital gold.
- Improved user experience: The pristine self-custodial safety of Bitcoin also makes it scary to handle safely, especially from the point of view of average users. A modern Layer 2 will offer users safe and simple self-custodial interactions for most of their daily needs while relying on Bitcoin’s robust but cumbersome Layer 1 security as a long-term store of value.
Why OP_CAT, STARKs and Starknet?
Why OP_CAT? STARKs require verifying chains of hashes, and little else. Their primary verification loop consists of simple algebraic operations (addition and multiplication modulo a small prime number) and verifying that entries pre-committed via Merkle trees are opened correctly. OP_CAT uniquely enables creating and opening entries in Merkle trees within Bitcoin Script, because the core operation enabling Merkle tree creation and verification is composed of concatenating two values, then hashing them (OP_CAT enables concatenation). While other covenant-enabling op codes may be more powerful, OP_CAT is the only one currently under debate that enables Merkle tree verification.
Why STARKs? Briefly, they offer the largest scale, are the most battle-tested, safest, require no trusted setup “toxic waste”, no exotic crypto primitives, and are even post-quantum secure. The new STARK prover-verifier, called Stwo, uses tiny numbers that fit comfortably on Bitcoin’s stack, for increased efficiency.
Why Starknet? Starknet on Ethereum already has a vibrant community of developers, as well as a programming language that puts the full power of scaling at their fingertips. To any developer who knows Rust, Starknet’s native (and open-source) language Cairo will seem familiar. The Bitcoin community today does not have an obvious high-level language for building a world of activity on top of the chain. I hope Cairo will fill this niche and become one of the native languages of Bitcoin.
Coming up…
Details on data availability, L2 consensus, forced withdrawals and the verifier itself, will be discussed in future blog posts. This is a global initiative, and we’d love to hear your feedback – please share your thoughts with our team via email or X.
