Author: Eli Ben-Sasson, co-founder of StarkWare; Translation: Golden Finance xiaozou
STARKs have finally reached their next challenge. Now, STARKs will demonstrate their scaling advantages on the most egalitarian currency ever created: Bitcoin. Once OP_CAT is adopted on Bitcoin, deploying STARK validators in Bitcoin script will become a reality. This opens a channel for secure, self-custodial transfers between Bitcoin and Starknet, creating an L2 that scales both Ethereum and Bitcoin.
Cryptocurrency can cleanse the digital and financial world. It can bring integrity to money, rebalance power in our society, taking it away from big tech companies and giving it back to sovereign individuals. It is a tool to empower humanity and grassroots communities. In short, it is a source of good. So we need a vision that shows this and that matters to everyone. I left my quiet academic career to realize this vision.
Such a vision would not be complete without extending the launch chain of this fantastic project. We extend Bitcoin and unleash the power of blockchain to change the world. StarkWare is supporting this initiative with practical measures and has launched a $1 million fund to support new research that will reveal the pros and cons of adopting OP_CAT on Bitcoin.
We had a very fruitful strategic partnership with Weikeng Chen of L2 Iterative Ventures (L2IV) through the ZeroSync Foundation, which ultimately led to the creation of the Bitcoin Wildlife Sanctuary. We leveraged their team’s hands-on approach to engineering and research to push the boundaries of our open-source work on deploying OP_CAT-based contracts and STARK validators in Bitcoin Script. We would also like to thank BitVM and the ZeroSync Foundation for exposing so many people to the capabilities of Bitcoin. We were also greatly influenced by Carter Feldman, founder of QED, who showed us new perspectives and open minds on the potential of Taproot.
Now, let's get back to basics and explain why what we are doing now makes sense.
1. 2008: The Breaking Moment
Let’s go back to 2008, right after the global financial collapse. In response, Satoshi Nakamoto published the revolutionary Bitcoin whitepaper. In this moment of rupture, Satoshi Nakamoto showed us how to do things differently. As a public, we can demand and enforce higher standards of integrity and transparency in finance. Instead of relying on the bastions of traditional banks, Satoshi Nakamoto introduced an inclusive protocol that invites everyone to join in. The protocol distributes value fairly and transparently to contributors broadly through Bitcoin mining and fees. The more widely distributed the contributors, the better and more secure Bitcoin will become.
Bitcoin gave us more than just a ledger — it gave us faith in change. It gave us faith at a time when the banks were screwing everything — when they were busy repossessing homes and hoping we all didn’t realize that despite all the mortgage lenders’ “believe in us” gestures, even home wasn’t “as safe as home.”
Bitcoin’s impact, if fully realized, could be far more far-reaching than what we see today. It can and should be used en masse as a global reserve currency. It could form the basis of a global “web of trust” that underpins all the social functions our free society requires: money, property management, and social interaction.
The Bitcoin whitepaper envisions a network that is actually used for payments, accessible to everyone, big or small, rich or poor, powerful or weak. Today, there are 1.5 billion people in the world who don't even have a bank account. Bitcoin payments are not just an option for these people, but actually their first medium of access to financial infrastructure. Today, the capacity offered by Bitcoin is too small, and the available capacity is too expensive for these 1.5 billion people. I hope to develop a technology that allows everyone to use Bitcoin and participate in the free society that Bitcoin sustains.
2. Important but neglected issues
Some see StarkWare as the Ethereum maxis. While we align with Ethereum’s values and are committed to Ethereum’s success, we are first and foremost a STARK maxis. Starknet is deployed on Ethereum as a L2, and connecting Starknet to Bitcoin is a natural extension of its features. This is consistent with our vision since founding StarkWare that STARKs are public goods that are used to scale all truly decentralized blockchain projects. Ethereum is, of course, an incarnation of the same ambitious mission described above, but it has taken a different path with different trade-offs. This is good because overall it increases our chances of successfully building a protocol that can resist state power. The core values of Ethereum are why we chose it as the settlement layer for Starknet in the first place, and those values remain. We firmly believe in Ethereum and are committed to its long-term success. Bringing ZK-STARKs to Bitcoin is not a departure from our path, it’s just a detour. To date, StarkWare has deployed all of its systems on Ethereum. But STARK extensions to blockchains were an idea proposed at the Bitcoin conference in the spring of 2013.
At the conference, I took the stage and spoke about my initial research on a type of cryptographic proof that would later be called STARKs, and many in the audience responded that this kind of cryptographic research was exactly what blockchain needed. In other words, I was already very interested in Bitcoin two years before Ethereum came out.
StarkWare has therefore been closely associated with Bitcoin since the beginning, and we have been observing the Bitcoin network with admiration. Taproot, and perhaps OP_CAT, expands the possibilities of Bitcoin in a way that I can now safely discuss publicly.
We have also supported groundbreaking Bitcoin projects such as ZeroSync, which pioneered the integration of ZK proofs with Bitcoin to enhance privacy and scalability. StarkWare also commissioned a report by researcher John Light titled "Validity Rollup on the Bitcoin Network", which re-evaluated the possibility of integrating existing validity rollups with Bitcoin and concluded that it could be an ideal match. Our next generation circle-stark prover-verifier - Stwo - targets the M31 finite domain. This domain works well with Bitcoin Script, which makes us well suited to provide the next generation of Bitcoin scaling.
3. The future I hope to see
My dream is to see Bitcoin reach the scale it needs to reach, to continue to serve everyone. This includes opening participation to everyone, with no financial barriers to entry. I believe that as long as we firmly adhere to Satoshi's commitment to decentralization and security, this dream will come true.
The internet started out as a niche playground for nerdy engineers and academics. It took years to scale it and finally turn it into the infrastructure of our lives. Blockchain is a tool that can democratize the internet and rebalance power by distributing trust and integrity to large communities of sovereign individuals rather than entrusting it to a few large companies. But to truly take power away and give it back to the masses, it will take scale.
I also believe that the opportunity of Bitcoin scaling should be seized to advance a value that is important to many in the Bitcoin community: privacy. The cryptographic technology that enables Bitcoin to scale also provides the raw materials for enhanced privacy features. In time, you will own everything: your keys, your coins, your confidentiality.
4. How to achieve such a future?
We, StarkWare, are taking three concrete steps today to scale Bitcoin:
Action 1: We will propose a new design pattern for Starknet that will enable a unified space by making Starknet a self-hosted decentralized L2 that simultaneously settles on both Ethereum and Bitcoin. That is, a single layer that settles on both chains at the same time. Our team will direct or sponsor all work required to achieve this goal. Details of the architecture being worked on will be announced in the coming weeks.
Measure 2: StarkWare has launched a $1 million fund to fund Bitcoin researchers and developers who study OP_CAT and its impact. These grants will be awarded to individuals and projects who sincerely support or oppose the upgrade and provide proof of concept for the use of OP_CAT. Details about the fund will be announced next week.
Measure 3: Finally, we believe that the OP_CAT Bitcoin soft fork is the safest path to Bitcoin expansion, especially to support STARK verification and rollup. Therefore, we announced public support for OP_CAT. OP_CAT makes trustless rollup possible on Bitcoin by enabling recursive contracts that can autonomously manage and update state, thereby greatly increasing transaction throughput without overloading the Bitcoin network.
5. What potential does Bitcoin expansion unlock?
By scaling Bitcoin, we will be able to process transactions for millions of users in one second, rather than the current rate of about 13 transactions per second. Some of the scale use cases we envision for Bitcoin include:
· Scaling Bitcoin and Ethereum at the same time: Today’s blockchain is fragmented. You can choose Bitcoin, the “digital gold” that stores value but has little other use, Ethereum, which aims to be the “world’s computer”, or other smaller chains. Starknet consolidates the fragmentation by offering a choice on the two largest chains (dApps can choose one or both). Starknet will scale both chains simultaneously without interfering with the independent governance of either chain.
· Privacy protection: STARKs—cryptographic proofs that will be used in the scaling process—already incorporate a wealth of unrealized privacy protection potential. The potential for privacy protection and the Bitcoin community are a natural fit. The “zero-knowledge” side of this technology is already well understood, but still needs to be translated into practical solutions. Integrating private L2 into the Bitcoin ecosystem, leveraging technologies such as Zcash, MimbleWimble or Noir, can significantly enhance transaction privacy.
Providing financial services to the marginalized: For us, Bitcoin’s mission has always been, in part, to empower the underprivileged. Approximately 1.5 billion people worldwide lack access to traditional banking services, a debilitating barrier to bottom-up financial mobility. Other attempts to scale Bitcoin have yet to provide a solution for mass use. Through new scaling methods and the addition of more tools, Bitcoin has the potential to provide an inclusive global financial system for the world’s unbanked.
Financial innovation for Bitcoin: Today, Bitcoin supports digital cash payments, but the modern market requires more: better self-custody options with programmable vaults, risk management and hedging tools, reputation, lending, derivatives, futures contracts, etc. All of these require more functionality that cannot and should not be built directly on Bitcoin. Making Starknet the L2 for Bitcoin has the best of both worlds: tremendous financial innovation backed by the security of Bitcoin as digital gold.
Improved user experience: Bitcoin’s original self-custody security also makes it non-trivial to operate securely, especially for regular users. A modern L2 will provide users with secure and simple self-custody interactions for most of their daily needs, while relying on the security of Bitcoin’s strong and reliable L1 for long-term value storage.
6. Why OP_CAT, STARKs, and Starknet?
(1) Why OP_CAT?
STARKs require verification of a hash chain, and not much else. Their main verification loop consists of simple algebraic operations (addition and multiplication modulo a small prime number) and verifying that entries pre-committed via a Merkle tree were opened correctly. OP_CAT specifically supports creating and opening entries in Merkle trees from within Bitcoin Script, as the core operations supporting Merkle tree creation and verification require concatenating two values and then hashing them (OP_CAT enables concatenation). While other contract-supported opcodes may be more powerful, OP_CAT is the only one currently being discussed that supports Merkle tree verification.
(2) Why STARKs?
In short, STARKs offer the greatest scale, are the most proven and secure, have no “toxic garbage” from a trusted setup process, have no exotic cryptographic primitives, and even have post-quantum security. The new STARK prover-verifier, called Stwo, uses small numbers that fit on the Bitcoin network for greater efficiency.
(3) Why Starknet?
Starknet on Ethereum already has a vibrant developer community and a programming language that puts all the scaling power at your fingertips. Cairo, Starknet’s native (and open source) language, will seem more familiar to any developer who knows Rust. There is no obvious high-level language emerging in the Bitcoin community today for building the world of on-chain activity. I hope Cairo can fill this gap and become one of Bitcoin’s native languages.