Bitcoin & Beyond is an educational series by the team at Cumulative Focus on a new and emerging class of builders in the Bitcoin ecosystem. Through interactive spaces, panels and presentations, the goal is to provide deep technical insights for innovative expansion projects.
In this episode, the crew discusses creating the first ZK (zero-knowledge) blockchain for Bitcoin using Orkon from Setria. Bulk updates are a new technology that promises to enhance the utility of Bitcoin, allowing various scalability improvements while maintaining the security of the Bitcoin infrastructure.
“A pool is a blockchain that uses another blockchain as a layer that provides data,” Orkun says emphatically.
Lots of other elements are taken into consideration in the collage design, but he believes they shouldn't be part of the definition. “Where is the settlement located, bridges? ZK or Optimistic? Execution layer? Doesn't matter.”
The motivation behind Setria
Citrea's motivation behind building a zero-knowledge backlog on Bitcoin stems from Bitcoin's unparalleled security and censorship resistance. Despite these strengths, Bitcoin has limitations in block size and script capabilities. “What you can do with Bitcoin other than simple payments is very limited today. We want to do more with Bitcoin's block space security,” Orkun noted.
Overcoming Bitcoin's limitations through modularity
Citrea attempts to address these limitations through modularity. By creating a batch cluster, developers can customize their cluster to create various applications, such as payment clusters, gaming clusters, and EVM clusters. This flexibility allows for various improvements that may extend the scope of the blockchain without requiring changes to its underlying protocol. Combining different services becomes fertile ground for experiments that were not possible before.
Security is crucial to Bitcoin and any layers built on top of it. “Creating an accumulator is the only way to actually get that security. Unless you're creating channels like Lightning or Mercury, which are still limited by Bitcoin's functionality.”
Citrea's innovation is to use Bitcoin as a layer that provides data. Thanks to landmark changes like SegWit and Taproot, developers have discovered new ways to record data in Bitcoin transactions. This makes it possible to use Bitcoin as a layer that provides data for aggregated data. “So you can publish data in Bitcoin, but that data can be random because it is not implemented at all in the blockchain,” Orkun explained.
Using Bitcoin to provide data involves trade-offs. Although it ensures high security, it may not be suitable for high-speed and low-cost applications. “If you want complete Bitcoin security, you should use Bitcoin as the layer that provides your data. However, for high-speed, low-cost applications, other layers such as Celestia may be more suitable.”
Clementine Bridge
To move bitcoins in and out of the system, Citrea built Clementine, a two-way peg based on BitVM that optimistically verifies ZK proofs. This mechanism aggregates proofs from Bitcoin, reducing the need for frequent settlements and enhancing security. “We just record these proofs on Bitcoin every hour,” Orkun explained. “Other groups can read the proof from there and execute based on that.”
The evolution of BTC bridges has seen a shift from custodial and standardized threshold bridges to modern crypto-economic security bridges. Fed bridges rely on majority consensus within the committee, while crypto-economic bridges like Stacks or tBTC use staked assets to ensure security. “In cryptoeconomic security, you still trust a consortium, but these people already own some other asset,” Orkun explained. “And if they steal money, you can downgrade that asset.”
But Clementine takes this a step further. It uses an optimistic approach inspired by BitVM to verify ZK proofs, which is secure and cost-effective. This approach allows proof to be compiled, making the process efficient and scalable.
The basic idea behind Clementine is to provide optimistic settlements for ZK decks. “We're just collecting proofs of Bitcoin from Bitcoin to settle less frequently because you can't settle on every single block. It would be expensive,” Orkun explained. By regularly recording data and compiling evidence, Clementine ensures the case remains accurate and secure.
To achieve this, the operator will first cover the user's withdrawal requests out of pocket and then compile the necessary proofs into a single submission to the network. If other operators suspect an error, they can dispute the transmission. Successful challenges result in the dishonest operator losing their initial bond and being removed from the network. If the operator's submission is not challenged, it can then recover the equivalent amount it disbursed from users' original deposits.
This setting introduces a trust-reducing assumption where only one participant needs to be honest to ensure security. “We call it low trust because now we have an assumption of 1 out of N. As long as one person in that N people is honest, your money is safe,” Orkun emphasized. This is a significant improvement over traditional models that require majority consensus regarding security.
Future plans and ecosystem impact
Looking to the future, Citrea plans to introduce Volition, a hybrid model that balances on-chain security with off-chain cost efficiency. This allows applications to choose how they store data based on their specific needs. Orkun also stressed the importance of transaction fees to Bitcoin's long-term security, with Citrea using Bitcoin as a data-providing layer that contributes to maintaining miner incentives and network security.
“So, depending on your usage, if you want to deploy a gaming app now, you can use off-chain data. It's very cheap and very fast, but it still has the interoperability of Bitcoin. If you want to create a stablecoin backed by Bitcoin app, you can use The data is on-chain so your stablecoin is fully secured on-chain, fully collateralized by Bitcoin, which is a little bit expensive but you can still get interoperability between the gaming app and the stablecoin app.
Bridging the flexibility of Bitcoin with the flexibility of pooling operations could push the boundaries of what is possible with Bitcoin. paying off Setria Website to learn more about their work. Follow our Bitcoin & Beyond series on therollup.co To learn more about the evolving state of Bitcoin scaling solutions.
This is a guest post by The Rollup. The opinions expressed are entirely their own and do not necessarily reflect the opinions of BTC Inc or Bitcoin Magazine.