By
Godfrey Benjamin
May 10th, 2024
Citrea was initially announced earlier this month and revealed as the first ZK rollup on Bitcoin.
Citrea, a zero-knowledge (ZK) rollup from Chainway Labs, has confirmed that it raised $2.7 million in a seed funding round led by Galaxy Ventures. Other participants in the round include Taproot Wizards co-founder Eric Wall, data availability blockchain Avail’s co-founder Anurag Arjun, and Delphi Ventures.
Citrea and Bitcoin
Citrea aims to bring the ZK rollup technology, which is used more on the Ethereum (ETH) network, to Bitcoin (BTC). Confirming the fundraising round to CoinDesk, Citrea says zero-knowledge technology will help to add more security to Bitcoin transactions. The statement reads:
“[Citrea is] the first rollup that enhances the capabilities of Bitcoin blockspace with zero-knowledge technology. Every transaction occurring on Citrea is fully secured by zero-knowledge proofs and optimistically verified on Bitcoin.”
Essentially, a ZK rollup is a layer-2 (L2) blockchain solution that handles storage and computation off-chain while leaving transaction data on the layer-1 (L1) network. This solution, primarily used on the Ethereum blockchain, increases transaction throughput and reduces transaction costs. This considerably scales the network because instead of posting single transactions on the L1, the technology only has to post valid batches periodically, bundled from the L2.
Since its inception, Bitcoin has been a relatively light network, without all of the additions users enjoy on Ethereum. However, Citrea hopes to make Bitcoin a lot more dynamic so that it accepts non-fungible tokens (NFTs) and accommodates use cases for decentralized finance (DeFi). Also, Citrea hopes to leverage ETH as the ZK rollup will be compatible with the Ethereum Virtual Machine (EVM).
Scaling the Bitcoin Blockchain
Citrea was initially announced earlier this month and revealed as the first ZK rollup on Bitcoin. According to an official blog post, Citrea explains that Bitcoin has the most secure and censorship-resistant blockspace. However, most scaling proposals offer to create new block spaces that do not scale Bitcoin. The post states that these new blockspaces do not inherit Bitcoin’s properties and may compete with the network long-term. Citrea also says that options like Lightning and sidechains have fallen short. Specifically, while the Lightning Network does not bring programmability to Bitcoin, sidechains do not actively utilize the Bitcoin blockchain.
Citrea notes that to scale Bitcoin blocks securely, it is necessary to “shard the execution with on-chain verifiability and data”. Easy verifiability is also only possible via ZK or fraud proofs. However, since fraud proofs require large amounts of data written to Bitcoin, ZK proofs are the best way to verify execution validity within Bitcoin’s block size limit.
“ZK Rollups create an execution shard and batch multiple transactions on the shard while verifying them on-chain with a succinct mathematical proof as well as minimal essential data to reconstruct the state. This method enables ZK Rollups to utilize underlying blockspace verifiably in the most efficient manner, scaling the L1 with its full security.”
Chainway Labs plans to launch a test network sometime in the second quarter of 2024.