## Introduction Zero-knowledge (ZK) technologies have emerged as promising solutions to enhance the scalability and privacy of blockchain networks. Two notable examples are zk-Rollups on Ethereum and zk-Compression on Solana. While both utilize ZK proofs to optimize performance, there are key differences in their approaches and applications. This article provides a comprehensive comparison of zk-Rollups and zk-Compression, highlighting their advantages, disadvantages, and potential use cases. ## zk-Rollups on Ethereum ### What are zk-Rollups? Zero-knowledge rollups (zk-Rollups) are layer-2 scaling solutions that increase Ethereum's transaction throughput by moving computation and state storage off-chain[1][2]. They bundle multiple transactions into a single batch, generating a cryptographic proof that attests to the validity of the entire batch. This proof is then submitted to the Ethereum mainnet, along with a small amount of data required to update the state[1][2]. ### How do zk-Rollups work on Ethereum? zk-Rollups consist of two main components: an off-chain virtual machine (VM) and on-chain smart contracts[2]. The off-chain VM executes transactions and generates ZK proofs, while the on-chain contracts verify the proofs and update the Ethereum state accordingly[2]. This hybrid approach allows zk-Rollups to benefit from Ethereum's security while offloading the bulk of the work to the layer-2 network[2]. ## zk-Compression on Solana ### What is zk-Compression? zk-Compression is a new primitive built on the Solana blockchain that enables developers to compress on-chain state[1]. By storing only the state roots (small fingerprints of compressed accounts) in on-chain accounts and the underlying data on the cheaper Solana ledger, zk-Compression reduces state costs by orders of magnitude[1]. ZK proofs are used to ensure the integrity of the compressed state[1]. ### How does zk-Compression function on Solana? zk-Compression works by securely storing state on cheaper ledger space instead of the more expensive account space, allowing applications to scale to millions of users[1]. Solana programs can mix and match between compressed and regular on-chain state, enabling atomic interaction with multiple programs, accounts, and compressed accounts[1]. ## Comparison: Key Differences 1. **Underlying blockchain**: zk-Rollups are built on Ethereum, while zk-Compression is a Solana-native technology[1][2]. 2. **Scaling approach**: zk-Rollups bundle transactions off-chain and submit validity proofs to Ethereum[1][2], while zk-Compression compresses on-chain state to reduce costs[1]. 3. **State storage**: zk-Rollups store transaction data on-chain in batches[1][2], while zk-Compression stores state roots on-chain and underlying data on the cheaper Solana ledger[1]. 4. **Composability**: zk-Rollups may fragment liquidity and present challenges to permissionless composability compared to applications on the same base layer[4], while zk-Compression allows Solana programs to mix and match compressed and regular state[1]. 5. **Complexity**: zk-Rollups use advanced cryptography, making them difficult to implement and maintain[3], while the complexity of zk-Compression is not explicitly mentioned. ## Use Cases ### Current Use Cases - **zk-Rollups**: Decentralized exchanges (DEXs) like Loopring use zk-Rollups to provide fast and low-cost trades on Ethereum[5]. - **zk-Compression**: No specific current use cases are mentioned, as zk-Compression is a new primitive. ### Potential Use Cases - **zk-Rollups**: Scaling decentralized applications (dApps) and enabling high-throughput use cases on Ethereum[1][2]. - **zk-Compression**: Enabling Solana-based applications to scale to millions of users by reducing state costs[1]. ## Conclusion Both zk-Rollups and zk-Compression offer promising solutions for enhancing blockchain scalability and performance. zk-Rollups have a more established track record, with current use cases in decentralized exchanges, while zk-Compression is a newer technology with the potential to significantly reduce state costs on Solana. Ultimately, the choice between the two technologies may depend on the specific needs of the application and the developer's familiarity with the underlying blockchain. As both technologies continue to evolve and mature, they will likely play a crucial role in driving the widespread adoption of blockchain technology. ## References [1] ZK Compression: Overview. (2024, June 21). ZK Compression. https://www.zkcompression.com [2] Zero-knowledge rollups. (2024, May 10). ethereum.org. https://ethereum.org/en/developers/docs/scaling/zk-rollups/ [3] Top Ethereum ZK Rollup Projects for 2024. (2024, May 29). KuCoin Learn. https://www.kucoin.com/learn/crypto/top-ethereum-zk-rollup-projects [4] What Are ZK Rollups? (2023, November 30). Chainlink Education Hub. https://chain.link/education-hub/zero-knowledge-rollup [5] ZK Rollups for the Crypto Blockchain Reduces Gas Fees. (n.d.). ZK Rollups. https://zkrollups.io Citations: [1] https://www.zkcompression.com [2] https://ethereum.org/en/developers/docs/scaling/zk-rollups/ [3] https://www.kucoin.com/learn/crypto/top-ethereum-zk-rollup-projects [4] https://chain.link/education-hub/zero-knowledge-rollup [5] https://zkrollups.io [6] https://www.cointribune.com/en/zk-compression-on-solana-the-game-changer-that-is-igniting-the-crypto-sphere/ [7] https://thedefiant.io/news/blockchains/zk-compression-scaling-on-solana-ignites-controversy [8] https://cryptoadventure.com/zk-compression-on-solana-cutting-on-chain-costs-with-new-tech/ [9] https://hacken.io/discover/zk-rollups-explained/ [10] https://starkware.co/zk-rollups-explained/ [11] https://www.kvarnx.com/content/what-is-the-difference-between-optimistic-rollups-and-zk-rollups [12] https://blog.thirdweb.com/zero-knowledge-rollups-zk/ [13] https://www.gate.io/state_compliance_tips [14] https://www.reddit.com/r/solana/comments/1dnx601/anyone_know_how_zk_compression_works/ [15] https://coinmarketcap.com/community/articles/6679990f5b200c2e3ca4b98a/ [16] https://www.linkedin.com/pulse/zk-rollups-vs-optimistic-rollups-overview-garima-singh-p1mvf [17] https://twitter.com/martypartymusic/status/1804935117259120670