As blockchain technology continues to gain traction, the need for scalable and secure solutions has become increasingly evident. Validity proofs—commonly referred to as zero knowledge (ZK) proofs—have emerged to address this challenge. In this blog post, we’ll explore the intricacies of these cryptographic proofs and the aspects that make them so powerful.
What are zero knowledge proofs?
First, it’s important to note that while the terms “validity proofs” and “zero knowledge proofs” are often used interchangeably, they mean slightly different things.
Zero knowledge proofs allow a prover to demonstrate to a verifier that a particular computation was executed correctly without revealing any of the sensitive input data consumed by that computation. Their privacy-preserving nature makes them highly desirable for applications that prioritize confidentiality and data protection.
The emphasis of most Layer 2 (L2) validity rollups, such as Starknet, however, is not to leverage proofs to preserve privacy. Instead, they use cryptographic proofs to establish the integrity of transaction execution with minimal computational effort by the verifier. The primary goal of these L2 solutions is scalability, and the cryptographic proofs they use are better described as “validity proofs.” Nevertheless, we will use the commonly accepted term “zero knowledge” for the purpose of this piece.
In their seminal 1991 paper titled “Checking Computations in Polylogarithmic Time,” L. Babai, L. Fortnow, L.A. Lewin, and M. Szegedy presented a remarkable example of the capabilities of these proofs. The authors described a protocol in which “a single PC can monitor the operation of a herd of supercomputers with powerful but unreliable software and untested hardware.” This means a machine with limited computational capacity can verify the integrity of computations performed by a set of far more powerful computers, even if the party controlling those computers is malicious or has an incentive to misreport the results.
Zero knowledge proofs and L2s
The primary goal of zero knowledge proofs in the blockchain context is to enable nodes to vouch for the validity of transactions while exerting minimal computational effort. L2 solutions employ these proofs to enable efficient verification of large batches of transactions, allowing for increased throughput and reduced costs compared to executing each transaction individually on the main blockchain. By offloading computation to an offchain environment and using proofs to establish the validity of that computation, zero knowledge rollups significantly enhance the scalability of blockchain networks without compromising security or decentralization.
STARKs
The STARK (Scalable, Transparent ARgument of Knowledge) proof system enables the proving and verification of computations. STARK enables processing a large computation, generating a proof that validates the computation’s correctness, and then verifying the proof in very few steps.
STARKs can play a key role in blockchain scalability by allowing large computations to be done offchain, where it is cheaper, leaving only the verification, which requires a fraction of the computation, to be done onchain. This results in many more transactions per second (TPS) at a fraction of the cost, while inheriting Ethereum’s security. As such, STARKs enable a new class of applications that were previously not feasible onchain.
StarkWare pioneered the STARK technology that powers StarkEx, its flagship scaling solution for Ethereum, and Starknet, a permissionless validity rollup. These solutions batch together and compute thousands of transactions, and then verify their validity onchain with a single STARK proof, resulting in improved user experience and reduced fees while maintaining the security of the Ethereum settlement layer.
Conclusion
While zero knowledge proofs offer unparalleled privacy and confidentiality, they are not employed by most ZK rollups for their ZK properties. Instead, they have emerged as a crucial component in L2 solutions, enabling efficient transaction verification and scalability. By leveraging the power of zero knowledge proofs, such as STARKs, blockchain networks can achieve increased throughput, reduced costs, and enhanced user experience without compromising security or decentralization. As the blockchain ecosystem continues to evolve, the adoption and further development of these zero knowledge proofs will play a pivotal role in unlocking the full potential of this transformative technology, paving the way for a new era of scalable and secure applications.
