Zero-knowledge (ZK) rollups are coming to #Bitcoin as two independent projects inch closer to incorporating this novel technology. This development promises to enhance network scalability and bolster privacy in Bitcoin transactions.

Chainway recently publicized their Data Availability (DA) adapter powered by the Sovereign Software Development Kit (SDK), potentially enabling the development of Bitcoin’s first ZK rollup.

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Concurrently, Kasar Labs and Taproot Wizards have announced a DA adapter, a tool designed to facilitate Starknet-based rollups using the Cairo programming language created by StarkWare.

ZK rollups batch together several non-standard transactions, for example, transactions for some sidechain, and record them on a base layer blockchain like Bitcoin, optimizing drastically computational costs and security. What distinguishes ZK rollups is their usage of zero-knowledge proofs that maintain computational integrity while protecting privacy, permitting the verification of transactions through the final proof alone, without revealing specific transaction details.

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An excellent ‘for dummies’ explainer thread on how rollups work in the Ethereum context can be found here. And for more technical details on ZK rollups in the Bitcoin context, check out this Bitcoin Magazine article.

With its unparalleled uptime and reorg resistance, the Bitcoin network is emerging as the most reliable platform for rollup transactions. However, to fully integrate ZK rollups into Bitcoin, a soft fork introducing a new opcode is necessary, which would enable Bitcoin to verify ZK proofs natively.

Projects Highlights

@Sovereign_Labs and Starknet have designed frameworks that circumvent the need for a new opcode through the use of the Ordinals protocol and inscription envelopes, a technology pioneered by Ordinals. This feature allows users and apps to recognize pertinent data through the use of the “ord” flag, facilitating the mathematical verification of the ZK proof in the latest state of the rollup.

Sovereign

Sovereign’s approach is grounded in three objectives:

  • Establish a standard interface to facilitate communication between rollups and DA layers.
  • Convert the business logic of the code into a form that can be cryptographically verified, achieved through integration with cryptographic compilers.
  • Provide default implementations for common blockchain primitives, such as tokens and NFTs.

The Chainway’s DA adapter is central in connecting Sovereign rollups to Bitcoin, enhancing data availability and promoting trustless verification processes, albeit with centralized sequencing overseen by the foundation.

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Plans to decentralize sequencing through a stake-based system are underway.

Starknet

Starknet, which operates atop the #Ethereum blockchain, broadens the utility of rollups through a dedicated ecosystem that includes Cairo, CairoVM, and Madara.

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The recent collaboration with Kasar Labs and Taproot Wizards aims to anchor Starknet’s open-source rollups to the Bitcoin network, promising a secure and robust foundation for developers.

Does Bitcoin Need ZK Rollups?

Inherently, Bitcoin doesn’t need much. It basically just works as it is. Yet, integrating ZK rollups could fundamentally transform its operational dynamics, potentially expanding user participation akin to the Lightning Network. This venture explores the spectrum of opportunities with Bitcoin, envisioning a platform capable of handling private and complex computations based on mathematical proofs.

Although realizing a full-fledged ZK rollup ecosystem depends largely on reaching a consensus for introducing a new opcode, these foundational steps signal a strong commitment to innovation. It is a promising avenue, albeit with an uncertain future regarding user adoption.