Storing data in a decentralized network is easy when everyone behaves honestly. The real challenge begins when participants lie, networks stall, and writers or readers act maliciously. Walrus addresses this challenge through Asynchronous Complete Data Storage (ACDS).
ACDS defines what it truly means for data to be stored reliably in a decentralized, adversarial environment.
Understanding the Problem
Walrus operates with storage nodes that may behave dishonestly and networks that may delay messages indefinitely. In such an environment, a simple “write and replicate” approach is not enough.
ACDS provides formal guarantees that ensure data remains usable despite these conditions.
The Three Guarantees of ACDS
Write Completeness
If an honest writer submits a data blob, all honest storage nodes holding a commitment to that blob will eventually store their assigned piece. This ensures that honest writes cannot be partially completed or silently dropped.
Read Consistency
If two honest readers attempt to read the same data, they will either both retrieve the correct data or both fail. This prevents inconsistent states, which are dangerous for applications that rely on shared data.
Validity
If an honest writer successfully writes data, any honest reader with the correct commitment can later retrieve it, regardless of network delays or malicious behavior.
Why Asynchronous Matters
Walrus does not assume synchronized clocks or bounded message delays. This makes ACDS particularly powerful, as it operates correctly even when attackers manipulate network timing.
By bounding operations within epochs and allowing message loss at epoch transitions, Walrus remains realistic and robust.
Blockchain as a Coordination Layer
Walrus uses an external blockchain (such as Sui) as a coordination layer. The blockchain handles ordering and commitments, while Walrus handles data storage and availability.
This modular approach prevents blockchain bloat while maintaining strong security guarantees.
Why ACDS Is Critical for Web3
Rollups, Layer-2 networks, and modular blockchains all depend on reliable data availability. If data cannot be retrieved consistently, these systems fail.
ACDS ensures that Walrus can serve as a dependable data layer for the broader Web3 ecosystem.
Conclusion
ACDS is not just a protocol—it is the backbone of Walrus’s reliability. By guaranteeing completeness, consistency, and validity under adversarial conditions, Walrus sets a new standard for decentralized storage.
In a world where attackers are expected, Walrus proves that data availability can still be guaranteed.
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