New Implementations Cut Verification Time to Seconds for Fair Data Exchange Protocol

Global: New Implementations Cut Verification Time to Seconds for Fair Data Exchange Protocol

A team of cryptography researchers announced two novel implementations of the Fair Data Exchange (FDE) protocol that dramatically lower verification and proof‑generation latency, enabling near‑real‑time, pay‑per‑file transactions on blockchain networks. The work, posted on arXiv in June 2025, targets the scalability bottlenecks that previously required hours of client‑side computation for files as small as a few tens of megabytes.

Scalability Challenges of Existing FDE

Earlier versions of the FDE protocol, presented at CCS’24, achieved atomic, pay‑per‑file exchange with a constant on‑chain footprint but relied on proof verification that grew with file size. As a result, clients experienced verification times measured in hours, making the approach impractical for everyday use.

VECKplus: Linear Verification

The first implementation, named VECKplus, reduces client‑side verification complexity to O(λ), where λ denotes the security parameter, rendering verification time independent of file size. Benchmarks on a commodity desktop show verification completing in roughly one second regardless of the file’s dimensions. Additionally, VECKplus limits expensive range‑proof generation to a Θ(λ)‑sized subset of the file, cutting proof‑generation time for a 32 MiB file from about 6,295 seconds to approximately 4.8 seconds—a speed‑up of roughly 1,300×.

VECKstar: Reducing Encryption Overhead

The second implementation, VECKstar, replaces bulk ElGamal encryption with a fast, hash‑derived mask while confining public‑key operations to a Θ(λ) sample linked by a file‑size‑independent zk‑SNARK. This change adds less than 0.1 second to verification and reduces communication overhead from at least ten times the plaintext size to under 50 percent, achieving performance close to plaintext‑scale.

Off‑Chain Operation via Lightning Network

Both implementations bridge Bitcoin’s secp256k1 curve and BLS12‑381 using a file‑size‑independent zk‑SNARK, allowing the FDE protocol to operate fully off‑chain on the Lightning Network. This shift lowers transaction fees from roughly USD 10 to under USD 0.01 and shortens payment latency to a few seconds.

Implications for Blockchain‑Based Data Exchange

The reported advancements suggest that atomic, pay‑per‑file exchanges can become viable components of decentralized applications without imposing prohibitive computational costs on end users. By minimizing on‑chain data footprints and leveraging off‑chain payment channels, the new designs may encourage broader adoption of secure, decentralized file marketplaces.

This report is based on information from arXiv, licensed under Academic Preprint / Open Access. Based on the abstract of the research paper. Full text available via ArXiv.