Paper 2026/843
Efficient Fair Data Exchange without In-Circuit Public-Key Operations
Abstract
Fair data exchange (FDE) ties payment to recovery of data matching an agreed commitment. Code-based FDE offers near-plaintext communication, but the sampled-ElGamal baseline incurs costly in-circuit checks when low redundancy requires many samples. We replace auxiliary ElGamal ciphertexts with direct KZG authentication and external witness linking. This leaves only field arithmetic in the consistency circuit and permits a BLS12-381 instantiation with EVM precompile support for settlement-key verification. We prove correctness, soundness, and zero knowledge under an external KZG setup in the algebraic group and random oracle models. Our implementation reduces aggregate sender computation from \(179.6\) to \(2.75\) seconds (\(65.3\times\)) for a \(2\,\)MiB file at redundancy \(\beta\approx1.1\), relative to the sampled-ElGamal baseline. Bulk ciphertext remains about \(1.1\times\) the plaintext size. The corresponding EVM implementation reduces gas for successful seller settlement by a factor of \(31.3\).
Metadata
- Available format(s)
-
PDF
- Category
- Cryptographic protocols
- Publication info
- Preprint.
- Keywords
- Fair data exchangeVerifiable encryptionzkSNARKsReed-Solomon codesPolynomial commitments
- Contact author(s)
-
dongwook1214 @ hanyang ac kr
jihyek @ kookmin ac kr
hoh @ hanyang ac kr - History
- 2026-09-24: last of 6 revisions
- 2026-04-30: received
- See all versions
- Short URL
- https://ia.cr/2026/843
- License
-
CC0
BibTeX
@misc{cryptoeprint:2026/843,
author = {Dongwook Kim and Jihye Kim and Hyunok Oh},
title = {Efficient Fair Data Exchange without In-Circuit Public-Key Operations},
howpublished = {Cryptology {ePrint} Archive, Paper 2026/843},
year = {2026},
url = {https://eprint.iacr.org/2026/843}
}
