Paper 2019/250

Function-Dependent Commitments from Homomorphic Authenticators

Lucas Schabhüser, Denis Butin, and Johannes Buchmann

Abstract

In cloud computing, delegated computing raises the security issue of guaranteeing data authenticity during a remote computation. In this context, the recently introduced function-dependent commitments (FDCs) are the only approach providing both fast correctness verification, information-theoretic input-output privacy, and strong unforgeability. Homomorphic authenticators--- the established approach to this problem ---do not provide information-theoretic privacy and always reveal the computation's result upon verification, thus violating output privacy. Since many homomorphic authenticator schemes already exist, we investigate the relation between them and FDCs to clarify how existing schemes can be supplemented with information-theoretic output privacy. Specifically, we present a generic transformation turning any structure-preserving homomorphic authenticator scheme into an FDC scheme. This facilitates the design of multi-party computation schemes with full information-theoretic privacy. We also introduce a new structure-preserving, linearly homomorphic authenticator scheme suitable for our transformation. It is the first both context hiding and structure-preserving homomorphic authenticator scheme. Our scheme is also the first structure-preserving homomorphic authenticator scheme to achieve efficient verification.

Metadata
Available format(s)
PDF
Category
Public-key cryptography
Publication info
Preprint. MINOR revision.
Keywords
Homomorphic AuthenticatorsCommitmentsDelegated Computation
Contact author(s)
lschabhueser @ cdc tu-darmstadt de
dbutin @ cdc tu-darmstadt de
History
2019-02-28: received
Short URL
https://ia.cr/2019/250
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2019/250,
      author = {Lucas Schabhüser and Denis Butin and Johannes Buchmann},
      title = {Function-Dependent Commitments from Homomorphic Authenticators},
      howpublished = {Cryptology {ePrint} Archive, Paper 2019/250},
      year = {2019},
      url = {https://eprint.iacr.org/2019/250}
}
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