Securing Abe’s mix-net against malicious verifiers via witness indistinguishability

Elette Boyle*, Saleet Klein, Alon Rosen, Gil Segev

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

3 Scopus citations

Abstract

We show that the simple and appealing unconditionally sound mix-net due to Abe (Asiacrypt’99) can be augmented to further guarantee anonymity against malicious verifiers. As our main contribution, we demonstrate how anonymity can be attained, even if most sub-protocols of a mix-net are merely witness indistinguishable (WI). We instantiate our framework with two variants of Abe’s mix-net. In the first variant, ElGamal ciphertexts are replaced by an alternative, yet comparably efficient, “lossy” encryption scheme. In the second variant, new “dummy” vote ciphertexts are injected prior to the mixing process, and then removed. Our techniques center on new methods to introduce additional witnesses to the sub-protocols within the proof of security. This, in turn, enables us to leverage the WI guarantees against malicious verifiers. In our first instantiation, these witnesses follow somewhat naturally from the lossiness of the encryption scheme, whereas in our second instantiation they follow from leveraging combinatorial properties of the Beneš-network. These approaches may be of independent interest. Finally, we demonstrate cases in Abe’s original mix-net (without modification) where only one witness exists, such that if the WI proof leaks information on the (single) witness in these cases, then the system will not be anonymous against malicious verifiers.

Original languageAmerican English
Title of host publicationSecurity and Cryptography for Networks - 11th International Conference, SCN 2018, Proceedings
EditorsDario Catalano, Roberto De Prisco
PublisherSpringer Verlag
Pages274-291
Number of pages18
ISBN (Print)9783319981123
DOIs
StatePublished - 2018
Event11th International Conference on Security and Cryptography for Networks, SCN 2018 - Amalfi, Italy
Duration: 5 Sep 20187 Sep 2018

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume11035 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349

Conference

Conference11th International Conference on Security and Cryptography for Networks, SCN 2018
Country/TerritoryItaly
CityAmalfi
Period5/09/187/09/18

Bibliographical note

Publisher Copyright:
© 2018, Springer Nature Switzerland AG.

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