![]() Gilad Asharov, Yehuda Lindell, Thomas Schneider, and Michael Zohner.More Efficient Oblivious Transfer and Extensions for Faster Secure Computation. In EUROCRYPT, volume 9056 of LNCS, pages 430-454. Albrecht, Christian Rechberger, Thomas Schneider, Tyge Tiessen, and Michael Zohner. As a proof-of-concept, we integrate our protocols in the client application of the open-source messenger Signal. The online phase of our fastest protocol takes only 2.92s measured on a real WiFi connection (6.53s on LTE) to check 1,024 client contacts against a large-scale database with 2 28 entries. Compared to previous smartphone implementations, this yields a performance improvement of factor 1,000x for circuit evaluations. Furthermore, we implement both protocols with security against malicious clients in C/C++ and utilize the ARM Cryptography Extensions available in most recent smartphones. In a protocol performing oblivious PRF evaluations via garbled circuits, we replace AES as the evaluated PRF with a variant of LowMC (Albrecht et al., EUROCRYPT'15) for which we determine optimal parameters, thereby reducing the communication by factor 8.2x. ![]() (PoPETS'17) while also allowing for malicious clients.Ĭoncretely, we present novel precomputation techniques for correlated oblivious transfers (reducing the online communication by factor 2x), Cuckoo filter compression (with a compression ratio of∼70%), as well as 4:3x smaller Cuckoo filter updates. In our work, we remove most obstacles for large-scale global deployment by significantly improving two promising protocols by Kiss et al. This is due to their high computation and/or communication complexity as well as lacking optimization for mobile devices. Unfortunately, even in a weak security model where clients are assumed to follow the protocol honestly, previous protocols and implementations turned out to be far from practical when used at scale. The most promising approaches addressing this problem revolve around private set intersection (PSI) protocols. As we find, even messengers with privacy in mind currently do not deploy proper mechanisms to perform contact discovery privately. However, such a procedure poses significant privacy risks and legal challenges. This allows the service provider to determine which of the user's contacts are registered to the messaging service. Mobile messengers like WhatsApp perform contact discovery by uploading the user's entire address book to the service provider.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |