Multiparty fully homomorphic encryption (MFHE) schemes enable multiple parties to efficiently compute functions on their sensitive data while retaining confidentiality. However, existing MFHE schemes guarantee data confidentiality and the correctness of the computation result only against honest-but-curious adversaries. In this work, we provide the first practical construction that enables the verification of MFHE operations in zero-knowledge, protecting MFHE from malicious adversaries. Our solution relies on a combination of lattice-based commitment schemes and proof systems which we adapt to support both modern FHE schemes and their implementation optimizations. We implement our construction in PELTA. Our experimental evaluation shows that PELTA is one to two orders of magnitude faster than existing techniques in the literature.

Skip Graphs belong to the family of Distributed Hash Table (DHT) structures that are utilized as routing overlays in various peer-to-peer applications including blockchains, cloud storage, and social networks. In a Skip Graph overlay, any misbehavior of peers during the routing of a query compromises the system functionality. Guard is the first authenticated search mechanism for Skip Graphs, enables reliable search operation in a fully decentralized manner. In this demo paper, we present a proof-of-concept implementation of Guard on Skip Graph nodes as well as a deployment demo scenario.

Skip Graphs are Distributed Hash Table (DHT)based data structures that are immensely utilized as routing overlays in Peer-to-Peer (P2P) applications. In this demo paper, we present the software architecture of our open-source implementation of Skip Graph middleware in Java. We also present a demo scenario on configuration and constructing an overlay of Skip Graph processes in a fully decentralized manner. Our implementation is capable of hosting data objects at the Skip Graph processes and serving as a P2P data storage platform as well. Our middleware implementation provides an open-source platform to support Skip Graph-based applications on top of it.