Verifiable secret sharing

About: Verifiable secret sharing is a research topic. Over the lifetime, 4241 publications have been published within this topic receiving 99569 citations.

Weak zero-knowledge beyond the black-box barrier

Abstract: The round complexity of zero-knowledge protocols is a long-standing open question, yet to be settled under standard assumptions. So far, the question has appeared equally challenging for relaxations such as weak zero-knowledge and witness hiding. Protocols satisfying these relaxed notions under standard assumptions have at least four messages, just like full-fledged zero-knowledge. The difficulty in improving round complexity stems from a fundamental barrier: none of these notions can be achieved in three messages via reductions (or simulators) that treat the verifier as a black box. We introduce a new non-black-box technique and use it to obtain the first protocols that cross this barrier under standard assumptions. We obtain weak zero-knowledge for in two messages, assuming the existence of quasipolynomially-secure fully-homomorphic encryption and other standard primitives (known based on the quasipolynomial hardness of Learning with Errors), and subexponentially-secure one-way functions. We also obtain weak zero-knowledge for in three messages under standard polynomial assumptions (following for example from fully homomorphic encryption and factoring). We also give, under polynomial assumptions, a two-message witness-hiding protocol for any language ∈ that has a witness encryption scheme. This protocol is publicly verifiable. Our technique is based on a new homomorphic trapdoor paradigm, which can be seen as a non-black-box analog of the classic Feige-Lapidot-Shamir trapdoor paradigm.

Belenios: a simple private and verifiable electronic voting system

Abstract: We present the electronic voting protocol Belenios together with its associated voting platform. Belenios guarantees vote privacy and full verifiability, even against a compromised voting server. While the core of the voting protocol was already described and formally proved secure, we detail here the complete voting system from the setup to the tally and the recovery procedures.

Lattice-Based zk-SNARKs from Square Span Programs

Abstract: Zero-knowledge SNARKs (zk-SNARKs) are non-interactive proof systems with short and efficiently verifiable proofs They elegantly resolve the juxtaposition of individual privacy and public trust, by providing an efficient way of demonstrating knowledge of secret information without actually revealing it To this day, zk-SNARKs are being used for delegating computation, electronic cryptocurrencies, and anonymous credentials However, all current SNARKs implementations rely on pre-quantum assumptions and, for this reason, are not expected to withstand cryptanalitic efforts over the next few decades In this work, we introduce the first designated-verifier zk-SNARK based on lattice assumptions, which are believed to be post-quantum secure We provide a generalization in the spirit of Gennaro et al (Eurocrypt'13) to the SNARK of Danezis et al (Asiacrypt'14) that is based on Square Span Programs (SSPs) and relies on weaker computational assumptions We focus on designated-verifier proofs and propose a protocol in which a proof consists of just 5 LWE encodings We provide a concrete choice of parameters as well as extensive benchmarks on a C implementation, showing that our construction is practically instantiable