Cryptology ePrint Archive: Report 2018/275

Lattice-Based zk-SNARKs from Square Span Programs

Rosario Gennaro and Michele Minelli and Anca Nitulescu and Michele Orrų

Abstract: Zero-knowledge SNARKs (zk-SNARKs) are non-interactive proof systems with short (i.e., independent of the size of the witness) 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 widely deployed all over the planet and are used to keep alive a system worth billion of euros, namely the cryptocurrency Zcash. However, all current SNARKs implementations rely on so-called pre-quantum assumptions and, for this reason, are not expected to withstand cryptanalitic efforts over the next few decades.

In this work, we introduce a new zk-SNARK that can be instantiated from lattice-based assumptions, and which is thus 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 (SSP) 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, showing that our construction is practically instantiable.

Category / Keywords: public-key cryptography / SNARK, zero-knowledge, post-quantum, YOLO

Date: received 16 Mar 2018, last revised 15 Oct 2018

Contact author: michele orru at ens fr

Available format(s): PDF | BibTeX Citation

Version: 20181015:202218 (All versions of this report)

Short URL: ia.cr/2018/275


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