Abstract:

Large scale cryptocurrencies require the participation of millions of participants and support economic activity of billions of dollars, which has led to new lines of work in binary Byzantine Agreement (BBA) and consensus. The new work aims to achieve communication-efficiency---given such a large n, not everyone can speak during the protocol. Several protocols have achieved consensus with communication-efficiency, even under an adaptive adversary, but they require additional strong assumptions---proof-of-work, memory-erasure, etc. All of these protocols use multicast: every honest replica multicasts messages to all other replicas. Under this model, we provide a new communication-efficient consensus protocol using Verifiable Delay Functions (VDFs) that is secure against adaptive adversaries and does not require the same strong assumptions present in other protocols.

Abstract

This work addresses the ongoing lack of legal clarity and inconsistent pronouncements regard- ing the regulatory status of cryptographic assets by introducing a novel series of classification approaches employing non-binary scoring systems. Novel taxonomies have been constructed based upon multi-level categorical and numerical discrimination methods following design science of information systems best practices. The aim is to provide greater explanatory insight with respect to the nuanced and complex ensemble of attributes which may be exhibited within this sui generis type of objects. The notions of Secu- rityness (S), Moneyness (M) and Commodityness (C) are proposed as candidate meta-characteristics for “TokenSpace”: a three-dimensional visual construction of subjective classification approaches towards a co- herent and customisable conceptual framework. TokenSpace can be used to make reasoned qualitative and / or quantitative comparisons of asset properties. TokenSpace has more in common with successful prior classification frameworks in other domains and greater development potential using axiomatic, empirical and qualitative approaches than the sorting, clustering, intuitive or na ̈ıve categorisation approaches pre- viously employed for cryptographic assets. TokenSpace provides a basis upon which real-time information feeds and predictive analytical tools may be developed in future.

Abstract:

We design, implement, and evaluate a zero knowledge succinct non-interactive argument (SNARG) for Rank-1 Constraint Satisfaction (R1CS), a widely-deployed NP language undergoing standardization. Our SNARG has a transparent setup, is plausibly post-quantum secure, and uses lightweight cryptography. A proof attesting to the satisfiability of n constraints has size 𝑂(log2𝑛)O(log2⁡n); it can be produced with 𝑂(𝑛log𝑛)O(nlog⁡n) field operations and verified with O(n). At 128 bits of security, proofs are less than 250kB250kB even for several million constraints, more than 10×10× shorter than prior SNARGs with similar features.

Abstract

This paper shows several connections between data structure problems and cryptography against preprocessing attacks. Our results span data structure upper bounds, cryptographic applications, and data structure lower bounds, as summarized next.