Revisiting cycles of pairing-friendly elliptic curves

A recent area of interest in cryptography is recursive composition of proof systems. One of the approaches to make recursive composition efficient involves cycles of pairing-friendly elliptic curves of prime order. However, known constructions have very low embedding degrees. This entails large parameter sizes, which makes the overall system inefficient. In this paper, we explore $2$-cycles composed of curves from families parameterized by polynomials, and show that such cycles do not exist unless a strong condition holds. As a consequence, we prove that no $2$-cycles can arise from the known families, except for those cycles already known. Additionally, we show some general properties about cycles, and provide a detailed computation on the density of pairing-friendly cycles among all cycles

DEFS - Data exchange with Free Sample Protocol

Distrust between data providers and data consumers is one of the main obstacles hampering digital-data commerce to take off. Data providers want to get paid for what they offer, while data consumers want to know exactly what are they paying for before actually paying for it. In this article, we present a protocol that overcomes this obstacle by building trust based on two main ideas. First, a probabilistic verification protocol, where some random samples of the real dataset are shown to buyers in order to allow them to make an assessment before committing any payment; and second a guaranteed, protected payment process, enforced with smart contracts on a public blockchain, that guarantees the payment of the data if and only if the data provided meets the agreed terms, and that refunds honest players otherwise.The architecture presented in this paper is supported and developed in the context of the i3-MARKET project [?]. The i3-MARKET project is an active European H2020 project focused on developing solutions for building an European data market economy by enhancing current marketplace platforms with innovative technologies (call H2020-ICT-2019-2 with grant agreement number 871754). This work is also supported by the TCO-RISEBLOCK (PID2019-110224RBI00), MINECO/FEDER funded project ARPASAT TEC2015-70197-R and by the Generalitat de Catalunya grant 2014-SGR-1504.Postprint (author's final draft

A protocol for data exchange with free samples using smart contracts

Distrust between data providers and data consumers is one of the main obstacles hampering digitaldata commerce to take off. Data providers want to get paid for what they offer, while data consumers want to know exactly what are they paying for before actually paying for it. In this paper, we summarize a protocol that overcomes this obstacle by building trust based on two main ideas. First, a probabilistic verification protocol, where some random samples of the real dataset are shown to buyers in order to allow them to make an assessment before committing any payment; and second a guaranteed, protected payment process, enforced with smart contracts on a public blockchain, that guarantees the payment of the data if and only if the data provided meets the agreed terms, and that refunds honest players otherwise.This research has been funded by i3Market (H2020- ICT-2019-2 grant number 871754). This work is also supported by the TCO-RISEBLOCK (PID2019-110224RBI00), ARPASAT (TEC2015-70197-R), Project RTI2018- 102112-B-I00 (AEI/FEDER,UE) and by the Generalitat de Catalunya grant 2014-SGR-1504Postprint (author's final draft

PlonKup: Reconciling PlonK with plookup

In 2019, Gabizon, Williamson, and Ciobotaru introduced PlonK – a fast and flexible ZK-SNARK with an updatable and universal structured reference string. PlonK uses a grand product argument to check permutations of wire values, and exploits convenient interactions between multiplicative subgroups and Lagrange bases. The following year, Gabizon and Williamson used similar techniques to develop plookup – a ZK-SNARK that can verify that each element from a list of queries can be found in a public lookup table. In this paper, we present PlonKup, a fully succinct ZK-SNARK that integrates the ideas from plookup into PlonK in an efficient way

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

New privacy practices for blockchain software

In this article, we present the software tools we have implemented to bring complex privacy technologies closer to developers and to facilitate the implementation of privacyenabled blockchain applicationsThis research is supported by the Ethereum Foundation Ecosystem Support, privacy and security in blockchain (RISEBLOCK, Id: PID2019- 110224RB-I00), intelligent, interoperable, integrative and deployable open source MARKETplace with trusted and secure software tools for incentivizing the industry data economy (i3-MARKET, European Commission, H2020, Id: 871754), a software architecture for rate-control over integrated satellite-terrestrial networks (ARPASAT, Id: TEC2015-70197-R), Information Security Group (ISG, Id: 2014-SGR-1504), Photoreal REaltime Sentient ENTity (PRESENT, European Commission, H2020, Id: 856879), and Técnicas avanzadas de cadenas de bloques para la internet de las cosas (Id: RTI2018-102112-B-I00)

Twisted Edwards elliptic curves for zero-knowledge circuits

Circuit-based zero-knowledge proofs have arose as a solution to the implementation of privacy in blockchain applications, and to current scalability problems that blockchains suffer from. The most efficient circuit-based zero-knowledge proofs use a pairing-friendly elliptic curve to generate and validate proofs. In particular, the circuits are built connecting wires that carry elements from a large prime field, whose order is determined by the number of elements of the pairing-friendly elliptic curve. In this context, it is important to generate an inner curve using this field, because it allows to create circuits that can verify public-key cryptography primitives, such as digital signatures and encryption schemes. To this purpose, in this article, we present a deterministic algorithm for generating twisted Edwards elliptic curves defined over a given prime field. We also provide an algorithm for checking the resilience of this type of curve against most common security attacks. Additionally, we use our algorithms to generate Baby Jubjub, a curve that can be used to implement elliptic-curve cryptography in circuits that can be validated in the Ethereum blockchain.This research has been partially funded by the projects Project RTI2018-102112-B-100 (AEI/FEDER, UE), i3Market (H2020-ICT-2019-2 grant number 871754) and TCO-RISEBLOCK (PID2019- 110224RB-I00)

New privacy practices for blockchain software

© 2021 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The benefits of blockchain technologies for industrial applications are unquestionable. However, it is a considerable challenge to use a transparent system like blockchain and at the same time provide privacy to sensitive data. Privacy technologies permit conducting private transactions about sensitive data over transparent networks, but their inherent complexity has been overwhelming for many developers. Closing the gap between developers and privacy-preserving technologies would help to the full adoption of the privacy by design framework for blockchain software. To this end, in this paper we present the software tools we have implemented to bring complex privacy technologies closer to developers and facilitate the job of implementing privacy-enabled blockchain applications.This research is supported by the Ethereum Foundation Ecosystem Support [9], TCO-RISEBLOCK (PID2019-110224RB-I00), H2020-i3-MARKET, ARPASAT (TEC2015-70197-R), 2014-SGR-1504, RTI2018-102112-B-I00 (AEI/FEDER,UE) and H2020 PRESENT (856879).Peer ReviewedPostprint (published version

An architecture for easy onboarding and key life-cycle management in blockchain applications

© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.New manufacturing paradigms require a large number of business interactions between multiple cyber-physical systems with different owners. In this context, public distributed ledgers are disruptive because they make it possible to securely and publicly record proofs of agreements between parties that do not necessarily trust each other. Many industry leaders have already achieved significant business benefits using this technology, including greater transparency, improved traceability, enhanced security, increased transaction speed and costs reduction. While the benefits of blockchain technologies for industrial applications are unquestionable, these technologies have an inherent complexity that might be overwhelming for many users. To decrease entry barriers for industry users to distributed ledger technologies, it is necessary to have an easy user onboarding process and a simple key life-cycle management. In this paper, we propose an architecture that facilitates these processes and simplifies how users utilize decentralized applications without sacrificing on the expected security. To achieve this goal, our architecture uses a middleware that allows us to decouple the digital signatures required for paying blockchain fees from the ones required for authorization. This approach has the advantage that users are not forced to create wallets, buy cryptocurrency, or protect their private keys. For these reasons, our solution is a promising way of enabling a reasonable transition to the integration of distributed ledger technologies in industrial business processes.Postprint (author's final draft