Blockchain Papers

Dmitriy V. Vinnik

The article discusses the V.V. Tselishchev’s original and unique systematic study of the specific and extremely complicated problems of Gödel results regarding the question of artificial intelligence essence. Tselishchev argues that the reflexive property should be considered not only as an advantage of human reasoning, but also as an objective internal limitation that appears in case of adding Gödel sentence to a theory to build a new theory. The article analyzes so-called mentalistic Gödel’s argument for fundamental superiority of human intelligence over machine one and the non-algorithmic nature of natural thinking. The discussion about the Gödel argument is not entirely speculative, but contains new knowledge. An example of such knowledge are the results of R. Smullyan levels of computers “awareness,” which are may be interpreted in a psychophysical sense. The concept of “zero level of intelligence” is proposed for such a reflexive property as “awareness of selfconsciousness.” Reflexive ranks below the awareness of self-consciousness can be considered negative levels of thinking in the sense that the intelligence, being reduced to them, significantly loses its completeness. Even self-consciousness turns out to be a negative level of thinking, since, according to Smullyan, the subject of self-consciousness is unaware of the type of thought to which he belongs. A thought experiment is proposed that allows us to establish the distribution of the properties of Smullyan stability and normality and to answer the question “Does an intuitive belief in the truth of a formal proof affect the truth of a proposition being proved?” According to intuitionism, the most unpleasant epistemic property is instability: beliefs that are not based on deep intuitions have no value. According to the constructivist philosophy of mathematics, instability is a less negative property than abnormality: the fact that high-ranking beliefs cannot be immersed to the very foundations is not significant because violation of truth due to lowering the rank of reflection is not critical.

M. Mohideen AbdulKader, S. Ganesh Kumar

No abstract is available for this record.

А. В. Анисимов, Andrey Novokshonov

We describe a fast three-round mutual authentication protocol for parties A and B belonging to the same coalition group. Parties A and B keep their own independent long-term private keys that are used in the process of authentication and can be used for other purposes. The scheme assumes an initial setup with a trusted third party T. This party initiates another secret information that includes factors of a large RSA modulus. For authentication, both parties must demonstrate each other the knowledge of their private keys without revealing them and the ability to factorize a large RSA modulus. Thus, the protocol based on the suggested scheme provides reciprocal authentication. The scheme possesses all desirable properties of an interactive proof, i.e., completeness, soundness, and zero-knowledge. The security of the protocol relies on assumptions of difficulty of the RSA factorization and existence of a cryptographic hash function.

Slim Bettaieb, Loïc Bidoux, Olivier Blazy, Philippe Gaborit

Designing code-based signatures is both an important and challenging problem. A standard way to tackle it consists to use the Fiat-Shamir heuristic along with an identification scheme that is required to be zero-knowledge. The authors of [1] have highlighted an issue within the zero-knowledge proof of the Veron identification scheme [2]. It turns out that the zero-knowledge proof of the AGS protocol [3] is impacted in a similar way. In this paper, we present a masking technique that solves the aforementioned issue without inducing any performance penalty. We introduce the Masked Veron and Masked AGS protocols that both leverage this masking technique and provide their zero-knowledge proofs. In addition, we present a new technique improving the performances of signatures built from code-based identification schemes subject to the attack described in [4]. The Masked Veron and Masked AGS protocols feature all the existing performance improvements from the literature.

和昕 袁, 百祥 刘, 海斌 阚, 泽宁 陈

A flexible and effective identity system scheme has always been one of the core needs of the information age. Traditional centralized public key infrastructure has a number of flaws, and the present distributed public key infrastructure based on blockchain has a number of issues with performance, resilience, non-repudiation, identity flexibility, and other factors. This paper innovatively combines blockchain with decentralized undeniable attribute-based signatures and proposes a novel distributed public key infrastructure, which uses threshold algorithms and attribute-based signatures for fine-grained management of identities; the paper also introduces non-interactive zero-knowledge proof to make the certificate undeniable and uses the blockchain consensus mechanism to synchronize the certificate library to achieve distributed identity authentication. Through experimental modeling and analysis combined with specific scenarios' actual landing demand, this article indicates that the solution is adequate in terms of security and usability.

Ulrich Haböck, Alberto Garoffolo, Daniele Di Benedetto

This document describes Darlin, a succinct zero-knowledge argument of knowledge based on the Marlin SNARK (Chiesa et al., Eurocrypt 2020) and the `dlog' polynomial commitment scheme from Bootle et al. EUROCRYPT 2016. Darlin addresses recursive proofs by integrating the amortization technique from Halo (IACR eprint 2019/099) for the non-succinct parts of the dlog verifier, and we adapt their strategy for bivariate circuit encoding polynomials to aggregate Marlin's inner sumchecks across the nodes the recursive scheme. We estimate the performance impact of inner sumcheck aggregation by about 30% in a tree-like scheme of in-degree 2, and beyond when applied to linear recursion.

Lukas Burkhalter, Hidde Lycklama, Alexander Viand, Nicolas Küchler · 5 authors

Federated Learning is an emerging decentralized machine learning paradigm that allows a large number of clients to train a joint model without the need to share their private data. Participants instead only share ephemeral updates necessary to train the model. To ensure the confidentiality of the client updates, Federated Learning systems employ secure aggregation; clients encrypt their gradient updates, and only the aggregated model is revealed to the server. Achieving this level of data protection, however, presents new challenges to the robustness of Federated Learning, i.e., the ability to tolerate failures and attacks. Unfortunately, in this setting, a malicious client can now easily exert influence on the model behavior without being detected. As Federated Learning is being deployed in practice in a range of sensitive applications, its robustness is growing in importance. In this paper, we take a step towards understanding and improving the robustness of secure Federated Learning. We start this paper with a systematic study that evaluates and analyzes existing attack vectors and discusses potential defenses and assesses their effectiveness. We then present RoFL, a secure Federated Learning system that improves robustness against malicious clients through input checks on the encrypted model updates. RoFL extends Federated Learning's secure aggregation protocol to allow expressing a variety of properties and constraints on model updates using zero-knowledge proofs. To enable RoFL to scale to typical Federated Learning settings, we introduce several ML and cryptographic optimizations specific to Federated Learning. We implement and evaluate a prototype of RoFL and show that realistic ML models can be trained in a reasonable time while improving robustness.

Yu Yu, Xiang Xie

This perspectives article surveys the most promising privacy-preserving cryptographic technologies including secure multiparty computation, zero-knowledge proofs and fully homomorphic encryption, and their various real-world applications.

Joe Moran

You are a humanities scholar and you are worried. You fear that the humanities are increasingly seen as irrelevant, unnecessary and quaint. You may even have begun to internalise this view. In the face of intractable contemporary problems – global pandemics, economic crisis and a climate emergency – how can your work seem like anything other than an indulgence? You hear the constant, ambient noise of public and political hostility aimed at what you do. In January 2020 the prime minister’s chief adviser, Dominic Cummings (a humanities graduate, like the prime minister), wrote a long blog post calling for ‘weirdos and misfits with odd skills’ to apply for new jobs at No. 10 Downing Street. He made it clear that he was looking for data scientists, software developers, economists and policy experts, not ‘Oxbridge English graduates who chat about Lacan at dinner parties with TV producers’.11 Dominic Cummings, ‘Two Hands are a Lot’, at https://dominiccummings.com/2020/01/02/two-hands-are-a-lot-were-hiring-data-scientists-project-managers-policy-experts-assorted-weirdos/ (2 January 2020, accessed 1 May 2020). Later that month the University of Sunderland announced that it would be shutting down its history, languages and politics courses, and replacing them with more ‘career-focused and professions-facing’ alternatives. In February the University of Portsmouth revealed plans to make more than half its English department redundant, citing the declining number of applications in this subject. In June 2020 the Australian education minister, Dan Tehan, announced that his government wanted to double student fees for courses in the arts and humanities while cutting them for nursing, agriculture, maths, science and information technology. The aim was ‘to power our post-Covid economic recovery’ by sending out a ‘price signal’ to encourage people to study in areas of growth.22 ‘Job-Ready Graduates to Power Economic Recovery’, at https://ministers.dese.gov.au/tehan/job-ready-graduates-power-economic-recovery (accessed 25 June 2020). The UK government made similar noises about pricing mechanisms and ending funding for humanities courses considered poor value for money. In August 2020 the A-level marking controversy, and the subsequent scramble for university places, inspired much media comment about the glut of worthless degrees in second-rate institutions, again focusing on humanities subjects. ‘The universities are churning out far more graduates than our society requires,’ wrote one columnist, ‘particularly in subjects like the creative arts and communications that have little relevance to the workplace.’33 Leo McKinstry, ‘We Must End This Absurd Obsession to Gain a Degree’, Daily Express, 20 August 2020. See also Emma Duncan, ‘Many Degrees are a Waste of Time and Money’, The Times, 15 August 2020. The current right-wing critique of universities as indoctrination camps where students are ‘factory-farmed to have the same boring and malevolent views’ has focused its ire on humanities subjects.44 Douglas Murray, ‘Our Universities Have Become Indoctrination Camps’, Sunday Telegraph, 16 August 2020. No wonder that, after reading these signs and portents, you feel beleaguered and dispirited. You crave some encouragement and cheer, and a reminder of why you first fell in love with the texts you spend your life examining. You need a story that will convince others, and yourself, of the worth of your work. You may take heart from the knowledge that, while this particular crisis is new, the issues are old. ‘The humanities are at the cross-roads, at a crisis in their existence,’ the historian J.H. Plumb wrote in the introduction to his Pelican edited collection, Crisis in the Humanities, in 1964. ‘They must either change the image that they present, adapt themselves to the needs of a society dominated by science and technology, or retreat into social triviality.’55 J.H. Plumb, ‘Introduction’, in Plumb (ed.), Crisis in the Humanities (Harmondsworth: Penguin, 1964), 8. This permanent crisis of identity and legitimacy in the humanities arises partly out of definitional fuzziness. The humanities have often been defined against something else – and against which they can be found wanting. In the Renaissance the studia humanitatis were the secular subjects, such as rhetoric, philosophy and ancient Greek and Latin, and thus the opposite of the highest form of study, divinity. Then, from the mid-nineteenth century onwards, the humanities began to be defined in opposition to the physical sciences. At first they were the senior partner. Charles Darwin’s frequent biblical and literary allusions, and the elegance of his own writing, show how influenced he was by the humanities. But in the century after Darwin’s death, the sciences grew in confidence and prestige. The main character in Saul Bellow’s 1987 novel More Die of Heartbreak, a Russian literature specialist, feels as if he has been confined to ‘the nursery games of humankind, which had to be left behind when the age of science began’. The humanities, he thinks gloomily, ‘would be called upon to choose a wallpaper for the crypt, as the end drew near’.66 Saul Bellow, More Die of Heartbreak (London: Penguin, [1987] 2004), 239. More recently, the humanities have come to seem like the poor relation of STEM. STEM is an acronym now routinely repurposed as both noun and adjective (STEM skills, STEM subjects, STEM jobs). We forget how new the acronym is and sometimes even what it stands for (science, technology, engineering and mathematics). The OED gives its earliest mention in print as 1968 but notes that it is ‘rare before 21st cent.’ In fact it began to be used widely in the US in the late 1990s, in debates about skills shortages in high-tech jobs and access to work visas for immigrants skilled in these fields. In Britain it has become an article of faith among policy makers that investing in STEM is vital to economic growth, especially in areas like life sciences, pharmaceuticals, computer coding and electronic engineering. 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Eranga Bandara, Xueping Liang, Peter Foytik, Sachin Shetty · 5 authors

Most of the existing identity systems are built on top of centralized storage systems. Storing identity data on these types of centralized storage platforms(e.g cloud storage, central servers) becomes a major privacy concern since various types of attacks and data breaches can happen. With this research, we are proposing blockchain and self-sovereign identity based digital identity (KYC - Know Your Customer) platform “Casper” to address the issues on centralized identity systems. “Casper ” is an Android/iOS based mobile identity wallet application that combines the integration of blockchain and a self-sovereign identity-based approach. Unlike centralized identity systems, the actual identities of the customer/users are stored in the customers’ mobile wallet application. The proof of these identities is stored in the blockchain-based decentralized storage as a self-sovereign identity proof. Casper platforms’ Self-Sovereign Identity(SSI)-based system provides a Zero Knowledge Proof(ZKP) mechanism to verify the identity information. Casper platform can be adopted in various domains such as healthcare, banking, government organization etc. As a use case, we have discussed building a digital identity wallet for banking customers with the Casper platform. Casper provides a secure, decentralized and ZKP verifiable identity by using blockchain and SSI based approach. It addresses the common issues in centralized/cloud-based identity systems platforms such as the lack of data immutability, lack of traceability, centralized control etc.

Xiaoqiang Sun, F. Richard Yu, Peng Zhang, Zhiwei Sun · 6 authors

Blockchain, which is usually regarded as a public, decentralized and distributed ledger, has attracted significant attention recently. In the environment of blockchain, all historical transaction data are recorded and stored. However, because blockchain is open and transparent, a malicious user may illegally access private transaction data, including transaction amount, account address, and account balance. As a cryptographic technique, zero-knowledge proof (ZKP) can be used to verify whether the prover has enough transaction amount in the environment of blockchain without leaking any private transaction data. This article provides a comprehensive survey on ZKP in the environment of blockchain with the aim of highlighting security problems and challenges. It first discusses the framework, models and applications of ZKP. Next, it provides an introduction of blockchain, and proposes a framework of ZKP in the environment of blockchain. Then, it highlights the current state of ZKP in the environment of blockchain. Finally, it identifies some potential problems and future research directions.

Elena Martínez

Digital voting systems offer significant benefits in terms of accessibility and efficiency for electoral processes. However, ensuring trust in these systems remains a critical challenge due to concerns around vote privacy, integrity, and verifiability. Cryptographic protocols have become essential tools to address these challenges by providing mathematically grounded guarantees of security and transparency. This article examines prominent cryptographic approaches—such as homomorphic encryption, mix-nets, zero-knowledge proofs, and blockchain technology—applied in digital voting. Their contributions toward enhancing voter privacy, election verifiability, and resistance to coercion are analyzed. The paper concludes with discussion on practical deployment challenges and future research directions.

Dr. Liam O'Connor

management by introducing decentralized, immutable, and transparent ledgers. At the heart of blockchain's robustness lies its cryptographic foundation, which ensures data integrity, authenticity, and security. This paper delves into the cryptographic techniques employed in blockchain systems to enhance data integrity. We explore fundamental mechanisms such as hash functions, digital signatures, and Merkle trees, as well as advanced methods like zero-knowledge proofs and homomorphic encryption. By analyzing these techniques, we aim to provide a comprehensive understanding of how cryptography fortifies blockchain against data tampering and unauthorized access.

Yuqi Bai, Lei Luo

Intuitively there is a drastic distinction between the pure decentralized block-chain systems like Defis and those that only utilize block-chain as an enhancing technology but remain centralized with real-world business model and conventional technologies like database, application server, etc. Our study explores extensively this distinction from a methodological point of view, classifies them into blockchain-complete and blockchain-partial, analyzes key features of the two types, and reveals the root cause of this distinction. We analyze the function or, in more strong words, the "ultimate purpose" of blockchain in the blockchain-partial systems, and present a conceptual model we named proof-chain that quite satisfactorily represented the general paradigm of blockchain in blockchain-partial systems. A universal tension between strength of proof-chain and privacy is then revealed and the zero-knowledge based proof-chain takes shape. Several case studies demonstrate the explaining power of our proof-chain methodology. We then apply proof-chain methodology to the analysis of the ecosystem of a collaborating group of blockchain-partial systems, representing the paradigm of public and private data domain whose border the proof-chain crosses. Finally, some derived guidelines from this methodology speak usefulness of our methodology.

Chao Li, Hui Yang, Bowen Bao, Zhengjie Sun · 6 authors

With the development of new generation information technology, the feasibility of smart city has been significantly improved, and a large number of smart city technologies have been proposed. In this context, a more feasible device access technology is of great significance to ensure the normal operation of smart city network services. Therefore, this paper proposes a secure blockchain device access scheme based on elliptic curve digital signature algorithm and zero knowledge proof algorithm.

Vijay Kumar Yadav, Rakesh Kumar Yadav, Shekhar Verma, S. Venkatesan

No abstract is available for this record.

Suthee Ruangwises

Nonogram is a pencil puzzle consisting of a rectangular white grid where the player has to paint some cells black according to given constraints. In 2010, Chien and Hon constructed a physical card-based zero-knowledge proof protocol for Nonogram, which enables a prover to physically show that he/she knows a solution of the puzzle without revealing it. However, their protocol requires special tools such as scratch-off cards and a sealing machine, making it impractical to implement in real world. The protocol also has a nonzero soundness error. In this paper, we develop a more practical card-based protocol for Nonogram with perfect soundness that uses only regular paper cards. We also show how to modify our protocol to make it support Nonogram Color, a generalization of Nonogram where the player has to paint the cells with multiple colors.

Sam Arman, Michael E. Hopkins, Simon McKean

In the United Kingdom, at the outbreak of the COVID-19 pandemic in March 2020, the national health service (NHS) took the unprecedented step of restructuring all of its services and workforce to cope with the expected influx of infected patients.1 Following a UK-wide lockdown and implementation of strict government guidelines, rates of COVID-19 infection reduced significantly and there was hope of a return to normal practice. However, the risks of exposure to the Sars-Cov2 virus to patients and healthcare staff remained. These risks were acutely felt amongst otolaryngologists due to the prevalence of the virus in the nose and throat in both symptomatic and asymptomatic patients.2 A significant number of extra measures and precautions were introduced to mitigate the potential spread of the virus amongst patients and healthcare staff during surgery. This was predicted to reduce the efficiency of surgical lists and limit the ability of departments to clear the backlog of patients awaiting surgery.3 The aim of this study was to investigate whether elective otolaryngology surgical services could return to pre-pandemic levels in an area where cases of COVID-19 infection were expected to, and indeed did, remain far below national rates. Retrospective and prospective data were collected for all fixed-term otolaryngology consultants at a single rural hospital during the period of 1 August-28 February for 2019/20 and 2020/21. Data recorded included number of theatre lists, number of planned (PLO) and performed operations (PFO), number of cancellations and reasons for cancellation. Data were also collected regarding the number of COVID-19 infections per week during 2020/21 at local and national levels. Statistical analysis was performed using SPSS statistical software and Chi-squared testing was used to compare categorical data. Our hospital trust covers a population of approximately 235 000 people with a population density of 8 people/Km2. The department normally performs approximately 1500 operations per year. Over the 2-year period, there were three substantive consultants performing surgery in the following sub-specialties: Otology, Rhinology, General ENT, General Paediatric ENT, Paediatric airway and Thyroid and Parathyroid surgery. The department also provides facial plastics services for the removal of all benign and malignant skin lesions from the head and neck under local anaesthetic. All surgical lists were planned and booked in advance by the operating consultant. At the beginning of August 2020, all ENT elective surgery was allowed to restart. New hospital protocols were introduced for all elective procedures under general anaesthetic (GA). These included patient shielding for a minimum of 2 weeks prior to surgery, a negative COVID-19 PCR test, mandatory FFP3 masks for all aerosol-generating procedures (AGPs) and fallow time following extubation. Our primary objective was to see whether normal ENT elective services could restart to pre-pandemic levels; this was interrupted by a surge in COVID-19 infections in December 2020 as all non-urgent surgery was cancelled. We therefore analysed the period 1 August-30 November (interwave recovery [IR]) and the period 1 December-28 February (second wave [SW]) with the previous year. There were zero cases of COVID-19 infection reported locally or nationally in August-February 2019/20. In 2020/21, there were 2949 cases of COVID-19 infection in our local authority area.4 This represents 0.07% of the 3 868 809 cases reported in the United Kingdom over the same period.5 The trend in the 7-day positive rate during this period at local and national levels is demonstrated in the graph (Figure 1). From 1 August 2019 to 28 February 2020, there were 123 planned theatre sessions compared to 111 in 2020/21 with the number of operations planned dropping from 4.5 to 4.1 per session. The total numbers of PLO, PFO and local anaesthetic skin procedures (LASP) are demonstrated in Table 1. In the year prior to COVID-19, 81% of PLO were performed and this was 9% higher than the second year, and this falls to a 5% decrease during the IR period. Overall, there was a 31.2% reduction in the number of PFO, and again, this falls in the IR to a 4.1% (144 vs. 138) decrease year on year. However, there were 1.8 operations performed per session during the IR in 2020/21 compared to 2.2 in 2019/20. There was a significant increase in the number of local anaesthetic skin procedures (LASP) in 2020/21 (p ≤ .00001) and this accounted for 27% of PFO in the IR compared to 6% the previous year. If we exclude LASP, there was a 26.1% decrease in the number of GA procedures performed between August and November year on year. There was a significant increase in the number of cancelled operations in 2020/21 compared to 2019/20 (p = .011); however, during August-November, there was no significant increase (p = .259). In 2019/20, 19% of PLO were cancelled compared to 28.3% in 2020/21. This percentage drops when analysing the IR (22%) to the same period in 2019/20 (17%). Overall, this represents a 15.5% increase in the number of cancellations and equates to a cancellation every 1.8 operational sessions; however, during the IR, this relates to a cancellation every 2.0 operational sessions. The reasons for cancelled operations are categorised and are shown in Figure 2. Our study shows that there has been a change in ENT elective surgical provision at our hospital since its re-introduction. It is unclear why fewer procedures were planned per list in 2020/21, but may possibly represent the expected delays caused by changes in standard operating procedures in response to the pandemic. These changes have been seen globally with the introduction of donning and doffing of personal protective equipment (PPE), the adaptation of theatres to protect essential apparatus from contamination and the refinement of surgical techniques to reduce the risk of transmission.6 The 31.2% reduction in PFO during 2020/21 can be mainly attributed to the second wave and the cancellation of all non-urgent surgery from the end of December 2020. During the IR period, there was a 4.1% decrease in PFO; however, on a per-session basis, this equates to an 18.1% reduction. This suggests that during periods of low community COVID-19 transmission, elective services are still unable to return to pre-pandemic levels. The reasons for this are likely multifactorial; however, the impact of wearing PPE during surgery cannot be underestimated, as it is known to affect surgical performance and non-technical skills.7 The return of near-normal operating surgical volume during the IR period may be explained by the significant increase in the number of LASP, as this accounted for 27% of all PFO. This significant increase (p ≤ .00001) is important as without LASP, the number of PFO would likely have dropped further, as LASP were not required to isolate pre-operatively or undergo covid-19 PCR testing as were not deemed AGPs. Consequently, last-minute vacancies left by cancellations could be filled at short notice. We found a significant increase in the number of operations cancelled in 2020/21 (p = .011). This was expected with a surge of COVID-19 during the winter months, as there was no significant increase in cancellations seen between August and November. We can therefore assume that during periods of low community transmission, hospital capacity is not affected and patients are willing to undergo surgery despite the extra safety and shielding requirements. Despite low numbers of community infections, necessary safety protocols have reduced the efficiency of surgical lists and their ability to adapt to change. The current NHS elective waiting list currently stands at over 4.5 million patients8 and previous studies have estimated that clearing a backlog of cases created by the pandemic may take 84 weeks, but this assumes activity returning at 110% of pre-pandemic levels.9 Our study suggests that this level of activity would be difficult to attain in otolaryngology and therefore we would expect clearance of waiting lists to take significantly longer. We suggest extensive triaging of patients on long waiting lists to ensure that procedures are still clinically indicated, as it is likely that in some cases, such as otitis media with effusion, criteria for intervention may no longer be met. However, we recognise that sufficient time will need to be provided to clinicians in order to facilitate this effectively. Surgical trainees across all specialties have been adversely affected by the pandemic with a significant reduction in operative experience and a greater than 50% reduction in logbook numbers.10 This has resulted in GMC-approved curriculum derogations by the joint committee on surgical training (JCST) to enable the progression of trainees at all levels.11 Our study has demonstrated that a rapid return to pre-pandemic activity is unlikely in the near-term even as rates of COVID-19 infection fall following a successful vaccination programme. The challenges trainees have faced in gaining sufficient operative experience will likely continue, although improve from present. This is important to acknowledge, as it will have implications for trainees attaining Certification of Completion of Training (CCT) this year and in the future. The study has its limitations. A lower-than-average number of COVID-19 cases cannot be assumed to have had less of an impact on the hospital providing ENT elective services. A smaller population and a smaller number of hospital beds available would mean even small increase in the 7-day positive rate could potentially impact the hospital's ability to provide elective surgery. Due to a lack of full-time substantive consultants, we were only able to compare a small number directly year to year. Our hospital was also without a full-time head & neck consultant during the second year and this meant sending patients to other centres in order to facilitate their care. The policies and guidelines implemented prior to restarting elective surgery were based on the best practice at that time and may not reflect advances in knowledge and the impact vaccination may have on future elective services. Low rates of COVID-19 infection do not necessarily mean that ENT elective services can return to pre-COVID levels. Implementation of new safety protocols to protect patients and staff has reduced the efficiency and speed at which elective ENT surgery can be delivered. This is likely to continue to impact waiting lists at a time when surgical activity is needed to exceed pre-pandemic levels. It is likely that workloads will increase, as extra theatre lists become more commonplace; however, in order to clear the backlog, NHS trusts will need to become more innovative in their approach. None. This study took the form of an audit, so National Research Ethics Service approval was not required. The local audit department approved the study. Sam Arman: Project lead involved with design, data collection and data analysis. Michael Hopkins: Involved with data analysis, editing and proofing final submission. Simon McKean: Project supervisor, involved with editing final publication None.

Lyuye Zhang, Maode Ma, Yue Qiu

No abstract is available for this record.

Zeba Mahmood, Vacius Jusas

This paper introduces a blockchain-based federated learning (FL) framework with incentives for participating nodes to enhance the accuracy of classification problems. Machine learning technology has been rapidly developed and changed from a global perspective for the past few years. The FL framework is based on the Ethereum blockchain and creates an autonomous ecosystem, where nodes compete to improve the accuracy of classification problems. With privacy being one of the biggest concerns, FL makes use of the blockchain-based approach to ensure privacy and security. Another important technology that underlies the FL framework is zero-knowledge proofs (ZKPs), which ensure that data uploaded to the network are accurate and private. Basically, ZKPs allow nodes to compete fairly by only submitting accurate models to the parameter server and get rewarded for that. We have conducted an analysis and found that ZKPs can help improve the accuracy of models submitted to the parameter server and facilitate the honest participation of all nodes in FL.

Matteo Varvello, Iñigo Querejeta Azurmendi, Antonio Nappa, Panagiotis N. Papadopoulos · 6 authors

Distributed Virtual Private Networks (dVPNs) are new solutions aiming to solve the trust-privacy concern of a VPN's central authority by leveraging a distributed architecture. In this paper, we discuss the requirements of a successful dVPN system and we present VPN-Zero: a dVPN system with strong privacy guarantees that provides traffic accounting and has minimal performance impact on its users. VPN-Zero guarantees that a dVPN node only carries traffic it has “allowlisted”, without revealing its allowlist or knowing the traffic it tunnels. This is achieved via three main innovations: (a) an attestation mechanism which leverages TLS to certify a user visit to a specific domain, (b) a zero-knowledge proof to certify that some incoming traffic is authorized (e.g., falls in a node's allowlist, without disclosing the target domain), and (c) a dynamic chain of VPN tunnels to both increase privacy and guarantee service continuation while traffic certification is in place. The paper demonstrates VPN-Zero functioning when integrated with two production systems: BitTorrent's Distributed Hash Table and ProtonVPN. Early evaluation results show that the median setup time of VPN-Zero is about 10 seconds.

C. Vijayalakshmi

E-Commerce has become more and more popular because of rich products, fast transactions, and free from time, locations, stores, and so on. However, the disclosure of personal data such as their IDs, addresses, and phone numbers has become a major concern for online activities. The current e-commerce model is at the crossroads of ownership and privacy. To address this, this article creates an enterprise protocol that uses smart personal contracts to protect privacy during the negotiation phase. This protocol allows contracting parties to conduct business without disclosing personal information such as identity, address, and phone number. Furthermore, we employ the zero-knowledge proof to ensure ownership.

Rong Yu, Zhenqi Wang, Conghui Zhang, Shaopeng Guan

In the housing rental market, some intermediaries often publish malicious rental prices or provide false housing information, taking advantage of the asymmetry and opacity of the rental market, to harm the interests of tenants. Blockchain has the characteristics of decentralization, immutability, and trustworthiness, which can well address the problems faced in the housing rental market. In this paper, we establish a secure transaction platform for housing rental based on blockchain. First of all, we replace the trusted third party in the traditional house rental platform using the blockchain technology to reduce the trust cost of the platform. Then, we adopt an identity access mechanism based on zero-knowledge proof to ensure the identity legality of users in the housing rental platform. Finally, homomorphic encryption algorithms are employed to protect the private information of users in the process of housing transactions. The evaluation results show that the proposed scheme can well solve the drawbacks of the traditional housing rental platform and ensure the safety of transactions between the rental parties on the platform.

Yang Yang, Robert H. Deng, Wenzhong Guo, Hongju Cheng · 7 authors

In this article, we proposedualtraceabledistributedattributebasedencryption withsubsetkeywordsearch system (DT-DABE-SKS, abbreviated as$\mathcal {DT}$) to simultaneously realize data source trace (secure provenance) and user trace (traitor trace) and flexible subset keyword search from polynomial interpolation. Leveraging non-interactive zero-knowledge proof technology,$\mathcal {DT}$preserves privacy for both data providers and users in normal circumstances, but a trusted authority can disclose their real identities if necessary, such as the providers deceitfully uploading false data or users maliciously leaking secret attribute key. Next, we introduce the new conception of updatable and transferable message-lock encryption (UT-MLE) for block-level dynamic encrypted file update, where the owner does not have to download the whole ciphertext, decrypt, re-encrypt and upload for minor document modifications. In addition, the owner is permitted to transfer file ownership to other system customers with efficient computation in an authenticated manner. A nontrivial integration of$\mathcal {DT}$and UT-MLE lead to the distributed ABSE with ownership transfer system ($\mathcal {DTOT}$) to enjoy the above merits. We formally define$\mathcal {DT}$, UT-MLE, and their security model. Then, the instantiations of$\mathcal {DT}$and UT-MLE, and the formal security proof are presented. Comprehensive comparison and experimental analysis based on real dataset affirm their feasibility.