The Open Vote Network is a self-tallying decentralized e-voting protocol suitable for boardroom elections. Currently, it has two Ethereum-based implementations: the first, by McCorry et al., has a scalability issue since all the computations are performed on-chain. The second implementation, by Seifelnasr et al., solves this issue partially by assigning a part of the heavy computations to an off-chain untrusted administrator in a verifiable manner. As a side effect, this second implementation became not dispute-free; there is a need for a tally dispute phase where an observer interrupts the protocol when the administrator cheats, i.e., announces a wrong tally result. In this work, we propose a new smart contract design to tackle the problems in the previous implementations by (i) preforming all the heavy computations off-chain hence achieving higher scalability, and (ii) utilizing zero-knowledge Succinct Non-interactive Argument of Knowledge (zk-SNARK) to verify the correctness of the off-chain computations, hence maintaining the dispute-free property. To demonstrate the effectiveness of our design, we develop prototype implementations on Ethereum and conduct multiple experiments for different implementation options that show a trade-off between the zk-SNARK proof generation time and the smart contract gas cost, including an implementation in which the smart contract consumes a constant amount of gas independent of the number of voters.
Aarushi Goel, Matthew Green, Mathias Hall-Andersen, Gabriel Kaptchuk
Abstract Set membership proofs are an invaluable part of privacy preserving systems. These proofs allow a prover to demonstrate knowledge of a witness w corresponding to a secret element x of a public set, such that they jointly satisfy a given NP relation, i.e. â( w, x ) = 1 and x is a member of a public set { x 1 , . . . , x đ }. This allows the identity of the prover to remain hidden, eg. ring signatures and confidential transactions in cryptocurrencies. In this work, we develop a new technique for efficiently adding logarithmic-sized set membership proofs to any MPC-in-the-head based zero-knowledge protocol (Ishai et al. [STOCâ07]). We integrate our technique into an open source implementation of the state-of-the-art, post quantum secure zero-knowledge protocol of Katz et al. [CCSâ18].We find that using our techniques to construct ring signatures results in signatures (based only on symmetric key primitives) that are between 5 and 10 times smaller than state-of-the-art techniques based on the same assumptions. We also show that our techniques can be used to efficiently construct post-quantum secure RingCT from only symmetric key primitives.
Abstract Traditional zero-knowledge protocols have been studied and optimized for the setting where a single prover holds the complete witness and tries to convince a verifier about a predicate on the witness, without revealing any additional information to the verifier. In this work, we study the notion of distributed-prover zero knowledge (DPZK) for arbitrary predicates where the witness is shared among multiple mutually distrusting provers and they want to convince a verifier that their shares together satisfy the predicate. We make the following contributions to the notion of distributed proof generation: (i) we propose a new MPC-style security definition to capture the adversarial settings possible for different collusion models between the provers and the verifier, (ii) we discuss new efficiency parameters for distributed proof generation such as the number of rounds of interaction and the amount of communication among the provers, and (iii) we propose a compiler that realizes distributed proof generation from the zero-knowledge protocols in the Interactive Oracle Proofs (IOP) paradigm. Our compiler can be used to obtain DPZK from arbitrary IOP protocols, but the concrete efficiency overheads are substantial in general. To this end, we contribute (iv) a new zero-knowledge IOP Graphene which can be compiled into an efficient DPZK protocol. The (D + 1)-DPZK protocol D-Graphene, with D provers and one verifier, admits O ( N 1 /c ) proof size with a communication complexity of O (D 2 ·( N 1â2 /c + N s )), where N is the number of gates in the arithmetic circuit representing the predicate and N s is the number of wires that depends on inputs from two or more parties. Significantly, only the distributed proof generation in D-Graphene requires interaction among the provers. D-Graphene compares favourably with the DPZK protocols obtained from the state-of-art zero-knowledge protocols, even those not modelled as IOPs.
Cong Deng, Lin You, Xianghong Tang, Gengran Hu · 5 authors
Zero-Knowledge Proof is widely used in blockchains. For example, zk-SNARK is used in Zcash as its core technology to identifying transactions without the exposure of the actual transaction values. Up to now, various range proofs have been proposed, and their efficiency and range-flexibility have also been improved. Bootle et al. used the inner product method and recursion to construct an efficient Zero-Knowledge Proof in 2016. Later, Benediky BĂŒnz et al. proposed an efficient range proof scheme called Bulletproofs, which can convince the verifier that a secret number lies in [0,2Îșâ1] with Îș being a positive integer. By combining the inner-product and Lagrangeâs four-square theorem, we propose a range proof scheme called Cuproof. Our Cuproof can make a range proof to show that a secret number v lies in an interval [a,b] with no exposure of the real value v or other extra information leakage about v. It is a good and practical method to protect privacy and information security. In Bulletproofs, the communication cost is 6+2logÎș, while in our Cuproof, all the communication cost, the proving time and the verification time are of constant sizes.
Blockchain is a technology that has desirable features of decentralization, autonomy, integrity, immutability, verification, fault-tolerance, anonymity, auditability, and transparency. In this paper, we first carry out a deeper survey about blockchain technology, especially its history, consensus algorithms' quantitative comparisons, details of cryptography in terms of public key cryptography, Zero-Knowledge Proofs, and hash functions used in the blockchain, and the comprehensive list of blockchain applications. Further, the security of blockchain itself is a focus in this paper. In particular, we assess the blockchain security from risk analysis to derive comprehensive blockchain security risk categories, analyze the real attacks and bugs against blockchain, and summarize the recently developed security measures on blockchain. Finally, the challenges and research trends are presented to achieve more scalable and securer blockchain systems for the massive deployments.
Quantum entanglement has shown distinguished features beyond any classical state. Many methods have been presented to verify unknown entanglement with the complete information about the density matrices by quantum state tomography. In this work, we aim to identify unknown entanglement with only partial information of the state space. The witness consists of a generalized Greenberger-Horne-Zeilinger-like paradox expressed by Pauli observables, and a nonlinear entanglement witness expressed by density matrix elements. First, we verify unknown bipartite entanglement and study the robustness of entanglement witnesses against the white noise. Second, we generalize such verification to partially unknown multipartite entangled states, including the Greenberger-Horne-Zeilinger-type and W-type states. Third, we give a quantum-information application related to the quantum zero-knowledge proof. It further provides a useful method in blindly verifying universal quantum computation resources. These results may be interesting in entanglement theories, quantum communication, and quantum networks.
Nowadays, there are a plethora of services that are provided and paid for online, such as video streaming subscriptions, car-share, vehicle parking, purchasing tickets for events, etc. Online services usually issue tokens that are directly related to the identities of their users after they sign up to a platform; users need to authenticate themselves by using the same credentials each time they use the service. Likewise, when using in-person services, such as going to a concert, after paying for this service, the user usually receives a ticket, which proves that he/she has the right to use that service. In both scenarios, the main concerns surround the centralization of these systems and that they do not ensure customersâ privacy. The involved service providers are trusted third partiesâauthorities that offer services and handle private data about users. In this paper, we designed and implemented FORT, a decentralized system that allows customers to prove their rights to use specific services (either online or in-person) without revealing sensitive information. To achieve decentralization, we proposed a solution where all of the data are handled by a blockchain. We describe and uniquely identify usersâ rights using non-fungible tokens (NFTs), and possession of these rights is demonstrated by using zero-knowledge proofsâcryptographic primitives that allow us to guarantee customersâ privacy. Furthermore, we provide benchmarks of FORT, which show that our protocol is efficient enough to be used in devices with low computing resources, such as smartphones or smartwatches, which are devices commonly used in our use case scenario.
Online voting is convenient and flexible, but amplifies the risks of voter coercion and vote buying. One promising mitigation strategy enables voters to give a coercer fake voting credentials, which silently cast votes that do not count. Current systems along these lines make problematic assumptions about credential issuance, however, such as strong trust in a registrar and/or in voter-controlled hardware, or expecting voters to interact with multiple registrars. Votegral is the first coercion-resistant voting architecture that leverages the physical security of in-person registration to address these credential-issuance challenges, amortizing the convenience costs of in-person registration by reusing credentials across successive elections. Votegral's registration component, TRIP, gives voters a kiosk in a privacy booth with which to print real and fake credentials on paper, eliminating dependence on trusted hardware in credential issuance. The voter learns and can verify in the privacy booth which credential is real, but real and fake credentials thereafter appear indistinguishable to others. Only voters actually under coercion, a hopefully-rare case, need to trust the kiosk. To achieve verifiability, each paper credential encodes an interactive zero-knowledge proof, which is sound in real credentials but unsound in fake credentials. Voters observe the difference in the order of printing steps, but need not understand the technical details. Experimental results with our prototype suggest that Votegral is practical and sufficiently scalable for real-world elections. User-visible latency of credential issuance in TRIP is at most 19.7 seconds even on resource-constrained kiosk hardware, making it suitable for registration at remote locations or on battery power. A companion usability study indicates that TRIP's usability is competitive with other e-voting systems including some lacking coercion resistance, and formal proofs support TRIP's combination of coercion-resistance and verifiability.
Abstract Software-controlled measuring instruments used in commercial transactions, such as fuel dispensers and smart meters, are sometimes subject to âmemory replacementâ attacks. Cybercriminals replace the approved software by a malicious one that then tampers with measurement results, inflicting a financial loss to customers and companies. To mitigate such attacks, legal metrology systems often require regular device attestation, where an auditor checks that the device possesses (âknowsâ) the approved software. However, current attestation methods usually require the software to be known by the auditor, thus increasing the risk of inadvertent leakage or malicious theft of proprietary information, besides facilitating its malicious adulteration. We describe how this issue can be addressed in legal metrology systems by using zero-knowledge proofs of knowledge (ZKPoK). These proofs enable attestation of possession of approved software, while ensuring its confidentiality from the auditor. To further provide publicly verifiable evidence of freshness, each such proof can be related to a fresh random value from a public randomness beacon. This article presents the basic conceptual idea, while also discussing pitfalls that should be avoided.
Open access
Physical Unclonable Functions (PUFs) and Hardware Security
In this paper we describe protocols which use a standard deck of cards to provide a perfectly sound zero-knowledge proof for Hamiltonian cycles and Flow Free puzzles. The latter can easily be extended to provide a protocol for a zero-knowledge proof of many-to-many k-disjoint path coverings.
Federated learning is known to be vulnerable to both security and privacy issues. Existing research has focused either on preventing poisoning attacks from users or on concealing the local model updates from the server, but not both. However, integrating these two lines of research remains a crucial challenge since they often conflict with one another with respect to the threat model. In this work, we develop a principle framework that offers both privacy guarantees for users and detection against poisoning attacks from them. With a new threat model that includes both an honest-but-curious server and malicious users, we first propose a secure aggregation protocol using homomorphic encryption for the server to combine local model updates in a private manner. Then, a zero-knowledge proof protocol is leveraged to shift the task of detecting attacks in the local models from the server to the users. The key observation here is that the server no longer needs access to the local models for attack detection. Therefore, our framework enables the central server to identify poisoned model updates without violating the privacy guarantees of secure aggregation.
FOG-enabled cyber-physical systems (FOG-CPSs) open new security challenges as the local edge devices are easier to compromise than a traditional cloud server. Remote data integrity checking (RDIC) plays an important role in safeguarding against data corruption from a storage server. Certificateless cryptography (CLPKC)-based RDIC schemes do not suffer from the drawbacks of the public key infrastructure (PKI)-based RDIC protocols. Most of the CLPKC-based RDIC schemes proposed in the literature deal with personal data. However, in a FOG-CPS, it is also important to audit a data file shared by a group of edge devices. Most of the existing group shared data auditing schemes lack mechanisms to defend against a semi-trusted data auditor applicable for a FOG-CPS scenario. In order to address these issues, in this paper, we propose a novel CLPKC-based group shared data auditing protocol tailored to the specific security requirements of a FOG-CPS. Besides, we perform a detailed cryptanalysis of two existing CLPKC-based privacy-preserving group shared data auditing schemes. The formal security analysis of our proposed protocol establishes metadata and data integrity proof unforgeability and claimed zero-knowledge privacy and reliability properties through rigorous proofs in the random oracle model setting. Performance evaluations establish the efficiency of our proposed protocol.
This is my first issue as editor-in-chief of The Philosophical Forum, and the beginning of what I hope to be a long and fruitful tenure at the helm of this esteemed journal. I would like to first thank the publishing team at Wiley for entrusting me with the continuation of the legacy of the Forum, and for giving me the freedom to take it where I think it is possible for it to go. The journal has a history of innovation in our field, and I look forward to seeing where it can go from here and to playing a role in its newest iteration, with the help of many others. The central focus of my work at the Forum will be to publish high-quality philosophy from across the diverse array of traditions around the world. I aim to make the journal an example of a truly global philosophical enterprise, rather than one limited to the Anglo-American West or any other region, culture, or tradition. For far too long, philosophy in the West has largely gone on with minimal to no engagement with philosophers and philosophical traditions outside of Anglo-America, Western Europe, and ethnically related enclaves such as Australia and New Zealand. This has been to the detriment of philosophy as a discipline. Numerous philosophers have decried this over the years and have struggled to change things (so far with limited success).1 And the problem is far wider than philosophy. The problem in our field is merely a local representation of a much broader problem in the Anglo-American West, particularly in the United States. I would like to tell you a story that hopefully drives home the need for more projects of the kind I propose here. A story that, like so many of recent years, begins in the spring of 2020. It was then that I realized that the wider social unwillingness to appreciate and collaborate with our international neighbors was truly a global disaster. By the winter of 2020 I was tired. Professionally, personally, existentially. I was sick of fighting and losing the same battles over and over. I was tired of struggling to help the field of philosophy become more expansive, global, and interdisciplinary in its scope, to help foster methodological pluralism, to generate interest in pursuing the kinds of âoff the beaten pathâ research that made philosophy the well-known synonym for the life of the mind that it's known as today. I encountered the same resistance again and again, the same promises to change followed by the continued philosophical neglect of most of the world and the entrenchment in a narrow way of understanding philosophy. However hard I and other like-minded philosophers pushed to change things, philosophy pushed back harder. It seemed that this work would always be ignored, seen as expendable, on the fringe, and devalued by many philosophers. Was I just going to work on these things and yell from the rooftops about globalizing philosophy for the rest of my productive years, only for this to fall on deaf ears in the United States and make no difference at all? My efforts seemed to be going nowhere. And then March 2020, a month we will all remember for the rest of our lives, brought an even more alarming realization. As our schools shut down and the world went online, global events showed that the problem was far bigger than just the field of philosophy, or even academia as a whole. At the beginning of the Covid-19 pandemic, doctors and medical experts in China were the only people in the world with either practical or research experience with the virus that eventually became known as SARS-CoV-2, and its associated disease. When the virus later took off first in Europe then later in the United States throughout March and into April of that year, scientists and physicians in the West struggled to understand the virus and the disease, in a race against the lightning-fast spread of the virus that quickly took hold of the world. Scientists and physicians in China, of course, had a head start of a couple of months on the rest of the world in understanding this virus. As the rest of the world looked on in shock in January and February 2020, the Chinese struggled to treat and understand the disease and the virus, as they imposed lockdowns across the country. It seemed for one brief moment that the virus might be contained in China, before it flared in late February in northern Italy, in Korea, then throughout Europe and to the rest of the world. By the time the virus took off in the United States in mid March, Chinese scientists and physicians working on the problem started to gain some initial understanding of the disease and the virus causing it. The obvious starting point for experts in the United States would be to consult with their counterparts in China, to learn from others who had been dealing with this new virus for months already. Almost inexplicably, that did not happenâat least in any large scale way. Not only did US-based experts routinely fail to turn to Chinese experts for help, but they often rejected those Chinese insights that did somehow make their way to US attention. Chinese doctors and scientists had some idea of the course of illness, as well as which strategies for treatment seemed to have some effectiveness. Of course, even in China they still did not have an enormous amount of knowledge about this new virus and its disease, but they had far more knowledge about it than anyone else in the world. Instead of devoting our effort to working with experts in China, the US largely chose to use the virus as yet another political weapon against China, spending more energy criticizing the Chinese government's responses to the increasing spread of the virus than we did trying to learn from their experiences with it or consulting with their scientists and physicians. Western media piled on, questioning whether Chinese data on the virus could be trusted, because of instances of data manipulation by the Chinese government in the past.2 Curiously, few of these same skeptics ever questioned Western data on the virus or Western medical interventions, despite a wealth of instances of data manipulation by Western pharmaceutical companies in the past in the interest of generation of profit,3 and the enormous influence of these companies over policymakers and regulatory bodies.4 The new and quickly spreading Covid pandemic was a medical crisis, not a political one. It was a crisis that threatened the rest of the world as much as it threatened China. In such a situation, one would hope that nations and people would be able to work together to focus on the crisis at hand. Yet things did not happen that way. Our prejudices, insularity, and political leanings won the day over knowledge, learning, and science, as they usually do. And many people suffered and died due simply to our unwillingness to learn from people who we saw as outside of our cultural and political sphere. This happened continually throughout the pandemic (and happens still today in the ongoing crisis of this virus). In 2021, researchers in Cyprus found evidence of a new hybrid variant of the virus combining two existing and circulating variants. This research was widely questioned and dismissed, as Western experts publicly claimed that the research was likely carried out incorrectly. There were so many expert naysayers in the West who seemed convinced (without evidence) that the finding was just a matter of sloppy research that Nature published an article âDeltacron: The Story of the Variant That Wasn'tâ.5 Unfortunately for the writers of this story, the variant very much was. Months later, when UK researchers also found the new variant, the same agencies and experts in the West that had dismissed the claims of the Cypriot researchers took the variant as âconfirmedâ, despite lack of peer-reviewed publication from these British researchers (which they had demanded from the researchers from Cyprus as a condition for trust). What was the difference, other than this time the British had found the variant, rather than the Cypriots? Similarly, when the Omicron variant of the virus first made its way through South Africa, where it was discovered, South African physicians and experts noted that the disease associated with the variant was proving less severe than those associated with earlier variants. Western experts manifestly dismissed this as mere anecdote, and unconfirmedâa position a number of South African experts publicly took issue with, even decrying it as racist.6 When British researchers later concluded, just as the South Africans had, that the Omicron variant caused less severe disease (and on the basis of no better data than what the South Africans had), it was somehow taken as more reliable by Western experts, treated as âconfirmedâ, and reported by Western media as now basically scientific fact. Apparently we have been misled for all these years about scientific method, and what truly confirms a hypothesis is not experimental demonstration, but being claimed by people with the right nationality. British and French claims are necessarily reliable and trustworthy, while Chinese, Cypriot, and South African claims are dubious, probably false, or at least in need of further confirmation by British, French, or American proclamation. There were countless similar situations that unfolded through the pandemic. But we can find the problem in other areas too. Look at what's covered in our news in the United States, for example. How often do those of you in the US see stories on current events in Asia, Africa, or the Americas outside of Anglo-America? Right now, go find a news source from India, Nigeria, Peru, or any host of other countries outside of Anglo-America and Western Europe. Next, find a US news source. Look at the US news page, and see how long it takes you to find a single story from any of the other newspapers featured on its page. Likely, you'll find few to none. Or walk into any bookstore in the US, and check out their sections on the histories of various European countries and then their sections on the histories of the various other parts of the world. I'll bet I can accurately predict the differences between these sections, because I've seen many of them over the years. In the sections on European countries, you'll find general histories of France, England, Germany, etc. Biographies of important figures in the histories of these countries. Probably specific topical selections, such as books on certain cities, important events, battles, cultural movements. In the section on Africa, if they have one, you'll find almost nothing. It's apparently a continent that barely exists, let alone has a history. You may find one or two books on travel, the geography of the continent, or the story of colonization, slavery, etc. If you can find anything at all, it's likely going to be a story of how white Western people colonially approached the continent. Asia and Latin America will get similar treatment, though you'll likely find a bit more on East Asia. China and Japan will have a few volumes, although 99% of what is available on China will be polemic treatises about how the Chinese are gaining influence in the world, and how this is a dangerous thing. You may find books with stark titles like How China Is Taking Over the World (not a real title as far as I know, but an example of the kind of book I have in mind). These are so prevalent that I coined a phrase years ago to refer to these: âenemy booksâ. The China section at your local bookstore (for those of you in the US) will probably consist of mostly enemy books, as will the section on the Middle East, where you can expect to find enemy books of the âwhy they hate usâ varietyâbooks about terrorists, extremism, the so-called problems of Islam, or dictators and tyrants. The situation in our bookstores mirrors our concerns in international relations, where the ânon-Westâ is treated in an altogether different way. Its concerns are less important, its ideas less compelling, its conflicts less tragic or in need of our attention. It is rendered invisible to the West in a way the West is never invisible to the rest of the world. The West has yet to shed the colonial attitudes of its past, anachronisms which have no place in a world of independent and equal nations, a globally connected world facing a number of enormous crises requiring people to think and work together. I began to realize that there was no easy way out of this mess. Turning my back on philosophy wasn't going to enable me to find a place where internationalization was welcomed. Resistance to the rest of the world, I observed, was endemic to my culture. So I could either fight the battles here in academia, in a place I knew well, or fight them somewhere completely unknown. Even if I lost those battles here, and even if winning them would do little in the overall scheme of things, I stood a better chance here than anywhere else, even if that chance was close to zero. Even if I continued to fail to make a difference, I had no alternative but to try. And in some ways, the neglect of the world in the practice of professional philosophy in the West seems an easier problem to solve than in other areas. This neglect cannot be chalked up completely to linguistic differences. While there is a great deal of scholarship in philosophy (and every other academic field) around the world conducted in languages other than English, many scholars outside of the Anglo-American world can and often do write in English. Philosophy in large swaths of the world neglected in Anglo-American venues is done almost wholly in English. A good example of the neglect of English-language philosophy can be seen when we look at what philosophers often mean by the âEnglish-speaking worldâ. The Philosophical Gourmet Report purports to rank philosophy departments in the English-speaking world, which it lists as including: the USA, UK, Canada, Australia, New Zealand, and This is a if it is truly to the English-speaking world. This not even most of the countries in which is the let alone the countries where is a widely and the or of For one, where is Or the nations of the Or English-speaking countries throughout Africa, such as Nigeria, and US lists often over nations from which international do not have to of English-language because is either the or a And if we to this number nations such as India, in which is widely and in which is conducted almost in English, the at least in all academic philosophy in the parts of the British for is done in English. Yet where are or African philosophers and philosophical traditions in venues in the In an enormous amount of philosophy in nations where is not the or a widely such as nations throughout Asia, Europe, the Middle East, and is done in English. Yet where is the work of these philosophers in venues in the For better or the has become a kind of academic to Latin in the European world, in the world, or Chinese in East history. This is not altogether a to the of the British the spread further across the than almost any only by and What the British started was by the global and influence of the United States in the late and which made the for a wider of people across the world. And as likely has the to with Islam, so the nations and also to a was from such cultural for the most because it on the basis of and situation similar to the spread of the the often and for its the use of the today the to with one another across and other So it out that we in the United States can the of many scholars outside of the Anglo-American world. they often their English-language work to our It is for the of our philosophy, for the of academia and the in which we are all learning, and the knowledge of the we with one learn from one with one There are far too many to learning, and knowledge today for to the of what we can together. at home and around the world, and other that on and work to the we our and work be international and globally because if we do not learn from one another and work together to solve the problems we such as and we may not at The same is the for philosophy, which is in of where it is the world on and it can and do Philosophy will not change and we change it is about our that is for this in the West and But we have to start and we can to even if at a from academic like philosophy where we can the of up to the world. can be at the of the for international of to our and being of the past There are many who are for The philosophers of the rest of the world are no less and than are those of in the âEnglish-speaking as by the Philosophical Gourmet And those philosophers have ideas and insights that the rest of have never In medical science, when we neglect or new ideas in the rest of the world, we the of and when we neglect the philosophy of the rest of the world, we the of losing knowledge that we could have had, losing and to the philosophical problems that we a where scholars from around the world can be and hopefully by other scholars around the we up a the US and US-based academia to research from around the not just here in our narrow These are as yet but these my initial for what The Philosophical Forum might My hope is to together independent of philosophical or culture. And it out that this journal is a for such a Over the years it was in its first in and then its current in The Philosophical Forum has published a of philosophical work in very different areas. For much of its it had the aim of together what was long seen in the West as the two and of and This was an and the journal has this through its years in of the most work on the of philosophy has been published in this journal. It is now time to forward to a new the between different and But one might do we do this mean that we will no publish from US-based That we will international That we will of the philosophical as in the Anglo-American What I is to an philosophical not simply to to a different kind of The of Western philosophy and philosophy those who in them outside the will still be but they will be just two many equal to other rather than the or And the I take here to this is but that we have largely to do in Western simply with other scholars around the world, interest in their it them the effort to their and their work for a global In of The Philosophical Forum, we will focus more on philosophical traditions and between these in of time and culture, and In to being a home for a more international I aim to The Philosophical Forum experimental and work as This is a place to out new to the of what is to new and new as well as with There of course, a between the of together people in different traditions of and the of new of about philosophy any other and change happen not through that philosophy has yet to through and through new things, and The most mind in the world still has an that is by its and what it When we understand we realize that if we to truly we have to our with others. It has always been this despite the stories we tell to history so as to the story of of the of great innovation and of the These all with new between of with up one or to with The of philosophy and in the world with the of together and ideas from to the The of was by with and of ideas from China to and Europe. of the with the of the West into the areas of the in Asia and the of people and The in Europe with first the of the and then the between Europe and the Americas starting in the The with the of like the British and the this made not happen in a or in of cultural only happens when we one and the new ideas this cultural happen only with The Philosophical Forum of course, a journal in the United States. Yet when I took over as my was to make the journal together an international and was I on from the and a that is A be a place we think and work of of philosophical And I will do my to see The Philosophical Forum forward a and truly philosophical that might help new of we need on our In this in the first issue of my tenure as of The Philosophical Forum, I would like to philosophers and those working in areas with philosophy to this ongoing of of up philosophy to a truly global rather than one only different and help help what philosophy can and in the in of do not have to be in the of the way philosophy has been done in the past in the West, simply because it has been done that way. can do better than do
Smart contracts are becoming more and more popular in financial scenarios like medical insurance. Rather than traditional schemes, using smart contracts as a medium is a better choice for both participants, as it is fairer, more reliable, more efficient, and enables real-time payment. However, medical insurance contracts need to input the patient's condition information as the judgment logic to trigger subsequent execution. Since the blockchain is a closed network, it lacks a secure network environment for data interaction with the outside world. The Data feed aims to provide the service of the on-chain and off-chain data interaction. Existing researches on the data feed has solved the security problems on it effectively, such as Town Crier, TLS-N and they have also taken into account the privacy-preserving problems. However, these schemes cannot actually protect privacy because when the ciphertext data is executed by the contract, privacy information can still be inferred by analyzing the transaction results, since states of the contract are publicly visible. In this paper, based on zero-knowledge proof and Hawk technology, a on-and-off-chain complete smart contract data feed privacy-preserving scheme is proposed. In order to present our scheme more intuitively, we combined the medical insurance compensation case to implement it, which is called MIPDF. In our MIPDF, the patient and the insurance company are parties involved in the contract, and the hospital is the data provider of data feed. The patient's medical data is sent to the smart contract under the umbrella of the zero-knowledge proof signature scheme. The smart contract verifies the proof and calculates the insurance premium based on the judgment logic. Meanwhile, we use Hawk technology to ensure the privacy of on-chain contract execution, so that no information will be disclosed due to the result of contract execution. We give a general description of our scheme within the Universal Composability (UC) framework. We experiment and evaluate MIPDF on Ethereum for in-depth analysis. The results show that our scheme can securely and efficiently support the functions of medical insurance and achieve complete privacy-preserving.
Open access
Blockchain Technology Applications and Security
Advanced Steganography and Watermarking Techniques
Nikita Konstantinovich Chistousov, Igor A. Kalmykov, Daniil Vyacheslavovich Dukhovnyj, Đ. Đ. ĐĐ°Đ»ĐŒŃĐșĐŸĐČ Â· 5 authors
Authentication protocols are expanding their application scope in wireless information systems, among which are low-orbit satellite communication systems (LOSCS) for the OneWeb space Internet, automatic object identification systems using RFID, the Internet of Things, intelligent transportation systems (ITS), Vehicular Ad Hoc Network (VANET). This is due to the fact that authentication protocols effectively resist a number of attacks on wireless data transmission channels in these systems. The main disadvantage of most authentication protocols is the use of symmetric and asymmetric encryption systems to ensure high cryptographic strength. As a result, there is a problem in delivering keys to the sides of the prover and the verifier. At the same time, compromising of keys will lead to a decrease in the level of protection of the transmitted data. Zero-knowledge authentication protocols (ZKAP) are able to eliminate this disadvantage. However, most of these protocols use multiple rounds to authenticate the prover. Therefore, ZKAP, which has minimal time costs, is developed in the article. A scheme for adapting protocol parameters has been developed in this protocol to increase its efficiency. Reductions in the level of confidentiality allow us to reduce the time spent on the execution of the authentication protocol. This increases the volume of information traffic. At the same time, an increase in the confidentiality of the protocol entails an increase in the time needed for authentication of the prover, which reduces the volume of information traffic. The FPGA Artix-7 xc7a12ticsg325-1L was used to estimate the time spent implementing the adaptive ZKAP protocol. Testing was performed for 32- and 64-bit adaptive authentication protocols.
This paper defines a new practical construction for a code-based signature scheme. We introduce a new protocol that is designed to follow the recent paradigm known as âSigma protocol with helperâ, and prove that the protocolâs security reduces directly to the Syndrome Decoding Problem. The protocol is then converted to a full-fledged signature scheme via a sequence of generic steps that include: removing the role of the helper; incorporating a variety of protocol optimizations (using e.g., Merkle trees); applying the FiatâShamir transformation. The resulting signature scheme is EUF-CMA secure in the QROM, with the following advantages: (a) Security relies on only minimal assumptions and is backed by a long-studied NP-complete problem; (b) the trusted setup structure allows for obtaining an arbitrarily small soundness error. This minimizes the required number of repetitions, thus alleviating a major bottleneck associated with FiatâShamir schemes. We outline an initial performance estimation to confirm that our scheme is competitive with respect to existing solutions of similar type.
Jiasi Weng, Jian Weng, Gui Hong Tang, Anjia Yang · 6 authors
We propose a new approach for privacy-preserving and verifiable convolutional neural network (CNN) testing in a distrustful multi-stakeholder environment. The approach is aimed to enable that a CNN modeldeveloperconvinces auserof the truthful CNN performance over non-public data frommultiple testers, while respecting model and data privacy. To balance the security and efficiency issues, we appropriately integrate three tools with the CNN testing, including collaborative inference, homomorphic encryption (HE) and zero-knowledge succinct non-interactive argument of knowledge (zk-SNARK). We start with strategically partitioning a CNN model into a private part kept locally by the model developer, and a public part outsourced to an outside server. Then, the private part runs over the HE-protected test data sent by a tester, and transmits its outputs to the public part for accomplishing subsequent computations of the CNN testing. Second, the correctness of the above CNN testing is enforced by generating zk-SNARK based proofs, with an emphasis on optimizing proving overhead for two-dimensional (2-D) convolution operations, since the operations dominate the performance bottleneck during generating proofs. We specifically present a new quadratic matrix program (QMP)-based arithmetic circuit witha single multiplication gatefor expressing 2-D convolution operations between multiple filters and inputs in a batch manner. Third, we aggregate multiple proofs with respect to a same CNN model but different testersâ test data (i.e., different statements) into one proof, and ensure that the validity of the aggregated proof implies the validity of the original multiple proofs. Lastly, our experimental results demonstrate that our QMP-based zk-SNARK performs nearly 13.9Ă faster than the existing quadratic arithmetic program (QAP)-based zk-SNARK in proving time, and 17.6Ă faster in Setup time, for high-dimension matrix multiplication. Besides, the limitation on handling a bounded number of multiplications of QAP-based zk-SNARK is relieved.
Zero-knowledge proof (ZKP) mixers are one of the most widely-used blockchain privacy solutions, operating on top of smart contract-enabled blockchains. We find that ZKP mixers are tightly intertwined with the growing number of Decentralized Finance (DeFi) attacks and Blockchain Extractable Value (BEV) extractions. Through coin flow tracing, we discover that 205 blockchain attackers and 2,595 BEV extractors leverage mixers as their source of funds, while depositing a total attack revenue of 412.87M USD. Moreover, the US OFAC sanctions against the largest ZKP mixer, Tornado.Cash, have reduced the mixer's daily deposits by more than 80%. Further, ZKP mixers advertise their level of privacy through a so-called anonymity set size, which similarly to k-anonymity allows a user to hide among a set of k other users. Through empirical measurements, we, however, find that these anonymity set claims are mostly inaccurate. For the most popular mixers on Ethereum (ETH) and Binance Smart Chain (BSC), we show how to reduce the anonymity set size on average by 27.34% and 46.02% respectively. Our empirical evidence is also the first to suggest a differing privacy-predilection of users on ETH and BSC. State-of-the-art ZKP mixers are moreover interwoven with the DeFi ecosystem by offering anonymity mining (AM) incentives, i.e., users receive monetary rewards for mixing coins. However, contrary to the claims of related work, we find that AM does not necessarily improve the quality of a mixer's anonymity set. Our findings indicate that AM attracts privacy-ignorant users, who then do not contribute to improving the privacy of other mixer users.
The use of oriented external electric fields (OEEF) as a tool to accelerate chemical reactions has recently attracted much interest. A new model to calculate the optimal OEEF of the least intensity to induce a barrierless chemical reaction path is presented. A suitable ansatz is provided by defining an effective potential energy surface (PES), which considers the unperturbed or original PES of the molecular reactive system and the action of a constant OEEF on the overall dipole moment of system. Based on a generalization of the Newton Trajectories (NT) method, it is demonstrated that the optimal OEEF can be determined upon locating a special point of the potential energy surface (PES), the so-called âoptimal bond-breaking pointâ ( optimal BBP ), for which two different algorithms are proposed. At this point, the gradient of the original or unperturbed PES is an eigenvector of zero eigenvalue of the Hessian matrix of the effective PES. A thorough discussion of the geometrical aspects of the optimal BBP and the optimal OEEF is provided using a two-dimensional model, and numerical calculations of the optimal OEEF for a S N 2 reaction and the 1,3-dipolar retrocycloaddition of isoxazole to fulminic acid plus acetylene reaction serve as a proof of concept. The knowledge of the orientation of optimal OEEF provides a practical way to reduce the effective barrier of a given chemical process.
Authentication is essential for the prevention of various types of attacks in fog/edge computing. Therefore, a novel mode-based hash chain for secure mutual authentication is necessary to address the Internet of Things (IoT) devices' vulnerability, as there have been several years of growing concerns regarding their security. Therefore, a novel model is designed that is stronger and effective against any kind of unauthorized attack, as IoT devices' vulnerability is on the rise due to the mass production of IoT devices (embedded processors, camera, sensors, etc.), which ignore the basic security requirements (passwords, secure communication), making them vulnerable and easily accessible. Furthermore, crackable passwords indicate that the security measures taken are insufficient. As per the recent studies, several applications regarding its requirements are the IoT distributed denial of service attack (IDDOS), micro-cloud, secure university, Secure Industry 4.0, secure government, secure country, etc. The problem statement is formulated as the "design and implementation of dynamically interconnecting fog servers and edge devices using the mode-based hash chain for secure mutual authentication protocol", which is stated to be an NP-complete problem. The hash-chain fog/edge implementation using timestamps, mode-based hash chaining, the zero-knowledge proof property, a distributed database/blockchain, and cryptography techniques can be utilized to establish the connection of smart devices in large numbers securely. The hash-chain fog/edge uses blockchain for identity management only, which is used to store the public keys in distributed ledger form, and all these keys are immutable. In addition, it has no overhead and is highly secure as it performs fewer calculations and requires minimum infrastructure. Therefore, we designed the hash-chain fog/edge (HCFE) protocol, which provides a novel mutual authentication scheme for effective session key agreement (using ZKP properties) with secure protocol communications. The experiment outcomes proved that the hash-chain fog/edge is more efficient at interconnecting various devices and competed favorably in the benchmark comparison.
M. Vijayalakshmi, S. Mercy Shalinie, MingâHour Yang, Shou-Chuan Lai · 5 authors
Supply chain management (SCM) governance is the streamline of the IoT product life cycle from its production to delivery. Integrating blockchain with supply chain management is essential to ensure end-to-end tracking, trustiness between manufacturers and customers, fraud and counterfeit elimination, and customizing administrative costs and paperwork. This paper proposes an RFID ownership transfer protocol with the help of zk-SNARKs (Zero Knowledge-Succinct Noninteractive Arguments of Knowledge) using Ethereum blockchain. When the owner performs RFID transfer, the transferred information will be recorded on the blockchain using smart contracts. When using a smart contract to transfer ownership on the Ethereum blockchain, because the content on the blockchain will not be tampered with, all accounts in the Ethereum can view the transfer results and verify them. The privacy of the supply chain is attained by generating the proof of product code via zk-SNARKs algorithm. This algorithm also enhances the scalability of the supply chain system by creating a trusted setup in off-chain mode.
Open access
Blockchain Technology Applications and Security
Physical Unclonable Functions (PUFs) and Hardware Security
I was intrigued to see that there was surprisingly little overlap in the responses by the three critics. It therefore seemed most sensible to treat each criticâs points separately, which is what I have done below. I hope I have managed to say something substantial on each of the points they brought up. While I harbour no illusions about my comments resolving all of the concerns raised to each criticâs satisfaction, I hope that the response helps to elucidate unclarities in the earlier exposition of my ideas and may, perhaps, provide resources for the further philosophical exploration of the views discussed. In relation to my discussion of Hohwyâs prediction-error minimization framework, Das rightly points out that nothing in this approach entails that our representations cannot carry information and hence yield knowledge about the external world. Indeed, some interpreters see this approach as a way of discovering the âhidden causesâ of whatever it is that brings about the changes in the outer nodes of our Markov blanket, arguing that the generative model ârecapitulatesâ the causal-probabilistic structure of the external environment that impinges on the organismâs sensory apparatus. It constantly generates, in a top-down manner, a flow of virtual or mock sensory signals that predicts the unfolding of sensory signals by external causes. 1 Similarly, some forms of Bayesianism see it as a way of discovering the true probabilities out there in the world (the âLordâs priorâ). What I am trying to argue is that neither appealing to the existence of some external item represented nor appealing to the accuracy of our representation (both the prediction-error minimizer and the Bayesian are likely to say that there are some structural features of the âhidden causesâ or the âtrue probabilitiesâ that our beliefs will capture) is necessary for the prediction-error minimization theory; in fact, that the theory would be in better shape if it dispensed with this idea. Considerations of parsimony aside, it is hard to make sense of the kind of connection supposed to exist between things inside and outside of the Markov blanket. On the one hand such a relation should be inside the Markov blanket for us to be able to think about it. Yet it also needs to reach beyond it to link up with the âhidden causesâ. But if we can conceptualize a relationship and one relatum, the status of the other relatum does not appear to be quite as inaccessible as the idea of the explanatory-evidentiary boundary makes out. As such, the notion of a âconnectionâ with something outside of the Markov blanket is something we should do without.2 Das notes that âif the form of intentionalism sketched above is right, nothing in Hoffmanâs account rules out the possibility that we can perceptually represent mind-independent properties of objects in our environmentâ. According to Dasâs intentionalism, we represent a certain property in our environment if we are in an internal state that âhas the biological function of indicating that propertyâ. Certain internal states of an organism might have the function of indicating the presence of water. Does that mean that our internal state represents the mind-independent property of there being water in our environment? Not according to Hoffmanâs account. What Hoffman sets out to show is that our perceptual capacities are not geared towards indicating properties the environment has no matter what, but that they have been shaped by evolution to indicate instances of fitness arising from an organism in an environment. An organismâs internal states do not have the function of indicating properties of the environment, but properties of the environment refracted through the lens of the organismâs specific interests and needs, i.e. instances of fitness. In these instances of fitness, properties of the organism and properties of the environment are so much bound up with one another that it is impossible to separate them. A realist critic might point out here that there must still be mind-independent properties of the environment, whether or not we can disentangle them from our representations or not. This move, however, pushes these properties into an epistemically inaccessible noumenal realm, and it becomes then unclear why the resulting position has any advantage over a more parsimonious rival that simply treats the mind-independent world as another part of the representational interface. In addition, an argument involving self-information entailed by non-self-locating claims is presented by Das, suggesting as an example that being in the British Library entails the existence of the British Library. I donât think Hoffman would disagree with this, any more than he would disagree with saying that the claim that there is a blue folder on my desktop entails that there is something that is blue. However, this does not yet get us to âproperties of mind-independent particularsâ, but only to properties (and individuals) in the interface. Hoffmanâs interface theory of perception does not rule out âthe possibility of there being self-locating truths or of self-locating truths entailing non-self-locating truthsâ, but claims that any such truths are strictly truths about what goes on within the representational interface. In addition, Das points out that âas long as we accept a sufficiently externalist conception of knowledge ⊠we can still be in a position to know that we are not in those sceptical scenariosâ irrealism raises. Externalism about mental states here means that such states âdepend on extrinsic properties of an agent, not just intrinsic onesâ. As an extrinsic property of me is one that essentially involves entities other than myself, externalism about knowledge clearly avoids the irrealist predicament. But anybody inclined towards irrealism is unlikely to assume that cognitive states essentially involve entities beyond the cognitive interface. The regarding impasse is then prone to reduce to a debate about where the burden of proof should lie: does the irrealist have to show that the existence of a mind-independent world is incompatible with the epistemic situation we find ourselves in (as Das seems to think), or does the realist have to show that the assumption of such a world presents an explanatory advantage that the irrealistâs representation-only view cannot match? It seems that one of the reasons why the debate between the realist and his opponent is so difficult to resolve is that the two have different ideas of what such a resolution would look like. The realist demands that his opponent ârules outâ the possibility of a mind-independent external world, while the opponent wants to see evidence of a unique feature of the realist conception of the world that cannot be replicated by ârealism in the imageâ, that is by the idea that the mind-independent world is part of the representational interface. The irrealist regards the realistâs demand as excessive, as no amount of epistemic insulation would rule out the possibility of it just happening to be case that there is the realistâs kind of world behind the representational interface (much like some events in the real world might just happen to correspond to events in some video game). The realist regards the irrealistâs offer of âexact replicationâ of his external world as insufficient, since his epistemic default is always the existence of something behind the representation. As long as we donât have proof that there cannot be such a thing we are justified in assuming that there is. I agree with Das that if we accept that perceptual do not represent the world as it is of this does not that these cannot be âtrue or The world behind might be with our by the of the it might out that the structure of the just to be that of But on such a is more than on the of the the of the are presents a argument that the for a substantial structural between representation and represented are is as a theory as it to I that there must be a argument to it than the claim to the the world might just out to entities with the structure as our perceptual an in Dasâs It is the claim that âif things appear to us to be a certain in the of those we should that things are that In the philosophical this claim was by the and by so we have another here where the between the irrealist and his some philosophical But are we to the of in a point that unclear to me is much the the of is supposed to be able to I look the world from an position it to and to most that there are real out there in the world, that the structure of is that all of my to me with that it is an whether two events happen or donât happen the that my has the resolution and so Yet some to cognitive of perception and that these do not the things are that of all of these can of be into our but that we appear to have much of what was appealing to the claim that the world see is more or the world all things the world as it and the world as our it are what is trying to the of the theory of or cognitive are any it as if the we the to the structure of the world âas it is in to the to which we this on a is different from the way things appear or not this is a matter we not but it seems to be that needs to be up by some kind of It is not a we can accept some further idea of what might it. concerns the that of parsimony not While it is than as irrealism only one kind of two and has the advantage of the of from the whether are as a to things are the most than simply as in our of parsimony are not the only idea that in is the point that what we mean by âthe is with like and so on of which essentially on to such an that it is unclear much sense we can make of a world beyond these This is of a for Das, to the claim that and so on are all in the world, and more or by our But those not to the that of the our idea of âthe is might be no more than by the will not only that a theory that with the noumenal might be more parsimonious but are likely to be such an of properties to to our cognitive be what the we in is the most As a we the existence of any substantial structural between our representations and the mind-independent world and are to accept an noumenal as the of all the world behind the representational as part of the representational seems to the most sensible An Dasâs argument on is the assumption that in the of we can simply assume the existence of an external world. do not to any evidence for While this point the argument can into the I am of the that if there is no evidence the existence of we are to the existence of for is that it would us to the existence of beyond the In this my philosophical is the of the one by any has to in explanatory entities that do not the idea of a noumenal world we cannot with in any the response should not be there are of blue behind the or there but explanatory do not have but no Das the that the irrealistâs to accept beyond the interface might be by the irrealistâs According to the irrealist cannot say what he is out to The is that the irrealist cannot the the as to something beyond the since for there is no such As such any this would be or he the as for something within the such as the representation of something beyond the interface. But the irrealist and his opponent to be about different the opponent about things beyond the he means mind-independent things with in some As such nothing the irrealist can say about such according to his disagree with what his opponent is resolve this it is to be that if irrealism is any theory that essentially on things beyond the interface needs to be this we cannot make such a theory part of our trying to between and Das is in that for the irrealist it is to an point outside of that representational but that does not that the of irrealism on such an The we to irrealism out to be is it according to the irrealistâs The to this to be a for the irrealist has the resources to that specific are not can that there are no and so he can that the beyond the representational is not Das the that if we make the assumption that on with entities the irrealist seems to be to to entities like and since he has with them. about the such a is since it our in with the entities The between the irrealist and his opponent is here not about the as such, but about to to It is that Das of in his of the he this to to real to a relation that us and our representational states with entities however, is an assumption that will appear to the we are that there is one relation that as a between the representational inside and the outside of the the irrealistâs claim that all our resources only to on to something within the representational is Yet there is nothing the irrealist from the as long as we it to about The of as to something within the representational interface than beyond it is an It is simply a of more in the debate about the cannot in on the of our theory by in since the of like and the like is by the other The is a that within the of the not a of the interface with entities that are not part of the interface. notes that that irrealism is not a but an about the external This might appear to The that I irrealism from is in the of truths it cannot be an that there is as would have it. The of irrealism with is on the idea that we can have an towards the external world there is such a world, or an is no such does not claim that we information to this but that on the of to us the more position is to the existence of an external world. or is a view of the world is the and irrealism is not. This is where the between irrealism and concerns the the irrealist into we accept a account of perception according to which the world we in is a that us will be on the The still on such as the two which will in on the they all the way to whatever the will on the since in the world us therefore have a of in which no is up the is a then nothing is real the sense of being have that that is and it if to an it is however, we simply up in a position to where we from inside the to the outside world of the our find ourselves inside the might also be that irrealism the and the theory about The a there is no behind the can we still make sense of the between the The an there is no true can we argue that are about the way things In response to the that the only in the interface. is nothing beyond the interface that the still be a the that is and we are epistemically with I it there are no the is and we are epistemically with like are are still The irrealist is hence not his and it since there are no in of he is not saying that there are no and that it the of so would by his point is that an we might up with a this however, that so that we will it. This is not if to get but by the for better than while we might to the of as this should not be as an theory that the of As the of is to point some position does not of the In this we should also point that something behind the of the that about mental the I to argue that no sense is to be of a behind the of can I still to the idea of of there being cognitive we since they are I do not that the of our cognitive that are inaccessible to us form a for the claim that all is The is for example by things that are to or of as by the of the and the of can about such and they can in our they to us in the way and them in to things that do and we inaccessible mental to of the mental we can As for the it is that out that we are about the way things cannot be the of outside of the of in to have an look the world. any must be from within the interface. we that certain as a world behind do not make sense we have this, we have not an true view of the world, an our view is better than the not in of approach to but in to the of The discussion in the by to the raised in the the whether it still a theory any true This is an which is in an of the debate between two different of the and The between these two is a matter of but one point is that is as some philosophical while is to be a with the any position of also the with a to the whether is to that the claims an irrealist be as might be part of a true a theory that does not to or but that of whatever there and is the point of our This point is simply âthe that our with an this is not a about the world, but a about our we carry them out according to the rules that form part of the in which we we find that we reach the that might have like has another it. I donât think there is here a would disagree but I also find it hard to see that this is an approach according to which is to are part of and about are by to that are also part of should this about by true means be to be an The I is that for there are two different sets of epistemic the of a of and is to truths about the world is the of water and so and the is to such truths as have no however, should we accept this of our epistemic it not the kind of epistemic that we to all of truths we might them in different I would to that we whether or not the on the is real water or a we the we trying to whether or some things are are with the epistemic we and have to all with some of these is no that us to the by it from those by epistemic outside of this about the whether the irrealist any It seems as if the irrealistâs can all be as claims about the of the with his the are to a to a no claim to or to such a claim can be to be have no for an can be to be in the world all the way or and The only other is are of a virtual world. we assume is we up with a the two of a theory of whatever there and of a point of our also be in of between the and his is the of all the claims by the true say that of whatever there is simply means that for the opponent up with the can show that the existence of to a Similarly, any entities to in an with can be further to an with The between this and the is that the is about the world, and to any entities still truths about the world, truths that are supposed to no matter what, or of there The to what is and is not in It is on by as the of and that certain entities cannot be in a theory of the world. It does however, a of the world that might why this is the these are then the is no whether or not the has a that of whatever there is and the point of our I that makes a case in of an But this in does not a that of whatever there is is to be Does this mean a about the world, or is it a about the we for the This it seems to the of the relation between irrealism and is as the position that I am while all other and things are a of my mental it is that the are irrealism is incompatible with the existence of any real However, we might also as the position that other are not of any about the of It is this form of that is in the discussion about the of other mental we for example in the of the two and it is also the one that we should have in in the we like we a representational or are different interface up as in a video or I the only one or are there other that do so as we about what is happening beyond our representational interface. such or is since it something the interface theory we cannot a view from outside of our interface into as it is in in to whether or not there are other we see from the The position that there are no other beyond our interface is as as the position that there is nothing beyond the since it the kind of true theory the in out to show to be The only response to the of the irrealist can is to say that from the within the interface which is the only we can there are other this does not provide us with any information about the of the irrealism and In one sense the is our view of the world the existence of other one then are they also real from the As long as an to this more than information within the interface it cannot be a from the can only be by us through our and if the interface our as a the existence of a in the the cannot be that my argument for irrealism on the of the world to the representational or as regarding it as a noumenal something behind the to which our This he such as or of the view of perception that forms the to much of the discussion in arguing that we should an account of According to such an are not representational about the they are and with the What this means on what we mean by âthe the world is an of and things in a mind-independent in a mind-independent a realist is into this of the view of This makes it of in a discussion where the of such a view of perception is being On the other the world also be with the representational interface. As for the irrealist our clearly are and with the representational the the position is clearly true from an irrealist the does not reduce to no more than in the to since the and the realist accept the existence of an true theory of the structure of the world, while the irrealist does not. on is the irrealist would to see an argument for the about the external world by or he the as from within the representational Similarly, to argue that a account of perception us ⊠with the objects or not be as being in with the irrealistâs It is that the here cannot be real entities out in a we would not be with a but with a realist view of But if the status of these objects is that they out to be of the representational or if they are simply with whatever our perceptual relation is to us to the irrealistâs of the representational there is no for the irrealist to to this account of While me in of a between an position and an beyond our epistemic reach I am about the the between the two of the might be to In some the can be as a to a world in it into a kind of hard to from the irrealist position in all but But of we cannot have it and must be that our response does not from one to the other to the of any is that the irrealist model be as it to account for the our appear to it seems to me that irrealism has resources to account for such for example no why of the should not be something that can within the representational nor would the claim that all perception within the of the interface that we cannot between or some according to the irrealist the and it does not link us up with entities of different in one a in the in we are to of our representational interface. But these are to other in different and it is this in structure that us to one from the in of us is likely to the of being be able to to in it will not this to the of our cognitive in a way that is quite different from the way our and this is what makes them as different of this is to point out that water cannot our but it does not from this that of water are and with the while of water are not. the are to cognitive states of one kind while the are to cognitive states of another kind The existence of these different us to and but it does not on that only the are with the also notes that we are of some features of the perceptual that are suggesting that the irrealist account for this by these features within the representational but that this would explanatory with and Yet this seems to that there is no more for such features than there is to example to in for the a with of of In the way in which the does not have to the âas if by an external of the of the features not be within the perceptual interface. a would the of the interface beyond It is only the features to that the perceptual interface has to from something like the features to something more
Ophthalmology is a discipline not merely concerned to the resolution of quantitative visual problems (visual acuity and visual fields), but, on the contrary, great number of patients of an ophthalmological office complain of the bad quality with which the visual tasks are related. âGoodâ vision in each eye, but with discomfort (asthenopia) may be caused by the lack of binocular fusion, be it due to the images of different sizes (aniseikonia, either by inadequate corrections of anisometropias or by different components â axial and refractive â of isometropias), be it due to diplopia and confusion (in heterophorias and convergence insufficiency). Notwithstanding, the most prevalent cause of such asthenopia discomforts is, essentially, monocular (although it may also be binocular), the intolerance to the use of accommodation. It is remarkable that in the history of ophthalmology, the accommodation is one of the newest ocular properties, only explained at relatively short time by Helmholtz,[1] but with its theory till recently disputed,[2,3] it allowed the differentiation between the concepts of hyperopia and presbyopia[4] and was quantified at the different ages by Duane.[5] As a matter of fact, the accommodation is an ocular function used in a practically continued mode. By definition, it should be in rest only if an eye is required to âseeâ objects at infinite distances while keeping the condition of being emmetropic or having hyperopia totally corrected by optical means. Hence, the natural, synchronic, association between accommodation and convergence for near fixations (a synkinetic relationship) led to propositions of formulations for an âobjectiveâ calculation of visual comfort.[6,7] The very laborious methods demanded the knowledge of the oculomotor balance at different positions of gaze, that of the respective binocular fusional capabilities and of the amplitude of accommodation. It is obvious that the evaluations of possible deviations of the visual axes at given distances (heterophorias) and the respective fusional capabilities of compensation are basic propaedeutic elements of the ophthalmological examination. However, in daily practice, such disturbances are of fewer clinical occurrences than those of accommodation and should be treated independently of it by several reasons, among which: (1) The relationship between accommodation and convergence is variable in different people;[8] (2) it is not reciprocal (accommodation evokes convergence â read as âophthalmic lenses change convergenceâ â while convergence almost does not change accommodation â read as âprisms practically do not influence accommodationâ;[9] and (3) although be assumed that the relationship between the stimulus to the accommodation, A (not necessarily its response) which causes a convergential effect (AC, the accommodative convergence) remains relatively constant during a subject's life (the AC/A relationship),[10] the convergence is, at the different ages practically unchangeable, while accommodation progressively decreases. At last, the accommodation performance may be even quantitatively normal for a specific age but â due to the continuity of the exercitation (to compensate for total or residual hyperopia) and/or by the relatively excessive and prolonged efforts to adjust images on the retina of objects at near distances â determine signs (esodeviations, by the accommodative convergence) and symptoms (headache, ocular pain, conjunctival hyperemia, lachrymation, blurring of images, âaversionâ to read and write, eyes rubbing, hordeola, etc. Therefore, as depending on the extension of time by which accommodation is exerted, the knowledge of its total capability (the measurement of its amplitude) is not so relevant than the amount by which its prolonged efforts (though a small part of such total capability) may be tolerated. Actually, for example, although a weightlifter may succeed to lift 1100 lb. by a very short time (a proof of maximal strain, as it is the measurement of the near point of accommodation, with which the amplitude of accommodation is calculated), he does not support to carry about a much smaller weigh all day long. Therefrom emerge the concept of accommodative tolerance.[11] Up to now, there are no rigorously established measurements for the accommodative tolerance, in different age groups. However, they may be estimated by empirical knowledge of approximate medium values for each age group and easily memorized [Table 1]. Variations of small magnitudes around them (e.g. ±1.5D or 2.0D for the 5-year-old group, but decreasing for older age groups) might be aggregated.Table 1: Approximative medium values of the accommodative tolerance (TA) for different age groups and respective estimated variationsAs a matter of fact, one knows that children with âhighâ hyperopia do not compensate them (though they might have, theoretically, higher accommodative capabilities to do so) and develop bilateral amblyopia by the worse quality of retinal images of such no conveniently corrected refractive unbalances. On the other side, it is well accepted that up to the 5 years of age hyperopia of +4D be âsafe,â well tolerated (continuously compensated, with no clinical problems). Therefore, for the 5-year-old children, that value (+4D), as a rule, should be the maximum dioptric value of no corrected (residual) hyperopia to be left, that is, the value of the accommodative tolerance for such an age group. For the 15-year-old group, it is exceptional that hyperopia over +3D (accommodation for ânear distancesâ is about 6D, or more, depending on the distance to the fixation point) be well tolerated. For 25-year-old people, the values of (sub-corrected or no corrected) well-tolerated hyperopia are reduced to about 2D (remember that 5D of accommodation is needed for the conventional near work distance); for the 35 years age group, the accommodative tolerance drops to, approximately, 1D; and at people 45 years old, it becomes null. A hyperope of +0.5D (who requires 3.5D â or more â for near distances) though might have an accommodation of up 6D does not, commonly, support exert it durably for his/her daily tasks. Therefore, one loses 1D of accommodative tolerance each 10 years, or about 0.1D/year, starting from the age of 5 years. This lead to the empirical equation of the accommodative tolerance (TA) as function of an age (y) as:[11] TA = 4,5 â 0,1 y How, then, is measured the accommodative tolerance of a patient, to know if it is, or not, adequate for his/her age? By now it is not measured. Nor, perhaps, such measurement shall one day be necessary, since the subject, or those who answer for the subject âknowâ that value. Therefore, simply ask for such a value, something as âWhat is the consultation reason?â Follow some examples about how to interpret the answer. Suppose three children, all of them with a +4D hyperopia in each eye and normal complementary examinations. Theoretically, the expected normal measurement for their accommodative tolerances should be 4.1D, practically identical to the value of the hyperopia. The âAâ child's parents relate that she started presenting a sporadic, intermittent, convergent strabismus some months ago, which became constant the last week. Till an opposite proof, we face a simple accommodative esotropia, to which the classical recommendation is the neutralization of the cause, a total correction of the hyperopia (+4D). The âBâ child's parents refer that they come to the ophthalmological examination only to know if everything is normal, there are no complaints, or manifestations which worry them. They are answering âOur child has accommodative tolerance for his 4D (minimum) of continued accommodative efforts, maybe more.â Hence, there is no validity to correct what is already naturally corrected, without signs and symptoms. Prescription zero. The âCâ child who presents a whole collection of very typical accommodative asthenopia signs draws forth more alternatives of optical prescriptions. Some would prefer to start by low prescriptions, as +1D. Now, a child who does not tolerate continuously accommodate 4 D for distant fixation and much more for near fixations (7 D or above), very much probably will follow with practically the same manifestations imputable to the use of accommodation, if it is kept in almost identical values (respectively, 3 and 6D). In an eventual return, the one decides to increase the correction to +1.5D with, probably, the same failure, for the mentioned reasons. It should be better to start with a âhighâ prescription, as +3.5D, which would neutralize, practically, almost all accommodative effort to distant fixations and would greatly reduce it for near visual work. Anyway, such a prescription very much probably would âelucidateâ the question, be it by making the signs and symptoms disappear, or by informing â if they were kept â that they are not due to the accommodative efforts (residual hyperopia of +0.5D in a child is too low as a possible cause). Obviously, would come the question: âBut the prescription could not be +3D?â to which the right answer is âI do not know. Let us ask the subject, or his/her family next timeâ.(It is expected that contented clients come back.). So, when the subject comes back, this value (+3D) is prescribed. Then, two things may happen: The return of symptoms and signs, though attenuated (conclusion: âWe have hit the bulls-eye with the first prescription, so that +3.5D is the accommodative tolerance of such a childâ) or the child remains healed (and the family happy, because âThe Doctor is decreasing the eyeglasses powerâ). Now, what about +2.5D? We do not know. Let us check next time, always with two alternatives: That by which the âcorrectedâ value of the accommodative tolerance for the child is found (then, +3D), or that with which the child follows without signs and symptoms and the family is grateful because the optical prescription is still lower (with the possibility it might be still reducedâŠ). Consider a young man, 20 years old, hyperopia +2.0D in each eye. The expected accommodative tolerance for his age is 2.5D which, theoretically, should be enough for the continued compensation of the hyperopia, but not, necessarily, for greater and persistent use of accommodation. Let us ask the young man. And he answers that he feels headache and visual blurring after some hours of using the personal computer (at 40 cm, i.e. +2.5D, which corresponds to 4.5D of prolonged accommodative efforts), but no complaints when the accommodation for near work is scarcely required (that is, he keeps an accommodation of 2.0D, or eventually little more, but not more and persistently). He is, clearly saying: âAlthough my accommodative tolerance be sufficient to keep me without continued correction of my hyperopia (2D of accommodation) I do not tolerate the sustained use of 4.5D of accommodation. I need eyeglasses for close proximityâ. If he had, also, complains for far visual attention, the prescription +1.5D for constant use (leaving an accommodation of only 0.5D for fixation to far objects and 3.0D for close work) should be convenient. However, by the young man report, perhaps, the prescription of +1.5D uniquely for the personal computer (at 25 cm) use be convenient, but the suggestion that he may use it also in a cine; or still a little more, eventually +2.0D (but then, only for near distances), and always based on the magnitude and subtleties of the informed complains. The benefits of using the accommodative tolerance concept for optical prescriptions imply the knowledge of the ocular refraction measurement with the accommodation totally relaxed, a condition which, by the way, corresponds to the proper definition of the balance state of the optical ocular system. However, as the accommodation is evoked by the command of an autonomic nervous system, the guarantee of such a complete relaxation is only given by cycloplegia. At last, optical prescriptions (mainly those of hyperopia) necessarily require two knowledges: That of the âstaticâ ocular refractometry (which is a kind of pleonastic construction, since there is no possible assurance of this measurement, if the accommodation is active, or âexcessiveâ, or spastic); and that of the accommodative tolerance (related to the subject's age and complains). Fortunately, however, those two only information, saving time of (other) examinations, are sufficient for almost the totality of good optical prescriptions.