Blockchain Papers

Qinglei Hu, Bing Xiao, Michael I. Friswell

This study investigates the robust fault-tolerant attitude control of an orbiting spacecraft with a combination of unknown actuator failure, input saturation and external disturbances. A fault-tolerant control scheme based on variable structure control is developed that is robust to the partial loss of actuator effectiveness, where the actuators experience a reduced actuation but are still active. The results are then extended to the case in which some of the actuators fail completely, although some redundancy in actuation is assumed. In contrast to traditional fault-tolerant control methods, the proposed controller does not require knowledge of the actuator faults and is implemented without explicit fault detection, separation and accommodation processes. Moreover, the designed controller rigorously enforces actuator saturation constraints. The associated stability proof is constructive and develops a candidate Lyapunov function that shows the attitude and the angular velocities converge asymptotically to zero. Simulation studies are used to evaluate the closed-loop performance of the proposed control solution and illustrate its robustness to external disturbances, unknown actuator faults and even input saturation.

A. J. Penny

Part of the SETI Institute's 42-telescope Allen Telescope Array (ATA) in California. (SETI Institute) Part of the SETI Institute's 42-telescope Allen Telescope Array (ATA) in California. (SETI Institute) The first Search for Extra—Terrestrial Intelligence (SETI) project of the modern era was done by Frank Drake in the spring of 1960, using the Green Bank 26 m telescope. He was looking for narrow—band radio emission from two nearby stars, t Ceti and ε Eri, over a frequency range of 400 kHz near the H i line. Since then there have been six major and many minor searches, made both on specific targets and also over the entire sky. The searches have extended to the optical and infrared, and to search for artefacts in the solar system and beyond. There have also been more than a thousand papers in the scientific press. The searches have all come up negative. What does this mean? Can future searches extend in a significant way the present area of the “ETI phase space” that has been searched for the existence of extraterrestrial intelligences (ETIs)? This article will briefly describe some of the component parts of SETI and put forward the case that SETI does indeed have an exciting future. SETI has two main aims. There is the expanding exploration of that phase space, always with the possibility of “contact” and the leap forward in our understanding of life in the universe and in many other fields of science and culture that would result. But SETI also addresses the future of humankind, looking for other civilizations that have trodden this path before us. If we find them, then we will know there is a possible way forward. If a particular SETI search comes up with a negative result, then we know that our future may not include the path that that search would have revealed. SETI activity has other components. It involves studies of: how evolution leads from the origin of life to intelligence; the rise and nature of technological civilizations; the problems of communications with fundamentally different entities; the possibilities of interstellar travel. It provides a logical extension to the growing field of astrobiology. Like all high—tech work, it has spin—offs, such as the Berkeley BOINC system of grid computing, originally designed to deal with the flood of SETI data from the Arecibo telescope with the SETI@home project, and which is now used in many fields, including medicine, molecular biology and climatology. And SETI provides a powerful forum for engaging with the public on the nature of scientific studies, using a subject in which the public is already interested. We know very little for sure. We know from our own example that technological civilizations can arise and persist for thousands of years, and send both “leakage” and deliberate radio and optical signals of their existence out to the galaxy. We know that our civilization arose in the last 10% of the age of the Earth before the increase in the Sun's output will render the surface of the Earth uninhabitable. We know that no ETI has left evidence of its existence in any of the searches that have been made, on the Earth, in the solar system, or further afield. Our existence means that other civilizations could exist, but gives no indication of their probability. Our recent knowledge of extraterrestrial planets suggests that Earths hospitable to life are common. However, since we do not know how life started, we do not know if life is common, rare, or if the Earth is the single case. Within the next decades the study of the atmospheres of Earth—like planets may resolve this point. However, we next do not know the probability that once life has started whether it then evolves to a technological civilization. We cannot say that evolution is bound to produce intelligence, and we are unable to predict the nature of other technological civilizations, or how long such civilizations exist. Civilizations thousands, millions, or billions of years older than ours could be of a very different nature to our own. However, the late arrival of intelligence on Earth is most compatible with an average time for the arrival of intelligence being much longer than the lifetime of stars, and thus with us being alone. But this is only a probabilistic pointer, not a proof. The view shows the first LOFAR station to be built in the UK at STFC's Chilbolton Observatory, with the Low Band Array in the foreground. Unlike conventional radio telescopes, there are no moving parts, but steering of the telescope is done in software. When completed, LOFAR will consist of more than 5000 separate antennas spread in ‘stations’ all over Europe. The project is based in the Netherlands where the core of the array is located. (STFC/SEPnet) The view shows the first LOFAR station to be built in the UK at STFC's Chilbolton Observatory, with the Low Band Array in the foreground. Unlike conventional radio telescopes, there are no moving parts, but steering of the telescope is done in software. When completed, LOFAR will consist of more than 5000 separate antennas spread in ‘stations’ all over Europe. The project is based in the Netherlands where the core of the array is located. (STFC/SEPnet) The lack of evidence of ETI is known as the Fermi Paradox. Once a civilization gets to our stage, it would only be a short time before it could build Von Neuman probes — autonomous self—replicating space probes — whereby every planet in our galaxy could be visited within a few tens of millions of years. The simplest explanation for the fact that we do not see such probes here, and that none of our searches have found signs of ETI, is that we are alone. However, there is no lack of credible alternative explanations of how the existence and even widespread existence of ETI would be compatible with the negative search results. These searches have as yet only explored a very small fraction of ETI phase space. So although there is some indication that we are alone, all we can presently say is that it is possible that ETI is out there, but we cannot with any degree of certainty predict how often ETI arises, or what their natures or lifetimes would be. The most common way of looking for ETI is to look for narrow—band radio emission. Our civilization emits such radiation from the 1 Hz wide carrier beam of analogue TV stations through to the kilohertz wide emissions of such things as airport radars. ETI may also emit such leakage radiation, although present searches are only sensitive to much more powerful radiation than we presently emit. Narrow—band radio waves are also the cheapest and most efficient method of interstellar communication that we know of, and so may be ETIs' way of communication, and even of signalling their existence to us (“beacons”). The narrow—band signature can also be distinguished from natural sources, even rare natural narrow—band ones such as masers. The Harvard and Argentinian searches with 26 m telescopes covered the entire sky, and the Arecibo “piggy—back” survey covered some 25% of the sky. But these have integration times of only a minute or so. The SETI Institute among others has done many longer integrations on individual targets such as nearby stars. Searches have become more powerful as receivers, electronics and data handling and analysis software improve, as for example in the billion 1 Hz spectral resolution channels of the 42—telescope Allen Telescope Array (ATA). The most recent surveys are now a trillion times more capable than Drake's 1960 observations. Following the recent development of high—powered lasers, which in theory could be matched with telescopes to outshine the Sun in nanosecond pulses, searches have started to look for such ETI signals in the optical. Pointed observations at Berkeley and Lick and an all—sky survey at Harvard are now looking for such nanosecond pulses. Again these are distinguishable from natural sources. If an ETI were using one of our most powerful lasers and a 10 m telescope, these searches would pick them up from hundreds of light—years away. More exotic radiation sources, such as the neutrinos from supernova SN1987A, are also investigated for signs of an artificial nature. The most famous such search was in 1967 when the Cambridge pulsar discovery team checked that the pulses had no sign of orbital motion. Different searches have different aims, usually based on some sort of premise of the nature of ETIs. The most obvious choice is of nearby long—lived stars, where ETIs on planets have had time to evolve. Such searches range from Drake's observation of two such stars in 1960, to the million stars planned for ATA. Since stars can differ in ages by billions of years, and ETIs take an unknown time to emerge, a search of a million stars gives a chance of picking up an ETI radiating for a thousand years, which may be a reasonable estimate of the time until an ETI changes into a fundamentally different mode. Then there are the all—sky surveys and surveys of areas of the sky, such as the galactic centre, where no presumption is made of where ETI is — on or off planets, near or far. These necessarily have shorter integrations per pointing, so are sensitive to rarer but brighter sources. The extreme of this is surveys of other galaxies, looking for extremely bright sources, but sources so rare that there is not one in our own Milky Way. There are also specialized searches. A recent proposal is for a search on the ecliptic plane, where an ETI would have been aware for a long time, using the radial velocity and transit planet detection methods, that there is an Earth in orbit around the Sun. Perhaps this would prompt them to signal to us. Searches have also been done looking for artefacts of an ETI civilization. The most famous of these are Dyson spheres, where an ETI surrounds a star with solar panels, probably on many discrete mounts, to tap a significant fraction of the star's energy. The outsides of these panels will be cool, shining in the infrared. Each new infrared catalogue that comes out is scanned for objects of strange non—natural looking colours. There have been searches for strange colours in the asteroid belt objects which might indicate an artificial nature, and for objects in the unstable Earth—Moon L4 and L5 Lagrangian points. There are notoriously many “sightings” of UFOs, which all have either been explained or have not contained enough information to determine their natures. The most interesting ongoing scientific investigation is the Norwegian Hessdalen Valley Project where there have been repeated sightings. The main limit on these searches is funding. There are almost no public funds. Very little sustained work is done outside the US, and within the US the main work is done through private funding and the efforts of determined individuals at Berkeley and Harvard. The SETI Institute, which grew out of the NASA work of the 1970s and 80s, is privately funded and the Berkeley and Harvard projects are done from within radio astronomy and electronics groups with university funding and private support. Outside radio and optical searches there is almost no concerted academic work on the other areas of ETI phase space such as solar system searches or catalogue analysis. Theoretical work depends on the intermittent interest of individuals. There is a lack of resources to fund fresh blood. Over the past 50 years there have been hundreds of papers describing the capabilities of searches and suggesting new methods. There have been as many speculating about the existence, origins, lifetimes and natures of ETIs, about composing and decoding messages, the prospects for interstellar travel and many allied matters. There has been much cross—fertilization with other fields including biology, philosophy, spaceship propulsion, linguistics and planetary science. Is intelligence a convergent property, etc? Some pointers to this extensive body of literature are given in the “Further reading”. An important field for SETI is the evolution of intelligence. Once life is started, does it then always evolve to intelligence? Intelligence seems such a useful attribute that evolution would home in on it, but for two billion years bacteria reigned alone. Since then there have been millions of species on Earth, out of which only one, us, has evolved advanced technology. Were we inevitable? Is evolution convergent? And then there is the “Man from Mars” problem, as it is known in linguistic studies. Can there be ways of communication that are so fundamentally different from our own that the message may be incomprehensible? Concepts such as “signs” and “signifiers” may not be present. How would a communication system based on smells be coded into a radio message? A standing controversy is whether it is dangerous to send out signals. In fact any advanced ETI would probably know about us already from our various radio emissions of the past six decades, or from visible signs such as the existence of our cities over the past four thousand years. And because we do not know about the nature of any ETI, a signal might either provoke or forestall an attack by any ill—intentioned ETI. So there is no reason not to transmit. But in any case there is probably presently little point, as signalling for thousands of years would be needed to give the class of ETIs not much more advanced than us a reasonable chance to pick us up. (Only such ETIs would not necessarily know all about us already.) In studying the future of humankind, we already know that certain classes of ETI, those that our searches would have picked up, are not common. How much does that tell us about the long—term evolution of civilizations like our own? Will we become a civilization that SETI searches could detect? Will we survive the bottlenecks of the near future: global warming, nuclear war, biological terrorism, grey goo, a catastrophic meteorite strike, the rise of the machines? In the more distant future, will we establish self—sustaining colonies off the Earth that will lessen our vulnerability? In the very distant future, will we become a race that can persist for a million or a billion years? SETI provides an avenue, the only observational avenue presently available to us, for exploring these puzzling questions. An example of how SETI thinks about our own future is the “Great Filter”. Taking from the Fermi Paradox that advanced ETIs are not common, Hanson (1998) pointed out that in the progress from star formation to such ETIs there must be a limiting pinch point. If this is behind us, then we are one of the extremely rare cases to have got this far, and our future prospects are not limited. But if it is in front of us, then we will very probably be extinguished. Paradoxically, discovery of ETIs like us, but not too advanced, would be bad news, as then it must be easy to get as far as us, and the Great Filter must be in front, and quite close. If we detect an ETI, what would happen next? First of all, there is the getting out of the news, and present SETI searchers subscribe to the International Academy of Astronautics SETI Permanent Study Group's “Post—detection Protocol”, which basically says “be sure, have it confirmed, and then spread the news widely”. No signal should be sent back until international agreement has been reached. In practice, the experience of search groups is that, when investigating ambiguous signals, the news can leak out in an uncontrollable way. What happens next would depend on the origin and nature of the signal. A solar system detection would have its own possibilities and problems. The result of a radio or optical detection of a distant source would depend on its nature. A continuous narrow—band signal which simply says “I am artificial” would revolutionize the scientific field and trigger funds for a great search for more details. Does it show signs of orbital motion? Is it associated with a star? It would also trigger public and philosophical interest. It is generally thought that the public would be intensely interested, but would not overreact. However, if there were to be some sort of code seen in the signal, then as well as the scientifically fascinating cryptological and linguistic tasks of finding out what the message is, the public interest would be overwhelming. Coming from an advanced civilization, does the message tell us how to behave, explain about religions, contain a cure for cancer? Is there some sort of danger in the message? If we respond, how do we have a conversation that may involve time lags of centuries? Astronomers would be interacting with the community in ways that are difficult to envision. Given the negative results so far, is it worth going on? We do not know what ETIs are like, so we cannot say how large the phase space of possible ETIs is and thus we neither know if we are looking in the best way nor what our chances of success are. Many SETI searchers remain optimistic. The quotation from Cocconi and Morrison's 1959 foundational paper that “The probability of success is difficult to estimate; but if we never search, the chance of success is zero” has many supporters. However, without knowing the nature of ETIs we cannot estimate by how much we improve our chances by any particular SETI search. Within the next decade we should be able to rule out (or discover) leakage radiation similar to our own from nearby habitable Earths — but the chance of hitting the perhaps thousand—year window for such radiation for a planet millions or billions older or younger than us must be very small. The author's personal opinion is that although we cannot know what our chances are it would be a failure of nerve not to go on looking, as long as each new search does cover significant new phase space at a reasonably modest cost. Planned radio searches will get more powerful, from the privately funded ATA array partly dedicated to SETI searches, to the use of new telescopes such as the European LOw Frequency ARray (LOFAR), for which the author is PI on a SETI Pilot Programme, and the South African 64—dish MeerKAT array, which has recently announced that it wishes to “explore further the potential for SETI”. And there is the giant Square Kilometre Array on which funding are to advanced receivers, electronics and software we are for giant forward. A major present is in the electronics and and so an in with and telescope that to and all—sky with in the other of searches, such as the optical new solar system searches of new and into the next decade is with possibilities to extend the ETI phase space we are by the almost lack of public funding. When to the public about SETI and tell them that almost none of their astronomy to SETI are that such an interesting field is being If the panels of the astronomy funding were to to fund SETI at a of one of one of their SETI would be and much more powerful and searches could be would be an thought for us all — that we were the search and in this into the unknown the race is looking

Michael S. Pardo

In a previous article, “The Gettier Problem and Legal Proof,” I argued that epistemic conditions that undermine knowledge in Gettier-type cases also potentially undermine legal verdicts. For this reason, I argued, there is a deeper connection between knowledge and legal proof than is typically presupposed or argued for in the scholarly legal literature. Thus, I concluded, legal proof includes something like a knowledge requirement – in the sense that legal verdicts aim not only at truth and sufficient evidential support but also, as with knowledge, an appropriate connection between their truth and justifying evidential support. This conclusion is compatible with different ways of articulating further epistemological details, and the argument that supports it does not depend on any novel or particularly controversial conceptions of the epistemic concepts or analysis of the Gettier problem. In a thoughtful reply to my article, Mark McBride focuses on the epistemic concept of safety as it applies to legal proof. McBride argues that my analysis depends on an account of knowledge in which safety is a necessary condition, and he argues that this dependence challenges my central claim. In this response, I explain why neither McBride’s specific examples nor general analysis undermine my central claim. They do, however, further clarify and illuminate epistemological issues underlying my central claim in ways that are useful and instructive.

M Thirunavukarasu

INTRODUCTION We, the generation living in the early years of the 21st century, occupy a special position in human history, in that we have witnessed unprecedented and unparalleled growth in the understanding and knowledge about the world around us and life on this planet. While we bask in that glory, let us not forget that there are some important and large questions that remain embarrassingly unanswered. The most conspicuous of those questions is one that is central to the field of psychiatry - “What is the mind?” Nevertheless, psychiatrists have brazenly avoided or ignored this question due to a learned lack of enthusiasm, given the historical inability to achieve a consensus about anything pertaining to the mind. Not to mention the inevitable criticism and/or possible ostracism that relentlessly pursues anyone who takes a stand on this controversial issue. Psychiatrists did not just want to open that can of worms! We simply hoped that if we managed to keep the can closed, the worms would suffocate and die and we would never have to face that uncomfortable question again. We believed that just like we managed to evade the exact definition of mental illness, we would be similarly successful in evading the definition of the mind. However, in the last several decades, human life has transformed so much that we are now faced with a relatively new concept - mental health, which too remains to be defined. The list keeps growing and our silence has been deafening. While our understanding of the human brain, human behaviour, and neurosciences has grown exponentially, the task of describing or defining the mind has also become increasingly difficult. Our wilful indifference or tactical retreat from confronting these tough questions is not helping us, one bit. Increasingly, we are educating ourselves with an explanation that any definition of mind or mental health is not even a possibility, let alone plausibility. Let me highlight the importance of this issue by discussing the well-known, controversial, yet insightful Rosenhan experiment. THE ROSENHAN EXPERIMENT In 1973, American psychologist David L. Rosenhan published the findings of his controversial study, ‘On being sane in insane places’ in the journal Science, stirring up a lot of reactions and criticisms among the psychiatric community.[1] It was a two-part experiment exploring the consistency and validity of traditional methods of psychiatric diagnoses. For the first experiment, Rosenhan arranged a group of 8 normal individuals called ‘pseudopatients’ who were known to have no psychological or psychiatric pathology. They included a psychology graduate student, 3 psychologists, a pediatrician, a psychiatrist, a painter and a housewife. Three of them were women and five of them men. Rosenhan was one among them. These pseudopatients appeared at 12 different psychiatric hospitals (11 university or state hospitals and 1 private hospital), reporting a false complaint of repeatedly hearing something such as “thud”, or “hollow” or “empty” and gaining secret admission. They used pseudonyms (false names) to feign their real identity. However, other than this fabricated complaint of auditory hallucination, no other and as would Rosenhan this experiment to if psychiatrists the pseudopatients with one fabricated as these were with the one who appeared at the private who was with of them were with and and at and to the study, these pseudopatients of the complaint admission. 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Pairat Thorncharoensri

In this thesis, we provide contributions to signature schemes and identi cation schemes in four di erent ways.\nFirst, we make contributions to universal designated veri er signatures. We propose the notion of a one-time universal designated veri er signature such that the number of veri ers verifying the signature is controlled by the signer. We also propose the notion of a universal designated veri er signature with threshold-signers such that the privacy and anonymity of the signer can be achieved.\nSecond, we propose a new notion called "policy-controlled signatures". In this notion, a policy-controlled signature can be veri ed by a veri er that satis es a policy assigned by a signer. We provide two extensions to this notion, which are "universal policy-controlled signatures" and "multi-level controlled signatures". Universal policy-controlled signatures allow a party called "a policy signer" to apply a policy on a signature on a particular message such that only a veri er that satis es this policy can verify this policy-controlled signature. In practice, some policies can be simply represented by a level of the security, for example, "POLICY= more than the fth level of security". From the above idea, a de nition of multi-level controlled signatures is introduced. It allows a signer to eliminate the unnecessary chain of attributes in the policy and simply assign the level of security as a policy instead. Hence, the size of the policy remains constant.\nNext, a new notion called "fair multi-signatures" is proposed. A multi-signature allows a group of parties to engage in an interactive protocol in order to generate a joint signature on an agreement. If all the signers follow the protocol honestly, then a multi-signature is generated and distributed fairly. However, if a dishonest signer refuses to complete his part in the protocol, but he has already obtained the other parties' contributions, then the honest signers cannot obtain a multi-signature and yet the dishonest signer can generate a multi-signature. Our notion of fair multisignatures ensures that if the protocol is completed, then every signer involved in the signing protocol can output a multi-signature. Meanwhile, if the protocol is not completed, then none of the signers involved in the signing protocol can output a multi-signature.\nFinally, in modern communications, the public becomes aware of privacy issues. Some identi cation systems provide privacy for users, especially those that are based on zero knowledge proof. However, a malicious user may take advantage of privacy to deny his malicious acts. Hence, we propose a new notion called "escrowed deniable identi cation schemes". In this notion, a trusted party is introduced to act as a transaction opener such that it can generate evidence of the conversation from the deniable transcript generated during the interaction between a prover and a veri er. In an identi cation scheme, the major concern about security is impersonation. The strongest type of attack against identi cation schemes is the reset attack. In this thesis, we provide an identity-based identi cation scheme secure against reset attack. We also provide proof of our scheme which is secure against reset attack in the standard model.

Hervé Chabanne, Céline Chevalier

No abstract is available for this record.

Shaoquan Jiang

No abstract is available for this record.

Somayeh Heidarvand

In this thesis, we investigate the notion of privacy for signatures belonging tothe second type, i.e., those which provide privacy with respect to the signed message. The first part of our work consists of one chapter in which one of the applications of blind signatures in on-line services and games is considered. In this way, we seek an ecient solution for a simple scenario in which a recipient can take a token from an issuer to be paid to an on-line service provider, without revealing anything about the service he intends to use. The second part of the work considers the problem of formalizing the notion of convertible non-transferable signatures, which is addressed in two chapters. Here the notion of transferability refers to transferring the validity of a signature with respect to a given message by the recipient of the signature to a third party. The basic idea for constructing concrete schemes for such signatures is to build a scheme in which a signature can be valid with regard to any random message unless some piece of information is revealed. Non-transferable (sometimes also called private) signatures enable the signer or the recipient to decide who can verify the issued signature. It is possible to construct such signatures by computing a non-transferable signature using a non-transferable proof (in an interactive or non-interactive way) to prove its validity to the designated veri er. The concept of non-transferable signatures was introduced into cryptography by proposing undeniable signatures, in which after is- suing the signature nobody can verify it with regard to the signed message without the cooperation of the signer. This restriction of veri cation is the point of dierence between traditional signatures that are universally veri able and non-transferable signatures. The best-known examples of non-transferable signatures are undeniable signatures, designated con rmer signatures, directed signatures, universally desig- nated veri er signatures, nominative signatures, etc. In the rst three signatures, it is the signer who is interested in making the signature recognizable only to himself or some pre-chosen party, while in the last two it is the recipient who makes the signature private to himself or some known party chosen by himself. Each of these signatures has its own natural application scenarios. Although these signatures are dierent in both nature and application, almost all of them are built from the same basic primitives: zero-knowledge proofs and commitments.

M. Thiyagarajan, S. Samundeeswari

No abstract is available for this record.

WU Yong-dong

An attack is mounted on a group signature scheme based on lattice posted in Asia Crypt 2010.It shows the group signature scheme is vulnerable to trap attacks and a dishonest group manager can get all group members′ signing keys and then forge all group members′ valid signatures.Meanwhile,the scheme can′t increase or delete group members flexibly and efficiently which is not applicable to dynamic groups.Every time a new member joins,the system has to update the public key and all group members′ signing keys which are of huge calculation and low efficiency.Also,the scheme doesn′t provide an effective method to revoke group members.Using statistical zero-knowledge proofs and time parameters,an improved scheme based on the hardness of the closest vector problem is proposed.The improved scheme is anti-trap attacks and can dynamic increase or deletes group members more efficiently and applicably.

Shuguang Liu, Michael D. Guiry

In this paper, we present a solution to the problem of e–contract validation in a supply chain with chain contracting topology. In chain contracting, there are multiple bi–lateral contracts that are related, for example one original contract between two partners is modified by subsequent negotiations to form other bi–lateral contracts between other parties in the supply chain. We study how to validate these contracts and ensure appropriate relationship between these contracts. We first identify key technical requirements for such a solution and then present our models that address these requirements. The models are based on the concepts of commitment scheme and zero–knowledge proof. It can be implemented in a contract engine that supports both the contract formation and contract execution phases of the contract life cycle. Also proposed is a cryptographic scheme to facilitate the electronic transfer of payments.

J. Ramkumar

In WS-BPEL process, Extensible Access Control Markup Language (XACML) is used as an authenticated tool to provide several services for an employee in an organization. There are several policies (XACML) used as an access control in Web Services. XACML policy as RBAC profile to support role based access controls policies. In an organization, there are several roles assigned to an employee based on their attributes. The attributes are used as an authenticating tool to assign the role and perform the task. The identity attributes are used for role provisioning policies to a particular employee i.e. social security number, date of birth, etc. are assigned as an identity attributes. In this aggregate zero knowledge proof knowledge (AgZKPK) and Oblivious commitment based envelope (OCBE) protocols are used during service (information) sharing between employees and to make it more flexible. This process may provide privacy to the user information and support multi-domain environment.

Dahui Li

RFID is one of the wireless network key technologies in NGN(next generation network).RFID tag dues to its basic functionsl,eading to the leak privacy problemI.ntroduces the RFID system composition,working principle,and analyzes the RFID in existing in the application of privacy issues of reason,then on RFID existing privacy protection schemes are analyzed,and points out its shortcomings.After the comprehensive understanding RFID’s privacy issues and some privacy protection technology founded,proposes a RFID identify agreement based on zero knowledge proof to promote healthy development of NGN.

Rony Patel, Jennifer Jacobs, Rochel Gelman

Memorizing Mathematics: The Failure to Apply Mathematical Axioms Within Restrictive Models Rony Patel Rutgers University Jennifer Jacobs Rutgers University Rochel Gelman Rutgers University Abstract: Arithmetic, along with all mathematics, is built on axioms. Mathematical education, however, favors mathematical models or algorithms without appeal to the axioms they depend on. Our series of studies demonstrate adult subjects’ inability to take advantage of the knowledge embodied in arithmetic axioms. It is likely that students’ ability to master generative proofs is related to the reliance on restrictive models. Our first set of studies focused on subjects’ ability to apply the addition-rule (mutually exclusive events) and the multiplication-rule (independent events) with multiple rational number representations (percentages, decimals, fractions, etc.). A second set of studies tested the understanding of group theory properties, exploiting the effect of the order of numbers (commutativity) and the effect of the digit zero (additive identity) on the long multiplication model (LMM). All studies conducted revealed participants ability to accurately perform arithmetic on chosen representation, but poor performance on choosing representation.

Mohammad Sadeq Dousti, Rasool Jalili

Abstract—Many cryptographic primitives, such as pseudorandom generators, encryption schemes, and zero-knowledge proofs, center around the notion of approximability. For instance, a pseudorandom generator is an expanding function which on a random seed, approximates the uniform distribution. In this paper, we classify different notions of computational approximability in the literature, and provide several new types of approximability. More specifically, we identify two hierarchies of computational approximability: The first hierarchy ranges from strong approximability—which is the most common type in the cryptography—to the weak approximability—as defined by Dwork et al. (FOCS 1999). We define semi-strong, mild, and semi-weak types as well. The second hierarchy, termed K-approximability, is inspired by the ε-approximability of Dwork et al. (STOC 1998). K-approximability has the same levels as the first hierarchy, ranging from strong K-approximability to weak K-approximability. While both hierarchies are general and can be used to define various cryptographic constructs with different levels of security, they are best illustrated in the context of zero-knowledge protocols. Assuming the existence of (trapdoor) one-way permutations, and exploiting the random oracle model, we present a separation between two definitions of zero knowledge: one based on strong K-approximability, and the other based on semi-strong K-approximability. Especially, we present a protocol which is zero knowledge only in the latter sense. The protocol is interesting in its own right, and can be used for efficient identification. Next, we show that our model for zero knowledge was not closed under sequential composition, and change the model to resolve this issue. After proving a composition theorem, we finally provide a version of the identification protocol which satisfies the requirements of the new model. Some techniques provided in this paper are of independent interest, such as proving a composition theorem in the presence of both simulator and knowledge extractor.

Bao Li

A generic way to construct a deniable group key establishment protocol from an unauthenticated group key es-tablishment protocol was proposed.The construction could be seen as a compiler.By using Schnorr's zero-knowledge identification scheme,this compiler could transform an unauthenticated group key establishment to a deniable group key establishment protocol with only additional two round communications and one round verification.It is very efficient and practical.The security and deniability proof is in the Random Oracle model.A concrete transforming example of the con-struction was also presented.

Zhenfu Cao, Zongyang Zhang, Yunlei Zhao

A zero-knowledge protocol allows a prover to convince a verifier of the correctness of a statement without disclosing any other information to the verifier. It is a basic tool and widely used in many other cryptographic applications. However, when stand-alone zero-knowledge protocols are used in complex environments, e.g., the Internet, the basic properties may not be sufficient. This is why researchers considered security of zero-knowledge protocols under concurrent composition and manin-the-middle attacks. Moreover, it is very likely that an adversary might break computers that run the protocol and get internal information of the parties. It is thus necessary to take account of the security of zero-knowledge protocols when adaptive corruptions are allowed. Previous adaptively secure zero-knowledge protocols work either in a stand-alone setting, or in a concurrent setting with trusted setup assumptions. In this paper, we study adaptive security of zero-knowledge protocols under both concurrent self composition and man-in-the-middle attacks in the plain model (i.e., without any set-up assumptions). We provide a construction of adaptively secure concurrent non-malleable zero-knowledge proof/argument for every language in NP.

Ronald Cramer

No abstract is available for this record.

Zeev Dvir, Dan Gutfreund, Guy N. Rothblum, Salil Vadhan

Abstract: We investigate the complexity of the following computational problem: Polynomial Entropy Approximation (PEA): Given a low-degree polynomial mapping p: Fn → Fm, where F is a finite field, approximate the output entropy H(p(Un)), where Un is the uniform distribution on Fn and H may be any of several entropy measures. We show: • Approximating the Shannon entropy of degree 3 polynomials p: Fn 2 → Fm 2 over F2 to within an additive constant (or even n.9) is complete for SZKPL, the class of problems having statistical zero-knowledge proofs where the honest verifier and its simulator are computable in logarithmic space. (SZKPL contains most of the natural problems known to be in the full class SZKP.) • For prime fields F = F2 and homogeneous quadratic polynomials p: Fn → Fm, there is a probabilistic polynomial-time algorithm that distinguishes the case that p(Un) has entropy smaller than k from the case that p(Un) has min-entropy (or even Renyi entropy) greater than (2 + o(1))k. • For degree d polynomials p: Fn 2 → Fm 2, there is a polynomial-time algorithm that distinguishes the case that p(Un) has max-entropy smaller than k (where the max-entropy of a random variable is the logarithm of its support size) from the case that p(Un) has max-entropy at least (1 + o(1)) · kd (for fixed d and large k).

Reza Sepahi, Ron Steinfeld, Josef Pieprzyk

No abstract is available for this record.

Paul Baecher, Marc Fischlin, Dominique Schröder

No abstract is available for this record.

Ching-Hua Yu, Bo‐Yin Yang

Abstract. When secure arithmetic is required, computation based on secure multiplication (MULT) is much more efficient than computation based on secure boolean circuits. However, a typical application can also require other building blocks, such as comparison, exponentiation and the modulo (MOD) operation. Secure solutions for these functions proposed in the literature rely on bit-decomposition or other bit-oriented methods, which require O(ℓ) MULTs for ℓ-bit inputs. In the absence of a known bit-length independent solution, the complexity of the whole computation is often dominated by these non-arithmetic functions. To resolve the above problem, we start with a general modular conversion, which converts secret shares over distinct moduli. For this, we proposed a probabilistically correct protocol for this with a complexity that is independent of ℓ. Then, we show that when these non-arithmetic functions are based on secure modular conversions, they can be computed in constant rounds and O(k) MULTs, where k is a parameter for an error rate of 2 −Ω(k). To promote our protocols to be actively secure, we apply O(k) basic zero-knowledge proofs, which cost at most O(k) exponentiation computation, O(1) rounds and O(k(ℓ + κ)) communication bits, where κ is the security parameter used in the commitment scheme.

Tobias Jeske

Smartmeters report the current electricity consumption over the internet back to their energy providers. Finely-sampled power consumption enables the energy provider to learn the habits of the customer's household in which the smart meter is installed. This paper presents a protocol which preserves customer privacy but also allows the detection of unregistered smart meters and prevents spamming and replay attacks. A trusted-third-party is not needed. This protocol, whose security proof relies on the strong RSA assumption and the random oracle model, is based on zero-knowledge techniques. The protocol has been implemented on different hardware platforms and benchmark results are given.

Bingsheng Zhang

No abstract is available for this record.