We present a technique that uses privacy enhancing technologies and biometrics to prevent the unauthorized lending of credentials. Current credential schemes suffer the weakness that issued credentials can be transferred between users. Our technique ensures the biometric identity of the individual executing the Issue and Show protocols of an existing credential system in a manner analogous to the enrollment and verification steps in traditional biometric systems. During Issue we create Pedersen commitments on biometrically derived keys obtained from fuzzy extractors. This issue-time commitment is sealed into the issued credential. During Show a verification-time commitment is generated. Correspondence of keys is verified using a zero-knowledge proof of knowledge. The proposed approach preserves the security of the underlying credential system, protects the privacy of the biometric, and generalizes to multiple biometric modalities. We illustrate the usage of our technique by showing how it can be incorporated into digital credentials and anonymous credentials.
Biometric Identification and Security
User Authentication and Security Systems
Advanced Steganography and Watermarking Techniques
Melissa Chase, Markulf Kohlweiss, Anna Lysyanskaya, Sarah Meiklejohn
A signature scheme is malleable if, on input a message and a signature, it is possible to efficiently compute a signature on a related message, for a transformation that is allowed with respect to this signature scheme. In this paper, we first provide new definitions for malleable signatures that allow us to capture a broader range of transformations than was previously possible. We then give a generic construction based on malleable zero-knowledge proofs that allows us to construct malleable signatures for a wide range of transformation classes, with security properties that are stronger than those that have been achieved previously. Finally, we construct delegatable anonymous credentials from signatures that are malleable with respect to an appropriate class of transformations (that we show our malleable signature supports). The resulting instantiation satisfies a stronger security notion than previous schemes while also scaling linearly with the number of delegations.
With an estimated 50 billion internet-enabled devices deployed by 2020, the arrival of the Internet of Things (IoT) or Internet of Everything (IoE) raises many questions regarding the suitability and adaptability of current computer security standards to provide privacy, data integrity and end entity authentication between communicating peers. In this paper we present a new protocol which combines zero-knowledge proofs and key exchange mechanisms to provide secure and authenticated communication in static machine-to-machine (M2M) networks. This approach addresses all of the aforementioned issues while also being suitable for devices with limited computational resources and can be deployed in wireless sensor networks. While the protocol requires an a-priori knowledge about the network setup and structure, it guarantees perfect forward secrecy.
This thesis discusses symmetric random walk, its definition and basic properties. The outset is focused on the probabilistic model and subsequently on basic properties, such as the final position at time n, its mean value and variance. Furthermore, we will see what the scaling must be for the walk to converge to zero, precisely what is the consequence of the strong law of large numbers. In the second chapter we will examine the distribution of the maximum of the symmetric random walk. In chapter 3 we will define stopping time and Markov property of random walks. Then we proof many auxiliary lemmas using basic knowledge of combinatorics. The final part is devoted to the proof of the arcsine distribution, which shows great persistence of the symmetric random walk. Powered by TCPDF (www.tcpdf.org)
Electronic cash is an electronic form of currency, which allows the cash transactions over communication networks under privacy protections. However, it still has some aspects that have not been well studied. Known constructions suffer from at least one of the following limitations: (1) relying on a random oracle, (2) not supporting multiple bank setting and users dynamically joining or (3) prohibitively expensive. In this paper, we propose a new electronic cash system that avoids all these limitations. In other words, our system is anonymous against chosen-ciphertext attack (CCA) in the standard model, and supports multiple banks enrolling and users dynamically joining, which is achieved by the utilization of non-interactive zero-knowledge proof and dynamic group signature. Finally, in the standard model, a formal security proof is given to claim that our system has CCA anonymity, unforgeability, traceability and no double-spending. Compared with the existing systems, ours has advantages of both the efficiency and security.
In this paper, we propose a novel cryptographic notion called subset membership encryption (SME), and provide a very efficient SME scheme. Given a system parameter generated by an encryptor (Alice), a decryptor (Bob) generates a randomized privacy-preserved attribute token P(G) from a set of attributes G. A message is encrypted using an attribute set A chosen by Alice and P(G) provided by Bob. It requires that A is a subset of G for Bob to decrypt the message. We propose a very efficient SME scheme, where both the size of P(G) and ciphertext are short and independent of G and A. In particular, it has three useful and practical applications to oblivious transfer as follows. 1) k-Out-of-n Oblivious Transfer (OT): SME can be naturally applied to a two-round OT, which features a great communication efficiency especially for the receiver, where the receiver only sends two group elements to the message sender. 2) Priced Oblivious Transfer (POT): Our POT protocol allows a buyer to purchase any number of items in each transaction and hide selected items, price and balance from the vendor. In comparison with previous POT protocols, our protocol is more flexible and eliminates the restriction that a buyer can only purchase one item in a transaction. Our POT scheme is very efficient since it does not require any zero-knowledge proof or homomorphic encryption. 3) Restricted Priced Oblivious Transfer (RPOT): We introduce a novel POT named RPOT where a vendor can set restrictions on items or prices in POT. For example, a seller could offer a discounted price to those buyers who have purchased some specific items previously from the same seller.
Consider the radial nonlinear wave equation $-\partial_t^2 u + Îu = u^3$, $u :\mathbb{R}_t \times \mathbb{R}_x^3 \to \mathbb{R}$, $u(t,x) = u(t,|x|)$. In this paper, we construct a Gibbs measure for this system and prove its invariance under the flow of the NLW. In particular, we are in the infinite volume setting. For the finite volume analogue, specifically on the unit ball with zero boundary values, an invariant Gibbs measure was constructed by Burq, Tvetkov, and de Suzzoni as a Borel measure on super-critical Sobolev spaces. In this paper, we advocate that the finite volume Gibbs measure be considered on a space of weighted Hölder continuous functions. The measure is supported on this space and the NLW is locally well-posed there, a counter-point to the Sobolev super-criticality noted by Burq and Tzvetkov. Furthermore, the flow of the NLW leaves this measure invariant. We use a multi-time Feynman--Kac formula to construct the infinite volume limit measure by computing the asymptotics of the fundamental solution of an appropriate parabolic PDE. We use finite speed of propagation and results from descriptive set theory to establish invariance of the infinite volume measure. To the best of our knowledge, this paper provides the first construction and proof of invariance of a Gibbs measure in infinite volume outside of the 1D case.
Open access
Advanced Mathematical Physics Problems
Nonlinear Waves and Solitons
Stability and Controllability of Differential Equations
Privacy is of the utmost importance in genomic matching. Therefore a number of privacy-preserving protocols have been presented using secure computation. Nevertheless, none of these protocols prevents inferences from the result. Goodrich has shown that this resulting information is sufficient for an effective attack on genome databases. In this paper we present an approach that can detect and mitigate such an attack on encrypted messages while still preserving the privacy of both parties. Note that randomization, e.g.~using differential privacy, will almost certainly destroy the utility of the matching result. We combine two known cryptographic primitives -- secure computation of the edit distance and fuzzy commitments -- in order to prevent submission of similar genome sequences. Particularly, we contribute an efficient zero-knowledge proof that the same input has been used in both primitives. We show that using our approach it is feasible to preserve privacy in genome matching and also detect and mitigate Goodrich's attack.
Nesrine Kaaniche, Ethmane El Moustaine, Maryline Laurent
Recent technological advances have given rise to the popularity and success of cloud storage. However, the prospect of outsourcing an increasing amount of data to a third party and the abstract nature of the cloud foster the proliferation of security and privacy challenges, namely, the remote data possession checking. This paper addresses this critical security concern, when storing sensitive data in a cloud storage service, and the need for users to trust commercial cloud providers. It proposes a deterministic Proof of Data Possession (PDP) scheme based on Interactive Proof System(IPS) and an original usage of the GPS scheme. Our approach has several advantages. First, it supports public verifiability which releases data owners from the burden of a periodical verification. Second, it provides constant communication complexity, where the exchanged messages between the storage server and the client are composed of constant number of group elements. Third, our solution is efficient and provably secure, as it is resistant to the fraudulence of the prover and the leakage of verified data.
Quantum zero-knowledge proofs and quantum proofs of knowledge are inherently\ndifficult to analyze because their security analysis uses rewinding. Certain\ncases of quantum rewinding are handled by the results by Watrous (SIAM J\nComput, 2009) and Unruh (Eurocrypt 2012), yet in general the problem remains\nelusive. We show that this is not only due to a lack of proof techniques:\nrelative to an oracle, we show that classically secure proofs and proofs of\nknowledge are insecure in the quantum setting.\n More specifically, sigma-protocols, the Fiat-Shamir construction, and\nFischlin's proof system are quantum insecure under assumptions that are\nsufficient for classical security. Additionally, we show that for similar\nreasons, computationally binding commitments provide almost no security\nguarantees in a quantum setting.\n To show these results, we develop the "pick-one trick", a general technique\nthat allows an adversary to find one value satisfying a given predicate, but\nnot two.\n
Quantum zero-knowledge proofs and quantum proofs of knowledge are inherently difficult to analyze because their security analysis uses rewinding. Certain cases of quantum rewinding are handled by the results by Watrous (SIAM J Comput, 2009) and Unruh (Eurocrypt 2012), yet in general the problem remains elusive. We show that this is not only due to a lack of proof techniques: relative to an oracle, we show that classically secure proofs and proofs of knowledge are insecure in the quantum setting. More specifically, sigma-protocols, the Fiat-Shamir construction, and Fischlin's proof system are quantum insecure under assumptions that are sufficient for classical security. Additionally, we show that for similar reasons, computationally binding commitments provide almost no security guarantees in a quantum setting. To show these results, we develop the "pick-one trick", a general technique that allows an adversary to find one value satisfying a given predicate, but not two.
Yiannis Sakellaridis and Akshay Venkathesh have determined, when the group\n$G$ is split and the field $\\F$ is of characteristic zero, the Plancherel\nformula for any spherical space $X$ for $G$ modulo the knowledge of the\ndiscrete spectrum.\n The starting point is the determination of good neighborhoods at infinity of\n$X/J$, where $J$ is a small compact open subgroup of $G$. These neighborhoods\nare related to "boundary degenerations" of $X$. The proof of their existence is\nmade by using wonderful compactifications.\n In this article we will show the existence of such neighborhoods assuming\nthat $\\F$ is of characteristic different from 2 and $X$ is symmetric. In\nparticular, one does not assume that $G$ is split. Our main tools are the\nCartan decomposition of Benoist and Oh, our previous definition of the constant\nterm and asymptotic properties of Eisenstein integrals due to Nathalie Lagier .\n Once the existence of these neighborhoods at infinity of $X$ is established,\nthe analog of the work of Sakellaridis and Venkatesh is straightforward and\nleads to the Plancherel formula for $X$.\n
BIOLOGY has evidently borrowed the terms âheredityâ and âinheritanceâ from everyday language, in which the meaning of these words is the âtransmissionâ of money or things, rights or dutiesâor even ideas and knowledge âfrom one person to another or to some others: the âheirsâ or âinheritors.â The transmission of propertiesâthese may be things owned or peculiar qualitiesâfrom parents to their children, or from more or less remote ancestors to their descendants, has been regarded as the essential point in the discussion of heredity, in biology as in jurisprudence. Here we have nothing to do with the latter; as to biology, the students of this science have again and again tried to conceive or âexplainâ the presumed transmission of general or peculiar characters and qualities âinheritedâ from parents or more remote ancestors. The view of natural inheritance as realized by an act of transmission, viz., the transmission of the parent's (or ancestor's) personal qualities to the progeny, is the most naive and oldest conception of heredity. We find it clearly developed by Hippocrates, who suggested that the different parts of the body may produce substances which join in the sexual organs, where reproductive matter is formed. Darwin's hypothesis of âpangenesisâ is in this point very consistent with the Hippocratic view, the personal qualities of the parent or the ancestor in question being the heritage. Also the Lamarckian view as to the heredity of âacquired charactersâ is in accordance with those old conceptions. The current popular definition of heredity as a certain degree of resemblance between parents and offspring, or, generally speaking, between ancestors and descendants, bears the stamp of the same conceptions, and so do the modern âbiometricalâ definitions of heredity, e.g., as âthe degree of correlation between the abmodality of parent and offspring.â In all these cases we meet with the conception that the personal qualities of any individual organism are the true heritable elements or traits! This may be characterized as the âtransmission-conceptionâ of heredity or as the view of apparent heredity. Only superficial instruction can be gained by working on this basis. Certainly, medical and biological statisticians have in modern times been able to make elaborate statements of great interest for insurance purposes, for the âeugenics-movementâ and so on. But no profound insight into the biological problem of heredity can be gained on this basis, for the transmission-conception of heredity represents exactly the reverse of the real facts, just as the famous Stahlian theory of âphlogistonâ was an expression diametrically opposite to the chemical reality. The personal qualities of any individual organism do not at all cause the qualities of its offspring; but the qualities of both ancestor and descendant are in quite the same manner determined by the nature of the âsexual substancesââi.e., the gametesâfrom which they have developed. Personal qualities are then the reactions of the gametes joining to form a zygote; but the nature of the gametes is not determined by the personal qualities of the parents or ancestors in question. This is the modern view of heredity. The main result of all true analytical experiments in questions concerning genetics is the of the transmission-conception of heredity, and the different of as as have in that to the same point of view, the as we may the conception of heredity just Here we can not the of the ideas concerning heredity, not even in the but it be as a that a very great of the terms by the modern biological have been the of the and that the of and are not from that old may be words as âtransmissionâ and The science of genetics is in a an science just as the in the times of who the an in chemical The as have the modern view of heredity, not from the old âtransmission-conceptionâ as but it from the of and who with more or less tried to the the great of the for the in of more in of and in of but have suggested that the elements for inheritance elements of or of the different or of the individual from the in question. has an elaborate hypothesis of heredity, that of the are of in the of a in the of a being in some the of an or a of that in the to organs, and that of the are of parts of the inheritance in question are the or ideas may have some interest as of the but they have no in the of is evidently the a view of heredity any The of the by and but as an expression of the insight by and is in the degree a all the of and it may is a that is not we to even to but that it may be by of the to the current This is the it is to a in all cases where or are being developed. terms are by their in or and from which they of not to the have the terms and and some as and to be in the science of The is nothing but a very with and it may be as an expression for the or in the by modern is the of all the in a or in a a is by the of this is in one point and the of the gametes in question in one point from to the nature of the it is as of no to any but that the a is from The have the great of being in their In accordance with this quite natural the of the may be to the of the We do not a but we are able to or in these the and The very by as may be with in so as the is the of the of the in question. these are is by the as of The the and the in the of the individual the organism is a and its reactions are determined by its with the of all may it be or the is with the The can be by the qualities and reactions of the in question. that some of are different then these produce more or less as to the personal qualities of the individual of of different it be quite to they have or have not the same we to be We may find that the in question so that they to the same the current of this or we may in cases that they a so that or more different may be of by or by of or may be characterized as are real the or of are again and again the for in the are and the of the of as to and characters of the has been the of natural which was a science of by the of the has of with in its concerning The of by from one to another have and the of are the in very but that is an point may be in one which the the view the of the in different are the main and the transmission-conception we may this conception as a in to the the has been gained in and The to an of the or the may an of the of the The of has its most in all where the are where with the or by to one this being characterized by the of the of any of and so This is to the all between the different in question the of and and have the point for as a of may be as the from one by is a nothing as to the qualities of the in question. to be (or even the of a of can be as as are very of be quite in and in to one and the same the was but The of the is a main point in the of of nature is not at all a for the of with is the of which the of have some The of from has been the for the that is not able to the nature of The of the of a by from to in the by the to the a of in the a great of those is for the of the of any be for the result of the no or have been at a in which is no as to the in have no This result has in been by in Here may the experiments of with experiments which have been quite of and which have been of great for the and of the The of these experiments has been on the that the but this matter to of no in the The that of and of in the of as a is a of the Also experiments with the of and the of as to may be as for this has at the same as to the by The famous of and its by to have the of in by the of the of in these of correlation have been in their of may be in but they have nothing at all to do with genetics or general are for insight into the nature of heredity. to heredity, it is a expression for a The are the in but generally the in is In no of the can be all of the as to the of and may even a that the is in in heredity speaking, a of the âtransmission-conceptionâ and nothing The characters of ancestors as as of are both in quite the same manner reactions of the of the gametes in question. between an ancestor and one or more of as heredity is in the as we have to the is not a of the personal of any The of a or a may be with a This in of its realized but not in of the of its it may be with the of gametes and its is its which are determined by its In the in are in of are The it is to by of any individual the to which it the the as as in the no The is an view of the reactions of as as true heredity is This view is an to the chemical view, as chemical have no is and in the same may be the of its or the of its that it is to this of heredity in its to the to the of we meet with true viz., the of and all of is a very great but is quite different from heredity. may be of and the of is not an is in to as of some of or in their of the of from more Certainly, of of and of all on by of with the not the but their But all this has nothing at all to do with the biological of heredity. is of to that the of by has in but this nothing as to for which is The very form of the may be to be in all its in cases of experiments in In nature and even in the chemical the chemical are not to be in quite The of a may be by to the with the we the question the of a may not be by some or from the individual organism in which the was developed. Here we meet with the cases of heredity, e.g., the of the gametes or as may be in certain cases of and of heredity may have the of or but they do not at all with the of heredity. In cases as that by viz., the âheredityâ of a form of by âtransmissionâ the of the not this may at the be as we have to do with a of the or the in and that may be the for the of heredity the which no or a The of being as quite it may be very to clearly from determined which the form of heredity both and The and not to be in with of any may be to in the and consistent of the that may be characterized as by or it be that as as are no between and of is but not is a The of or, is of for the question of the inheritance of âacquired and are in the most both the of the with the the with the of the of the in question. The of with and the experiments of that of the are by as no with has any for the Lamarckian view, the most to the experiments by for the of their have not but have the of some by and are at the same the in personal qualities being to the in are their of it is that their in biology as ideas has been most some cases of apparent of may have with Lamarckian e.g., of by as âthe that has of the was that with analytical that has the great But at the the from the is in on the of for are for the the that the was not at all the of to point the of as to the of in The and more the The of or of in may be for the of not to we have an times by viz., the of with as it has been that we have the essential The in have been the the been from the and to the result be a of the those The to to no for the The are a to of with and in the of this are to any questions of and they make as to the nature of heredity and has the of as a be an in heredity. to the of it has been by e.g., that is a old and This is quite not in a manner the of but even tried a to But it can not be that the of as a true analytical as an of in as a at any and of a from this analytical been in the times of or it even been in by the the real of have been by the of The may then be characterized as and may to a certain with the most of of with a of for a a we may even that the may be as of the or ideas may as be but they are by the of The of a in question is the conception at by and is a between different This has been by may be as an In very on experiments with as that was as a of of and experiments to the Lamarckian view have as even these may be as all the of experiments is in quite in of But we in and that for a of the the is a The of in question is to this can not statements just as to their but accordance with conception the famous words from the be from and some very of have the for the is that we different as different in This is an essential but no in the to that view be In a very manner be for are the in the degree or of any as it different e.g., the of by and may be very as of the of the in and they a in The of the in question between the but this is not the e.g., with or even with very some of the are the between the may or may even with of as to the in the and is no as to their But that these are with the of between the to have the the of the the reactions of the may different all of or has nothing at all to do with or of of genetics to some may to has great the of in all of from to may be with different in of the to not from that be of may in one be different in e.g., the of the that of In another may or their may be of may produce and it is to that some of on the reverse is realized on In of both characterized by a degree of to produce in the the in of The are the of the in as as in the just are of just as as the of different chemical as to chemical it may be to that different chemical or of which are to be and may quite to point the of for different of and in different or in with The essential point in the matter of that a in the same manner all chemical or in as in chemical or are not to at less to do so in the same all even quite may be for the of as some are to a This is a in as in the of has the of this point for the the of as to the and are a of the and we find in current this of with and we even have with the that the of a may in in different or but that in they into one In this of the of the in a is that view has been by in this but be in the is not for an to with questions of and between the are the of and the of and is We have with some of the it is to at The of this of has an of and cases that at with the have been more on a and have quite in accordance with The of a of this of it may be that the most of the essential point in the of the personal in heredity. the same it the of as being by the of the that the personal qualities of the organism in are the of the reactions of the The of one of may have the the of for any to be even in cases where no of to as to the cases of it is not to of the in the or for their and being reactions of that may have in the be a of to the of different as as Here we meet with the questions of correlation and of can not into a discussion as to the of with its in a discussion is to be may point that cases of presumed correlation may be cases of or more characters to the even one The and even the that they are reactions of different The of and as to the are in some with of correlation and of The discussion of the for and as to may the of may be has in as to in a of the the of we an between the of and the the in manner may be able to of the the main of the a on this it may be suggested that the or of a may be more to from its the from the of the may be of any as working as to the of is the nature of these can not as a discussion be in that the is and and even have this the in their and has clearly that it may be quite to a is to or to the of a in the that can as be determined in this by is the of between the gametes a may be The facts, that a may be in some but in and that in different cases may be very that are The famous of as to the form of may be as an In the is in it is and in both cases the one has that is a of and from in one as with But from in with as in and in the with this it is as not to or is the form of for the of which the of are to be the most is the most may even be an expression for a of in the The of the by in all cases be and it is quite to that the of the in are in cases in but in as to with chemical reactions it be in that a may be the of of any as as the of any in the in question. The elaborate of of has very and the most is the most of any in question. The or in are quite the of in the it may be that for one may be elements for the of quite this be the then the of characterized by the of in the of different able to may be by a in which be any is no to that the the of into The of by of the of are a of interest in this to cases of in which and do not the it at be that some apparent are by of the for The experiments of and have to that may and be or as to the of the is no for or In inheritance we meet with of the same nature as in the of as the for the more or less of the different of in may the as has in cases the different degree of with which the of gametes is realized may the of in the as has Here we can not the in a of the a of concerning this Only one of may be viz., the to or In cases of inheritance the in question be to by the act of or, in accordance with the and the to the in some manner be In this which is very with the conception of as be of to be in the of the modern some cases in the of as to the of to be a the insight by experiments as as by concerning the of has the question in a The of and have to quite as to the of In cases no is no is in cases is no for any or of as to this has the in question. But cases of these as to the of the of are the most and most has in a and manner that the in with the be of cases to these and gained an with and was in But even this may with The for is has clearly of the concerning the of the with the of the of that of and in is a The is determined by different in the same and the of by and of these a of in be these the of the in question. we have to and we for the the which is between as and as in of no a as an and it is not to find that the of the of the be the of the so it is in the of experiments with as has clearly of heredity in concerning both and may be with in question. in that certain in for the view that we have no inheritance but true as as in the cases of as we may in the cases of may then in a more manner the true nature of the apparent in as we can that this not with be in that have been very between the in these experiments are with great and parts of the those may have can not be to it is that in may have great the and in a which into and to be into has a very the and form of the in question. Here are not the the of viz., that or characters may be determined by different and that one of may have different it that is in a very but may be even very for this the may be into But is to do in the as as to the is as the of be a with But all the of the of do not as to to the that the of and so on may be regarded as or of the and of all things in the as their This view is even in those cases where can be In the discussion as to the of true the have of a as characters of in cases where the elements of the in question are as it may be is not at all for the of But the of for is quite different from the that elements have for the of heredity. The question of as the presumed of to be an not able to any for âthe of the in the The organism is in its and by its parts of the individual are as to In has been no as to this and as to has for a the same view the of and who have suggested that is determined or at any by a of the we the in the of the The of and the of parts in the individual may their the of the But these as a not or the of the in question. on we the problem of by Here we have to point the that with a more those substances or the reactions of which we of characterized by the of The of the of their to that this as as the and of in the some of the of The discussion of to the question of or In the of modern of presumed of in e.g., as to in But more analytical experiments have in cases in the the characters in question to be more reactions at has the question in a quite a working the be not of but of the gametes as a not be as the by of the of a with be of of the that this be able to âthe of so with in and so or by Here we again the question of that the by and are more consistent with the real nature of the in question. the has not been able to that cases of are of but even the as to in and by as a not to any real for cases as has viz., nature being for in some may at the of being to or to different of in the in question. But a to the real of The very of as to the of certain characters in have clearly a or a in of any be in that a of are in and these concerning all and a to the of all it be suggested that in parts of the some of may or even the of which the The to be to the of by e.g., the of and of Here we the of in or with so by be a for the of the in e.g., for the nature of the of the (or for the in not be produce at are to point that may have a as to but that this question is in of the problem of or may be but the in modern genetics in the of as the we the of as an essential for the of matter in and for the or of we in of to find in the of and the of the and in be But this is not the The experiments of in a manner the of in the a degree of and in things it we may in modern genetics be of the and of that things in nature may be and the in heredity we may the in nature as as in more of the famous of and the of to the modern of and all as to point the of the in question. Here we not the it is to that the essential point is the or of of the The experiments of as to have in the most manner that the which produce the in this viz., the and of are able to act in a manner the of the and has the of in with the may in some cases be certain to be by but it is that in all is the in the of to the of which may the of of be that are from by in be with But is no for this in the between the in characters may be a of as it be is not at all with has the between the of in and in and as the in nature have all as in experiments with The chemical to may be the of and so on. The may be by more But are of very for the of The by the great of experiments as to and not personal as a of any as by and been are meaning from point of of characters gained to an of and the may the of as to may be as to the old question of this problem in the famous cases of has in a most manner been into terms by the and experiments of and This of the and has been for for the The not to a true or of heredity, but may be regarded as an for an that in its may be to be and even all may some to But as it to be the most in may then be as the of in ancestors and descendants, or, as in accordance with this heredity for those of the that find their expression in the and developed it is to this for its real but for the and of the great problem of heredity. In this the of famous as in as in has been the for the and the old in This is a in the of the of it at and to ideas of and in and a great of the of But just these qualities have the of for the analytical of modern which has in a true in
In this article, the authors propose an approach for privacy preserving distributed clustering that assumes malicious model. In the literature, there do exist, numerous approaches that assume a semi honest model. However, such an assumption is, at best, reasonable in experimentations; rarely true in real world. Hence, it is essential to investigate approaches for privacy preservation using a malicious model. The authors use the Pederson's Verifiable Secret Sharing scheme ensuring the privacy using additively homomorphic secret sharing scheme. The trustworthiness of the data is assured using homomorphic commitments in Pederson's scheme. In addition, the authors propose two variants of the proposed approach - one for horizontally partitioned dataset and the other for vertically partitioned dataset. The experimental results show that the proposed approach is scalable in terms of dataset size. The authors also carry out experimentations to highlight the effectiveness of Verifiable Secret Sharing scheme against Zero Knowledge Proof scheme.
Cognitive radio plays an important role in improving spectrum utilization in wireless services. In the cognitive radio paradigm, secondary users (SUs) are allowed to utilize licensed spectrum opportunistically without interfering with primary users (PUs). To motivate PU to share licensed spectrum with SU, it is reasonable for SU to pay PU a fee whenever the former is utilizing the latter's licensed spectrum. SU's detailed usage information, such as when and how long the licensed spectrum is utilized, is needed for PU to calculate payment. Providing usage information to PU, however, may compromise SU's privacy. To solve this dilemma, we are the first to propose a novel privacy-preserving mechanism for cognitive radio transactions through commitment scheme and zero-knowledge proof. This mechanism, on one hand, only allows PU to know the total payment to SU for a billing period, plus a little portion of SU's usage information. On the other hand, it guarantees PU that the payment is correctly calculated. We have implemented our mechanism and evaluated its performance.
Looping of the colonoscope shaft is the most common problem associated with a colonoscopy procedure. One study has shown that looping occurred in 91 out of 100 cases [1]. Looping can have a variety of effects ranging from extended procedure times, incomplete examinations, or even perforation of the colon wall [2]. Another study shows that 37 perforations occurred in 116,000 patients [3]. Looping increases discomfort for the patient, requiring larger amounts of anesthesia, and increasing operation time. Looping forces the doctor to reposition the colonoscope by twisting and retracting the shaft with varying degrees of success. This additional maneuvering of the colonoscope shaft during the procedure places extra stress on the inner lining of the colon wall.The problem of looping can be lessened with the help of manipulation by the doctor. By applying pressure to the abdomen and rotating the patient on his/her left or right side, looping can be reduced [4]. Some examples of existing equipment that is currently used to help combat this problem include: a double balloon sheath around the distal tip, a shape locking overtube guide, a general overtube, or a variable stiffness colonoscope. These are devices that passively prevent looping from forming. A better way to try and solve this problem is to constantly monitor the shape of the colonoscope shaft to determine if and when a loop will form and prevent it from happening. Some of the devices that employ a similar method to this include: the computer assisted NeoGuide system, fluoroscopy, and magnetic endoscopic imaging. The first of these devices uses a computer controlled, articulated colonoscope such that each segment follows the exact same path as the segment preceding it. The latter two give the doctor a 3D image of the shaft. If these devices were less expensive, then they might be more widely used, but as it is they are very expensive.With this in mind, a proof of concept method for detecting the shape of the colonoscope shaft during the procedure is introduced. If the shape of the colonoscope shaft is known then looping can be detected and avoided more easily. It would be more beneficial to avoid a loop all together than to backtrack once it is already formed.A model was developed that consists of multiple sets of connected links to be placed along the middle of the colonoscope shaft. These links are free to rotate in two different directions to show the motion of the shaft in full. Each rotation joint is equipped with a 6 mm rotational potentiometer, an angular displacement sensor. The potentiometer is a variable resistor that increases its resistance linearly from zero to a peak value over a range of 240 deg. Every rotation joint has a potentiometer attached to it through a modified pin. Figure 1 shows a single link with potentiometer attached.This only shows a single link but the entire model has 20 links connected together to give an image of a much larger stretch of the colonoscope. The link system is designed to conform to the inside of the colonoscope shaft only increasing the stiffness marginally. The system setup is shown in Fig. 2.Figure 2 above shows the complete system diagram with all components and order of attachment. Once the model was finished it each sensor was wired together in series on the power and ground pins with a power supply. The sensor output pins were wired separately and returned to the end of the system to a data acquisition device to process the signals. The signals acquired are voltage readings from each potentiometer. Signal express was used to acquire the signal and save it as a file. The file was then inserted into a computer program in matlab, which graphed an image of the model.The linkage was formed into a straight line to show the baseline reading for the system. The second configuration was a small alpha loop with 3 cm radius. This was formed because the alpha loop is one of the most common types of loops found in the colonoscopy procedure. Both configurations are shown in Fig. 3.Once this was done, the voltage readings from the sensors were recorded into a file. This file was then inserted into a program that manipulates these values into corresponding angles based upon calibration charts. From the corresponding angles a graphical image was produced that closely resembles the original model. The matlab graphs are set to the same scale as the original model. The graphical images can be seen in Fig. 4. The straight line and alpha loop configuration both very accurately resemble the physical model with little error (Figs. 4(a) and 4(b)). This shows that the model can accurately predict complex shapes and configurations, with little error, that are commonly found inside the colon during a procedure.From the results presented above, it can be seen that the linkage model method with attached potentiometers can easily manage loops commonly found in the everyday procedure. This ability combined with the graphical imaging software can help a doctor to potentially see a loop as it is about to be formed. As has been previously said, the key to stopping loop formation is the prediction of loops before they form. With this model and software, loops can be accurately predicted and viewed during a procedure. With little to no training at all a doctor can look at the computer screen and be able to tell if the shaft of the colonoscope is approaching the tipping point between loop formation and following the colon wall around a curve such as in the sigmoid colon. This would be greatly helpful with decreasing the numbers of incomplete colonoscopies due to loop formation. Along with this, knowing the curvature of the shaft of the colonoscope and the basic knowledge of the shape of the colon, the doctor can give a more accurate description of locations of polyps discovered in the colon.Overall, this method of loop detection that has been discussed could serve as an additional tool to helping a doctor complete a colonoscopy procedure. This method could reduce procedure time due to loop formation as well as decrease pain to the patient. The doctor could also decrease the number of incomplete colonoscopies that result from looping of the colonoscope shaft.
Soft Robotics and Applications
Mathematics, Computing, and Information Processing
New British Society for Rheumatology guideline for the treatment of ANCA vasculitis This article refers to BSR and BHPR guideline for the management of adults with ANCA associated vasculitis, by E. Ntatsaki et al., doi:10.1093/rheumatology/ket445, on pages 2306â09. In this issue of the journal an expert panel from the British Society for Rheumatology (BSR) presents an update of the 2007 BSR guideline for the treatment of ANCA-associated vasculitides (AAVs) [1]. It is remarkable that in recent years enough new evidence has accumulated to call for a revision of these recommendations, in particular because it is still challenging to conduct well-designed trials in these rare conditions. Many of the authors of the guideline have contributed significantly to the field. The British vasculitis scene belongs to the most active and productive groups worldwide and is a key part of the European Vasculitis Society (EUVAS). The guideline reflects the rapidly increasing evidence from controlled trials available in the past years and now includes biologicals [namely rituximab (RTX)] as a mainstay of treatment. The Rituximab versus Cyclophosphamide in ANCA-associated Vasculitis (RITUXVAS) EUVAS trial initiated by British vasculitis experts was one of the landmark studies in this context [2]. A milestone in 2013 was the approval of RTX for the treatment of AAV. This represents the first formal drug approval for AAV by the European Medicines Agency (EMA) in more than 40 years. Accordingly, questions concerning the appropriate use of RTX are among the most prominently discussed issues in this well-structured and straightforward guideline. Despite of the significant accrual of knowledge in recent years, the guideline also reflects that we still have to face a lot of uncertainty in the treatment of AAV patients. The guideline [1] refers to patients with disease consistent with the 2012 Chapel Hill Consensus Conference definitions [3] and thereby formally excludes a significant proportion of AAV patients. This underlines the urgent need for real diagnostic, not just classification, criteria. The ongoing EUVAS/ACR study for the development of diagnostic and classification criteria for primary vasculitis will probably establish such standards. Other definitions need international harmonization in order to increase the comparability of reported data. The present guideline defines remission as BVAS â€1 and a daily prednisolone dose of â€10 mg for at least 6 months. The 2007 European League Against Rheumatism (EULAR) recommendations on clinical trials in AAV suggest a BVAS of zero and a prednisolone dose of â€7.5 mg/day [4]. Several other definitions have been used in different trials and observational studies. Furthermore, the 6 month criterion for remission in the new BSR guideline [1] is problematic. The guideline recommends switching to maintenance therapy after successful induction of remission, after treatment with CYC for example. Strict compliance with the above-mentioned definition could lead to a therapeutic gap of several months or prolonged use of CYC, which clearly is not the intention of the authors. This illustrates the difficulty in defining clinically and scientifically meaningful endpoints. Other uncertainties pertain to drug treatment regimens per se. Although it is generally accepted that high-dose glucocorticoids are the mainstay of treatment, there is still a notable lack of proven information on dosing, tapering or duration of therapy. The availability of RTX for induction of remission in AAV represents a major progression. Drug approval in this case was granted on the basis of randomized controlled trialsâthe RAVE trial [5] and the RITUXVAS trial [2]. These studies helped to establish an alternative treatment to CYC, yet a lot of important questions remain unanswered, such as who is the ideal patient for treatment with RTX and who should still be treated with CYC? There is a consensus that when considering first-line treatment, RTX may be the better choice for younger patients in order to preserve fertility, an advantage of RTX. While this is mechanistically logical, it still lacks formal proof. The guideline also states that RTX may be preferred in patients at high risk of infections [1]. When looking at the data from RAVE [5, 6] and RITUXVAS [2], no clear superior treatment for patients at high risk of infection could be determined during the relatively short observational periods. Considering the treatment of CYC-refractory patients, the overwhelming consensus among experts that RTX should be the drug of first choice is contrasted by a prominent lack of sufficient data. Another ongoing controversy outlined in the guideline [1] is the use of RTX for maintenance of remission. According to some uncontrolled retrospective data (e.g. [7]) and the as yet unpublished results from the French MAINRITSAN trial, addressing repetitive RTX administration for maintenance, moderate repeated doses of RTX (0.5â1 g) given at relatively long intervals (4â6 months) seem to be a promising future option. Apart from proving that RTX represents an option for maintenance there is hope that it may even be superior to conventional standard maintenance treatment such as AZA. Finding the optimal dose in order to maintain maximum remission rates and to reduce potential side effects is another major issue for future research. The ongoing RITAZAREM study assessing RTX administered as a 1 g dose every 4 months vs standard AZA will help to answer these questions. When looking at distinct clinical situations in AAV, in many cases the evidence level is still that of case series. This is especially true for the rarest of the rare AVV entities, e.g. eosinophilic granulomatosis with polyangiitis (EGPA). The guideline, capturing the available data, mainly refers to GPA and microscopic polyangiitis, but not EGPA. When considering the sparse data on many of the relevant topics, this guideline [1] will be a most valuable aid for clinical decisions in daily work. The generation of further evidence from clinical trials will hopefully lead to an update of the EUVAS/EULAR 2009 [8] recommendations, making standardization of the diagnostic and classification standards a worthwhile future task of the EULAR/EUVAS. Disclosure statement: The authors have declared no conflicts of interest.
Abstract Mix network plays a key role in electronic voting to preserve anonymity and lots of mixnet schemes have been proposed so far. However, they requires complex and costly zero-knowledge proofs to provide their correct mixing operations. In 2010, Sebe et al. proposed an efficient and lightweight mixnet scheme based on a cryptographic secure hash function instead of zero-knowledge proofs. In this paper, we present a more efficient and faster mixnet scheme than Sebe et al.'s scheme under the same assumption. Also, our scheme is secure. Key Words : Zero-knowledge proof, e-Voting, Anonimity, Mixnet, hash function â . Introduction Mixes are a means of untraceable communication based on a public key cryptosystem, as published by D.Chaum in 1981 [1] . A mix-network or mixnet accepts as input a collection of ciphertexts, and outputs associated plaintexts(or ciphertexts) in a randomly permuted order. A well constructed mixnet makes it infeasible for an adversary to determine which plaintext output corresponds to which ciphertext input more efficiently than by guessing at random. Proposed by D.Chaum in 1981 as a technique for anonymous e-mail and e-voting, mixnet can be categorized into decryption mix-nets and re-encryption mix-nets
Internet Traffic Analysis and Secure E-voting
Cryptography and Data Security
Advanced Steganography and Watermarking Techniques