Based on distributed key management, the trust mechanism of the local group, zero-knowledge proof and timestamp exchange mechanism of OLSR routing protocol, a new lightweight and robust group-key management protocol for Ad Hoc Networks is proposed. the protocol achives the advantages of low energy consumption, high efficiency and high availability by reducing both the number of control messages and the energy spent with cryptographic operations. Then, we demonstrates the security and anti-offensive of the protocol through safety analysis. Finally, simulation results show that the proposed protocol can ensure the security of Ad Hoc networks with a very low-impact on the performance of secure routing protocol.
Lalitha Bhavani Jivanadham, A. K. M. Muzahidul Islam, Nafees Mansoor, Sabariah Baharun
Driven by the technology advances in Micro-Electro-Mechanical Systems which has facilitated the development of smart sensors; we have witnessed in recent years the emergence of WSNs in environment, military, surveillance, natural disaster relief, healthcare, etc. These WSNs carry the promise of drastically improving and expanding the quality of services across a wide variety of settings and for different segments of the population. Therefore, it is very important to develop a WSN with robustness and security in mind. Typically, the sensors are smaller in sizes that have limited processing and computational power resources, and are inexpensive, thus enabling the network to have a large coverage area and longer range. By using hundreds or thousands of them it is possible to build a high quality, fault-tolerant sensor network where failure of one or few nodes does not affect the operation of the network. They are also self-configuring or self-organizing. In this paper, we propose formation of a Secured Cluster-based architecture for a Dynamic Wireless Sensor Network that uses two topology management operations: node-move-in and node-move-out. The proposed security protocol integrates one round Zero Knowledge Proof and AES algorithm to apply for node authentication, where only authenticated nodes will be accepted during node-move-in operation. We also show that it requires O(h+q) rounds for a node to join into a network securely, where h is the height of the dynamic cluster-based wireless sensor network and q is the number of neighbouring nodes of a joining node.
In this paper, through introducing the Williams public-key cryptosystem in detail, the analysis of the characteristics of the system, and the combination with zero knowledge proof, we set up a zero-knowledge proof scheme based on Williams public-key cryptosystem. The scheme will enrich the theory of cryptography, and particularly zero-knowledge proof theory.
Controlled access to confidential information and resources is a critical element in security systems. Role-based access control (RBAC) has gained widespread usage in modern enterprise systems. Extensions have been proposed to RBAC for incorporating spatial constraints into such systems. Several solutions have been proposed for such models and many researchers are now focusing on enforcing system policies. In this paper we propose a security framework for RBAC systems with spatial constraints based on identity-based encryption. In our framework, we use identity-based encryption with zero knowledge proof (ZKP) to provide authentication and information security. We also show how Near Field Communication (NFC) can be used to establish the integrity of a user's proof of location. Simulation results in Java validate our model. Furthermore, security analysis has been done to show how our framework protects against well-known attacks.
The increasing trend of embedding positioning capabilities (e.g., GPS) in mobile devices facilitates the widespread use of Location Based Services. For such applications to succeed, privacy and confidentiality are key issues. Over all privacy will have to be managed through a combination of technology, legislation, corporate policy, and social norms. There are many data privacy schemes including Zero Knowledge Proof (ZKP) those can be used for location privacy. ZKP is also useful for removing the bottleneck problem introduced by use of trusted third party. In the earlier work, authors proposed the concept of middleware architecture in which, request and response are not routed through middleware for every transaction. This has reduced the dependency on middleware. This paper presents correspondence between the authentication techniques used in above said architecture and zero knowledge proof technique. Use of the concept of zero knowledge proof for authentication and authorization in the domain of location based services is also explored.
KabulâIn the traditional pose of Afghan men, Abdul Zia sits quietlyâsquatting down on his haunches close to the ground. But something about Abdul Zia doesnât look like the rest of the men crouched along the streets of this capital city. Over his Pashtu turban are khaki, military-issue ear warmers. The hood of his dirty, 1970s ski jacket, likely a western cast off, is riddled with holes. His beard is grubby and matted.His posture carries none of the pride associated with most Afghan men, who hold themselves like warriors. His hands, when they emerge from beneath his thin and ripped shalwar kameez, are mottled and scarred. Between the black dirt lining his fingers, is dried and fresh blood from the wounds caused by the biting, relentless wind. He would wash, if all the water didnât turn to ice. He is curling himself into the tiniest possible ball, trying desperately to keep warm. Abdul Zia is just one of almost 400,000 Afghans displaced from their homes by the fightingânow living in appalling conditions in camps in the capital city. Throughout the country, the official statistics are fast approaching 750,000, but the reality is much worse.Overflowing with more than 20,000 residents with nowhere else to go, the Nasaji Bagrami internally displaced peopleâs camp in the center of Kabul must be as close to hell on earth as any place on the planet. Yet, these lost people displaced by an international conflict rarely capture the worldâs or even their own nationâs attention. A sprawling mass of mud huts and UNHCR logo-ed tarpaulins, the camp is a freezing nightmare of poverty, misery, and death. Amongst the bitter and hungry, Taliban recruiters find easy pickings to join their radical insurgency. The ground sparkles with ice particles, formed around the mudâa perilous quagmire where the incautious slip or sink. The ice goes down at least a yard, probably more. The Kabul River, normally a trail of brown sludge snaking through the city, is now frozen solid and piled high with at least three feet of snowâthe same snow that falls on tarpaulins, precariously balanced above hastily built mud walls. Not strong enough to bear the weight, tarpaulins collapse regularly onto freezing families who must then spend the rest of the night digging themselves free. âWe huddled round her to try and keep her warm,â Abdul Zia says. âI sat here, and my wife sat there,â he adds as he motions to two people sitting opposite each other with crossed legs. Just four days ago, in that space between them, lay their two-month old daughter Shah Gul. In temperatures 4 degrees Fahrenheit below zero, with the worst snowfall the country has seen in decades, Shah Gul was freezing to death. She contracted neither pneumonia nor hypothermia. Her little body simply froze, and there was nothing her desperate parents could do to stop it. Just a week earlier, their two-year-old son, Akhtar, had succumbed to the same fate. Abdul Zia and his wife are not alone. In the first week of February, as many as 40 children froze to death in the Nasaji Bagrami campâone of at least 10 camps in Kabul and several hundred throughout this war-torn country. Thereâs no tally of how many other children like Shah Gul or elderly people succumbed that week. The same day Abdul Zia told his story, 16-year-old Fatima was desperately thin and struggling to breathe. Her frantic mother described how the effects of the cold had cost her daughter the use of her legs. Fatima died later that day. Abdul Zia and his family have been living here for six years. A sprawling maze of mud, open sewerage, and ripped tarpaulins, there is no infrastructure or logic to the âinformal settlementsâ that so many people now call home. But itâs not really homeâhome is 400 miles away, on the outskirts of Lashkar Gah, the capital of war-ravaged Helmand province. Helmand is a sprawling expanse of over 22,000 square miles. In the 1960s and 1970s, it was dubbed the âAmerica of Afghanistan,â with a huge hydroelectric plant and dam designed for massive cotton production, which needs substantial water supplies. These ambitious plans sputtered along through the arrival of Russian troops and later the Taliban. For if it wasnât cotton, other crops could use the vast irrigation promised by this massive investment in water resources. Indeed, with low production costs and easy export routes, the fertile soil of Helmand province provided the perfect growing conditions for poppy. Helmand became the epicenter of the Afghan heroin trade. Today, the province produces over half of the opium in the global drug trade. Whatever the rootsârich poppy crop or tribal affiliationsâHelmand is one of the most strongly held Taliban areas and has proved one of the biggest headaches for American-led forces since the invasion in 2001. In fact, the majority of all combat and civilian casualties alike have been in this province. The total civilian casualties are impossible to quantify, but since 2007, nearly 25,000 have been recorded. Yet nearly six years since the start of the major western offensive known as Operation Mountain Thrust, the Taliban, rather than showing signs of retreat, are stronger than ever. One of the principal justifications for the âSecurity Assistanceâ in Afghanistan is the protection of the civilian population from the worst Taliban excesses. Yet UN figures suggest that from 2001 to 2005, more civilians were killed by NATO forces than by insurgents. The Taliban arenât the only ones from whom civilians, like Abdul Zia and his family, need protection. Whatâs striking is that, with NATOâs formal mechanism of compensation for civilian casualties, much less attention is being paid today to the hundreds of thousands who are neither killed nor injured, but internally displaced by the fighting. Abdul Zia, like 90 percent of his fellow Helmandis, worked as a farmer. His wife was looking after their seven children in their modest but comfortable home when it was suddenly hit in an airstrike. Six of his children were killed instantly. His home lost, Abdul Zia fled to Kabul with his wife and only surviving child. Few in Abdul Ziaâs position have the courage or knowledge to confront those who killed their family members and ask for compensation. While NATO has rightly recognized the need to redress families for civilians deaths and that the pre-2006 levels of âcollateral damageâ were unacceptable, it is not enough. The internally displaced population of Afghanistan requires sustainable, practical solutions that enable them to go home or to re-establish themselves elsewhere. For Abdul Zia and his family, it was a perilous journey by foot from the outskirts of Lashkar Gar to Kabul that he undertook because he thought his family might be safe there. In the capital, he found refuge in Nasaji Bagrami, where most of his neighbors are Helmandi. But rather than sanctuary, he found despair with his two youngest children, born in the camp, dying just the same. With the fighting still escalating in Helmand, they have no option to return homeâstuck in a city that doesnât want them.Abdul Ziaâs family are direct civilian casualties of the operations of international military forces in Afghanistan. For most here, it is irrelevant whether the culprits were the Taliban or the international military forces. In these camps and in the streets of the city, their only wish, after 30 years of war, is for the fighting to end, allowing them to go home. For many, the victor is besides the point with more and more seeing the return of the Taliban as the only option. As long as the fighting continues, the numbers of those fleeing into the capital will rise. The Internal Displacement Monitoring Center now estimates that at least 400 people, literally running for their lives, arrive in Kabul every day. While their displacement may have been caused by international forces, it would appear that they then slip through a series of loopholes. The official mandate of the UNHCR is the care of refugees, but to achieve the status of refugee, civilians need to flee one country and enter another. Internally displaced people are those who have been forced leave their homes but who have not crossed an internationally recognized state border.Even if the internally displaced flee for the same reasons as refugees, the fact that they have not crossed an international frontier denies them the protections afforded to those with official refugee status. While the UNHCR works tirelessly to re-integrate the internally displaced, it has already been overwhelmed by four million refugees who have returned to Afghanistan since 2001, consuming enormous resources to reintegrate, re-house, and support those who have grown up in camps in Pakistan or as exiles in Iran. Because IDPs are not defined as refugees under international law, they remain the responsibility of their own government. But the cabinet of President Hamid Karzai seems generally unable or unwilling to assist them. UN agencies have been known to step in when the problem becomes a humanitarian crisis, like this winter, but in general IDPs remain ignored and abandoned. The areas where they settle do not even receive the official title of âcamps,â but rather âinformal settlements,â and are thus not afforded the protection of aid agencies or international law that official refugees receive. As fighting has intensified with a surge in military operations against Taliban strongholds, 91,000 Afghans have fled their homes in the first half of 2011, up from 42,000 in the first half of 2010. âThis is a largely hidden but horrific human rights crisis,â says Horia Mosadiq, an Amnesty International researcher in Kabul. Furthermore, Western military forces, while taking positive steps to mitigate the level of civilian casualties, have no strategy for dealing with those who are not injured or killed during operations, but displaced. The Internal Displacement Monitoring Center, in a 2011 report, found that in the Afghan cables published by Wikileaks in 2010, the U.S. government did not make a single reference to any displacements. The UN Guiding Principles on Internal Displacement require governments to assist their internal refugees, but such demands are not legally binding. There are also no guidelines to identify these individuals in the first place. The right to housing is guaranteed by the International Covenant on Economic, Social, and Cultural Rightsâa treaty signed and ratified by Afghanistan. The ability to live somewhere with security, peace, and dignity is a fundamental human right recognized under this same pact, which also imposes obligations on signatory nations to provide access to health care, water, and sanitation. Yet, the countryâs government officials actively prevent agencies from providing clean water and even basic latrines. Afghan law forbids the intervention of UN agencies in what are referred to as the âKabul Informal Settlements.â The government argues that rather than civilians fleeing fighting, these people are economic migrants. While it has a responsibility under international law to provide for internally displaced people, it does not have such an obligation to help people leaving the provinces to seek a better life in the bright lights of the capital. Indeed, international aid agencies are barred from giving any assistance that would contribute to the permanence of internal migrantsâ settlements, including building latrines, creating schools, and providing health care systems. Who gets assistance from the small number of local Afghan aid groups and international aid groups is all too often a matter of luck. The migratory pressures often go far beyond the simple and direct need for Afghans to remove themselves from military engagements and deadly force to safety. Increasing numbers are also being forced to move to survive economically. While the government brands these as individuals seeking a more prosperous life, more often the move is simply a case of needing to feed oneâs self. At the root of this dilemma is a keen desire by the Afghan government and the international community to discourage pure economic migration to the nationâs capital, which is ill-prepared to absorb them. Already bursting at the seams, the population of Kabul has mushroomed from 800,000 in 2001 to over 3 million today. A 2011 report by the Brookings-Bern Institute points out that internally displaced people usually leave their homes for the same reasons as economic migrantsâimproved security, some hope of integration into a stable social framework. For economic migrants, these factors influence where they go, not when. This is the crucial difference. Internally displaced people like Abdul Zia and his family had no choice but to leave their villages, fearing for their lives and their familyâs safety. When they arrive, they are condemned, often for years, to cramped, squalid, desperate conditions in what are effectively refugee settlements with no access to water, education, or health care. For their children to attend school, they need national identity cards, which often get left behind or destroyed in a desperate scramble to flee an attack on their homes. Peter Nicolaus, head of the UNHCR mission in Afghanistan, acknowledges the full extent of the crisis. âThe problems in the KIS [Kabul Informal Settlements] cannot be overestimated,â he says. This winter, just 10 minutes from the presidential palace and several UN guesthouses, Abdul Ziaâs children and at least 38 others were freezing to death. Once the humanitarian crisis kicked in, the and other agencies to provide and the people from the relentless âWe have a humanitarian problem every continues, this it was had on a with the other would responsibility for the IDPs in the areas and those in Kabul under the care of In this didnât go to and up to step in here as over people, and for two in February, were the in an a military position in which and barred all from Afghanistan. while UNHCR were running out of almost half a million and other were in in In the for years, only half the aid was are nearly the snow there will be there will be will have to but the less the less a the aid has still not the UNHCR did under these is to that the IDPs in the âinformal settlementsâ are not the responsibility of the While they look after the million refugees from the problem falls to the Afghan government. While there is an Afghan for and the to be on of rather than on the needs of internally displaced individuals or many that their homes have displaced and The Afghan does some for refugees and But is them to their place of solutions and humanitarian care. most of those go home at this strategy is a of and resources. to a report by Amnesty the Afghan to internal displacement is to that it doesnât while displaced also on aid The Amnesty report one aid as are not to even call them are told they are and an Afghan official like not in those mass areas where But these are not In to in as an an Afghan needs of and identity is to people like Abdul Zia who fled his home in the of an The Afghan government actively even to the status of that they themselves this title to get Indeed, the government says they have been in the camps for more than two years, they are and would any status like a to life in these most economic are men, IDPs to of and most of the residents of Nasaji Bagrami are Afghan government officials that families are to by the of aid as as and rather than fleeing fighting. his and the of his children, Abdul Zia says that he has been to Nasaji Bagrami by aid and of a âI want to go he want to live like in this There of a substantial for the Afghan government to IDPs their status. they to them as of conflict and them as economic migrants, they have no responsibility to provide them with water, health care, or Afghan officials that they help their own but that they in be to on international aid that may be But because of the government has effectively barred from legally such aid to even the most The of these is to turn an economic or dilemma into a desperate humanitarian crisis or other a for the for and infrastructure for them, they will But they as every of they have on to a government official or He then âThe country live in of where these people go becomes by the of in Afghanistan. For over 30 years of a of and have to a of and of the with the of of is a to the of the internally displaced to their their them in in and around Kabul where have it is the on whom usually âI do the says Abdul as most to to all military forces with and western are for lives, because they were their and they killed Nicolaus, has as to is to he âThe There is no country in the that could with this of migration into Indeed, head of the UN for the of in Afghanistan points to this just something that in the capital. right Afghanistan. in every major center have these settlements, have these and because of a of of access to water, or health care, it simply the conditions for the most As huddled in the one that to Abdul Zia and six other a has has that there are in the camp, and after other these people and the with a of and One of those who has the is He out from the because of the his position demands or because he has and so many of the residents He does not have the look of Abdul Zia and his His do not frozen by too for any one human to He is the camp and is not huddled into a on the ground. He and âI says âI for all these are and want to them all by the of have into have they the being by the and others to Afghanistan, the of and for the is only the of for there is the of where to these families who have lost In 2005, a with the of providing and IDPs with of But to they their is a bitter and since to it would require vast of that are already for by far more and than the refugees One under this is on the outskirts of Kabul. One aid in the Amnesty report are and itâs There is no water Yet, the need is the government areas in where there is no a âWe have to be about the of the a of But if living in a or in the of a city center in temperatures of below zero, but prevent itâs He adds that many of these families have been living in Kabul for 10 years, with no of any in their âWe need to prevent this he have to is how to with the of these conditions rather than dealing with the when they A first says of is to a and of even a small of the âWe are families out of the KIS and into just Kabul. about and the official he points a of the population of Afghanistan are IDPs or million The international aid officials is that the Afghan government must the that their hands, allowing them to provide basic and stop more civilians from more than any who have succumbed to the of the While enormous have been by western military forces to civilian casualties, it is that the âcollateral damageâ those who have been displaced and will from or the of Afghanistan. The children freezing to death in the camp are just as much civilian casualties as those hit by At the same must be to UNHCR to make they the vast number of IDPs who they now In conflict like Afghanistan, it is and for the UNHCR mandate to to only refugees who have crossed the UN mandate be in conflict to IDPs a humanitarian crisis like this displacement is migration only has been But there is the reality that military officials need to as Not only do the IDPs a humanitarian crisis, but a and crisis as These housing these bitter people and their are fertile for Taliban is that the Taliban, simply a small of through of refugees in the camps of Pakistan while their Afghanistan was being by of the The same is UN has found that children as as are being by the Taliban for such as digging where are then of these children are being often their as with the being by far With growing the and what are now seen as a of hungry, and people is in the for the Taliban to
Politics and Conflicts in Afghanistan, Pakistan, and Middle East
Terrorism, Counterterrorism, and Political Violence
Mark Vinkovits, Erion Elmasllari, Claudio Pastrone
Ubiquitous systems and the Internet of Things (IoT) are on the rise. However, there are issues from businesses and users which hinder the wide-spread application of such systems. In the FP7 EU project ebbits, which deals with integrating IoT into business systems, we collected real-world requirements from participants. From these we designed a complete anonymous network solution including addressing, discovery, authentication and reputation management. Our authentication system relies on Non Interactive Zero Knowledge Proofs augmented for fine granulated access right decisions and accounting. Anonymous reputation is created using reputation tickets, which are obtained through public votings. A reputation ticket is an unforgeable evidence of trustworthiness held by the provider and presented to a consumer on request. Discovery also has to specially be designed for anonymous environments else they leak information about the identity. We provide an attribute based discovery mechanism built with Bloom-filters. Our concept protects privacy but still enables discovery based on partial matches.
Noninteractive zero-knowledge (NIZK) proof systems are fundamental primitives used in many cryptographic constructions, including public-key encryption secure against chosen ciphertext attack, digital signatures, and various other cryptographic protocols. We introduce new techniques for constructing NIZK proofs based on groups with a bilinear map. Compared to previous constructions of NIZK proofs, our techniques yield dramatic reduction in the length of the common reference string (proportional to security parameter) and the size of the proofs (proportional to security parameter times the circuit size). Our novel techniques allow us to answer several long-standing open questions in the theory of noninteractive proofs. We construct the first perfect NIZK argument system for all NP. We construct the first universally composable NIZK argument for all NP in the presence of an adaptive adversary. We construct a non-interactive zap for all NP, which is the first that is based on a standard cryptographic security assumption.
Direct Anonymous Attestation (DAA) is a special signature scheme that enables remote authentication of a user while preserving privacy under the user's control. Thus, in this paper, based on existing schemes and mechanisms, we firstly construct a DAA signature scheme which is proven secure without random oracles. By making certain reasonable assumptions and employing the techniques of non-interactive zero-knowledge(NIZK) proof system and Two-Party Computation(2PC) scheme, we prove that our scheme satisfies anonymous and untraceable, and compares with existing DAA schemes in the aspects of security and efficiency.
We deal with the general problem of scattering by open-arcs in\ntwo-dimensional space. We show that this problem can be solved by means of\ncertain second-kind integral equations of the form $\\tilde{N}\n\\tilde{S}[\\varphi] = f$, where $\\tilde{N}$ and $\\tilde{S}$ are first-kind\nintegral operators whose composition gives rise to a generalized Calder\\'on\nformula of the form $\\tilde{N} \\tilde{S} = \\tilde{J}_0^\\tau + \\tilde{K}$ in a\n{\\em weighted, periodized} Sobolev space. The $\\tilde{N} \\tilde{S}$ formulation\nprovides, for the first time, a second-kind integral equation for the open-arc\nscattering problem with Neumann boundary conditions. Numerical experiments show\nthat, for both the Dirichlet and Neumann boundary conditions, our second-kind\nintegral equations have spectra that are bounded away from zero and infinity as\n$k\\to \\infty$; to the authors' knowledge these are the first integral equations\nfor these problems that possess this desirable property. Our proofs rely on\nthree main elements: 1) Algebraic manipulations enabled by the presence of\nintegral weights; 2) Use of the classical result of continuity of the Ces\\`aro\noperator; and 3) Explicit characterization of the point spectrum of\n$\\tilde{J}^\\tau_0$, which, interestingly, can be decomposed into the union of a\ncountable set and an open set, both tightly clustered around -1/4. As shown in\na separate contribution, the new approach can be used to construct simple\nspectrally-accurate numerical solvers and, when used in conjunction with\nKrylov-subspace solvers such as GMRES, gives rise to dramatic reductions of\nKrylov-subspace iteration numbers vs. those required by other approaches.\n
The migration of web applications to Cloud computing platform has raised concerns about the privacy of sensitive data belonging to the consumers of cloud services. The traditional form of security tokens like username/password used to access cloud services are prone to phishing attacks and hence do not provide complete security. In this work we propose to extend the Microsoft's CardSpace identity management tool, to include more robust security tokens using the zero knowledge proof concept. These security tokens are in the form of SAML token supported by Windows Communication Foundation (WCF) and hence can prove interoperable with the existing security platforms.
Radio frequency identification has enabled exciting new prospects in wireless ID services, particularly for personnel. Unfortunately, the earliest applications relied upon acquiescent mechanisms that accepted and returned data with no intermediary processing. The advent of smart cards made possible an on-chip revolution in the use of contact identification devices. What I explore here is the extension of these embedded systems to their non-contact counterparts (namely RFID). The processing layer is of utmost importance to us in the study of privacy controls, as it opens the discussion on how personnel ID in general may evolve from storage devices that may be intercepted and duplicated into cryptographically sound logic devices that can resist common attacks and directly participate in the decisions concerning disclosure. This brings us to one of the most vital aspects of the research, the zero-knowledge proof. Frequently RFID is applied as a convenient means of answering questions about discrete state (from a comfortable distance). Wherever possible, we wish to answer those questions without compromising user privacy in the process. The integration of RFID and embedded systems allows us to perform proofs based on internal comparisons and calculations rather than irrevocable release of the data. This is the security of the embedded systems used widely in electronic commerce with the convenience of near-field communications. It holds the promise of a better all-around user experience, with better protections, more control, and easier methods of performing common objectives.
In many applications, the password is sent as cleartext to the server to be authenticated thus providing the eavesdropper with opportunity to steal valuable data. This paper presents a simple protocol based on zero knowledge proof by which the user can prove to the authentication server that he has the password without having to send the password to the server as either cleartext or in encrypted format. Thus the user can authenticate himself without having to actually reveal the password to the server. Also, another version of this protocol has been proposed which makes use of public key cryptography thus adding one more level of security to the protocol and enabling mutual authentication between the client & server.
CertiCrypt is a framework that enables the machine-checked construction and verification of cryptographic proofs in the Coq proof assistant. CertiCrypt instruments the code-based game-based approach to cryptographic proofs, and builds upon many areas, including probability and complexity theory, algebra, semantics of programming languages, and program optimizations. In this thesis, we illustrate the application of CertiCrypt on two examples: the Hashed ElGamal encryption scheme and zero-knowledge protocols. Like previous case studies in CertiCrypt, these examples demonstrate the feasibility of formalizing complex cryptographic proofs. However, using CertiCrypt requires a high level of expertise in Coq, and is time consuming. In order to ease the adoption of formal proofs by the cryptographic community, we develop a semi-automated tool, called EasyCrypt, for elaborating security proofs of cryptographic systems from proof sketches. Proof sketches are checked automatically using SMT solvers and automated theorem provers, and then compiled into verifiable proofs in the CertiCrypt framework. We illustrate the application of EasyCrypt with two examples: the Hashed ElGamal encryption system, and the Cramer-Shoup encryption system. Finally, we extend the language of CertiCrypt with a formalization of polytime functions.
Chida and Yamamoto propose a batch proof algorithm to enhance the performance of multiple instances of zero knowledge proof of partial knowledge. When multiple instances of zero knowledge proof of partial knowledge need to be proved simultaneously, their proof algorithm employs a batching mechanism to reduce the cost in computation and communication. Unfortunately, their batch proof algorithm is not sound and vulnerable to an attack, which completely breaks soundness of the proof. More precisely, an adversary can design the multiple partial knowledge statements in a special way such that no matter how he is challenged he can always pass the verification as a prover in the batch proof scheme while he does not have the knowledge he claims. The attack is presented and is formally illustrated to always succeed.
Privacy-preserving set operations are useful for many data mining algorithms as building tools. Protocols for privacy-preserving set operations have considered semi-honest and malicious adversarial models in cryptographic settings, whereby an adversary is assumed to follow or arbitrarily deviate from the protocol. Semi-honest model provides weak security requiring small amount of computation, on the other hand, malicious model provides strong security requiring expensive computations like homomorphic encryption. However, efficient computation of such set operations are desirable for practical implementations. In this paper, we build efficient and private set operations avoiding the use of expensive tools like homomorphic encryption, zero knowledge proof, and oblivious transfer. Our protocol is constructed in game-theoretic model. In other words, instead of being semi-honest or malicious, the parties are viewed as rational and are assumed (only) to act in their self-interest. We show that our protocol satisfies computational Nash equilibrium.
Abstract : Zero-knowledge proofs (ZKPs) are protocols that enable a prover to convince a verifier of the truth of a statement without leaking any other information. The main properties of ZKP include completeness, soundness and zero-knowledge. These features are correlated with each other, and together with the lighter computational requirements, makes zero-knowledge protocols very attractive in authentication service in airborne networks. Although useful, the non-interactive zero-knowledge proofs based on standard cryptographic assumptions used to be inefficient and not useful in practice. The use of pairing-based ZKP on elliptic curves can potentially enhance the security strength of the system. Besides these advantages, pairing-based ZKPs can also integrate smoothly with other pairing-based cryptographic schemes (e.g., identity-based encryption, pairing-based signatures, key agreement, and proxy re-encryption) making the combined schemes quite efficient.