Within strategic management research, the process theory school of thought concentrates on the strategy formation process, instead of strategy content. Originating from Mintzberg's (1978) division between intended and emergent strategy, followed by Burgelman's (1983) further interpretation of induced and autonomous strategizing, it has since been widely acknowledged that an organization's realized strategy also includes strategic actions outside the planned and implemented corporate strategy.\n\nHow does this strategy formation take place in a changing regulatory environment? This study presents longitudinal process data of semi-structured interviews and archival analysis as a single-case study of a successful Finnish retailer. This study aims to provide a description of the case organization within its unique setting, and to also identify the market incumbent's patterns of actions as either autonomous or induced strategizing behavior.\n\nA secondary research question is presented: what type of interaction do these strategies represent with the organization's environment? The identified sequences of autonomous and induced strategizing of the case organization are thus further classified according to Burgelman and Grove's (2007) four-part framework for strategic dynamics.\n\nIt can be conclude that within the unique context of the case study, the market incumbent has achieved a stronger position within Finnish retail trade, amidst regulatory changes. This has been supported by the case organization's repetitive actions: First of all, its induced strategizing (represented by acts such as decentralization, and continuous chain concept development) are based on an accumulated knowledge about the market and regulation, i.e. an understanding of "one's ground rules", and acting within these regulatory constraints. Secondly, especially beneficial have been the case organization's autonomous strategizing (vertical mergers including acquisition of Spar and branching into gasoline sales with the ABC chain as well as ecommerce; horizontal integration into the real estate business) which have allowed changing retail trade by "bending its rules", i.e. identifying non-regulated activities to pursue. As implications to further research and practitioners, this study suggests that autonomous strategizing should be carried out if aiming for rule-changing behavior and ultimately having an effect on one's market and non-market environment.
Krishna M. Singh, Meena Meena, Burton E. Swanson, M.N. Reddy · 5 authors
This In-Depth Study of the Pluralistic Agricultural Extension System in India is a full analysis of the pluralistic extension system in India, how it has changed over many years and the direction it is currently moving. \n \nChapter-1 outlines the Evolution of the Pluralistic Agricultural Extension System in India and the changes that have occurred since about 1871, including the establishment of the Department of Agriculture in 1882. Following independence in 1947, many changes have happened as outlined in this first chapter, including the Community Development Program (CDP), the Intensive Agricultural District Program (IADP), including dissemination of high-yielding varieties during the Green Revolution, the Training and Visit (T&V) approach and then the move to the decentralized, farmer-led and market driven approach influenced by the Agricultural Technology Management Agency (ATMA) model. \n \nChapter-2 gives an Overview of the Public Extension System within the Ministry of Agriculture (MoA), the State Departments of Agriculture and then provides more detailed information about the Krishi Vigyan Kendra (KVK) and the public extension system in India. It starts with an overview of the organizational structure at the national level, including the Department of Agricultural Research and Extension (DARE), then into the Department of Agriculture and Cooperation (DAC) and Directorate of Extension within DAC. Then, it moves into the KVKs, which are a critical linkage at the district level between research, extension and farmers. In short, KVKs focus on the specific agro-ecological conditions within each district and then, after conducting research on these different crops, livestock and other farming systems. Then it moves into the development of the ATMA model through two World Bank projects, which is now expand across all Indian districts. \n \nChapter-3 outlines the Directorates of Extension Education within each State Agricultural Universities (SAUs). India is unique in having Extension units established within each SAU, since this extension approach was first introduced by selected US Land Grant Universities into these SAUs in the late 1950s and early 1960s. This chapter outlines the historical development of the extension within each SAU and then outlines the mandate, organizational structure, human resources and methods used within these SAUs and their relationship with the public extension system. \n \nChapter-4 outlines the Private Sector Advisory Services being provided in India, especially in the provision of good advisory services through private Agri-Business Companies through the sale of inputs to farmers. In India, there are over 280,000 input supply firms, but many do not have sufficient knowledge and experience in providing good advisory services to farmers. At first, the public and private sector did not want to work together but through the ATMA approach, the public and private sector started working together and then, in 2004, the National Institute of Agricultural Extension Management (MANAGE) started training and giving diplomas to the participants from these private sector firms, especially in Andhra Pradesh (see: http://www.manage.gov.in/daesi/daesi.htm). \n \nChapter-5 summarizes the role and activities of the different Commodity Boards currently operating in India, including: Central Silk Board (CSB), Coconut Development Board (CDB), Coffee Board, Coir Board, Rubber Board, Spices Board, Tea Board, Tobacco Board, National Dairy Development Board (NDDB), National Horticulture Board (NHB), Cashew Export Promotion Council (CEPC), National Jute Board (NJB), and the National Federation of Cooperative Sugar Factories (NFCSF) and how each of these boards carry out extension and advisory services to the farmers being served. \n \nChapter-6 outlines the Institutional Mechanism for Capacity Building to strengthen the pluralistic extension system in India. This chapter starts with an overview of the National Institute of Agricultural Extension Management (MANAGE), which is an autonomous organization that has had the most impact on strengthening the extension system in India. Next, it discusses the paradigm shift within the National Institute of Agricultural Marketing (NAIM) in India; and then outlines the role of the Extension Education Institutes (EEIs). Finally, it moves to outline the role and structure of the State Agricultural Management and Extension Training Institutes (SAMETIs), especially in strengthening the ATMA model in India. \n \nChapter-7 is the conclusion chapter that outlines the Strengths and Weaknesses of Indiaâs Pluralistic Extension System. It starts by outlining the Policy Framework and Reforms for strengthening the pluralistic extension system in India. Next, it outlines how to strengthen research-extension linkages as well as capacity building among extension workers. Next, it addresses how to empower farmers, including women farmers. It also outlines the use of Information Technology (IT) and how to strengthen it through different approaches. This chapter also outlines the changing role of government in extension and how the ATMA model can be strengthened following very specific details. The other issue is how to strengthen the SAMETIs, since they still need to be strengthened in providing service to district and block level extension workers. This chapter ends with a brief summary the key role that the public extension system can play in India.
Payman Mohassel, Seyed Saeed Sadeghian, Nigel P. Smart
Abstract. We propose the first general framework for designing actively secure private function eval-uation (PFE), not based on universal circuits. Our framework is naturally divided into pre-processing and online stages and can be instantiated using any generic actively secure multiparty computation (MPC) protocol. Our framework helps address the main open questions about efficiency of actively secure PFE. On the theoretical side, our framework yields the first actively secure PFE with linear complexity in the circuit size. On the practical side, we obtain the first actively secure PFE for arithmetic circuits with O(g · log g) complexity where g is the circuit size. The best previous construction (of practical interest) is based on an arithmetic universal circuit and has complexity O(g5). We also introduce the first linear Zero-Knowledge proof of correctness of âextended permutation â of ciphertexts (a generalization of ZK proof of correct shuffles) which maybe of independent interest.
IntroductionOn several occasions, Paul Ricoeur used expression of to characterize his philosophical enterprise and its unity. We know for a fact that after having investigated finitude of act of willing and evil that pervades human freedom, Ricoeur's project was to dedicate an entire volume to creative capacity of acting consciousness. That type of creation, understood against backdrop of a poetics, should emphasize function of imagination, which consists in practical power to innovate, rather than psychological function of reproducing perceptions. This projected completion of philosophy of will in a poetics never saw light of day; because of this, Ricoeur's philosophy is caught up in a sort of incompleteness. Probably because he saw it fit to accentuate mediations that separate subject from his or her origins and potencies, he never dedicated a book to practical imaginary. Instead of a poetics of will, Ricoeur published his book on Freud, in which he explores discovery of unconscious and its consequences for concept of interpretation.1Does this necessarily mean that project of a of had simply been abandoned? Actually, Ricoeur never ceased to reflect upon rela- tion between symbolic imaginary and human action. If we no longer seem to find topic of will thematically analyzed in his work, this is without a doubt due to his increasing suspicion towards a topic that stems from both psychology and metaphysics. However, we can find many texts which attest to fact that he continued to approach action and imaginary together. The 1976 article Imagination in Discourse and in Action,2 to mention only one, explicitly takes up thread of an investigation to which he earlier gave the ambitious name of poetics of will.3 As its title indicates, this text elaborates on passage of theory of productive imagination from sphere of discourse to that of action. This extension of imagination from semantics to praxis was, from that moment on, presented as a necessary introduction to a poetics of will, now grounded in a redefinition of potencies of imaginary. If, therefore, it is true that Ricoeur revived his earlier project, it must be added that this was done through a radical redefinition of its meaning. And that transformation is in itself a sound proof of evolution of his philosophy from a theory of consciousness to a hermeneutics of capacities.This evolution, which is confirmed by Ricoeur himself, is due to an inner logic in his work, and I cannot explicate it fully here. Instead, I will focus on what is at stake in approaching action through powers of imaginary. In fact, originality of Ricoeur's method lies in his decision to place imagination at heart of a practical anthropology attentive to capacities of each individual. Ricoeur constantly reasserts fundamental claim according to which there is no pure action, no action that can be described independently of language that expresses it and concrete modes of its effectuation. Ricoeur's anthropol- ogy is an anthropology of capacities, that is, of action; and this not in mode of subjective virtuality but rather as a real potency. This phenomenology of capable human being is loosely inspired by Merleau-Ponty's practical rewriting of cogito: Consciousness is in first place not a matter of 'I think that' but of 'I can.'4 By encompassing in same approach action and imagination, Ricoeur remains faithful to methodological principle that grants priority to description of possible over that of actual. As a faculty of producing fictions, imagination acquires a fundamental heuristic function: it is not only that which guides action, but also what makes it intelligible for philosophy.Ricoeur's own trajectory regarding this question is one that goes from definition of imaginary as a faculty of knowing, towards approaching imagination as a practical faculty shedding light on human capacities. âŠ
This article is about one type of cryptocurrencybitcoin.The main topic of this work is a level of risk connected with cryptocurrency market.The work consists of theory, a definition of cryptocurrency and bitcoins, an analysis of risk level in this kind of investments on cryptocurrency market and a bibliography. A definition of cryptocurrency and bitcoinsA Cryptocurrency is a modern digital medium of exchange.It is a new decentralized, limited and peer-to-peer payment system.Most cryptocurrencies are created to introduce new units of currency, whose total amount is limited.All cryptocurrencies use cryptography to control the creation and transfer of money.The first cryptocurrency was Bitcoin, created in 2008 and introduced in 2009.Nowadays it is the most popular cryptocurrency which is used as an open source software.The creator of Bitcoin was Satoshi Nakamoto, a person or a group of people.Nakamoto published a work on The Cryptography Mailing list in which he described the Bitcoin currency.Next year, the first Bitcoin software was launched on the network, which started Bitcoin's flow.Bitcoins are introduced to the market by a process called mining.In this process engage computer network participantsusers who provide their computing power, next verify and record payments into a network in exchange for minted bitcoins and transaction fees.Bitcoins are transferred by wallet software
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Economic and Business Development Strategies
Digitalization and Economic Development in Agriculture
Economic, Social, and Public Health Issues in Russia and Globally
Given a list L with n elements, an order query on L asks whether a given element x2L precedes or follows another element y2 L. More generally, given a set of m elements from L, an order query asks for the set ordered according to the positions of the elements in L. We introduce two formal models for answering order queries on a list in a verifiable manner and in zero-knowledge. We also present efficient constructions for these models. Our first model, called zero-knowledge list (ZKL), generalizes membership queries on a set to order queries on a list in zero-knowledge. We present a construction of ZKL based on zero-knowledge sets and a homomorphic integer commitment scheme. Our second model, privacy-preserving authenticated list (PPAL), extends authenticated data structures by adding a zero-knowledge privacy requirement. In this model, a list is outsourced by a trusted owner to an untrusted cloud server, which answers order queries issued by clients. The server also returns a proof of the answer, which is verified by the client using a digest of the list obtained from the owner. PPAL supports the security properties of data integrity against a malicious server and privacy protection against a malicious client. Though PPAL can be implemented using our ZKL construction, this construction is not as efficient as desired in cloud applications. To this end, we present an efficient PPAL construction based on blinded bilinear accumulators and bilinear maps, which is provably secure and zero-knowledge (e.g., hiding even the size of the list). Our PPAL construction uses proofs of O(m) size and allows the client to verify a proof in O(m) time. The owner executes the setup in O(n) time and space. The server uses O(n) space to store the list and related authentication information, and takes O(min(m log n; n)) time to answer a query and generate a proof. Both our ZKL and PPAL constructions have one round of communication and are secure in the random oracle model. Finally, we show that our ZKL and PPAL frameworks can be extended to support fundamental statistical queries (including maximum, minimum, median, threshold and top-t elements) efficiently and in zero-knowledge.
From the perspective of local deficit financing,this paper tries to expound the internal logic between fiscal decentralization and local government 's land finance. Theoretical analysis shows that: fiscal decentralization in China aggravates local deficit financing, and the latter becomes an incentive for local governments to grab offbudgetary financial revenue, which will impel them to take active land finance strategy to increase local fiscal revenue. At the same time, our empirical test among them using provincial panel data shows that fiscal decentralization and local deficit financing both have obvious positive driving effects on land finance. Finally, we put forward a series of suggestions on land finance governance respectively from the following 5 aspects: deepening tax distribution reform, improving local fiscal revenue structure, changing land finance formation mechanism, promoting administrative performance evaluation mechanism and strengthening budget supervision.
Bitcoin is making near-daily headlines, whether about its volatile exchange rate, the regulatory issues it raises, or its criminal associations. As the public becomes familiar with the idea of virtual currencies, many people struggle to understand why users exchange government-backed (ârealâ) currencies for Bitcoin. This article explores the appeal and danger of investing in Bitcoin for speculative gain, for moral purposes, for its spending power, and for its criminal applications.
Small islands are disadvantaged by conventional development strategies and have sought unusual means of achieving economic development and raising their global profiles. The small Channel Island of Alderney, with a largely non-existent physical resource base, and steady population decline, has sought to develop several service sector activities, increasingly involving the internet and virtual activities. Internet gambling has proved successful. Bitcoin minting offers unique possibilities. Alderney has achieved economic development without significant local assets other than creativity and ingenuity, and a somewhat distinctive political status.
The practical and theoretical meaning of the rise and fall of new local and virtual currencies suggest that two basic theories of money both have their validity and reasons for coexistence. The drive for increasing efficiency in the payment mechanisms is in full swing and still presents many opportunities for improvement.
Many tasks requiring multiple autonomous underwater vehicles (AUVs) are simple, with static goals, of short duration, and require few AUVs, often of the same type. Simple coordination mechanisms that assign roles to AUVs before the mission are sufficient for these multi-AUV systems. However, for tasks that are complex and dynamic, of long duration (implying that AUVs will come and go during the mission), and that have many heterogeneous AUVs, organization of the system will not work. In addition, due to changes in the situation, the system will likely need to be reorganized during the mission. We are developing a distributed, context-aware self-organization/reorganization scheme for advanced multi-AUV systems. This is a two-level approach in which a meta-level organization first self-organizes, assesses the context, and uses contextual knowledge to design a task-level organization appropriate for the context that can then carry out the mission. We are extending our prior work by distributing both the context assessment process and the organization design process. The result will be a system that can self-organize efficiently and effectively for its context and that can reorganize appropriately as the context changes.
Just like the personal computer revolution, it is possible that Knowledge Management (KM) will in the 21 century experience a decentralizing revolution that gives more power and autonomy to individuals and selforganized groups. Seven decades after Vannevar Bushâs still unfulfilled vision of the Memex. Levyâs scenario stresses the dire need to provide overdue support tools for knowledge workers in our Knowledge Societies, not at the expense of Organizational KM Systems, but rather as the means to foster a fruitful co-evolution. With a prototype system addressing these issues about to be converted into a viable Personal KM system (PKMS), the author follows up on recent publications and considers the impact and potential of a novel memebased approach aiming to aid individuals throughout their academic and professional life and as contributors and beneficiaries of organizational performance and in light of the anticipated next generation of KM systems. 1 A NEXT GENERATION OF KM The first generation of Knowledge Management (KM) has been described as the capturing, storing, and reusing of existing knowledge including âsystems of managing knowledge like company yellow pages, experts outlining processes they are involved in, creating learning communities where employees/customers share their knowledge, creating information systems for documenting and storing knowledge, and so on. These first-generation KM initiatives were about viewing knowledge as the foremost strategic asset, measuring it, capturing it, storing it, and protecting it. They were about treating knowledge as an asset, recognizing how it influences strategy, and wanting to make the most of it by managing it properlyâ (Pasher & Ronen 2011). The second KM generation needs to focus on creating new knowledge and innovation, a process which starts with the âreuse or new use of existing knowledge, adding an invention, and then creating a new product or service that exploits this invention.â This process requires creativity and the awareness that old knowledge becomes obsolete. For reaping the appropriate rewards, it is essential to systematically exploit the knowledge captured and created (Pasher & Ronen 2011). In reviewing a wider range of features for the âNext KM Generationâ (suggested by Sveiby, Wiig, Snowdon, McElroy, Ponzi, Miles, St Onge, Allee), the identified seven key themes prioritize confirm this need, but also strongly emphasize the personal and social nature of knowledge (Grant 2008). 1.1 The Personal KM Agenda Despite these accentuations and in contrast to Organizational KM (OKM), Personal KM (PKM) has been placed historically in a narrow individualistic confinement (Cheong & Tsui 2011b). In limiting its scope, PKM has been labelled as sophisticated career and life management with a core focus on personal enquiry (Pauleen & Gorman 2011) or as a means to improve some skills or capabilities of individuals (Davenport 2011), negating its importance relating to group member performance, business processes, or new technologies. This state surprises in light of prominent past suggestions to develop a âMemexâ for making oneâs âintellectual excursions more enjoyableâ (Bush 1945), to offer assistance in allocating oneâs âattention efficiently among the [emerging] overabundance of information sourcesâ (Simon 1971), or to provide adequate organizational leadership for building, connecting, and energizing dynamic knowledge-creating environments and their expansion (Nonaka 2000). As a result, PKM remains âa real and pressing problemâ, and Bush's dream of a âMemexâ has yet to be fully realized on a wide scale (Davies 2011). Appropriately, Wiig argues for shifting the focus of KM toward strengthening the ability of people for enabling them to act in the best interest of their enterprise and its desired strategies and performance (Wiig 2004). In this context, PKM needs more appropriately to be regarded as a bottom-up approach to KM (Pollard 2008), as opposed to the more traditional, top-down Organizational KM. As such, PKM also âgoes beyond Personal Information Managementâ (PIM) which focusses predominantly on information processing without the emphasis on creating new knowledge (Cheong & Tsui 2011a). But, although there are many PKM tools available, âthey are not integrated with each otherâ, and the âcurrently available PKM systems can provide only a partial support to knowledge workersâ (Osis 2011). âWhile today we have many powerful applications for locating vast amounts of digital information, we lack effective tools for selecting, structuring, personalizing, and making sense of the digital resources available to usâ (Kahle 2009). Meanwhile, the organizational, commercial, social and legal innovations driven by technological progress and economic pressures continue to have profound impacts. Work has suffered from a process of fragmentation which will continue to accelerate. Its implications include oneâs slipping control over constant interruptions, the loss of time for real concentration, and less learning by observation and reflection (Gratton 2011). With specializations and domain-specific knowledge on the rise, peoplesâ identification has shifted from their company to their profession, and vertical hierarchies and traditional career ladders have been replaced by sideways career moves between companies and a horizontal labour market (Florida 2012). The âFuture of Employmentâ study estimates 47% of the current US employment to be still at risk due to recent technological breakthroughs able to turn previously non-routine tasks into well-defined problems susceptible to computerization (Frey & Osborne 2013). What is overdue is in the opinion of the author â an innovative PKM technology to provide the means for life-long-learning, resourcefulness, creative authorship and teamwork throughout an individualâs academic and professional life and for his/her role as contributor and beneficiary of organizational and societal performance. It needs to support the notion that knowledge and skills of knowledge workers are portable and mobile and with it their options on where, how, and for whom they will put their knowledge to work. 1.2 Intents and Barriers to Overcome In Wiigâs opinion (2011), individuals need to be highly knowledgeable not only to function competently as part of the workforce, but also in their daily lives and as public citizens: âIn a society with broad personal competences, decision-making everywhere will maximize personal goals, provide effective public agencies and governance, make commerce and industry competitive, and ensure that personal and family decisions and actions will improve societal functions and Quality of Life.â But, âfor better performance, people must [also] be provided with resources and opportunities to do their best. They need knowledge and understanding as well as motivation and supportive attitudes.â Such resources may well be autonomous PKM capacities, networked in continuous feedback loops, where individuals are able to determine how their expertise will be used or exchanged with people, communities, or organizations close to them. Levy (2011) expects such systems nourished by the creative conversation of the many networked PKM devices to assume an elementary role that enables the emergence of the distributed processes of collective intelligence, which in turn feed them. Accordingly, he sketches a scenario which stresses the vital role of future education âto encourage in students the sustainable growth of autonomous capacities in PKMâ and which envisages KM to experience âa decentralizing revolution that gives more power and autonomy to individuals and self-organized groupsâ (Levy 2011). Although the author concurs that PKM Systems (PKMS) are destined to become potent drivers of human development (Schmitt 2014b), an enabling technological environment benefitting such a novel solution is presently facing severe barriers wasting individualsâ time and efforts (Schmitt 2014f). The remedies have been summed up into five provisions: 1. Digital personal and personalized knowledge is always in the possession and at the personal disposal of its owner or eligible co-worker, residing in personal hardware or personalized cloud-databases. 2.
According to EU competition law, the existence of an anticompetitive agreement can be inferred from a number of coincidences and indicia only in the absence of another plausible explanation of the facts at stake. According to U.S. federal law (antitrust law included), only a complaint that states a plausible claim for relief can survive a motion to dismiss at the pleading stage. What is plausible, however? After explaining the relationship between facts and evidence law, this chapter analyses the general meaning of the notion of plausibility, discusses the degree of discretion that it introduces, how it affects the justifications that judges and fact-finders make for their choices, and remarks on how this concept relates to substantial accuracy. On the other hand, the chapter acknowledges that antitrust law, by relating our understanding of what is plausible to economic models, debunks these concerns and raises another striking issue. Since economics is rooted in various axioms and value-choices, the link that antitrust law establishes among plausibility, standards of proof and economics grants to these axioms and value-choices the possibility of affecting the antitrust decisions about facts, although these decisions (as all factual decisions) should amount to pure descriptions of the concrete facts disputed at trial or during the administrative procedure.
The research of fiscal decentralization is based on the reconstruction of measurement index.In view of the combination of fiscal decentralization principles and its reality in China,the paper devises seven measurement indexes of fiscal decentralization,makes an empirical analysis of their corresponding effects on economic growth,and estimates the economic effect of the fiscal decentralization reform in counties directly administered by province.The paper gives support to the significance of revenue and expenditure decentralization within the system and gives decision-making power to county-level governments.However,the contribution of full-covered measurement index of fiscal decentralization to the economic growth is not ideal.Therefore,it is urgent to endow the county-level governments with financial resources and decision-making power within system,to tighten the control of their non-budget financing,and to intake the counties administered by province into the new type of fiscal system featuring the match of financial power and responsibility.
Andrew Sunil Rajkumar, Eleonora Cavagnero, Deena Class, Katharina Ferl
Over the last three decades, Brazil has made significant investments in social programs, including a comprehensive healthcare system. Since returning to democracy in 1985 and with the 1988 Constitution, quality healthcare has been explicitly identified as a right of citizenship and a responsibility of the government. The Unified Health System (SUS) that provides free universal care for all Brazilians was instituted following a sustained push from civil society organizations. With the subsequent declines in poverty that followed re-democratization, the country has also seen concomitant declines in under-five mortality and maternal mortality as well as increases in life expectancy. Coverage for vaccinations and pre-natal care is almost universal. Brazil's Primary Care Strategy (which includes the Family Health Strategy) marks a meaningful shift from curative hospital-based care to preventive ambulatory care with a strong pro-poor focus. A highly decentralized system has led to complex patterns of funding and service provision with the Federal, State and Municipal governments involved. Before formation of the SUS, Brazil's healthcare system was dominated by private organizations that received large government subsidies. Brazil's system remains highly privatized with the private sector receiving substantial funds from all levels of government.
Nicolas T. Courtois, Pinar Emirdag, Filippo Valsorda
Abstract. In this paper we study the question of key management and practical operational security in bitcoin digital currency storage systems. We study the security two most used bitcoin HD Wallet key management solutions (e.g. in BIP032 and in earlier systems). These systems have ex-tensive audit capabilities but this property comes at a very high price. They are excessively fragile. One small security incident in a remote corner of the system and everything collapses, all private keys can be re-covered and ALL bitcoins within the remit of the system can be stolen. Privilege escalation attacks on HD Wallet solutions are not new. In this paper we take it much further. We propose new more advanced combi-nation attacks in which the security of keys hold in cold storage can be compromised without executing any software exploit on the cold sys-tem, but through security incidents at operation such as bad random number or related random events. In our new attacks all bitcoins over whole large security domains can be
In the last few years the efficiency of secure multi-party computation (MPC) increased in several orders of magnitudes. However, this alone might not be enough if we want MPC protocols to be used in practice. A crucial property that is needed in many applications is that everyone can check that a given (secure) computation was performed correctly â even in the extreme case where all the parties involved in the computation are corrupted, and even if the party who wants to verify the result was not participating. This is especially relevant in the clients-servers setting, where many clients provide input to a secure computation performed by a few servers. An obvious example of this is electronic voting, but also in many types of auctions one may want independent verification of the result. Traditionally, this is achieved by using non-interactive zero-knowledge proofs during the computation. A recent trend in MPC protocols is to have a more expensive preprocessing phase followed by a very efficient online phase, e.g., the recent so-called SPDZ protocol by Damgard et al. Applications such as voting and some auctions are perfect use-case for these protocols, as the parties usually know well in advance when the computation will take place, and using those protocols allows us to use only cheap information-theoretic primitives in the actual computation. Unfortunately no protocol of the SPDZ type supports an audit phase. In this paper, we show how to achieve efficient MPC with a public audit. We formalize the concept of publicly auditable secure computation and provide an enhanced version of the SPDZ protocol where, even if all the servers are corrupted, anyone with access to the transcript of the protocol can check that the output is indeed correct. Most importantly, we do so without significantly compromising the performance of SPDZ i.e. our online phase has complexity approximately twice that of SPDZ.
In a hybrid network system which combines a wired network adopting PKI authentication and a wireless network adopting IBE authentication,it is difficult to authenticate other nodes in view of the different security polices and cryptosystem.To solve this problem,a cross-domain authentication scheme based on zero knowledge proof is proposed.An agency node is settled between the two heterogeneous trustworthy domains to certificate nodes'commitments in the zero knowledge proof.Then a authentication protocol between heterogeneous trustworthy domains is designed to realize the authentication between nodes in different domains,and the correctness,security and efficiency of the protocol are analyzed.The results show that the proposed protocol is feasible and effective.
We consider Primary-Secondary-Resolver Membership Proof Systems (PSR for short) and show different constructions of that primitive. A PSR system is a 3-party protocol, where we have a primary, which is a trusted party which commits to a set of members and their values, then generates a public and secret keys in order for secondaries (provers with knowledge of both keys) and resolvers (verifiers who only know the public key) to engage in interactive proof sessions regarding elements in the universe and their values. The motivation for such systems is for constructing a secure Domain Name System (DNSSEC) that does not reveal any unnecessary information to its clients. We require our systems to be complete, so honest executions will result in correct conclusions by the resolvers, sound, so malicious secondaries cannot cheat resolvers, and zero-knowledge, so resolvers will not learn additional information about elements they did not query explicitly. Providing proofs of membership is easy, as the primary can simply precompute signatures over all the members of the set. Providing proofs of non-membership, i.e. a denial-of-existence mechanism, is trickier and is the main issue in constructing PSR systems.
The interactive zero-knowledge proof protocol for the graph isomorphism was studied,and subgraph isomorphism certification algorithm was proposed by analyzing the basic model based on zeroknowledge proof.The security of most of the zero knowledge proofs was guaranteed by complex mathematical operations and large scale computations of interaction on both sides.Modulo operation was directly applied to the file encryption,and that only required a few parameters,which greatly reduced the storage space,and the method was simple and effective.Because of the characteristic of the zero-knowledge proof,it has better level of security,and meets the demand of basic protection.The algorithm is suitable for the authentication algorithm of login and vote that cannot be traced.