The introduction of user-payment for health services is frequently followed by concern about the impact on equity of access for poor people. Decentralizing governments often try to remedy the created inequities by putting in place safety nets in the form of exemptions and waivers in the user-fee systems. However, where user payments merely operate as local government strategies for health financing, without national policy they are likely to be self-defeating, as local governments are frequently more interested in raising revenue to meet recurrent costs of devolved services than in promoting equity. Thus guidelines put in place by the central government to operationalize safety nets are seen by local governments as being contradictory to this goal, and are thus ignored or altered to suit the district revenue aims. This study was carried out to investigate the context and the constraints in implementing exemption schemes. Data were collected in two selected administrative districts of Uganda (Mbarara and Mukono). Qualitative approaches to data collection were adopted, namely focus group discussions and key informant interviews with policy-makers, health administrators, service providers and community members. These methods were combined with document review. We found little evidence of safety-net guidelines initiated by decentralized/local governments, since district local governments had little motivation to extend exemptions, waivers or credits. The conclusion is that safety nets such as waivers and exemptions will only be effective if they are backed by a national health financing policy, they reconcile the often competing demands of local government revenue needs, and are strictly enforced and supervised by both the local and central governments. The implications of the findings for remedying the tension between the needs for cost recovery and for attainment of equity goals through exemption policies for the poor and indigent are discussed.
Zero-knowledge interactive proof is a useful tool for designing identification and digital signature schemes. We propose a new interactive proof based identification and signature scheme.
FlexiInternational develops and maintains FlexiFinancials, a suite of object-oriented, client/server software products for accounting. These interacting applications support general ledger, accounts payable and receivable, purchasing, fixed assets, order processing, inventory maintenance, and workflow functions. This paper describes a distributed component, transaction-based architecture that comprises the foundation for future development.
Although ABS has been widely spread on the commercial market for twenty years, throughgoing investigations with rigorous theoretical background have been lacking in the automotive literature. The control strategies of commercial ABS are mostly based on table rules to be calibrated through various experiments and tests, and the system dynamics cannot be effectively considered in the controller design. Due to the challenges in the automobile industry it is desired to develop a technique which still enhances the control performance and robustness with respect to various vehicle types and environment conditions. Motivated by these goals, a robust adaptive control algorithm is developed in this work. The proof of asymptotic stability is based on the Lyapunov method. The objective of such control is to maximize the tire friction under the assumption of knowing the optimal value of target slip. It is shown that, without any prior knowledge of the tire force and system parameters, the slip error is bound to converge to zero asymptotically. The robustness of the control system with respect to variation of the system parameters is guaranteed. The brake dynamic system to be controlled includes mechanical motion equations and the hydraulic circuit equations. A two-level control scheme is applied for the controller design, which considers the both parts separately.
We describe efficient constructions for various cryptographic primitives in private-key as well as public-key cryptography. Our main results are two new constructions of pseudo-random functions. We prove the pseudo-randomness of one construction under the assumption that factoring (Blum integers) is hard while the other construction is pseudo-random if the decisional version of the Diffie--Hellman assumption holds. Computing the value of our functions at any given point involves two subset products. This is much more efficient than previous proposals. Furthermore, these functions have the advantage of being in TC 0 (the class of functions computable by constant depth circuits consisting of a polynomial number of threshold gates). This fact has several interesting applications. The simple algebraic structure of the functions implies additional features such as a zero-knowledge proof for statements of the form " y = f s ( x )" and " y ≠ f s ( x )" given a commitment to a key s of a pseudo-random function f s .
Some of the salient biology is reviewed, so that it can be seen how suitable the immune system is as a prototype of "bottom up" artificial intelligence. It is stressed that the immune system is entirely distributed (to first approximation). Its agents, the cells, are highly complex. Much is known about these cells and their interaction with each other and with pathogens, and the system is of high biological and medical interest. Major questions to be addressed include the following: 1) what are the "goals" of the immune system, and how can feedback promote these goals? 2) how can spatial organization allow non-specific chemical signals to select specific immune elements that contribute effectively to system goals? 3) how and in what sense can immune system performance be improved in the absence of an overall goal? and 4) how does the immune system compare with other autonomous decentralized systems.
We present a complete promise problem for SZK, the class of languages possessing statistical zero-knowledge proofs (against an honest verifier). The problem is to decide whether two efficiently samplable distributions are either statistically close or far apart. This characterizes SZK with no reference to interaction or zero-knowledge. From this theorem and its proof we are able to establish several other results about SZK, knowledge complexity, and efficiently samplable distributions.
Energy management systems/supervisory control and data acquisition (EMS/SCADA) systems are usually geographically distributed and have operational organizations. They are changing in accordance with the various and varying environments, and they should be flexible enough to adapt to those changes quickly. The paper proposes a new architecture called SCOPE (System Configuration of Power Control System) to realize flexible and reliable EMS/SCADA systems. SCOPE makes application programs independent of the operational organization and system configuration of the EMS/SCADA system, i.e., application programs are not influenced by changes in them. These properties make EMS/SCADA systems flexible and reliable, and also the development of EMS/SCADA systems becomes efficient and economical. Through developing and evaluating a SCOPE prototype system, it has been confirmed that the flexibility and maintainability of EMS/SCADA systems based on the SCOPE architecture has been improved.
The basic principles of the intelligent home technology are presented and it is described how it can be modeled as a multi-agent system. Because of the complexity of the system it is argued that it should be generated by an evolutionary process and maintained according to the principles of the immune system.
Sung Jun Park, Tae‐Hoon Kim, Dong Ho Won, Young Hwa An
We propose a new notion of an entrusted undeniable signature which is a variant of the undeniable signature. Also we propose a provably entrusted undeniable signature whose security can be proved. The proposed entrusted undeniable signature is a new type of undeniable signature in which the signer confirms his(her) signature to any verifier without the help of court but the verifier can't run the disavowal protocol in the undeniable signature which only court can run to solve the dispute later. The proposed scheme is constructed by a combination of the undeniable signature and zero-knowledge interactive proof system. The proposed provably entrusted undeniable signature is much the same as our entrusted undeniable signature but using the public key residue cryptosystem, which is polynomially secure, for the commitment scheme.
We consider which aspects of the two prover model are necessary for their striking language recognition and zero-knowledge capabilities. We approach this question by looking at an alternative, more symmetric model which we call the double verifier model. We find that in this model the shared randomness of the verifiers is key to the language recognition power: if the verifiers don't share randomness the power is PSPACE; otherwise it is MIP=NEXPTIME. We find that the shared randomness of the provers is necessary for zero-knowledge: if the provers don't share randomness, statistical zero-knowledge is only possible for languages in BPP/sup NP/; else it is possible for all of NEXPTIME. These results have immediate implications for the standard two-prover model. We see that correlations between the verifier's queries is crucial for the language recognition power of two prover proofs. In particular, the natural analog of IP=AM does not hold in the two-prover model unless NEXPTIME=PSPACE. Similarly, we see that shared randomness, or correlation of the provers answers, is necessary for the statistical zero-knowledge of two prover proofs.>
A new framework is proposed for the analysis of communication protocols that require accountability, such as those for electronic commerce. Informal arguments are presented to show that a heretofore un-explored property "provability" is pertinent to examine the potential use of communication protocols in the context of litigation, and in the context of audit. A set of postulates which are applicable to the analysis of proofs in general (e.g., zero knowledge proofs), and the proofs of accountability in particular, are proposed. The proposed approach is more natural for the analysis of accountability then the existing belief logics that have been used in the past for the analysis of key distribution protocols. Some recently proposed protocols for electronic commerce and public-key delegation are analyzed to illustrate the use of the new analysis framework in detecting (and suggesting remedies for eliminating) their lack of accountability, and in detecting and eliminating redundancies.>
We suggest a systematic way to design secure password-based authentication protocols, which is the password verifier model. The method makes use of zero-knowledge interactive proof (ZKIP), which has been known not to be useful for the protection of passwords. For the proper usage of ZKIP, we introduce a specialized form of ZKIP, which has a secret coin tossing stage.
Concerns use of spacecraft as autonomous coordinated teams. Generalized reasoning capability offered by advanced distributed software technology and AI can cope with unexpected events and uncertainty, and so close the loop of perception, decision and eventually deliberation. The team members play interchangeable roles and negotiate about the task. We present a multi-agent system to provide a high degree of autonomy and support for coordination among team members. We use JPL formation flying mission initial architectures as benchmark. Our target is to avoid inconsistencies/disagreements between two or more participants in a collaborative context, increase the system's fault tolerance in cases such as loss of a member while the system still operates reliably. We address cooperation between collaborating independent autonomous agents. In a top-down organization agents are coordinated hierarchically, where the agents at the top of the hierarchy make the majority of the intelligent group decisions. In a more structured but still hierarchical organization, lower-level agents exercise more intelligence. A lower-level agent can advance a plan for the others to follow, and a higher-rank agent decides on the best plans. Although more rigid, the centralized intelligence organization allows for less communication among agents, so is more straightforward to implement. The decentralized approach requires more communication, but the intelligence is truly distributed, which makes for a more flexible, adaptive and efficient organization.
The problem of suppressing zero-input limit cycles in coupled-form state-space digital filters when the quantization is performed after the multiplication is addressed. To the extent of the authors' knowledge, no proof has been presented that the parasitic oscillations are suppressed for poles anywhere in the unit circle, under that condition. Some authors have addressed this subject, but their results constrain the poles to a bounded region inside the unit circle. With the objective of exploring this topic further, the authors present a proof that for poles whose angle is either 0, /spl plusmn/45, /spl plusmn/90, /spl plusmn/135 or 180 degrees and whose radius is lower than one, the second-order state-space coupled-form digital filter is free of zero-input limit cycles when quantizers placed just after the multipliers implement magnitude truncation.
This paper proposes a new proof-based approach to safe evolution of distributed software systems. Specifically it extends the simple certification mechanism of proof-carrying code (PCC) to make it interactive and probabilistic, thereby devising code with interactive proof (CIP). With CIP, a code consumer is convinced, with overwhelming probability, of the existence and validity of a safety proof of a transmitted code through interaction with a code producer. The class of safety properties that are provable by CIP is larger than the class provable by PCC, provided that each code consumer is allowed to spend a reasonable amount of time on verification. Moreover, CIP can be further extended to devise code with zero-knowledge interactive proof (CZKIP). This concept is useful, for example, when the code producer wants to use the safety proof as a kind of "copyright" of the code.
A zap is a 2‐round, public coin witness‐indistinguishable protocol in which the first round, consisting of a message from the verifier to the prover, can be fixed “once and for all” and applied to any instance. We present a zap for every language in NP, based on the existence of noninteractive zero‐knowledge proofs in the shared random string model. The zap is in the standard model and hence requires no common guaranteed random string. We present several applications for zaps, including 3‐round concurrent zero‐knowledge and 2‐round concurrent deniable authentication, in the timing model of Dwork, Naor, and Sahai [J. ACM, 51 (2004), pp. 851–898], using moderately hard functions. We also characterize the existence of zaps in terms of a primitive called verifiable pseudorandom bit generators.
We consider the problem of designing an efficient oblivious transfer (OT) protocol that is provably secure in a concurrent setting, i.e., where many OT sessions may be running concurrently with their messages interleaved arbitrarily. Known OT protocols use zero-knowledge proofs, and no concurrent zero-knowledge proofs are known that use less than a poly-logarithmic number of rounds (at least without requiring a pre-processing phase, a public random string, an auxiliary string, timing constraints, or pre-distributed public keys). We introduce a model for proving security of concurrent OT protocols, and present a protocol that is proven secure in this model based on the decisional Diffie-Hellman problem. The protocol is efficient, requiring only a slightly non-constant number of rounds.
In order to be competitive, telecommunications service providers need new technologies that facilitate the rapid introduction of new services and resolve the problems how to use the services safely. This paper introduces a network platform based on mobile agent and provides a security mechanism based on zero knowledge proof in the mobile communication system. In this way, service providers can provide the new services rapidly, expediently and safely.
This paper discusses the nature of the paradigm shift that will be accelerated as the next-generation Internet (NGI) pervades society. First, we define the NGI society as one in which the network is so ubiquitous that no one will be conscious of connecting with it. Then we investigate trends and expectations of current NGI research and development projects worldwide. Secondly, we have performed comprehensive questionnaire-based market research into new technologies. This reveals that Japan can be expected to create global markets by developing NGI applications in home-electronic appliances, mobile assistants, transportation systems, and animation games. Furthermore, we generalize the discussion on the nature of the paradigm shift as follows. Although modern western rationalism produced the astonishing growth of the industrialized countries in the 19th-20th centuries, this approach alone no longer offers the prospect of much further advance. The 21st century paradigm for science and technology, for social, economic and governmental systems, and for industrial structures and working styles will necessarily shift towards autonomous and cooperative decentralization. The Internet is a decentralized computer system that is operated autonomously and cooperatively by individuals and small organizations. The NGI will further accelerate this paradigm shift. We conclude that this approach is essentially similar to the traditional oriental philosophy of harmony, and urge that it should be adopted in positioning Japan within the global, information-oriented network society of the 21st century.
Decentralization is commonly championed as a means for achieving equity. To date, however, there has been little discussion of the mechanisms underlying this relationship, and several of the few empirical investigations that have addressed the topic have found the converse; that decentralization has exacerbated inequalities. This article examines the performance and equity in financing of the Honduras Ministry of Health's (MOH) decentralized user fee system. The MOH of Honduras established a national user fee policy in 1989. It provided a framework of rules and regulations and decentralized administration of the system to the regional offices. A survey conducted under the auspices of this study provided detailed information about the structures and operations of MOH user fee systems. The survey revealed that the systems vary markedly by region, creating horizontal inequities, and that they have numerous other shortcomings. The average price of a consultation is low, US dollars 0.16, and revenues have consistently equalled just 2% of MOH expenditures. The systems' administrative costs are equal to 67% of their revenues. Eliminating the user fee systems in all but the national and regional hospitals would actually save money and/or enable the MOH to provide more care. Average consultation prices are highest in health posts, intermediate in centres and lowest in the national hospitals, thereby encouraging the inappropriate use of the MOH's pyramidal referral system and fostering MOH inefficiency. Fee levels and exemption practices are horizontally and vertically inequitable. The likelihood of paying for an ambulatory visit is highest at a health post, 89%, and lowest at a hospital, 49%. Individuals from the poorest one-fifth of households are the most likely to have to pay for care. Honduras' experience demonstrates that a decentralized user fee system is not necessarily equitable, and that, more generally, the gains that can be realized from decentralizing user fee systems are not automatic. They must be anticipated, planned for and cultivated by a well-designed and well-implemented initiative that is not a single, one-time event, but rather a dynamic, on-going enterprise.
Most economists agree that new investments in highways at this point in time in the United States have little impact on overall growth in output. New highways play a more important role in shifting economic activities among places, drawing jobs from other locations into the highway corridors, a phenomenon known as negative spillovers. The objective of this dissertation is two-fold, to examine the proposal to decentralize highway finance, which aims to solve the financial responsibility mismatch problem that stems from economic spillovers of highways, and to test the hypothesis of economic spillovers of highway investment at the metropolitan level. First, to better understand how spillovers influence the highway investment decision, the theoretical framework from the interjurisdictional tax competition literature is borrowed to model governments' investment behaviors. Numerical simulations show that decentralized local governments, which independently maximize output in their own jurisdiction, may engage in wasteful investments in highways with the presence of spillovers. Second, to shed more light on the spatial detail of economic spillovers, empirical tests of the spillover hypothesis are conducted at the metropolitan level, with census tracts as the unit of observation. The results of the quasi-experiment reveal census tract employment growth patterns that confirm the existence of negative spillovers caused by the opening of the Interstate 105 in 1993. The benefiting area, which grew substantially after the highway was opened, is limited to a long narrow corridor around the highway, while nearby locations outside the corridor experienced slow growth relative to the rest of the metropolitan area after controlling for various factors. Together, these results suggest that although negative spillovers are present at the metropolitan level, decentralizing highway finance may not be an effective policy to deal with the financial responsibility mismatch problem. Highway finance should remain centralized within metropolitan areas, and regional governing bodies should pay special attention to the distributional impact of highway projects.