Abstract. A commitment multiplication proof, CMP for short, allows a player who is committed to secrets s, s ′ and s ′ ′ = s · s ′ , to prove, without revealing s, s ′ or s ′ ′ , that indeed s ′ ′ = ss ′. CMP is an important building block for secure general multi-party computation as well as threshold cryptography. In the standard cryptographic model, a CMP is typically done interactively using zero-knowledge protocols. In the random oracle model it can be done non-interactively by removing interaction using the Fiat-Shamir heuristic. An alternative non-interactive solution in the distributed setting, where at most a certain fraction of the verifiers are malicious, was presented in [1] for Pedersen’s discrete log based commitment scheme. This CMP essentially consists ofa few invocations ofPedersen’s verifiable secret sharing scheme (VSS) and is secure in the standard model. In the first part ofthis paper, we improve that CMP by arguing that a building block used in its construction in fact already constitutes a CMP. This not only leads to a simplified exposition, but also saves on the required number ofinvocations ofPedersen’s VSS. Next we show how to construct non-interactive proofs of partial knowledge [8] in this distributed setting. This allows for instance to prove non-interactively the knowledge of ℓ out of m given secrets, without revealing which ones. We also show how to construct efficient non-interactive zero-knowledge proofs for circuit satisfiability in the distributed setting. In the second part, we investigate generalizations to other homomorphic commitment schemes, and show that on the negative side, Pedersen’s VSS cannot be generalized to arbitrary (black-box) homomorphic commitment schemes, while on the positive side, commitment schemes based on q-one-way-group-homomorphism [7], which cover wide range ofcurrently used schemes, suffice. 1
The notion of efficient computation is usually identified in cryptography and complexity with probabilistic polynomial time. However, until recently, in order to obtain constant-round zero-knowledge proofs and proofs of knowledge (for NP), one had to allow simulators and knowledge-extractors to run in time which is only polynomial on the average (i.e., expected polynomial time). Whether or not allowing expected polynomial-time is necessary for obtaining constant-round zero-knowledge proofs and proofs of knowledge, has been posed as an important open question. This question is interesting not only for its theoretical ramifications, but also because expected polynomial time simulation is not closed under composition. Therefore, in some cases security is not maintained when a protocol that utilizes expected polynomial time simulation (or extraction) is used as a part of a larger protocol.A partial answer to the question of the necessity (or non-necessity) of expected polynomial-time was provided recently by Barak, who gave the first constant-round zero-knowledge argument with a strict (in contrast to expected) polynomial-time simulator. His was also the first protocol that is not black-box zero-knowledge. That is, the simulator in his protocol utilizes the description of the code of the verifier in an essential way.In this paper, we completely resolve the question of expected polynomial-time in zero-knowledge arguments and arguments of knowledge. First, we show that there exist constant-round zero-knowledge arguments of knowledge with strict polynomial-time extractors. As in the simulator of Barak's zero-knowledge protocol, the extractor for our proof of knowledge is not black-box and uses the code of the prover in an essential way.On the negative side, we show that non-black-box techniques are essential to both strict polynomial-time simulation and extraction. That is, we show that no constant-round zero-knowledge argument (or proof) can have a strict polynomial-time black-box simulator. Similarly, we show that no constant-round zero-knowledge argument (or proof) of knowledge can have a strict polynomial-time black-box knowledge extractor. Thus, for constant-round black-box zero-knowledge arguments (resp., arguments of knowledge), it is imperative that the simulator (resp., extractor) be allowed to run in expected polynomial-time.
We analyze the governance structure and the financing of Kyrgyz education, with special emphasis on the general secondary education system. General secondary schools are under the authority of oblasts and rayons. Our main findings are as follows: 1. The oblast and rayon authorities in Kyrgyzstan are in fact delegated offices of the central administration, with highly non-transparent reporting lines, very little budgetary independence, diffused political responsibility and politicized control over financial flows to lower levels of government. 2. The principle that funds from the central budget for specific functions should be transferred directly (without any intermediaries) to the level of government responsible for those functions is not observed in Kyrgyzstan. In particular, the categorical grants for education are determined and negotiated in a very non-transparent way. 3. The Kyrgyz education sector is fragmented, and the divided responsibilities for management and for finances make rationalization and reform very difficult to accomplish. Moreover, the situation is compounded by the fact that education decentralization has a formal character, and is not accompanied by real delegation of authority and responsibility. 4. The general secondary education system in Kyrgyzstan, although managed according to the rules and procedures common to other post Soviet republics, displays a remarkable degree of regional and ethnic differentiation. The financing levels also vary significantly among oblasts. 5. Parental contributions make up at least 30% of the school budgets in Bishkek. Their collection and use vary greatly among schools, but in all cases are beyond the effective control of either parents or the central and local authorities. Moreover, the emerging system of entrance fees for first grade students is unconstitutional and violates human rights and pedagogical principles. In order to deal with these issues, the Kyrgyz Republic needs to correct the present non-transparent and dysfunctional governance structure of Kyrgyz education, because otherwise any efforts to improve the delivery of educational services or their financing may remain ineffective. The Kyrgyz Republic also needs to define education standards that it will be able to enforce and finance in all schools. Finally, it needs to implement a regulatory system governing parental contributions, which would serve the schools and at the same time allow for transparent and well-monitored use of private funds in public schools.
This paper attempts to identify the key financing issues and constraints for accessing maternal health services in Tanzania. Access to the services is of concern because despite high use of antenatal care the 1990s saw an appreciable decline in the number of births that take place in a health facility (currently 44 percent) and in the number of births attended by skilled health workers (36 percent). The current analysis finds that the great majority of women who access antenatal care services do not pay for the services nor do they pay for drugs and transportation related to the services. While many delivery services (and related drugs and transportation) also are free of charge a greater number of women who access the services do pay something. Costs are particularly high for caesarian-section delivery-related supplies. Evidence is mixed on the impact of user fees instituted in 1993 and especially on their impact on the use of maternal health services. Enrollment in the prepayment-oriented Community Health Fund (CHF) begun in 1996 is low and thus far available in only 23 districts; an exemption policy is inconsistently applied so many members are still charged user fees. Evidence is not yet available to evaluate the effect on access of the more recent and still limited financing efforts of national health insurance and decentralization. Given that financing barriers may play a role in preventing access to maternal health services the paper recommends that further research on user fees be undertaken to help guide health policy implementation. The findings could solidify support for the country’s national waiver and exemption policy and help determine which key maternal health-related expenses should be waived. The paper also suggests that expanding the CHF and the national health insurance program could help reduce financial barriers and promote greater equity in access to these services. The Sector Wide Approach also has potential to improve efficiency of external funding by eliminating the duplication of efforts among donors and providing a single policy for the government to implement. (authors)
This article examines the influence of New Public Management ideas on recent changes in the Portuguese central government. Its purpose is to analyse the tendency to make public organizations more autonomous and to decentralize following the example of other countries inspired by the practice of the private sector and New Public Management stressing managerial flexibility. The message it conveys is that changes were primarily guided by values of the public domain, juridicial concerns and the primacy of politics, building a public governance that emphasizes the role of politicians and opens the administrative system to the sociopolitical environment.
The terrorist attacks of September 11, 2001 have had a profound impact on American policing, requiring that police agencies substantially modify various elements of their policies, operations, and training. This article examines several types of changes local American police agencies will have to implement if they are to effectively meet the challenges of preventing, deterring, responding to, and investigating terrorist acts. Police agencies face a compelling need for more sophisticated intelligence gathering and analysis, as well as better dissemination of terrorism intelligence among local, state and federal agencies. There is also the need for more sophisticated operational policies with regard to terrorism response, greater cooperation and sharing of resources among local public safety agencies, and more comprehensive training that educates police officers to the realities of contemporary terrorist methods and activities. Finally, the need for effective investigation and prosecution of terrorist acts demands that agencies ignore or overcome the traditional organizational boundaries and rivalries that impede the achievement of these and other goals. The article also points some of the difficulties involved in implementing the necessary changes within a highly decentralized system of thousands of relatively autonomous local agencies, and it illuminates some of the initiatives undertaken by the New York Police Department (NYPD) to overcome these obstacles and more effectively prepare for the terrorist threat.
Zero-knowledge proofs are proofs that are both convincing and yet yield nothing beyond the validity of the assertion being proven. Since their introduction about twenty years ago, zero-knowledge proofs have attracted a lot of attention and have, in turn, contributed to the development of other areas of cryptography and complexity theory.
A 4-round zero-knowledge interactive proof system for NP (Non-deterministic Polynomial) is presented when assuming the existence of one-way permutations and collision-free hash functions. This construction is more efficient than the original construction of 5-round zero-knowledge proof system for NP. The critical tools used in this paper are: zap, hash-based commitment scheme and non-interactive zero-knowledge.
Abstract. We introduce the notion of a dynamic accumulator. Anaccumulator scheme allows one to hash a large set of inputs into one short value, such that there is a short proof that a given input was incorporated into this value. A dynamic accumulator allows one to dynamically add and delete a value, such that the cost of an add or delete is independent of the number of accumulated values. We provide a construction of a dynamic accumulator and an efficient zero-knowledge proof of knowledge of an accumulated value. We prove their security under the strong RSA assumption. We then show that our construction of dynamic accumulators enables efficient revocation of anonymous credentials, and membership revocation for recent group signature and identity escrow schemes.
Carlos Eduardo Frickmann Young, Carlos A. Roncisvalle
The objective of this study is to examine the evolution and characteristics of the financing for the nvironment in Brazil, in order to identify the advances and retreats after the Rio 92 Conference. Brazil has a very decentralized administration, composed of three independent levels of public administration: the federal government, 27 state governments, and more than 5000 municipios, " or municipalities; all of them with specific environmental institutions. However, at the time of the completion of this report, there were no indicators that aggregate information from these different institutional levels for the 1992-2001 period.(1) Thus, this study was a first effort to generate this kind of figures. Given the very short time for its completion, the main priority was to identify the resource flows from the federal government and some selected states. Efforts to estimate spending on pollution control and other environmental activities by the private sector were also made. In addition, the issue of funding sources is also discussed. Despite many methodological problems involved in the elaboration of these indicators, it was possible to identify trends and conclusions for environmental spending. At the federal government level, it was estimated that environmental expenditures were between 0.4% and 1% of the federal spending. Another important finding was that, although there was an official commitment to increase efforts in this area after the Rio 92 Conference, the overall federal government expenditures in environmental issues did not increase during the 1993-2000 period. Moreover, a matter of concern was the declining quality of this spending, with fewer resources directed to end-activities and more money diverted to means-expenditures. An important cause of this was the increasing share of debt related expenditures (interests and amortization) in the total budget. On the other hand, investments suffered cutbacks, particularly in the more recent period, and the expenditures in personnel fell systematically by 25% in constant prices during the second half of the nineties. Environmental projects are the most important single element in international cooperation agreements. However, the flow of foreign resources presented a declining trend since 1994, oscillating between 6% and 17% of total expenditures. Most of these resources come from external credit operations (loans), which means that in the long term, they represent an extra pressure of financial expenses in the budget. The proportion of international donations/total expenditures in 2000 fell to the lowest level in the series (2.0%), clearly indicating the decline of international support for environmental projects in Brazil. Results for the 1996-98 period show that, if sanitation costs are included (an overestimate since it also considers water supply), environmental expenditures are relatively more important for local governments: around 9% of the total public spending in the sample of municipios considered. State governments are in the second position, spending around 1.5% of their budget on environmental issues, in contrast to the less than 1% of the federal government. For this reason, there remains a clear need to generate better aggregate figures for the states and municipios for the whole period. The methodologies used for public budgeting and expenditure control vary widely, making it very hard to supply compatible aggregate numbers. In the three states where longer time series were estimated (São Paulo, Paraná and Rio Grande do Sul), there was no consistent trend of increasing expenditures on environmental objectives. Another gap that needs to be fulfilled refers to the private sector environmental spending. There were positive signals which indicated that the private sector is getting more concerned with the environmental issues, particularly those agents that have interests/responsibilities at the international level. It was calculated that the environmental spending of the industry sector was around R$ 160 million per year, slightly less than 1% of its value added. Although it is expected that this number will increase in the future, it is considerably lower than the public sector spending on environmental issues. It is very difficult to aggregate all these figures, but assuming for the year 2000 that the public spending on environmental issues was of 1.5% of the total, the public environmental spending would be of 0.33% of GDP, and an annual expenditure per capita of R$ 22.9 per capita (US$ 9.2 per capita). If the estimated industrial environmental spending (R$ 160 million) is added, the total spending becomes R$ 4.1 billion (0.34% of GDP), or R$ 23.9 per capita (US$ 9.6 per capita). Most of the funding for environmental projects comes from the government (mainly federal, through BNDES), international development agencies, or from companies' own resources. The private financial sector has a minor role on the financing of environmental expenditures but, gain, there are signals of positive changes, with the creation of innovative private funds specialized in environmentally friendly projects that combine financial and "green" interests as an example. The consolidation of economic instruments in international environmental agreements, particularly the Kyoto Protocol on greenhouse gases emissions, may accelerate this new financial market. Another potential source of funding for environmental projects is connected to the implementation of economic instruments in the environmental management system. Command-andcontrol procedures, such as licensing and emission standards, largely dominate the environmental regulation in Brazil. However, some interesting experiences, such as the "green" tax rebound (ICMS verde) and the recent changes in the water resources policy adopting the user/polluter-pays principle, indicate that the role of economic instruments will increase and, consequently, that there is potential for developing self-sustained financial mechanisms to sponsor environmental expenditures. (1) After the completion of this research, the Brazilian Institute of Geography and Statistics (IBGE) published estimates of public spending for the 1996-98 period (IBGE 2001). Whenever relevant, these figures were also added to the analysis, but with an alert that they were obtained using different methodological procedures."
We construct 2-round (i.e., 2-message), public-coin, black-box (concurrent) zero-knowledge proof systems and arguments for any language in NP under the assumption that the prover is resource-bounded during the execution of the protocol.
Fernando Filgueira, Herman Kamil, Fernando Lorenzo, Juan Andrés Moraes · 5 authors
This paper analyzes the reasons behind Central Government (CG) bailouts of Subnational Governments (SNGs) in the case of Uruguay. We argued that Uruguay represents a good example of the risks of fiscal decentralization, in the context of adjustment policies, and when SNGs` responsibilities and resources have not been carefully defined. We show that, in unitary countries where SNGs lack the opportunities to misbehave that they have in federal countries (e. g. , public debt issuance, international borrowing), SNG officials find ways to finance deficits through non-compliance with politically contestable obligations. In particular, SNGs in Uruguay finance their deficits by accumulating debts with other government agencies and obtaining discretionary transfers from the CG. Through statistical analyses we show that debts and deficits are mainly related to vertical fiscal imbalances and economic conditions in the SN jurisdictions. Yet, the analysis of recent bailout episodes suggests that institutions and political factors play a role (i. e. , they are important ex-post factors). This implies that bailouts have been more than simple compensations for structural imbalances, thus creating opportunities for strategic behavior on the part of SNG authorities (partly confirmed by the disparate fiscal performance of Montevideo vis-à-vis the rest of the country).
We analyze Georgian education finance and show that it is embedded in the overall structure of Georgian rayon finances, reflecting all their weaknesses: inequalities, lack of transparency, unmanageability, room for corruption. The budgetary and political independence of rayons is very limited. The steep fiscal inequalities between rayons are only partially and ineffectively addressed by the system of transfers. The transfers moreover are heavily negotiated and non-transparent. Thus education finances depend on general income of the rayons, which effectively determines the level of financing. At the same time, however, the role of the rayons in the management of the sector is very limited. The actual spending patterns for Georgian general education schools are very closely related to per capita income of the rayons without the transfers (about 75% of education spending), and to student teacher ratio (about 25% of education spending). The dependence of the education system on rayon wealth is our main empirical finding, and it contradicts widespread belief among Georgian education professionals. It is not surprising therefore that the education sector in poorer and in mountainous rayons with very low student teacher ratio has to adapt to this situation. It responds by reducing the number of teachers per class, thus lowering standards of service delivery despite high per student costs. The first step required to change this situation is to increase budgetary independence and education management role of rayons. Without strong local governments it will not be possible to decentralize Georgian education. Moreover the influence of fiscal inequalities on education finance should be broken by taking it out of general rayon income and by basing it on a per student education grant to rayons (education subvention). This would lead to significant redistribution of public funds in Georgia. Such a move needs to be carefully prepared. It is necessary to subject education subvention to buffer mechanisms, in order to protect rayons from drastic changes to their present education spending patterns. Moreover, Georgia should begin thinking about a per student formula for education subvention, which recognizes unavoidable higher per student costs of providing education in different geographical and social settings.
We consider the problem of constructing Concurrent Zero Knowledge Proofs [6], in which the fascinating and useful "zero knowledge" property is guaranteed even in situations where multiple concurrent proof sessions are executed with many colluding dishonest verifiers. Canetti et al. [3] show that blackbox concurrent zero knowledge proofs for non-trivial languages require #4 k) rounds where k is the security parameter. Till now the best known upper bound on the number of rounds for NP languages was #(log k), due to Kilian and Petrank [16]. We establish an upper bound of #(log k) on the number of rounds for NP languages, thereby closing the gap between the upper and lower bounds, up to a #(log log k) factor.
This article is concerned with an analytical summary of how the Japanese container ports have been taking place overcapacity problem in a systematic way. It focuses on institutional aspects of the overcapacity problem from the viewpoint of accounting cost and opportunity cost. The first issue arises due to the port authority's accounting system and insufficient disclosures of financial statements of port business to the port users and taxpayers. The second issue is inherently related to resource allocation between the state government and local governments through the budget system and income distribution programmes. Since a proper allocation of economic resources in the port sector as a whole will depend on investment decisions being taken within a coherent framework for ensuring that costs are passed on to port users, these issues are closely related to each other in reality. Although the budget system is completely controlled by the state government, the local governments have authoritative power over port planning, financing, and management, which is assured by the Ports and Harbours Law. The overcapacity problem appears to be an inevitable result.
We consider the situation of a physical entity that is the compound entity consisting of two ‘separated ’ quantum entities. In earlier work it has been proved by one of the authors that such a physical entity cannot be described by standard quantum mechanics. More precisely, it was shown that two of the axioms of traditional quantum axiomatics are at the origin of the impossibility for standard quantum mechanics to describe this type of compound entity. One of these axioms is equivalent with the superposition principle, which means that separated quantum entities put the linearity of quantum mechanics at stake. We analyze the conceptual steps that are involved in this proof, and expose the necessary material of quantum axiomatics to be able to understand the argument. 1
China’s economic reform over the past two decades has decentralized various decision rights from the central government to local governments, including the control rights of enterprises. We develop two opposing hypotheses on how governments influence the allocation of human capital in listed companies in the process of decentralization. A positive view suggests that local governments, with enhanced profit incentives and competitive pressure among jurisdictions, promote efficiency in firms and markets, resulting in more professionally managed companies. An alternative view conjectures that local governments, subject to conflicts of interest with the central government, regulate firms and markets for their private interests, resulting in a lack of professionalism and fragmented markets. We present new data on the boards of directors of 621 companies that went public during 1993 through 2000 in China. We report that over 30 percent of the directors are affiliated with various layers of governmental agencies. The presence of politicians, especially those affiliated with local governments, is associated with fewer directors possessing business experience or expertise in law, accounting, or finance, fewer academician directors, and fewer directors from non-local administrative regions. Low education levels, few woman directors, and high director seniority also characterize boards populated with local politicians. The overall evidence is inconsistent with the positive view, but supports the agency view of government decentralization.
Fiscal decentralization reform, the reform of fiscal relations between different levels of government, is an important fiscal policy issue in many African countries. While for many African nations the decentralized delivery of government goods and services is a relatively new concept, the issue of intergovernmental fiscal relations has been a constant and important fiscal policy consideration in Nigeria since the country's independence in 1960. Despite Nigeria's long history with a federal government structure, until recently it was hard to truly consider Nigeria as an effectively decentralized country. For much of the country's history, successive military regimes dismissed elected officials and legislative bodies at all levels of government and replaced them with military appointees; since under military rule subnational governments in Nigeria were accountable to the country's military authorities rather than to state or local electorates, we cannot properly speak of political and fiscal decentralization during this period. Nonetheless, in many respects Nigeria's basic decentralized federal administrative structure was maintained by successive military regimes. Under military rule, state and local governments continued to operate as distinct government units, provide important government services, collecting own source revenues and receiving intergovernmental transfers, albeit at the direction of military governors and appointed local executives rather than at the discretion of the local electorate. However, with the return of civilian rule to Nigeria in 1999, which entailed the adoption of a new constitution and the election of government officials and legislative assemblies at all levels of government, Nigeria instantaneously became one of the most decentralized countries in Africa.To this effect, this paper presents a broad overview of intergovernmental fiscal relations in Nigeria. This paper follows the main conceptual building blocks or pillars of fiscal decentralization and subnational publc finance. After a brief overview of Nigeria's federal system, Section 2 discusses the assignment of functional responsibilities in Nigeria's federal system. Section 3 presents an analysis of revenue assignments, considering what revenue sources are available to each level of government. Section 4 looks at the design and implementation of Nigeria's system of intergovernmental transfers. Section 5 considers subnational fiscal management issues, including the importance of capital "development" budgets in the Nigerian budget process. Finally, Section 6 considers the role and status of local governments and state-local government relations.