We look at the question of how powerful a prover must be to give a zero-knowledge proof.We present the first unconditional bounds on the complexity of a statistical ZK prover.The result is that if a language possesses a statistical zero-knowledge then it also possesses a statistical zero-knowledge proof in which the prover runs in probabilistic, polynomial time with an NP oracle.Previously this was only known given the existence of one-way permutations. Extendingthese techniques to protocols of knowledge complexity k(n) >0, we derive bounds on the time complexity of languages of "small" knowledge complexity.Underlying these results is a technique for efficiently generating an "almost" random element of a set S E P.Namely, we construct a probabilistic machine with an NP oracle which, on input 1" and 6 > 0 runs in time polynomial in n and lg 6-1, and outputs a random string from a distribution within distance 6 of the uniform distribution on S n {O, l}~.
In this note, we present new zero-knowledge interactive proofs and arguments for languages in NP. To show that x ε L, with an error probability of at most 2-k, our zero-knowledge proof system requires O(|x|c1)+O(lgc2|x|)k ideal bit commitments, where c1 and c2 depend only on L. This construction is the first in the ideal bit commitment model that achieves large values of k more efficiently than by running k independent iterations of the base interactive proof system. Under suitable complexity assumptions, we exhibit zero knowledge arguments that require O(lgc|x|kl bits of communication, where c depends only on L, and l is the security parameter for the prover. This is the first construction in which the total amount of communication can be less than that needed to transmit the NP witness. Our protocols are based on efficiently checkable proofs for NP[4].
To measure subnational governments, only external money flows are counted, excluding intra-level transactions in measuring a level of government and all intergovernmental transactions in measuring general government. Control, finance, and administration should be distinguished in measuring centralization and each level’s share of general government, administered expenditures being net of grants given to other governments and financed expenditures net of grants received. Disparate decentralization of finance, control, and administration brings vertical imbalance, measured by the portion of a government’s expenditures not covered by its own resources and by the ratio of intergovernmental grants to total government expenditures.
One strand of endogenous-growth\tmodels assumes constant returns to a broad concept of capital. I extend these models to include tax- financed government services that affect production or utility. Growth and saving rates fall with an increase in utility-type expenditures; the two rates rise initially with productive government expenditures but subsequently decline. With an income tax, the decentralized choices of growth and saving are "too low," but if the production function is Cobb-Douglas, the optimizing government still satisfies a natural condition for productive efficiency. Empirical evidence across countries supports some of the hypotheses about government and growth.
This paper considers the relative centralization or decentralization of public finance, and relates the equity and efficiency issues ot the special features of developing economies. The paper considers the centralization of taxation and service provision in Indonesia in relation to these theoretical prinicples and indicates ways in which we may expect decentralization to proceed in the Indonesian context.
H.G. (Mike) Jones and I had numerous meetings with EEGSA staff. We discussed rural electrification plans, reviewed documents, and collaborated on collecting information on decentralized energy alternatives. Meetings were also held with USAID/Guatemala, USAID/ROCAP, NRECA, MEM, PVOs, and equipment vendors. A preliminary draft report and spreadsheet for comparing decentralized power alternatives was completed. The report and findings were presented to EEGSA and the methodology transferred to EEGSA staff. A set of recommended followup activities was also presented to EEGSA.
Quadratic residuosity and graph isomorphism are classic problems and the canonical examples of zero-knowledge languages. However, despite much research effort, all previous zero-knowledge proofs for them required either unproven complexity assumptions or an unbounded number of rounds of message exchange.
We show how to construct a public-key cryptosystem (as originally defined by DiNe and Hellman) secure against chosen ciphertezt attacks, given a public-key cryptosystern secure against passive eavesdropping and a noninteractive zero-knowledge proof system in the shared string model. No such secure cryptosystems were known before. A concrete implementation can be based on quadratic residuosity intractability.
Although the recent performance of the U.S. macroeconomy is being hailed as "the longest modern peacetime expansion s n failures of depository institutions have been closely linked to certain depressed productive sectors in the country. The most stark examples can be found in the depressed farm-belt and oil-producing regions. Observations indicate that financial firms do not or cannot diversify against industry-specific risk when choosing their loan portfolios. Such behavior may be explained by extensive government regulation of the industry's scale and scope or by technological costs of intermediating credit that encourage specialized lending by region or by industry. This paper does not attempt to formally explain why depository institutions engage in specialized lending; rather, it examines some implications of regional and sectoral banking in terms of macroeconomic perf~rmance.~ It considers the short-run implications of bank-capital immobility when banks produce real services in channeling the flow of funds into investments. We illustrate how regional banking conditions can affect the mix of aggregate investment and the level of future aggregate output in the absence of macroeconomic fluctuations. Given the current deregulatory trend in structural policy changes, the nature of the financial services industries has come under intense scrutiny. Recent banking literature has formalized how financial contracts are related to imperfect information. A recurring theme has been that when information is costly, the quantity and nature of external finance has allocative consequences. Diamond (1984) demonstrates how financial intermediaries (hereafter referred to as banks) can improve the efficiency of capital markets by diversifying and thus minimizing information costs; however, perfect diversification makes bank capital and the dispersion of bank asset returns irrelevant to bank portfolio choice. These strong informational assumptions allow the intermediation process to work more smoothly than we observe. If these conditions are not met, bank capital and the risk of bank assets affect bank profitability. Bernanke and Gertler (1987) show how the inability to eliminate variability in portfolio returns implies that "health" of a'bank's balance sheet can affect the flow of funds to risky bank investments. In their model, depositors cannot observe the ex-post returns on bank projects at any cost and bank capital must absorb random asset returns; insufficient bank capital may constrain banks from investing in risky but profitable investments. In a similar framework, Samolyk (1989) examines how the interest-rate risk associated with the maturity transformation in bank portfolios affects bank asset management. This paper will analyze the implications of imperfect information for investment in a decentralized banking ~ystern.~ We present an intertemporal model of banking similar to that of Bernanke and Gertler. Bankers possess a specialized technology that allows them to channel resources to investment projects that would not be funded in direct credit markets. They also have information about their portfolio returns. Unlike Bernanke and Gertler , this analysis attempts to incorporate the notion that there is more than one productive sector in the economy. We assume that in the short run, bank
Regional disparities in terms of income and employment showed marked decline under various regional policies during the Period of Rapid Economic Growth. However, the drastic changes in Japanese industries after the Oil Crises in 1970s have caused structural recessions in some regions which have been dependent on resourceand energy-intensive industries. Furthermore, the economic activities are rapidly concentrating in Tokyo Metropolitan Region under the internationalization of Japanese economy. Regional income disparities began to widen again since the early 1980s under these circumstances.This paper aims to examine the trend of industrial differences in Japanese regions in the postwar period, and to identify its current problems. Three analytical methods, namely the analysis of coefficient of variation, the rate-share analysis, and the shiftshare analysis are applied using employment data for the years 1955 to 1985.Major findings of the study are summarized as follows:(1) Manufacturing sector showed a clear decentralization of employment during the period 1960-1985, whereas the decentralization of tertiary sector was not very clear.(2) Marked decentralization was found in the high-tech machinery industry which have been rapidly concentrating in North and South Tohoku Regions. Despite the recession of manufacturing industries after the Oil Crises, these regions showed remarkable employment growth.(3) The shift-share analysis of manufacturing sector has showed low growth performance in the western part of Japan. These regions had been specialized in the heavy and petoro-chemical industries during the Period of Rapid Economic Growth, and suffered much damage in the Oil Crises.(4) Locational patterns of tertiary sector differ among industries. Finance, retail and wholesale industries have been concentrated in metropolitan regions, whereas local regions have been specialized in the service industry.(5) The shift-share analysis of tertiary sector has identified little difference of growth performance which comes from the industrial structure of each region. However, a marked difference has been found in the differential shift components between metropolitan and local regions, which indicates a clear gap of locational attractiveness among them.
The prosecution of George Reynolds in the mid-1870s and the United States Supreme Court's 1879 affirmation of that conviction are usually viewed as the key legal events leading to mass prosecution of Mormon polygamists in the late 1880s.While Reynolds v. the United States (1879) seemed to dispose of the crucial first amendment defense relied upon by the Mormons, it did not lead to the prosecutions.Rather, they were triggered by the passage of thé Edmunds Act in 1882 as well as a major Supreme Court decision in 1885 over the cohabitation prosecution of Salt Lake Stake President Angus M. Cannon.When Reynolds was first prosecuted in 1875 there was no crime of cohabitation on the federal statute books.Only polygamy was a crime and could not be prosecuted without proof of a marriage ceremony, evidence almost impossible for prosecutors to secure.Enforcement of the anti-polygamy laws in Utah was a "dead letter."At least until 1885 and the Angus Cannon prosecution.When Brigham Young and Orson Pratt delivered the first public sermons on polygamy in August 1852 (Arlington 1985, 226; Van Wagoner 1986, 84), they were making public a principle revealed to Joseph Smith, Jr., in 1843 (D&C 132) but practiced with the greatest secrecy (Van Wagoner 1986, 1-69;Foster 1974).The sermons set in motion events that resulted in forty years of confrontation with the federal government and would threaten the Church's very existence.In spite of later national outrage, it was apparently not a crime in the early Utah Territory for a man to marry more than one woman at a time.
While the intuition underlying a zero knowledge proof system [GMR85] is that no “knowledge” is leaked by the prover to the verifier, researchers are just beginning to analyze such proof systems in terms of formal notions of knowledge. In this paper, we show how interactive proof systems motivate a new notion of practical knowledge, and we capture the definition of an interactive proof system in terms of practical knowledge. Using this notion of knowledge, we formally capture and prove the intuition that the prover does not leak any knowledge of any fact (other than the fact being proven) during a zero knowledge proof. We extend this result to show that the prover does not leak any knowledge of how to compute any information (such as the factorization of a number) during a zero knowledge proof. Finally, we define the notion of a weak interactive proof in which the prover is limited to probabilistic, polynomial-time computations, and we prove analogous security results for such proof systems. We show that, in a precise sense, any nontrivial weak interactive proof must be a proof about the prover's knowledge, and show that, under natural conditions, the notions of interactive proofs of knowledge defined in [TW87] and [FFS87] are instances of weak interactive proofs.
Brotowasisto, Oscar Gish, Ridwan Malik, Paramita Sudharto
This paper describes health care financing and expenditures in Indonesia, a developing country spending around $US 9.40 per capita annually for health care (2.6% of GOP). Per capita health care spending has held constant in real terms over the last five years. The public sector accounts for 36.8% of all health care expenditure, or 43.1% if health care spending by state enterprises is included. About 13% of the population, almost all of them government employees and their families, are covered by some form of health insurance. In 1984, 62% of the population was spending privately – at then current exchange rates – an average of $US 2.70 per capita annually for health care, another 30% averaged $US 8.35 each, and the upper 9% $US 31.90. The Government is reviewing various ‘social financing’ mechanisms with a view to expanding health insurance coverage both for those in formal wage employment and the bulk of the population which remains either on the land or is part of the ‘informal’ sector. Steps are also being taken to increase the efficient use of resources by, among other things, making greater use of evaluation techniques and economic methodologies. Such efforts are coupled with more decentralized authority being given to the provinces and districts. Particularly important to future health efforts is the further expansion of community-based activities, especially in the form of the Posyandu (integrated health post).