Composable security of delegated quantum computation

Delegating difficult computations to remote large computation facilities, with appropriate security guarantees, is a possible solution for the ever-growing needs of personal computing power. For delegated computation protocols to be usable in a larger context---or simply to securely run two protocols in parallel---the security definitions need to be composable. Here, we define composable security for delegated quantum computation. We distinguish between protocols which provide only blindness---the computation is hidden from the server---and those that are also verifiable---the client can check that it has received the correct result. We show that the composable security definition capturing both these notions can be reduced to a combination of several distinct "trace-distance-type" criteria---which are, individually, non-composable security definitions. Additionally, we study the security of some known delegated quantum computation protocols, including Broadbent, Fitzsimons and Kashefi's Universal Blind Quantum Computation protocol. Even though these protocols were originally proposed with insufficient security criteria, they turn out to still be secure given the stronger composable definitions.Comment: 37+9 pages, 13 figures. v3: minor changes, new references. v2: extended the reduction between composable and local security to include entangled inputs, substantially rewritten the introduction to the Abstract Cryptography (AC) framewor

The Impact of Warrant Introduction Australian Experience

The impact that derivative trading has on the underlying security is essential to our understanding of security market behaviour, and important in the fields of market efficiency and pricing of such derivatives. This paper examines the impact that the introduction of exchange traded derivative warrants has on the underlying securities’ price, volume and volatility in the Australian market. The major findings of significant negative abnormal returns, reduction in skewness, no change in beta and small changes in variance are consistent with recent research findings in the US, UK and Hong Kong. However findings of derivative warrant listing resulting in decreased trading volume in contrast with most prior research in the field.Derivatives, Warrants, Market Efficiency, Event Study.

Social Security and Individual Welfare: Precautionary Saving, LiquidityConstraints, and the Payroll Tax

Recent advances in the examination of efficiency gains from dynamic tax reforms have used simulation models to isolate intragenerational and/or intergenerational effects. Important considerations having to do with uncertainty or capital market imperfections are frequently missing from such a framework. In this paper, we focus on the welfare gains from introducing social security retirement annuities, given lifetime uncertainty and borrowing restrictions.Our principal findings are four. First, given the considerations mentioned above, "precautionary saving" exceeds life-cycle saving (that would have taken place in the absence of lifetime uncertainty), lending further support to the notion that the perfect-certainty version of the life-cycle model provides an inadequate explanation of observed saving behavior. Second, the introduction of an actuarially fair social security system leads to a significant partial equilibrium increase in lifetime consumption and welfare, accompanied by a reduction in the capital stock.The increase in lifetime welfare is reduced, however,and in many cases eliminated, when borrowing restrictions are imposed.Third, extending the model to general equilibrium, we find that the partial equilibrium gains in lifetime welfare from participation in social security are offset by the interaction of higher steady-state interest rates and binding liquidity constraints. Finally, replacing the proportional payroll tax with a progressive tax (essentially a linear tax with an exemption), we show that age-specific tax schemes can restore much of the potential gain from introducing social security.

The Flypaper Effect: Evidence from the Italian National Health System

Public expenditure reduction in Italy is achieved through a revision of social security and health care programmes. In particular, public health expenditure control has been implemented through a reform that imposes more stringent budget rules at local level and a considerable reduction in the grants-in-aid from central government. The response to a decrease in categorical lump-sum grants from the central to local governments might result in an asymmetrical response to intergovernmental grants: local spending is highly responsive to increases in grants, but it is relatively insensitive to grants reduction [Stine, 1994; Gramkhar and Oates, 1996]. In our paper we have estimated this hypothesis using a sample of cross-sectional and time- observations covering the 20 Italian regions over the period 1989-1993. Two different models have been estimated based on different budget balance rules. The empirical results of our model show the existence of a standard and a super flypaper effect in both models. The introduction of the soft-budget constraint hypothesis results in a stronger effect of grants and a lower response of own resources which shows that before reducing expenditure regional governments prefer to incur some deficit.flypaper effect, health care, Italy, soft-budget constraint

Financial Innovation, Market Participation and Asset Prices

This paper proposes that the introduction of non-redundant assets can endogenously modify trader participation in financial markets, which can lead to a lower market premium and a higher interest rate. We demonstrate this mechanism in a tractable exchange economy with endogenous participation. Investors receive heterogeneous random incomes determined by a finite number of macroeconomic factors. They can freely borrow and lend, but must pay a fixed entry cost to invest in risky assets. Security prices and the participation structure are jointly determined in equilibrium. The model reconciles a number of features that have characterized financial markets in the past three decades: substantial financial innovation; a sharp increase in investor participation; improved risk management practices; an increase in interest rates; and a reduction in the risk premium.

Crime and the Church: An Analysis of Crime in Chicago Based on the Location of Churches

Based upon publicly available data, there are approximately 43 crimes committed per 1,000 residents in Chicago, IL with a percentage that is 149% higher than the average city in Illinois. For years, researchers, politicians, and individuals have struggled with what can be done to deter crime. One method that is often tried is the introduction of community programs and outreach. This research aims to analyze the relationship between churches and crimes committed to determine if increasing church presence is a viable method for crime reduction. Using data from the Chicago CLEAR data set of crimes committed from 2001 to present couple with church location data, visualizations were created to illustrate crime progression over the years. The churches used come from both the Department of Homeland Security\u27s Homeland Infrastructure Foundation-Level Data and the Chicago Church Finder. Data cleaning was done in Python, exploration was done with manual review, visualizations were created in Python using Bokeh graphing tool and Tableau, and density clustering was performed using Python

The labour market and fiscal impact of labour reductions: The case of reduction of employers' social security contributions under a wage norm regime with automatic price indexing of wages. NBB Working Paper Nr. 36

This paper investigates the possible labour market and fiscal impacts of labour tax reductions in a typically Belgian setting, i.e. a wage norm regime with automatic price indexing of wages. We consider reductions in employers' social security contributions and fiscal compensation through value added or production taxes. Reductions in employers' social security contributions can only have significant employment effects if they effectively reduce labour costs. These reductions are only partly self-financing, and the cost per job created is high. The remaining negative impact on the government budget should be compensated through an alternative means of financing this expenditure, since not–compensating for the budgetary loss is not a realistic option in the long run. For this purpose, various financing schemes can be envisaged, but an increase in value added tax and the introduction of a tax on production (mimicking environmental taxes affecting firms' production costs) are the two possibilities considered in this paper. The alternative financing mechanisms destroy some of the positive employment effects of the initial reductions. However, on balance the combined measures can create some employment without worsening the government budget balance. The reaction of wages to the reduction in employers' social security contributions and to the fiscal compensation measures proves crucial. The more the initial reductions in employers' contributions are used to finance higher gross wages, and the more the inflationary effects of fiscal compensation measures are passed on in wages, the less positive the impact on employment will be. This means that little job creation is to be expected without a special co-ordination effort between all labour market players. Labour tax reductions are by no means a substitute for other labour market reforms

Are Regtech, Fintech, Blockchain the Future?

British Financial Supervision and Control Authority has identified new technologies as a component of fintech. These components include regtech, insurtech, blockchain. These new areas of the market development are incomprehensible to a wide range of people. However, this area attracts venture capital which is actively growing worldwide. The prospects of development of these areas are interesting for many reasons: reduction of financial costs for market participants, reduction of information processing time, security of financial transactions, information security and completeness. The article describes: objective reasons of the occurrence of such a kind of the product, risks of using these products and advantages of their introduction in all spheres of life, as well as the scope of regtech implementation.Keywords: Fintech, regtech, blockchain, insurtec