32,672 research outputs found
Foundations, Properties, and Security Applications of Puzzles: A Survey
Cryptographic algorithms have been used not only to create robust ciphertexts
but also to generate cryptograms that, contrary to the classic goal of
cryptography, are meant to be broken. These cryptograms, generally called
puzzles, require the use of a certain amount of resources to be solved, hence
introducing a cost that is often regarded as a time delay---though it could
involve other metrics as well, such as bandwidth. These powerful features have
made puzzles the core of many security protocols, acquiring increasing
importance in the IT security landscape. The concept of a puzzle has
subsequently been extended to other types of schemes that do not use
cryptographic functions, such as CAPTCHAs, which are used to discriminate
humans from machines. Overall, puzzles have experienced a renewed interest with
the advent of Bitcoin, which uses a CPU-intensive puzzle as proof of work. In
this paper, we provide a comprehensive study of the most important puzzle
construction schemes available in the literature, categorizing them according
to several attributes, such as resource type, verification type, and
applications. We have redefined the term puzzle by collecting and integrating
the scattered notions used in different works, to cover all the existing
applications. Moreover, we provide an overview of the possible applications,
identifying key requirements and different design approaches. Finally, we
highlight the features and limitations of each approach, providing a useful
guide for the future development of new puzzle schemes.Comment: This article has been accepted for publication in ACM Computing
Survey
Economic FAQs About the Internet
This is a set of Frequently Asked Questions (and answers) about the economic, institutional, and technological structure of the Internet. We describe the history and current state of the Internet, discuss some of the pressing economic and regulatory problems, and speculate about future developments.Internet, telecommunications, congestion pricing, National Information Infrastructure
Economic Policy Analysis and the Internet: Coming to Terms with a Telecommunications Anomaly
The significant set of public policy issues for economic analysis that arise from the tensions between the âspecial benefitsâ of the Internet as a platform for innovation, and the drawbacks of the âanomalousâ features of the Internet viewed as simply one among the array of telecommunications systems, is the focus of discussion in this chapter. Economists concerned with industrial organization and regulation (including antitrust and merger law) initially found new scope for application of their expertise in conventional policy analyses of the Internetâs interactions with other segments of the telecommunications sector (broadcast and cable television, radio and telephone), and emphasized the potential congestion problems posed by user anonymity and flat rate pricing. Policy issues of a more dynamic kind have subsequently come to the fore. These involve classic tradeoffs between greater efficiency and producer and consumer surpluses today, and a potential for more innovation in Web-based products and service in the future. Many such tradeoffs involve choices such as that between policies that would preserve the original âend-to-endâ design of the original Internet architecture, and those that would be more encouraging of market-driven deployment of new technologies that afforded ISPs with greater market power the opportunity to offer (and extract greater profits from) restricted-Web services that consumers valued highly, such as secure and private VOIP.public policy, telecommunications, Web-based products, user anonymity
The Beginnings and Prospective Ending of âEnd-to-Endâ: An Evolutionary Perspective On the Internetâs Architecture
The technology of âthe Internetâ is not static. Although its âend-to- endâ architecture has made this âconnection-lessâ communications system readily âextensible,â and highly encouraging to innovation both in hardware and software applications, there are strong pressures for engineering changes. Some of these are wanted to support novel transport services (e.g. voice telephony, real-time video); others would address drawbacks that appeared with opening of the Internet to public and commercial traffic - e.g., the difficulties of blocking delivery of offensive content, suppressing malicious actions (e.g. âdenial of serviceâ attacks), pricing bandwidth usage to reduce congestion. The expected gains from making âimprovementsâ in the core of the network should be weighed against the loss of the social and economic benefits that derive from the âend-to-endâ architectural design. Even where technological âfixesâ can be placed at the networksâ edges, the option remains to search for alternative, institutional mechanisms of governing conduct in cyberspace.
Incentive Systems in Multi-Level Markets for Virtual Goods
As an alternative to rigid DRM measures, ways of marketing virtual goods
through multi-level or networked marketing have raised some interest. This
report is a first approach to multi-level markets for virtual goods from the
viewpoint of theoretical economy. A generic, kinematic model for the monetary
flow in multi-level markets, which quantitatively describes the incentives that
buyers receive through resales revenues, is devised. Building on it, the
competition of goods is examined in a dynamical, utility-theoretic model
enabling, in particular, a treatment of the free-rider problem. The most
important implications for the design of multi-level market mechanisms for
virtual goods, or multi-level incentive management systems, are outlined.Comment: 18 pages, 5 figures; graphics with reduced resolution. Full
resolution available on author's homepage. Accepted contribution to the
Workshop 'Virtual Goods' at the Conference AXMEDIS 2005, 30. November - 2.
December, Florence, Ital
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