CZ:Featured article/Current: Difference between revisions

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== '''[[Economics]]''' ==
== '''[[Passive attack]]''' ==
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The term '''economics''' refers both to an intellectual discipline and to a profession.  
A '''passive attack''' on a communications system is one in which the attacker only eavesdrops; he may read messages he is not supposed to see, but he does not create or alter messages. This contrasts with an [[active attack]] in which the attacker may create, forge, alter, replace or reroute messages.


The intellectual discipline of economics is an attempt to gain an  understanding of  the processes that govern the production, distribution  and consumption of [[wealth (economics)|wealth]], and to use that understanding to assist in the prediction of the consequences of economic activities. It uses the methodology of [[science]] and can be considered to be a science insofar as it produces testable propositions (see [[/Tutorials#Economics as a science|economics as a science]]), although some branches of the subject are widely considered to be normative (see [[/Tutorials#Normative economics|normative economics]]). Like other sciences, it is subject to a continuing process of revision.
Generally, the term "passive attack" is used in the context of [[cryptanalysis]]. However, the term is actually considerably broader than that. For example, wiretapping an unencrypted line is a passive attack. So is [[traffic analysis]], attempting to infer useful information from the source, destination, timing and size of messages without reading the content. There are also situations where the attacker is active in some way — such as probing an air defense system to obtain data on their radar systems or tricking an enemy into encrypting known text ([[ULTRA]] called this "gardening") — but the actual cryptanalysis is a passive attack.


The profession of economics includes academics<ref>For a light-hearted look at the life of an academic economist, see Axel Leijonhufvud's ''Life among the Econs''[http://www.kysq.org/diss/LifeamongtheEcon.pdf]</ref>  who construct, develop and teach economic theory,  and practitioners who use economic theory  to make forecasts or to advise upon political, commercial and regulatory decisions. Its most influential application is to the management of the economy. Mistaken decisions in that context can do more damage than in most others.
''[[Passive attack|.... (read more)]]''


===The methodology of economics===
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The traditional methodology of economics has been  first to formulate a theory, and then to examine how far it provides  operationally useful conclusions. Its pioneers have often adopted an  [[instrumentalism|instrumentalist]] approach:  basing  a theory on arbitrary axioms - such as consistently rational human behaviour - and then advocating its acceptance solely  on the grounds that it had  provided  operationally useful results. That methodology has  proved to be vulnerable to changing conditions, however, and there  has recently been a tendency to move away  from an exclusively axiom-based  approach  towards a greater recognition  of  observed behaviour.  Among the  techniques that have been coming into use for that purpose are those of [[Philosophy of economics#Behavioural economics|behavioural economics]] and [[neuroeconomics]].
 
''[[Economics|.... (read more)]]''
 
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Revision as of 07:26, 5 May 2012

Passive attack

A passive attack on a communications system is one in which the attacker only eavesdrops; he may read messages he is not supposed to see, but he does not create or alter messages. This contrasts with an active attack in which the attacker may create, forge, alter, replace or reroute messages.

Generally, the term "passive attack" is used in the context of cryptanalysis. However, the term is actually considerably broader than that. For example, wiretapping an unencrypted line is a passive attack. So is traffic analysis, attempting to infer useful information from the source, destination, timing and size of messages without reading the content. There are also situations where the attacker is active in some way — such as probing an air defense system to obtain data on their radar systems or tricking an enemy into encrypting known text (ULTRA called this "gardening") — but the actual cryptanalysis is a passive attack.

.... (read more)

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