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== '''[[Active attack]]''' ==
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In [[cryptography]] an '''active attack''' on a communications system is one in which the attacker changes the communication. He may create, forge, alter, replace, block or reroute messages. This contrasts with a [[passive attack]] in which the attacker only eavesdrops; he may read messages he is not supposed to see, but he does not alter messages.
==Footnotes==
 
== Active attacks on communication ==
 
Active attacks that target the communication system itself include:
* [[man-in-the-middle attack]]; the attacker tricks both communicating parties into communicating with him; they think they are talking to each other
* [[Stream_cipher#Rewrite_attacks | rewrite attacks]]; the attacker can replace a message with anything he chooses
 
'''Successful active attacks are devastating!''' If the attacker can replace messages and have them taken as genuine, it is all over. The security system is then at best worthless; at worst it is of great value to the enemy.
 
Fortunately, these attacks are '''generally hard to execute'''. The attacker must not only intercept messages, break whatever [[cryptography]] is in use (often ''both'' an authentication mechanism and a cipher), and send off his bogus message; he also has to block delivery of the genuine message. Moreover, he has to do it all '''in real time''', fast enough to avoid alerting his victims and to beat whatever synchronisation mechanisms the network may be using. A cryptosystem that an enemy can break in hours or days would generally be considered insecure, even worthless, but it will prevent active attacks as long as the enemy cannot break it quickly enough to replace messages.
 
''[[Active attack|.... (read more)]]''
 
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Latest revision as of 09:19, 11 September 2020

The Mathare Valley slum near Nairobi, Kenya, in 2009.

Poverty is deprivation based on lack of material resources. The concept is value-based and political. Hence its definition, causes and remedies (and the possibility of remedies) are highly contentious.[1] The word poverty may also be used figuratively to indicate a lack, instead of material goods or money, of any kind of quality, as in a poverty of imagination.

Definitions

Primary and secondary poverty

The use of the terms primary and secondary poverty dates back to Seebohm Rowntree, who conducted the second British survey to calculate the extent of poverty. This was carried out in York and was published in 1899. He defined primary poverty as having insufficient income to “obtain the minimum necessaries for the maintenance of merely physical efficiency”. In secondary poverty, the income “would be sufficient for the maintenance of merely physical efficiency were it not that some portion of it is absorbed by some other expenditure.” Even with these rigorous criteria he found that 9.9% of the population was in primary poverty and a further 17.9% in secondary.[2]

Absolute and comparative poverty

More recent definitions tend to use the terms absolute and comparative poverty. Absolute is in line with Rowntree's primary poverty, but comparative poverty is usually expressed in terms of ability to play a part in the society in which a person lives. Comparative poverty will thus vary from one country to another.[3] The difficulty of definition is illustrated by the fact that a recession can actually reduce "poverty".

Causes of poverty

The causes of poverty most often considered are:

  • Character defects
  • An established “culture of poverty”, with low expectations handed down from one generation to another
  • Unemployment
  • Irregular employment, and/or low pay
  • Position in the life cycle (see below) and household size
  • Disability
  • Structural inequality, both within countries and between countries. (R H Tawney: “What thoughtful rich people call the problem of poverty, thoughtful poor people call with equal justice a problem of riches”)[4]

As noted above, most of these, or the extent to which they can be, or should be changed, are matters of heated controversy.

Footnotes
  1. ↑ Alcock, P. Understanding poverty. Macmillan. 1997. ch 1.
  2. ↑ Harris, B. The origins of the British welfare state. Palgrave Macmillan. 2004. Also, Oxford Dictionary of National Biography.
  3. ↑ Alcock, Pt II
  4. ↑ Alcock, Preface to 1st edition and pt III.

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