CZ:Featured article/Current: Difference between revisions

From Citizendium
Jump to navigation Jump to search
imported>Chunbum Park
(→‎Acid rain: Active attack)
imported>John Stephenson
(template)
 
(32 intermediate revisions by 4 users not shown)
Line 1: Line 1:
== '''[[Active attack]]''' ==
{{:{{FeaturedArticleTitle}}}}
----
<small>
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)]]''
 
{| class="wikitable collapsible collapsed" style="width: 90%; float: center; margin: 0.5em 1em 0.8em 0px;"
|-
! style="text-align: center;" | &nbsp;[[Active attack|notes]]
|-
|
{{reflist|2}}
{{reflist|2}}
|}
</small>

Latest revision as of 10:19, 11 September 2020

After decades of failure to slow the rising global consumption of coal, oil and gas,[1] many countries have proceeded as of 2024 to reconsider nuclear power in order to lower the demand for fossil fuels.[2] Wind and solar power alone, without large-scale storage for these intermittent sources, are unlikely to meet the world's needs for reliable energy.[3][4][5] See Figures 1 and 2 on the magnitude of the world energy challenge.

Nuclear power plants that use nuclear reactors to create electricity could provide the abundant, zero-carbon, dispatchable[6] energy needed for a low-carbon future, but not by simply building more of what we already have. New innovative designs for nuclear reactors are needed to avoid the problems of the past.

(CC) Image: Geoff Russell
Fig.1 Electricity consumption may soon double, mostly from coal-fired power plants in the developing world.[7]

Issues Confronting the Nuclear Industry

New reactor designers have sought to address issues that have prevented the acceptance of nuclear power, including safety, waste management, weapons proliferation, and cost. This article will summarize the questions that have been raised and the criteria that have been established for evaluating these designs. Answers to these questions will be provided by the designers of these reactors in the articles on their designs. Further debate will be provided in the Discussion and the Debate Guide pages of those articles.

Footnotes
  1. ↑ Global Energy Growth by Our World In Data
  2. ↑ Public figures who have reconsidered their stance on nuclear power are listed on the External Links tab of this article.
  3. ↑ Pumped storage is currently the most economical way to store electricity, but it requires a large reservoir on a nearby hill or in an abandoned mine. Li-ion battery systems at $500 per KWh are not practical for utility-scale storage. See Energy Storage for a summary of other alternatives.
  4. ↑ Utilities that include wind and solar power in their grid must have non-intermittent generating capacity (typically fossil fuels) to handle maximum demand for several days. They can save on fuel, but the cost of the plant is the same with or without intermittent sources.
  5. ↑ Mark Jacobson believes that long-distance transmission lines can provide an alternative to costly storage. See the bibliography for more on this proposal and the critique by Christopher Clack.
  6. ↑ "Load following" is the term used by utilities, and is important when there is a lot of wind and solar on the grid. Some reactors are not able to do this.
  7. ↑ Fig.1.3 in Devanney "Why Nuclear Power has been a Flop"

Retrieved from "https://citizendium.org/wiki/index.php?title=CZ:Featured_article/Current&oldid=759442"