What Is Security?

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Security is a measurement, not a characteristic.

It is unfortunate that many software projects list security as a simple requirement to be met. Is it secure? This question is as subjective as asking if something is hot.
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Security must be balanced with expense.

It is easy and relatively inexpensive to provide a sufficient level of security for most applications. However, if your security needs are very demanding, because you're protecting information that is very valuable, then you must achieve a higher level of security at an increased cost. This expense must be included in the budget of the project.
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Security must be balanced with usability.

It is not uncommon that steps taken to increase the security of a web application also decrease the usability. Passwords, session timeouts, and access control all create obstacles for a legitimate user. Sometimes these are necessary to provide adequate security, but there isn't one solution that is appropriate for every application. It is wise to be mindful of your legitimate users as you implement security measures.
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Security must be part of the design.

If you do not design your application with security in mind, you are doomed to be constantly addressing new security vulnerabilities. Careful programming cannot make up for a poor design.


labih lanjut layari web ni : http://phpsec.org/projects/guide/1.html#1.1