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The Practice of Information Security

The discipline of information security (often shortened to info-security) has many different elements, but they all boil down to the main goal of keeping your information safe. They can be distilled into three areas that are the foundation for all information security work: confidentiality, integrity, and availability. The acronym C.I.A. is often used to refer to them (no relation to the government agency). This triad represents the goals of information security efforts (see Figure 1.1). Each one requires different tools and methods and protects a different area or type of information.

Figure 1.1. Principles of Information Security



The confidentiality segment of info-security keeps your data from being viewed by unauthorized individuals. This can be information that is confidential to your company, such as engineering plans, program code, secret recipes, financial information, or marketing plans. It can be customer information or top-secret government data. Confidentiality also refers to the need to keep information from prying eyes within your own company or organization. Obviously, you don't want all employees to be able to read the CEO's e-mail or view the payroll files.

There are multiple ways to protect your private data from getting out. The first way is to deny access to it in the first place. But sometimes that is not possible, as in the case of information going over the Internet. In that case, you have to use other tools, such as encryption, to hide and obscure your data during its journey.


The integrity factor helps to ensure that information can't be changed or altered by unauthorized individuals. It also means that people who are authorized don't make changes without the proper approval or consent. This can be a subtle distinction. If a bank teller is secretly debiting someone's account and crediting another, that is an integrity problem. They are authorized to make account changes but they didn't have approval to make those ones. Also, data integrity means your data is properly synchronized across all your systems.


Having your information secure doesn't do you much good if you can't get to it. With denial of service attacks becoming more common, a major part of your info-security goals is not only keeping the bad guys from accessing your information, but making sure the right people can access it. Many computer criminals are just as satisfied to destroy your data or take your Web site offline. The availability element also includes preparing for disasters and being able to recover cleanly when they do occur.

In this example, Tom knew he had to apply each of these principles to completely secure his company's network. He found the software tools that would tackle each area. He was going to need all the help he could get. From the news and trade articles he had read, he knew the chilling statistics.

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