Information security (Infosec) is usually defined as the combination of communications security (Comsec) and computer security (Compusec). The definition may also include radiation security (Radsec), which refers to emissions from devices such as monitors and printers (also known as TEMPEST). In short, the term Infosec relates to the security of any information that is stored, processed or transmitted in electronic or similar form. But what do we mean by security?

To the average person, "security" corresponds with "confidentiality"; that is, ensuring that information is available only to those people properly authorized to receive it. This is generally achieved through some form of encryption. However, "security" increasingly includes a number of other important factors:

• Integrity, which ensures that information has not been changed or tampered with;
• Availability, which ensures that communications and computing systems are not disrupted in their normal operations;
• Authentication, which ensures that a person accessing or providing information is actually who they claim to be; and,
• Non-repudiation, which ensures that a person is not able to deny the receipt of information if they have, in fact, received it.

These factors are rapidly growing in importance as our day-to-day business is increasingly conducted by electronic means.