First of all Information security means protecting information and information systems from unauthorized access, use, modification, or destruction. The terms information security, computer security and information assurance are frequently used interchangeably. These fields are interrelated and share the common goals of protecting the confidentiality, integrity and availability of information.
Information security, sometimes shortened to infosec, is the practice of protecting information by mitigating information risks. It is part of information risk management.
With the introduction of the computer, the need for automated tools for protecting the files and other information stored on the computer became evident. This is especially the case for a shared system as like internet. Thus, computer security is the generic name for the collection of tools designed to protect data and to prevent hackers.
Computer Security rests on confidentiality, integrity and availability.
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Confidentiality is the concealment of information or resources. Cryptography can be the better choice for maintaining the privacy of information, which traditionally is used to protect the secret messages. Similarly, the privacy of resources, i.e. resource hiding can be maintained by using proper firewalls. Confidentiality is sometimes called secrecy or privacy.