Security service (telecommunication)

Security service is a service, provided by a layer of communicating open systems, which ensures adequate security of the systems or of data transfers as defined by ITU-T X.800 Recommendation.
X.800 and ISO 7498-2 (Information processing systems – Open systems interconnection – Basic Reference Model – Part 2: Security architecture) are technically aligned. This model is widely recognized

A more general definition is in CNSS Instruction No. 4009 dated 26 April 2010 by Committee on National Security Systems of United States of America:

Another authoritative definition is in W3C Web service Glossary adopted by NIST SP 800-95:

Information security and Computer security are disciplines that are dealing with the requirements of Confidentiality, Integrity, Availability, the so-called CIA Triad, of information asset of an organization (company or agency) or the information managed by computers respectively.

There are threats that can attack the resources (information or devices to manage it) exploiting one or more vulnerabilities. The resources can be protected by one or more countermeasures or security controls.

So security services implement part of the countermeasures, trying to achieve the security requirements of an organization.

In order to let different devices (computers, routers, cellular phones) to communicate data in a standardized way, had been defined.

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