CISSP – Glossary term O

CISSP LogoThis is my personal glossary about my preparation for obtain CISSP Certification and understand all Security keywords.  Here all keywords  beginning by letter O.




Object: A passive entity, such as a system of file.

Object reuse: The processes of protecting the confidentiality of objects that are reassigned after initial use.

Objectives: Specific milestones that an organization wants to perform in order to meet its goal.

One-time pad: A cryptographic key-stream that can be used only once.

One-time password: A password that’s valid for only one log-on session.

One-way function: A problem that’s easy to compute in one direction but not in the reverse direction.

Open Message Format: A message encrypted in asymmetric key system by using the sender’s private key. The sender’s public key, which available to anyone is used to decrypt the message. This format guarantees the message’s authenticity.

Open System: A vendor-independent system that complies with an accepted standard, which promotes interoperability between systems and components made by different vendors. (Unix-Like…)

Open System Interconnection (OSI) Model: The seven-layer reference model for networks. The layer are:

  1. Physical
  2. DataLink
  3. Network
  4. Transport
  5. Session
  6. Presentation
  7. Application

Operating system (OS): Software that controls computer hardware and ressources and facilitates the operation of application software.

Orange book: See Trusted Computer System Evaluation Criteria (TCSEC).

Output FeedBack (OFB): One of four operating modes for DES. OFB is a stream cipher often used to encrypt satellite communications. In this mode previous plaintext is used as feedback for key generation in the next key-stream; however, the resulting cipher-text isn’t chained together (unlike with CFB).

Owner: An individual in an organization who’s responsible for management of an asset, including classification, handling, and access policy.