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Protection against unauthorised disclosure of information. Access control can prevent a subject from reading a file, while cryptographic confidentiality protects message contents against specified adversaries using cryptography.

An operating system supporting multiple users with distinct identities and protection requirements. Access control determines which users may access shared resources.

The Bell-LaPadula model protects information confidentiality by controlling information flow between security levels. Its simple security property says that a subject may read only objects whose classification does not exceed its maximum clearance:Thus a user cleared for confidential material cannot directly read a secret file. A readwrite permission includes reading and must satisfy the same restriction. This is an access control rule about who can learn existing contents; it says nothing by itself about where a cleared subject can subsequently copy them.