hardware mechanism

A security control implemented in physical circuitry or dedicated electronic components — rather than in software or firmware — that enforces a security policy by making a constrained behavior structurally impossible to override through software means. Because software is vulnerable to various forms of attack, hardware-enforced controls are more attractive: unauthorized reconfiguration cannot be achieved without physical access to the device. In standards practice, the term is used wherever a policy requirement must be made unconditional: NIST SP 800-53 control AC-4(7) invokes the concept directly, requiring that one-way information flows be enforced "using hardware mechanisms." Organizations use such controls at policy-enforcement points to govern information flows between systems, and standards bodies call attention to the trustworthiness of the filtering and inspection components — hardware, firmware, and software — that are critical to that enforcement.