What is the key function of misuse case diagrams?

The key function of misuse case diagrams is to evaluate threats and mitigation strategies. Misuse case diagrams are a security-oriented extension of traditional use case diagrams, which facilitate the identification of potential threats to a system by showcasing how an attacker might misuse a system’s functionality.

Through these diagrams, security professionals can visualize scenarios where a system's features could be exploited or attacked, leading to a breach or failure of the system. By outlining these misuse cases, teams can then evaluate and establish appropriate mitigation strategies to counteract potential threats. This proactive approach to understanding security vulnerabilities is essential in developing robust security measures within software development lifecycles.

In contrast, other options such as illustrating user interface designs, creating user personas, or documenting software features do not center around security analysis. These functions focus more on usability and functionality rather than the identification and management of security threats and vulnerabilities.