The information security architect of a large service provider advocates an open design of the security architecture, as opposed to a secret design. What is her main argument for this choice?

The main argument for an open security design is rooted in Kerckhoffs's Principle, a fundamental concept in cryptography and security engineering. This principle posits that a system's security should not rely on the secrecy of its design or implementation (i.e., security by obscurity). Instead, an open design allows for rigorous and extensive public scrutiny by a wide community of security researchers, academics, and ethical hackers. This broad, independent peer review process is far more effective at identifying and rectifying potential vulnerabilities than a small, internal team could ever be. The resulting architecture is more robust because its strength has been proven through transparent, extensive testing.

A. Open designs are easily configured: Configuration complexity is a function of the system's architecture and features, not whether its design is public or secret.
B. Open designs have more functionality: The range of functionality is a design choice and is entirely independent of whether the system's design is open or proprietary.

1. Anderson, R. J. (2008). Security Engineering: A Guide to Building Dependable Distributed Systems (2nd ed.). Wiley Publishing. In Chapter 21, Section 21.1.1, "The Open Design Principle," Anderson states, "The open design of a system to public scrutiny is the only reliable way of finding out whether it is a good one... Systems that have been subjected to years of determined attack by clever people are the only ones you can trust." This directly supports that extensive testing is the key benefit.

2. Pfleeger, C. P., Pfleeger, S. L., & Margulies, J. (2015). Security in Computing (5th ed.). Prentice Hall. In Chapter 1, Section 1.4.2, "Principle of Open Design," the authors explain, "The principle of open design states that the security of a mechanism should not depend on the secrecy of its design or implementation... decades of experience have shown that open design is a more effective development practice... public scrutiny is a powerful tool for finding and eliminating security vulnerabilities."

3. Saltzer, J. H., & Schroeder, M. D. (1975). The Protection of Information in Computer Systems. Proceedings of the IEEE, 63(9), 1278–1308. https://doi.org/10.1109/PROC.1975.9939. This foundational paper on computer security principles lists "Open design" as a key principle (Section I.A.4), stating, "The design should not be secret... It is better to expose the design to public scrutiny so that flaws can be discovered."