A Model for When Disclosure Helps Security: What Is Different About Computer and Network Security?

Abstract

This Article asks the question: When does disclosure actually help security? The discussion begins with a paradox. Most experts in computer and network security are familiar with the slogan that there is no security through obscurity. The Open Source and encryption view is that revealing the details of a system will actually tend to improve security, notably due to peer review. In sharp contrast, a famous World War II slogan says loose lips sink ships. Most experts in the military and intelligence areas believe that secrecy is a critical tool for maintaining security. Both cannot be right - disclosure cannot both help and hurt security. Using a law and economics approach to resolve the paradox, Part I provides a model for deciding when either the Open Source or the military/intelligence viewpoints is likely to be correct. The model analyzes the costs and benefits of disclosure for both attackers and defenders. The model also sheds light on when disclosure is likely to provide net benefits in two other important cases: information sharing (such as between the FBI and the CIA) and the public domain. Part II explains why many computer and network security problems appear different from the traditional security problems of the physical world. The analysis focuses on the nature of the first-time attack or the degree of what the paper calls uniqueness in the defense. Many defensive tricks, including secrecy, are more effective the first time there is an attack on a physical base or computer system. Secrecy is far less effective, however, if the attackers can probe the defenses repeatedly and learn from those probes. It turns out that many of the key areas of computer security involve circumstances where there can be repeated, low-cost attacks. For instance, firewalls, mass-market software, and encryption algorithms all can be attacked repeatedly by hackers. Under such circumstances, a strategy of secrecy - of security through obscurity - is less likely to be effective than for the military case. Part III applies the analytic tools developed earlier in the paper to issues including the following: the enlargement of the public domain in a world of search engines; the relationship between disclosure and deterrence; the importance of not disclosing passwords or the combination to a safe; why secrecy in surveillance may improve security (while also threatening other important values); and variables that affect when Open Source or proprietary software may provide better security. Part III also explains how the academic literature on the Efficient Capital Markets Hypothesis can illuminate important issues in computer and network security. In short, this Article provides the first systematic explanation of how to decide when disclosure improves security, both for physical- and cyber-security settings.