Beyond the Castle Model of cyber-risk and cyber-security

• The “castle” approach to security, walls in layers, is ill-matched to developments in technology, organizations, and society.
• Technological walls are expensive to build and maintain, and there are typically many non-obvious gateways.
• Barriers limit responsiveness. There are pressures to trade walls for anywhere-anytime access.
• The mental and social separation between inside and outside is no longer clear, especially for Millenials.
• The strategy known as “computing in compromised environments” is a new possibility for security in cyberspace.

The predominant metaphor for secure computing today is modeled on ever higher, ever better layers of walls. This article explains why that approach is as outmoded for cyber security today as it became for physical security centuries ago. Three forces are undermining the Castle Model as a practical security solution. First, organizations themselves tear down their walls and make their gateways more porous because it pays off in terms of better agility and responsiveness – they can do more, faster and better. Second, technological developments increasingly destroy walls from the outside as computation becomes cheaper for attackers, and the implementation of cyberwalls and gateways becomes more complex, and so contains more vulnerabilities to be exploited by the clever and unscrupulous. Third, changes in the way humans and technology interact, exemplified (but not limited to) the Millennial generation, blur and dissolve the concepts of inside and outside, so that distinctions become invisible, or even unwanted, and boundaries become annoyances to be circumvented. A new approach to cyber security is needed: Organizations and individuals need to get used to operating in compromised environments. The article's conclusion hints at more nuanced forms of computation in environments that must be assumed to be potentially compromised.