Bruce Schneier’s book “Beyond Fear” details a five-step process to analyze and evaluate security systems, technologies, and practices.  He uses these steps repeatedly throughout his book to analyze and comment on ideas about security “solutions” including use of armed pilots on airliners, computerized voting machines, online shopping, and national ID cards.

1.        Step 1.  What assets are you trying to protect?. To define the scope of the problem.

2.       Step 2.  What are the risks to these assets?  What is being defended, what are the consequences if it is successfully attacked, who wants to attack it, how they might attack, and why.

3.       Step 3.  How well does the security solution mitigate those risks?.  How the solution interacts with everything around it, evaluating both its operation and its failures.

4.       Step 4.  What other risks does the security solution cause?  Addresses the “unintended consequences”.  What new problems are created?

5.        Step 5.  What costs and tradeoffs does the security solution impose?  Most security costs money; but other trade-offs may be more important (convenience, issues involving basic freedom, privacy, etc.).

These five steps don’t lead to an answer, but rather provide the mechanism to evaluate a proposed solution.  They lead to another question: Is the security solution worth it?  In other words, is the benefits of mitigating the risks (Step 3) worth the additional risks (Step 4) plus the other trade-offs (Step 5)?

These steps are provided here because of their importance and seminal value.