So to summarize all of this, the principles of
secure design should underlie all designs and mechanisms
including implementation. Otherwise, they're just
going to be too hard to use or they won't
achieve your ends. But in order to do this, this requires a very good
understanding of the goals of the mechanisms and
the environment in which your program
is to be used. You have to ask, "How do I apply this principle?" Not just, well, let's
just put it in there. But these are principles, and principles guide you. They say what you should be doing but they don't say
how you should do it, and that's where the
understanding of the mechanism, the goals of the mechanism and of the environment in which
you're working come into play. Also of course,
careful design and analysis and implementation
underlies all of this.