"Bumper sticker" definition of secure software

[neumann at csl.sri.com (Peter G. Neumann)]

You suggest: 

  Secure software is software that remains dependable despite efforts to
  compromise its dependability.

You need a bigger-picture view that encompasses trustworthiness
and assurance.

"Dependable systems are systems that remain dependable despite 
would-be compromises to their dependability."

"Trustworthy systems are systems that are worthy of being trusted
to satisfy their requirements (for security, reliability, survivability,
safety, or whatever)."

Security is generally too narrow by itself, because a system that is
not reliable is not likely to be secure, especially when in 
unreliability mode!

The principle of Keep It Simple is inherently unworkable with respect to
security.  Security is inherently complex.  Trustworthiness is broader and
even more complex.  But if you don't think about trustworthiness more
broadly, what you get is not likely to be very secure.

Forget the bumper sticker approach.