Abstract
After thirty years of work on computer security, why are
almost all the systems in service today extremely vulnerable to
attack? The main reason is that security is expensive to set up
and a nuisance to run, so people judge from experience how
little of it they can get away with. Since there’s been little
damage, people decide that they don’t need much security. In
addition, setting it up is so complicated that it’s hardly ever
done right. While we await a catastrophe, simpler setup is the
most important step toward better security.
In a distributed system with no central management like the
Internet, security requires a clear story about who is trusted
for each step in establishing it, and why. The basic tool for
telling this story is the “speaks for” relation between principals
that describes how authority is delegated, that is, who
trusts whom. The idea is simple, and it explains what’s going
on in any system I know. The many different ways of encoding
this relation often make it hard to see the underlying order.