If you ask any Internet researcher “What would be the most important feature to include in a future Internet if we could start from scratch?”there is a pretty good chance the answer will include something about better security. One way to think about the problem is that the Internet was designed by a fairly small community who wanted access to each other’s computers; today’s Internet is used by a large, global community, including a reasonable number of criminals who would also like to gain access to a lot of other computers. Thus, the design of making open access the default isn’t clearly a good match to today’s world.There are a lot of theories about how this situation might be improved. One problem, of course, is that the Internet