Managing high-tech computer security against smart and persistent intruders

Summary form only given as follows. Yesterday, computer security was perceived as a passive lock, once applied then forgotten about. Today, computer security is an ongoing effort, a war against a range of “infotruders” who get smarter and remain persistent in proportion to the data treasure under attack. The question addressed here is how to build management guidelines, how to budget and allocate resources in order to achieve proper balance between what is necessary to secure information, and what is a panic-device-driven “Maginot line” which costs too much, and protects too little