Resumen
The article focuses on computer security systems and prevention of computer hacking. Most security problems are caused by buggy software, which is the oldest unsolved problem in computer science. A secure computer system cannot be built without building correct systems that are hack-resistant. The primary challenge is to learn how to build hack-resistant systems that can cope with the failure, under attack, of some components. Another issue in this area is of simplifying security-critical programs. Only possible solutions for the security of complex components are to split off the security-sensitive pieces into small, auditable modules, or to provide new operating system primitives that will have the same effect. There are other approaches to address the security issue, like building fault-tolerant systems out of unreliable components. Fault-tolerant systems, however, deal with natural failures, and hackers do their best to shift odds and to create improbable situations they can exploit. If these challenges are met then networks would be able to survive and even flourish.

Resumen
This article reports that unsolicited commercial email, or spam, peddles a variety of dubious products, ranging from pharmaceuticals to abandoned bank accounts. The so-called "phishers" try to steal user names and passwords for online banking. And then, systems are infested with viruses, worms and other malware. Although there are would-be solutions to these problems, some of them have the potential to do far more harm than good. An obvious approach to spam fighting is some form of sender authentication. Authenticated email solves some problems. If nothing else, it hinders the spread of email worms, since the infected machine will be positively identified. Furthermore, there are some situations where a list of permitted senders is in fact used. In the best of these schemes, purported identity is used to drive some sort of challenge and response scheme. Authenticated email would provide some protection here, though even without it successful "joe jobs" forgery of a legitimate user's identity are relatively uncommon.