So You Want to Be a Security Expert

So You Want to Be a Security Expert:
I regularly receive e-mail from people who want advice on how to learn more about computer security, either as a course of study in college or as an IT person considering it as a career choice.

First, know that there are many subspecialties in computer security. You can be an expert in keeping systems from being hacked, or in creating unhackable software. You can be an expert in finding security problems in software, or in networks. You can be an expert in viruses, or policies, or cryptography. There are many, many opportunities for many different skill sets. You don't have to be a coder to be a security expert.

In general, though, I have three pieces of advice to anyone who wants to learn computer security.

• Study. Studying can take many forms. It can be classwork, either at universities or at training conferences like SANS and Offensive Security. (These are good self-starter resources.) It can be reading; there are a lot of excellent books out there -- and blogs -- that teach different aspects of computer security out there. Don't limit yourself to computer science, either. You can learn a lot by studying other areas of security, and soft sciences like economics, psychology, and sociology.
  
  
• Do. Computer security is fundamentally a practitioner's art, and that requires practice. This means using what you've learned to configure security systems, design new security systems, and -- yes -- break existing security systems. This is why many courses have strong hands-on components; you won't learn much without it.
  
  
• Show. It doesn't matter what you know or what you can do if you can't demonstrate it to someone who might want to hire you. This doesn't just mean sounding good in an interview. It means sounding good on mailing lists and in blog comments. You can show your expertise by making podcasts and writing your own blog. You can teach seminars at your local user group meetings. You can write papers for conferences, or books.

I am a fan of security certifications, which can often demonstrate all of these things to a potential employer quickly and easily.

I've really said nothing here that isn't also true for a gazillion other areas of study, but security also requires a particular mindset -- one I consider this essential for success in this field. I'm not sure it can be taught, but it certainly can be encouraged. "This kind of thinking is not natural for most people. It's not natural for engineers. Good engineering involves thinking about how things can be made to work; the security mindset involves thinking about how things can be made to fail. It involves thinking like an attacker, an adversary or a criminal. You don't have to exploit the vulnerabilities you find, but if you don't see the world that way, you'll never notice most security problems." This is especially true if you want to design security systems and not just implement them. Remember Schneier's Law: "Any person can invent a security system so clever that she or he can't think of how to break it." The only way your designs are going to be trusted is if you've made a name for yourself breaking other people's designs.

One final word about cryptography. Modern cryptography is particularly hard to learn. In addition to everything above, it requires graduate-level knowledge in mathematics. And, as in computer security in general, your prowess is demonstrated by what you can break. The field has progressed a lot since I wrote this guide and self-study cryptanalysis course a dozen years ago, but they're not bad places to start.

This essay originally appeared on "Krebs on Security," the second in a series of answers to the question. This is the first. There will be more.