Wired has a Bruce Schneier essay posted that dives “Inside the Twisted Mind of the Security Professional.” Mostly, he talks about having a security mindset.

The lack of a security mindset explains a lot of bad security out there: voting machines, electronic payment cards, medical devices, ID cards, internet protocols. The designers are so busy making these systems work that they don’t stop to notice how they might fail or be made to fail, and then how those failures might be exploited. Teaching designers a security mindset will go a long way toward making future technological systems more secure.