But in computer security, such things are not always black and white.
He is the author of several books on computer security and information technology.
A career in computer security is not a bad choice for a young man or woman today.
But to experts in computer security, they sound like something else.
His interests include computer security and the game of Go.
"I want to teach people and have them learn about computer security."
Still, his most enduring research was done in computer security.
"But if we don't protect against these rare cases, then the whole field of computer security will get a bad name."
"The present state of computer security just isn't working," he said.
I'm just a cautious person when it comes to my computer security.