AT&T chief security officer Ed Amoroso, speaking before a packed auditorium Thursday at his company's cybersecurity conference, wanted to test the collective knowledge of those in the room. How well-studied were they in the visionaries who've had the greatest impact on IT security? Not very well, it turns out, as few could put names to the faces projected as part of Amoroso's slide show. Amoroso was giving props to the giants on whose shoulders today's security pros stand.They're not all computer scientists, but they've done important work that has influenced IT security. Security pros who know and cite some or all of the following people in their conversations with Amoroso show they have a real commitment to the discipline of security, he says.

Here they are, in the order Amoroso presented:

1) Edsger Dijkstra -- The late professor emeritus of computer sciences and mathematics at the University of Texas at Austin believed that simplicity and clarity are the two attributes of any computing system that mean the difference between success and failure, Amoroso said. Nowhere is this truer than in security.

2) Peter Neumann -- Neumann, who spent a decade at the Computer Science Lab at Bell Labs in Murray Hill, N.J., devoted much of his career to researching security, crypto applications, overall system survivability, reliability, fault tolerance, and risk avoidance.

3) Dorothy Denning -- Denning was the Patricia and Patrick Callahan Family Professor of Computer Science and director of the Georgetown Institute for Information Assurance. She left Georgetown to become a professor in the Department of Defense Analysis at the Naval Postgraduate School, where she addresses cybercrime and cyberterrorism, information warfare and security, and cryptography.

4) Clifford Stoll -- "I spend almost as much time figuring out what's wrong with my computer as I do actually using it," the highly quotable writer once said.

5) Richard Feynmann -- Amoroso remembers the late scientist, teacher, raconteur, and musician by the following quote, "I opened safes whose contents were bigger and more valuable than what any safecracker opened. I have them all beat."

6) Dennis Ritchie -- "What we wanted to preserve was not just a good environment in which to do programming but a system around which a fellowship could form," said one of the creators of the C programming language and the Unix operating system.

7) David Parnas -- The director of the University of Limerick (Ireland) Software Quality Research Laboratory once said, "As a rule software systems do not work well until they have been used and have failed repeatedly in real applications."

8) C.A.R. "Tony" Hoare -- "The threshold for my tolerance of complexity is much lower than it used to be," the Oxford University Computing Laboratory emeritus professor of computing once said. The worse and more complicated systems are, the easier they are to exploit, Amoroso agrees.

9) Donald Knuth -- This professor emeritus of the Art of Computer Programming at Stanford University once said, "Any inaccuracies in this index may be explained by the fact that it has been sorted with the help of a computer." Amoroso sees the logic in this. "It's healthy to have a healthy mistrust for anything that's automated," he says. "This is what we learn from Donald Knuth."

10) Whitfield Diffie --"I began worrying about how you could secure the whole North American telephone system. How could you ever have a spontaneous call between two people and have it secure?" Sun's VP, fellow, and chief security officer once said.