WASHINGTON -- Gartner Security & Risk Management Summit 2014 -- Former National Security Agency Director Keith Alexander says security professionals have their work cut out for them in the days ahead.

Shedding his customary uniform for an everyday suit and tie, the former general -- who retired last month and is now hanging out a shingle as a security consultant -- offered a wide range of views in a keynote presentation here. The gist: Data and malware are growing at rates so fast that it will be difficult for any security organization to keep up.

"In the coming year, it's estimated that we will create approximately 3.5 zetabytes of unique data -- that's more information than humans have produced in the last 5,000 years combined," Alexander said. "New technology is doubling every year. The top ten most in-demand jobs in 2013 were all jobs that didn't exist in 2004.

"So what we're doing right now is preparing students for jobs that don't yet exist, using technology that hasn't yet been invented, and facing problems that we don't know about yet. It's a huge challenge," he said.

At the same time, malware is growing at a corresponding rate, the former NSA director said. He recalled a recent partnership between the NSA and the Department of Defense in which the organizations uncovered 1,500 pieces of malware on US secret networks.

"What causes me the greatest concern is what might happen if our nation was hit by a destructive cyber attack," Alexander said, noting that most of the country's critical networks are operated by private industry. "If [a destructive attack] hit one of our Wall Street banks, the monetary damage could be in the trillions of dollars. We're not ready." He called for more cooperation across agencies, and across government and private industry.

Not surprisingly, Alexander also condemned recent "media leaks" -- he never mentioned Edward Snowden by name -- and said that they have contributed to recent physical attacks and an increase in deaths in places such as Iraq and Afghanistan. "The situation isn't getting better, it's getting worse," he said.

Even less surprisingly, Alexander defended the actions of the NSA in its intelligence-gathering and surveillance activities. He pointed to three recent investigations -- including one headed by ACLU investigator Jeff Stone -- which all indicate that the NSA is acting according to law.

"The NSA is not authorized to do something without a court order describing how to do it," Alexander said. "If you have a problem with what the NSA is doing, it's probably not with the NSA itself, but with what they've been asked to do."