It's not enough to build a wall anymore.

To protect data, you need to make it invisible, says Tom Patterson, global security boss at Unisys Corp. and a leader on the team that CEO Peter Altabef has recruited to turn around sales and profits after consolidating the general staff at the shrunken, Blue Bell-based computer-services company.

"Used to be we protected computers by putting them in separate buildings. Then we built firewalls.

"But now all the computers are connected - on smartphones, to cloud servers, by sensors, with suppliers in China. They are all vulnerable, when the bad guys find their way in," said Patterson, downing breakfast at HubBub Coffee on Penn's campus as he waited to address the Securities Industry and Financial Markets Association (SIFMA) cybersecurity conclave at the Wharton School.

That's why Unisys and its rivals - from IBM to venture-backed, ex-spy-run startups based near Washington - have rolled out "micro-segmentation" systems, like Unisys Stealth, which encrypt data packets so they become invisible to all but authorized users, even from neighboring packets.

The SIFMA conclave - off-limits to the public "because we let our hair down," Patterson says - now focuses on mainstream Wall Street managers, not just IT nerds. "They understand now what happens when their information is taken away," said Patterson, a veteran of U.S. intelligence work, who trained at Deloitte. "They've moved beyond legal compliance," or merely observing good security practices because it's the law, to "catastrophe avoidance," building flexible system architecture to resist daily attacks by competitors, thieves, terrorists, foreign governments, and automated mischief-makers.

Altabef has a lot of convincing to do. After the company announced a new bond issue, boosting its debt load, Unisys stock fell below $8 a share last week for the first time since the 2008-09 recession. Yearly sales of $3 billion are half the level of the early 2000s.

Unisys claims a long list of blue-chip clients - financial multinationals, airlines, the U.S. border patrol, and tech companies like PBF Energy, which operates oil refineries in South Jersey and Delaware.

Unisys Stealth isolates hackers threatening PBF refinery controls, and allows automatic updates "without the need to change applications, buy new hardware, or change our firewall rules," PBF chief information officer Richard Loew said in a statement.

About one-fifth of Unisys sales are to the federal government; another quarter is to state, local, and foreign governments. The firm employs more than 1,000 in Colombia alone, where Unisys systems developed to fight drug trafficking and guerrillas have led to peaceful uses, the government says.

"They have been in Colombia for years. They have back offices, call centers, software development," Luis Carlos Villegas, Colombia's ambassador to the U.S., told me last year.

Unisys' decades-old U.S. and foreign pension commitments have been a drain on its profitability, compared to new competitors unburdened by legacy costs.

But Unisys' long record at innovation has kept the firm adapting, says Patterson. "I'm very optimistic," he said. "We worked on Super Bowl security this year, and lots of other things you won't hear about. The good guys are much more successful than the bad guys." In cyberspace, victory is most often silent.

215-854-5194 @PhillyJoeD