Darren Guccione should be sleeping well these days, even though it's his job to stay one step ahead of hackers.

His company, Keeper, a password-security and data-storage app provider, has landed some big customers in recent weeks.

Guccione signed up Samsung, the world's biggest phone maker, and America Movil, the largest wireless carrier in Latin America, to offer Keeper on new phones. Orange, one of Europe's top carriers, also came onboard.

The deals will result in the company's password-security app being preloaded on tens of millions of new smartphones in the next 18 months, Guccione says.

“These deals could triple the size of the business within 18 to 24 months,” he says. “We've hit that inflection point as a company.”

He declines to offer specific financial data but says Keeper is profitable and expects revenue in the tens of millions next year. Its headcount has doubled in the past year to more than 60, Guccione says.

The company is based in Chicago, where it has about 22 people in the West Loop. Its technology team is in El Dorado Hills, Calif., where Keeper's chief technology officer, Craig Lurey, is based. It also has some support staff in the Philippines.

Keeper promises encrypted password security, giving users a single master password, and secure storage of photos and other files. It uses a “freemium” model—customers can use it free on one device, but a premium version that costs $29.99 a year allows for unlimited devices, cloud storage and backup. Corporate customers pay $750 a year, plus $48 per user.

Guccione won't say exactly how many paying customers Keeper has but says it has nearly 9 million registered consumer users and more than 3,000 corporate customers. The four-year-old company has emerged as one of Chicago's most innovative and fastest-growing startups.

Keeper is benefiting from a never-ending escalation in hacking and security breaches, the shift of sensitive activities such as banking and health data to mobile, and the pervasiveness of passwords.

“The password has been a stubborn vestige,” says Jeff Schmidt, CEO of Chicago-based cybersecurity firm JAS Global Advisors. “Everyone knows they're bad. They're not real strong security, and humans use them in ways that make the situation much worse. We like them to be easy to remember, and we try to keep track of a lot of them. But there really are no usable alternatives.

“There's a spot for those guys (password-management apps). The key is making it usable.”

Keeper has taken a big first step by signing up carriers and phone makers. But like security, the pursuit of simplicity is a never-ending struggle.