Still, when a new mobile service takes off, it is usually far more vulnerable. Before a major breach or hole is discovered, analysts say, tech entrepreneurs take possible security risks as an accepted trade-off for building their product at a rapid pace. Stricter password requirements and airtight encryption take a back seat to user growth, convenience and feature introductions.

And in many ways, mobile apps and services — which have been taking off most rapidly lately — face security challenges different from those of technology built for their desktop predecessors. The information at risk on mobile devices is often more personal than on desktop devices, because mobile devices now include things like digital wallet apps, location-tracking recommendation services, and photo-messaging apps.

Government officials say the amount of data flowing through some young companies’ networks rivals what the government itself can collect. The danger, some officials note, is that government agencies have no jurisdiction to protect it, or even the ability to share classified threat information with the companies, leaving the onus to protect personal data from cybercriminals and nation-states upon the companies themselves.

Aaron Grattafiori, a security researcher at iSEC Partners, a security firm, said start-ups could not always anticipate their potential security holes.

“There’s a lot more user information on a phone than there used to be,” he said. “Often start-ups can be in over their heads before they know it.”

And start-ups are asking for increasingly personal information. ThirdLove, a lingerie company, uses a mobile application to gauge a woman’s bra size using an iPhone camera. After signing up, users take a photograph of their torso in a fitted tank top and send it to the company, which uses virtual sizing algorithms to determine their bra size. The company says it has gone through extensive security audits to protect sensitive information, and claims to use top-level encryption, said Heidi Zak, a founder of the company.

“No one ever accesses those photos,” she said. “Most women are in a tank top and their heads are cut off.” Ms. Zak declined to say how many customers the service had, but said that 85 percent of the customers had used the free sizing software.