The Internet has changed since the terrorist attacks of Sept. 11, 2001 — perhaps enough that the cybersecurity of Apple's iPhones is a top economic priority, one high-ranking Bush-era official said.

"I think everybody agrees that where the government has a lawful order they ought to be able to get everything that is available," former U.S. Homeland Security Secretary Michael Chertoff told CNBC's "Closing Bell" on Monday.