In his first major policy speech as director of the F.B.I., James B. Comey on Thursday plans to wade deeper into the debate between law enforcement agencies and technology companies about new programs intended to protect personal information on communication devices.
Mr. Comey will say that encryption technologies used on these devices, like the new iPhone, have become so sophisticated that crimes will go unsolved because law enforcement officers will not be able to get information from them, according to a senior F.B.I. official who provided a preview of the speech.
The speech was prompted, in part, by the new encryption technology on the iPhone 6, which was released last month. The phone encrypts emails, photos and contacts, thwarting intelligence and law enforcement agencies, like the National Security Agency and F.B.I., from gaining access to it, even if they have court approval.