investigators say members of isis lure sympathizers to social media and apps where the messages self-destruct or encrypted. law enforcement has been pressing the technology industry for access to that data when national security is a but so far more privacy concerns have won out. c.i.a. director john brennan. >> i do hope that this is going to be a wake-up call, particularly in areas of europe where i think there has been a misrepresentation of what the intelligence and security services are doing. >> reporter: brennan warns more attacks like paris could be coming. >> i would anticipate that this is not the only operation that isil has in the pipeline. >> reporter: the tech industry says calls to weaken encrypted products undermine cyber security. scott, a law enforcement source is confident the attackers used encrypted communication, but it's unclear whether investigators have the