>> reporter: the gunman could have been communicating with hussein, the notorious head of isis's hacking division, killed recently in a drone attack. he's said to have inspired the attack and may have directed it. this terror chatter in the dark is one of the major stops. terror groups are perfecting the use of encrypted communications. conversation chopped up into a jumble by mathematical algorithm ims. >> they do a good job of keeping what their saying. >> reporter: jihadists have their own brand, developed or modified by supporters of al qaeda. experts say it helps terrorists communicate in secret and there's a mobile version of it. isis developed a mobile app that provides updates on news and propaganda with video. and jihadi websites publish