police believe the paris attackers used encryption to help cloak their operation. >> i think we saw in paris that intelligence agencies had no idea that these guys were going to do this. that presents a huge problem, because the united states has been very reliant on its ability to monitor e-mails and phone traffic. if it's losing that, it's going to be harder for it. >> i thank our listeners for tuning in and -- >> a senior fellow at the new america thinktank, showed us one encryption tool being used by isis. >> so this is telegram app. it offers isis unprecedented ability to reach recruits and fans without worrying about its information being intercepted. and unless you subscribe to the channel, you wouldn't even know about it. >> telegram is a free app that isis uses to spread its propaganda and recruit new members.