sources warn what the attackers said may never be known because these encryptions are so hard to crack. officials also say new evidence reveal they tried to cover their tracks by changing cell phone s.i.m. cards. with me to talk about this is cnn national security expert peter bergen. i m also joined by martin boes, senior security principle and provides customers with information security protection and describes himself as a good hacker. that was a mouthful. thank you for joining me. peter, i m going to start with you. the significance of what was found out that these paris attackers were using encryption devices to hide their communications. well, i think the very one of the most significant things, carol, is telegram, one of the