Immediately following the attacks in Paris politicians were demanding bans on effective cryptography. That would lead one to believe that the attackers used cryptography to conceal their communications. As it turns out the attackers coordinated their efforts over regular old unencrypted Short Message Service (SMS):
Yet news emerging from Paris — as well as evidence from a Belgian ISIS raid in January — suggests that the ISIS terror networks involved were communicating in the clear, and that the data on their smartphones was not encrypted.
European media outlets are reporting that the location of a raid conducted on a suspected safe house Wednesday morning was extracted from a cellphone, apparently belonging to one of the attackers, found in the trash outside the Bataclan concert hall massacre. Le Monde reported that investigators were able to access the data on the phone, including a detailed map of the concert hall and an SMS messaging saying “we’re off; we’re starting.” Police were also able to trace the phone’s movements.
This is why jumping to conclusions is foolish. The politicians and other assorted government goons demanding effective cryptography be banned didn’t wait long enough to learn whether the attackers actually used encrypted communications. Now that evidence exists suggesting they didn’t the entire narrative being used to justify the proposed bans has fallen apart.
So how did the various governments’ intelligence services miss the attacks? Probably because the unencrypted messages were buried so deeply in random noise nobody noticed them.
Another possibility is complacency. When you’re looking for boogeymen everywhere you will find them everywhere. Western governments are always looking for terrorist attacks and see them everywhere from foreign nations to local airports. Their security briefings are overflowing with warnings against imminent terrorist attacks. But when you constantly hear about imminent terrorist attacks that never happen you became so numb to the warnings that when a credible threat does exist you dismiss it as yet another overreaction from an overly paranoid intelligence agent seeking a promotion.
Either way mass surveillance did nothing to thwart the attacks and most likely hindered efforts to do so.