The Isis reportedly used encrypted communication to coordinate the Paris attacks, according to French officials.
"I think what we're going to learn is these guys are communicating via these encrypted apps, this commercial encryption which is very difficult or nearly impossible for governments to break, and the producers of which don't produce the keys necessary for law enforcement to read the encrypted messages", said CIA former deputy director Michael Morell in a television interview on Sunday.
End-to-end encrypted apps the terrorist outfits use, like WhatsApp, Signal, RedPhone, Wickr, and Telegram, have made it difficult for the government to decrypt communications.
Without the decryption key, which companies refuse to share with governments for fear of infringement of users' privacy, authorities are unable to access message traffic.
Telegram, the ephemeral messaging app, allows users to create channels that permit communication with 200 people simultaneously.
The app has been used to disseminate "tutorials on manufacturing weapons and launching cyberattacks, calls for targeted killing and lone-wolf attacks, and more", reported Middle East Media Research Institute (MEMRI).
Former security personnel and media analysts are blaming the US National Security Agency (NSA) whistleblower Edward Snowden for compromising the surveillance ability of intelligence agencies and helping terrorists to "go dark" with their communication technology.
However, al Qaeda has been using forms of encrypted communications since the 1990s, and blaming Snowden is "outlandish", says Ars Technica's Sean Gallagher. He adds that even if the "golden key" was handed over to governments, it would hardly curb the use of peer-to-peer encryption and other digital tools by terrorist groups.
Help in shutting down Twitter accounts of Isis members, and monitoring channels of communication of their network has been offered by hacktivism group Anonymous.
Anonymous, which took down thousands of Isis-connected Twitter accounts after the Charlie Hebdo attacks, has started the #OpParis operation already, shutting down 5,500 accounts by 17 November since its launch on 14 November.
We report that more than 5500 Twitter account of #ISIS are now #down! #OpParis #Anonymous #ExpectUs
â€” #OpParis (@opparisofficial) November 17, 2015
Their information-sharing forum revealed they have taken down more than 7,000 accounts as of noon, 18 November.
Their new website, #opIceISIS, will index Isis members based on their real names, location, picture, Twitter, Facebook, and YouTube accounts, which they are willing to share with governments.
I don't think working against the government is the solution. Working with to an extent is what could work. Not that we trust them that much â€” #OpParis (@opparisofficial) November 18, 2015
I'm not saying we lose our independence, but by letting governments and the people know about important intel we could help. No coverups.
â€” #OpParis (@opparisofficial) November 18, 2015
The group is famous for hacking and trolling accounts of members of the Ku Klux Klan, Monsanto's GMO business, and multiple oppressive regimes.