Would Encryption Backdoor Stop Paris-like Terror Attacks?

With 129 people killed in Paris terror attacks and dozens critically wounded, the law enforcement and intelligence officials are reviving their efforts to force companies to put some backdoors in encryption so that they can access your information.
How did the Intelligence agencies fail to Intercept terrorist plans of these attacks?
In the wake of the Paris terror attacks, Former CIA Director

How NSA successfully Broke Trillions of Encrypted Connections

Yes, it seems like the mystery has been solved.



We are aware of the United States National Security Agency (NSA) powers to break almost unbreakable encryption used on the Internet and intercept nearly Trillions of Internet connections – thanks to the revelations made by whistleblower Edward Snowden in 2013.



However, what we are not aware of is exactly how did the NSA apparently

How to Crack RC4 Encryption in WPA-TKIP and TLS

Security researchers have developed a more practical and feasible attack technique against the RC4 cryptographic algorithm that is still widely used to encrypt communications on the Internet.



Despite being very old, RC4 (Rivest Cipher 4) is still the most widely used cryptographic cipher implemented in many popular protocols, including:


SSL (Secure Socket Layer)
TLS (Transport Layer