"Encryption works. Properly implemented strong crypto systems are one of the few things you can rely on." How is it, then, that agents from the NSA and its British counterpart known as the Government Communications Headquarters (GCHQ) are reportedly able to bypass the crypto protections provided by Internet companies including Google, Facebook, Microsoft, and Yahoo?
The short answer is almost certainly by compromising the software or hardware that implements the encryption or by attacking or influencing the people who hold the shared secrets that form one of the linchpins of any secure cryptographic system.