http://www.theregister.co.uk/2013/03/01/post_cryptography_security_shamir/

“In the Second World War if you had good crypto protecting your communication you were safe. Today with an APT sitting inside your most secure computer systems, using cryptography isn’t going to give you much protection.

“It’s very difficult to use cryptography in an effective way if you assume that an APT is watching over the computer system, watching everything that is being done, including the encryption and decryption process.”