Steganographic Key Leakage Through Payload Metadata

Steganography is the ancient art of invisible communication, where the goal is to hide the very fact that you are trying to hide something. It adds another layer of protection after cryptography, because encrypted message looks like gibberish and everyone immediately notices that you want to hide something.

read more............http://blogs.cisco.com/security/steganographic-key-leakage-through-payload-metadata/