chaff and winnow - technical definition

A privacy technique that is simpler than encrypting a message with a key. Chaff is the unusable part of a plant, and winnow means to separate the chaff so it can be discarded. Thus, chaff is sent (fake packets) along with real packets, and the chaff is winnowed at the other end by comparing a message authentication code (MAC) stored in each packet. The receiving end knows which are the valid MACs and which are not. See cryptography.