Playfair

Part of speech: noun, adjective

Definitions

1. A cipher technique used for encrypting messages by substituting pairs of letters to enhance security
2. A method of encoding that involves arranging letters in a grid for secret communication between parties
3. A manual symmetric encryption system that transforms plaintext into ciphertext using a keyword for ciphering pairs of letters

Etymology: The Playfair cipher is named after Lyon Playfair, the British scientist and politician who popularized it. The method itself is older than him. Charles Wheatstone devised it, and it is sometimes called the Wheatstone-Playfair cipher for that reason. Playfair's role was promotional: he championed the system to the British government, which then used it in the field. The same name appears on a set of craters, which are named after John Playfair, the Scottish mathematician, scientist and minister of the Church of Scotland. The two Playfairs were not related to each other as far as the naming goes; the cipher and the craters simply share a surname. Lyon Playfair's own name is the one that stuck to the cipher, so the word now points to the later popularizer rather than the inventor.