Question 198 - 212-81 discussion

Homophonic Substitution

https://en.wikipedia.org/wiki/Substitution_cipher#Homophonic_substitution

An early attempt to increase the difficulty of frequency analysis attacks on substitution ciphers was to disguise plaintext letter frequencies by homophony. In these ciphers, plaintext letters map to more than one ciphertext symbol. Usually, the highest-frequency plaintext symbols are given more equivalents than lower frequency letters. In this way, the frequency distribution is flattened, making analysis more difficult.

Incorrect answers:

Playfair Cipher - (Playfair square or Wheatstone-Playfair cipher) is a manual symmetric encryption technique and was the first literal digram substitution cipher. The scheme was invented in 1854 by Charles Wheatstone, but bears the name of Lord Playfair for promoting its use.

Scytale Cipher - is a tool used to perform a transposition cipher, consisting of a cylinder with a strip of parchment wound around it on which is written a message. The ancient Greeks, and the Spartans in particular, are said to have used this cipher to communicate during military campaigns.

ADFVGX Cipher - cipher was a field cipher used by the German Army on the Western Front during World War I. ADFGVX was in fact an extension of an earlier cipher called ADFGX. Invented by Lieutenant Fritz Nebel (1891--1977) and introduced in March 1918, the cipher was a fractionating transposition cipher which combined a modified Polybius square with a single columnar transposition.