A way to defeat frequency analysis as a method to determine the key is to use
A.
Substitution ciphers
B.
Transposition ciphers
C.
Polyalphabetic ciphers
D.
Inversion ciphers
Explanation:
C: The use of several alphabets for substituting the plaintext is called polyalphabetic ciphers. It is designed to make the breaking of a cipher by frequency analysis more difficult. Page 330.
Polyalphabetic ciphers – The use of several alphabets for substituting the plaintext is called polyalphabetic ciphers. It is designed to make the breaking of a cipher by frequency analysis more difficult