polyalphabetic cipher
nounA polyalphabetic cipher is a secret code that uses more than one set of letter swaps to hide a message.
The Vigenère cipher is a famous polyalphabetic cipher that uses a keyword to change the letter swaps.
SYNONYMS
OTHER MEANINGS
2. A cipher in which each letter of the plaintext can be replaced by different ciphertext letters at different positions.
Because the same letter can encrypt differently each time, a polyalphabetic cipher hides repeated patterns better than a simple substitution cipher.
3. A method of encryption designed to defeat frequency analysis by shifting alphabets periodically.
Breaking a polyalphabetic cipher often requires finding the key length before analyzing letter frequencies.
4. Any encryption scheme that cycles through multiple substitution alphabets according to a key.
Modern stream ciphers can be seen as an advanced form of polyalphabetic cipher.