polyalphabeticsubstitution
nounA secret code that uses a different mixed-up alphabet for each letter you write.
The spy used polyalphabeticsubstitution so that the same letter never looked the same twice.
RELATED WORDS
OTHER MEANINGS
2. A method of encryption where multiple cipher alphabets are used in a repeating pattern to hide letter frequencies.
Breaking polyalphabeticsubstitution requires finding the key length before analyzing letter patterns.
3. A classical cryptographic technique that shifts alphabets differently for each position in the message.
Leon Battista Alberti described an early form of polyalphabeticsubstitution in the fifteenth century.
4. Any cipher system in which plaintext symbols map to different ciphertext symbols depending on their position.
Modern textbooks treat polyalphabeticsubstitution as a stepping stone toward stronger encryption.