Vigenere cipher

This term refers to a polyalphabetic substitution method that provides significantly more security than a simple Caesar cipher by using a keyword to shift letters differently throughout the text. It is often discussed in the context of historical cryptography as a bridge between simple substitution and more complex mechanical encryption.

In technical discussions, the term is frequently associated with the Tabula Recta, the square grid used to determine the ciphertext letter. While once considered unbreakable, it is now easily solved using Kasiski examination or frequency analysis of the keyword length.