vigenere cipher the vigenere ciphermisattributed to thcentury cryptographer blaise de vigenere (others had independently invented it earlier)was impossible to crack for hundreds of years it is essentially the caesar cipherexcept it makes use of multipart key the so-called vigenere key is wordor even random series of letters each letter represents number by which to shift the letter in the messagea represents shifting letter in the message by represents represents and so on for exampleif vigenere key is the word "cat,the represents shift of the represents and the represents the first letter of the message gets shifted by the second letter by and the third letter by for the fourth letterwe repeat the key of this use of multiple caesar cipher keys is what gives the vigenere cipher its strength the possible number of combinations is too big to brute force