A portion of a VigenËre cipher square is given below using five (1, 2, 14,
16, 22) of the possible 26 alphabets. Using the key word bow, which of
the following is the encryption of the word advance using the
VigenËre cipher?
Exhibit:

A.
b r r b b y f

B.
b r r b b y h

C.
b r r b c y f

D.
b r r b j y f

Explanation:
The VigenËre cipher is a polyalphabetic substitution cipher. The key
word bow indicates which alphabets to use. The letter b indicates the
alphabet of row 1, the letter o indicates the alphabet of row 14, and
the letter w indicates the alphabet of row 22. To encrypt, arrange the
key word, repetitively over the plaintext as shown in Table.
Exhibit:

Thus, the letter a of the plaintext is transformed into b of alphabet in
row 1, the letter d is transformed into r of row 14, the letter v is transformed
into r of row 22 and so on.