Best way to model table with header characters?

[doa24uk]

Hi guys,

I'm looking for the best way to model this table in Java.

I thought about using seperate Arrays but it a) seems cumbersome b) Arrays don't have a key (index) character.

Eventually my method will:

Accept two string inputs (a plaintext & a key)

For example, suppose that the plaintext to be encrypted is:

ATTACKATDAWN

The person sending the message chooses a keyword and repeats it until it matches the length of the plaintext, for example, the keyword "LEMON":

LEMONLEMONLE

The first letter of the plaintext, A, is paired with L, the first letter of the key. So use row L and column A of the Vigenère square, namely L. Similarly, for the second letter of the plaintext, the second letter of the key is used; the letter at row E and column T is X. The rest of the plaintext is enciphered in a similar fashion:

Plaintext: ATTACKATDAWN
Key: LEMONLEMONLE
Ciphertext: LXFOPVEFRNHR

[Norm]

Arrays don't have a key (index) character

Given that the collating sequence for the letters you are using doesn't have any holes. The letters are contiguous, You could compute an index into an array by giving the letter A the value of 0 and subtracting the value of A from the letter to get the index. The indexes would be 0-25 for A to Z