function plaintext = decrypt(ciphertext, key)

key = lower(key) - double('a') + 1;
key(key < 0) = 27;
ciphertext = lower(ciphertext) - double('a') + 1;
ciphertext(ciphertext < 0) = 27;

keyIndex = mod(0:(numel(ciphertext)-1), numel(key))+1;
k = key(keyIndex);

plaintext = arrayfun(@(m,n) find(v(m,:) == n), k, ciphertext) - 1;
plaintext(plaintext == 26) = double(' ') - double('a');
plaintext = upper(char(plaintext + double('a')))
end