neanias

rotate :: Int -> [Char] -> [Char]
rotate k list | k >= 0, k <= length list = drop k list ++ take k list
              | otherwise = []
              

makeKey :: Int -> [(Char,Char)]
makeKey n = zip xs ys
  where
    xs = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" -- You can use ['A'..'Z']
    ys = rotate n xs