Here is another classic cipher in Swift. This time it’s Vigenere. Similar to the way Caesar cipher works, Vigenere cipher improves on a couple of things. If you can recall my previous article, Caesar cipher works by shifting each letter in the plaintext a certain number of places down the alphabet. Vigenere cipher tries to improve on that approach by utilizing the keyword to offset each plain text letter by the keyword letter. This, of course, requires the keyword to be of the same length as the plain text.