If you're using this kata as a basic example for students:

• you might want to look into the commercial version of this site ( qualified.io )
• you need not publish your kata ( that definitely is a duplicate ); anyone with the link can see, and solve, a Draft kata
• you might even point your students towards any of the existing Caesar Cipher kata

Frankly, if I were your student, I'd have my thoughts about being pointed towards a retired kata with a lot of negative feedback.

On the topic of this being a duplicate or not: please see the Kata Best Practices - Make Sure Content is New - "Every new kata should ideally teach something different." "Duplicate" apparently has a fairly broad understanding on here. And I did not invent that quote myself just to annoy you - that's ex cathedra.

Hi, really not a duplicate;-)?
And your students don't like these about 100 same or similar cipher- katas: https://www.codewars.com/kata/search/my-languages?q=cipher
What is a duplicate? return "hello world" and return "Hello World!" is no duplicate too:-)?
(Edit: Haven't seen the "Retired")

Fixed