I recently had a bit of fun learning about and coding a Vigenere Cypher. Once I read how it was done, I spent the down time I had during a kids’ swim practice to code a class in Swift to do the transform.
A month later, I had a client looking for a relatively secure way to share an account password. I wrote up a document explaining how to get and use a PGP certificate key pair, but process is really time consuming and confusing for people looking to obfuscate a short password. So, I ported my code for easy use here.
THIS IS NOT AN EXAMPLE OF GOOD, SECURE ENCRYPTION IN OUR CURRENT DAY AND AGE
The cypher encrypts letters. I maintain upper case/lower case consistency. Spaces, numbers, symbols, and characters from the non-latin alphabet just pass through in original cleartext.
The full details of the algorithm are written up here.
The source code is available on that page or on my GitHub.