If you are at all interested in encryption and its history, then you undoubtedly heard of Caesarian cipher. The Caesar cipher was developed and used by Julius Caesar to encrypt messages between him and his generals. The mechanics behind it is to encrypt plain text by shifting each letter in the plaintext a certain number of places down the alphabet. For example, we could shift alphabet down 3 letters so that A would become D, B would become C… A would become X, etc.
I should mention that Caesarian cipher is extremely easy to decrypt. Don’t use it to encrypt sensitive data. However, I would consider it an “additional step” to already secured information. For example, when storing access token in keychain, we could encrypt it using Caesarian cipher to provide an additional layer of security. After all, it is possible to get information stored in a keychain especially if you know / get a hold of / a Mac password (this assumes keychain being synched).