Question:

Assume a company with 200 employees. A new security policy demands encrypted message exchange using private key cryptography. To support different encryption algorithms (Julius Caeser), you decide to create a Crypto interface to the different encryption / decryption implementation details of managing secrets.

Require:

1. Write encryption and decryption formula for Julius Caeser algorithm.
2. Use Julius Caeser algorithm to perform encryption and decryption. The plain text is KARDAN and key length is 9.

Note: Complete steps of the solution is required.