Cryptography Java Program

I only have some knowledge in JAVA when it comes to programming, so I would like to have it written in JAVA language. Additional requirements not listed in the PDF file are as follows: 1. I only need to be able to use these characters: "A-Z", "a-z", "0-9". (Upper case letters, lower case letters, and numbers zero through nine. 2. In addition to those characters, we will be using only these special characters: period, question mark, comma, and space. So there are 66 characters max. (0-65) Attached is a pdf file of the assignment. (The assignment says to utilize division, but that part can be omitted.)