Hi, I'm very new to C++ and i'm trying to find the best way to solve this problem:

First, i want my program to generate a random 6 digit integer as a variable (i have this part done).This random integer is the variable x. After that integer is done, the user will then input a string of text, the string of text will always be 6-20 characters (again i have this part done already). This string is called japesen. After this (where it gets complicated at), I want to generate a type of passcode based on the japesen and the integer x. Finally, i want another program to be able to return the original string japesen using only the passcode and the random integer x. I have no idea where to even start with this. Any help would be greatly appreciated! Thanks!