Powershell/Encryption : simple encryption with symmetric algorithm

Hi Mates,
I was just curious on how to create my personal encryption algorithm. I've read various books but I've never tried to build my own one.
Using Powershell I tried to create something simple, easy to understand and to manipulate in order to re-user, disrupt, change and so on.
There are some comments inside it that explain better what is the logic behind it and what are the "keys" that are part of the entire "process".

I don't want to waste my time creating  Synopsis, Description and so on......at least in this moment, maybe in the future I'll do it (....I know it's better.... :-) )

Anyway try to understand the script referring to the comments inside it.
ah.....it works fine with Powershell 5.0 ($psversiontable.psversion.......everytime I've to review how to check the version via command line ......ahahahahgrsh)
Here you have to code.....





Hope this help.
Bye