Encrypt and Decrypt Password stored in database in ASP.Net MVC

Article: ASP.Net MVC: Encrypt and Decrypt Username or Password stored in database

Hello, nice to meet you, greetings from Peru.

I got a system where the password 123 is converted to (-q

How can i know process of creating this encryption or hashing or salting?

I'm not sure

There is no interface to change the key and the code is compiled TT_TT

Pls help

Thank you so much,

Jaime