c# - What is the easiest way to encrypt a password when I save it to the registry?

Question

Currently I'm writing it in clear text oops!, it's an in house program so it's not that bad but I'd like to do it right. How should I go about encrypting this when writing to the registry and how do I decrypt it?

OurKey.SetValue("Password", textBoxPassword.Text);

Answer 1

You don't decrypt authentication passwords!

Hash them using something like the SHA256 provider and when you have to challenge, hash the input from the user and see if the two hashes match.

byte[] data = System.Text.Encoding.ASCII.GetBytes(inputString);
data = new System.Security.Cryptography.SHA256Managed().ComputeHash(data);
String hash = System.Text.Encoding.ASCII.GetString(data);

Leaving passwords reversible is a really horrible model.

Edit2: I thought we were just talking about front-line authentication. Sure there are cases where you want to encrypt passwords for other things that need to be reversible but there should be a 1-way lock on top of it all (with a very few exceptions).

I've upgraded the hashing algorithm but for the best possible strength you want to keep a private salt and add that to your input before hashing it. You would do this again when you compare. This adds another layer making it even harder for somebody to reverse.