How to get current encoding type used by .NET to write/read configuration for config file?

Question

I am doing connection string encryption. we use our own encryption key with AES algorithm to do this. during the process, we need to convert string to byte array and then convert byte array back to string. I found the encoding play an important role on those conversions.

So I need to know the encoding C# is using to get above conversion right. Any idea how to get current encoding programmably?

Answer 1

If you're looking to store an encrypted string in a config (or other plain text) file, you're better off storing the encrypted bytes as a base64-encoded string.

byte[] encrypted = // encrypt your data

string encryptedString = Convert.ToBase64String(encrypted);

Likewise:

string encryptedString = // read the config value

byte[] encrypted = Convert.FromBase64String(encryptedString);

You can use the first code block to obtain a base64-encoded string representation of your encrypted data, then save that string in the config file. Use the second block to convert that same string from the file back into an encrypted byte array.

Answer 2

Just in case if you don't know, but .NET have built-in support for Encrypting Configuration Information Using Protected Configuration. The encryption will be transparent for the application but operation system will guarantee that only accounts allowed to decipher that configuration (will have have access to key container) will be able to decrypt it.

I don't know your security model, but I guess you still need to get/store a key in order to decrypt connection string. So effectively connection string are as safe as the key which will be used to decrypt them. If it isn't as safe as in OS's key container I would recommend to reconsider your design.