impersonation encryption?

[VBAHole22]

I am trying to encrypt an impersonation string in a web.config file. Has anyone accomplished this?

I see many articles about AES and DPAPI encryption and how useful it is in protecting connection strings in the web.config. That's great and it works because in your code you request the connection string from the appSettings and you can work it over as you see fit to decrypt it.

But in impersonation the programmer doesn't appear to have any control over when and where the string is interpreted so how can it be encrypted?