Re: How to programmatically get the Authorization code without requiring the user approval in OAuth

I'm not sure I fully understand all of your questions, so feel free to follow up and clarify. I've also split out your message here to a new thread so as not to bother the members of the old thread.

It's not possible to get an authorization code without processing the app authorization flow. The user needs to authorize the app at least once in order for the app to be able to access the user's account. That authorization process occurs on the Dropbox web site.

The Dropbox .NET SDK implements much of the app authorization flow for you, and offers example code, but use of the SDK is optional. If you don't want to or can't use it for your use case or environment for whatever reason, you can use the Dropbox API directly without the SDK. You can find information on implementing the authorization flow directly in the OAuth Guide and authorization documentation. That does have to be implemented as documented though; Dropbox doesn't offer a way to use a certificate/PKCS file and apps shouldn't handle user credentials (like the username/password) themselves.