I'm working on a website that will allow users to log in using OAuth credentials from the likes of Twitter, Google, etc.  To do this, I have to register with these various providers and get a super-secret API key that I have to protect with pledges against various body parts.  If my key gets ganked, the part gets yanked.

The API key has to travel with my source, as it is used at runtime to perform authentication requests.  In my case, the key must exist within the application in a configuration file or within the code itself.  That isn't a problem when I build and publish from a single machine.  However, when we throw source control into the mix, things get more complicated.  

As I'm a cheap bastard, I'd much prefer to use free source control services such as TFS in the cloud or GitHub.  This leaves me with a slight conundrum:  

How can I keep my body intact when my API keys are in my code, and my code is available in a public repository?

I can think of a number of ways to handle this, but none of them are that satisfying.


I could remove all private info from code, and edit it back in after deployment.  This would be a severe pain to implement (I won't detail the many ways), and isn't an option.
I could encrypt it.  But as I have to decrypt it, anyone with the source could figure out how to do so.  Pointless.
I could pay for private source control.  LOL j/k spend money?  Please.
I could use language features to segregate sensitive info from the rest of my source and therefore keep it from source control.  This is what I'm doing now, but it could easily be screwed up by mistakenly checking in the secret file.


I'm really looking for a guaranteed way to ensure I don't share my privates with the world (except on snapchat) that will work smoothly through development, debugging and deployment and be foolproof as well.  This is completely unrealistic.  So what realistically can I do?

Technical details:  VS2012, C# 4.5, source control is either going to be TF service or GitHub.  Currently using a partial class to split the sensitive keys off in a separate .cs file that won't be added to source control.  I think GitHub may have the advantage as .gitignore could be used to ensure that partial class file isn't checked in, but I've screwed that up before.  Am hoping for a "oh, common issue, this is how you do it" but I may have to settle for "that doesn't suck as much as it could have", :/

Don't put your secret information in your code. Put it into a configuration file which is read by your code at startup. Configuration files shouldn't be put on version control, unless they are the "factory defaults", and then they shouldn't have any private information.

See also the question Version control and personal configuration file for how to do this well.
