[wp-hackers] Hooking into WP theme/plugin update downloading

[Jeremy Hough]

I have a working (and extended) setup of Jeremy Clark's Self-Hosted 
Plugin Update API 
(https://github.com/jeremyclark13/automatic-theme-plugin-update). I am 
setting up my update server to force/require https connections to 
encrypt transmissions. I am wanting to use oAuth for authentication (and 
provide access to restricted content).

Is there any type of hook in wordpress I can use so that when an update 
is instantiated, the download behavior can be redefined so that the 
provided update zip url will be downloaded using an oAuth-signed request?

Thanks for any insight,

Jeremy Hough