The article says the backdoor has been present for "5+ years". Microsoft's acquisition of Skype was completed in Oct. 2011 (just over 5 years ago). Based on the timing, that seems unlikely unless MS's first order of business was to backdoor Skype.

Given the context of this API, it would be of very little value to the NSA. (It is only accessible by applications that are already running on the user's computer, and only provides access to Skype.)

If the NSA wanted to intercept or forge Skype conversations and had access to Microsoft to do so, they would have a much easier time doing so on the server side.

I respond to this link earlier in these comments. The so-called collaboration is of the same nature as any other communications company in the world responds to warrants, subpoenas, etc in their home country.

Despite the tone of the article, there is nothing to suggest that anyone at Microsoft was doing anything more than creating the most cost-effective method to handle requests it was coerced to fulfill.

Alternatives to "collaboration":

1. Deny all requests. Get held in contempt of court. Go out of business.

2. Have dedicated staff to manually dig through every data repository to handle each request in a bespoke manner.

Why would Microsoft be working with the NSA on this?