How Microsoft Handed The NSA Access To Encrypted Messages

• Secret files show scale of Silicon Valley co-operation on Prism
• Outlook.com encryption unlocked even before official launch
• Skype worked to enable Prism collection of video calls
• Company says it is legally compelled to comply

Microsoft has collaborated closely with US intelligence services to allow users' communications to be intercepted, including helping the National Security Agency to circumvent the company's own encryption, according to top-secret documents obtained by the Guardian.

The files provided by Edward Snowden illustrate the scale of co-operation between Silicon Valley and the intelligence agencies over the last three years. They also shed new light on the workings of the top-secret Prism program, which was disclosed by the Guardian and the Washington Post last month.