Skype, the Internet-based calling service, began its own secret program, Project Chess, to explore the legal and technical issues in making Skype calls readily available to intelligence agencies and law enforcement officials, according to people briefed on the program who asked not to be named to avoid trouble with the intelligence agencies.
Project Chess, which has never been previously disclosed, was small, limited to fewer than a dozen people inside Skype, and was developed as the company had sometimes contentious talks with the government over legal issues, said one of the people briefed on the project. The project began about five years ago, before most of the company was sold by its parent, eBay, to outside investors in 2009. Microsoft acquired Skype in an $8.5 billion deal that was completed in October 2011.
A Skype executive denied last year in a blog post that recent changes in the way Skype operated were made at the behest of Microsoft to make snooping easier for law enforcement. It appears, however, that Skype figured out how to cooperate with the intelligence community before Microsoft took over the company, according to documents leaked by Edward J. Snowden, a former contractor for the N.S.A. One of the documents about the Prism program made public by Mr. Snowden says Skype joined Prism on Feb. 6, 2011.
Microsoft executives are no longer willing to affirm statements, made by Skype several years ago, that Skype calls could not be wiretapped. Frank X. Shaw, a Microsoft spokesman, declined to comment.