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Yahoo announces latest move in privacy battle

Jessica Morris, special to CNBC.com

Yahoo announced its latest move in its ongoing battle with state surveillance agencies over the protection of users' private information.

The tech giant said it had encrypted online traffic moving between its data centers since the end of March this year, as well as emails that used its servers and others set-up in a similar way. In addition, an encrypted version of instant messaging service Yahoo Messenger would be released in coming months.

Hector Mata | AFP | Getty Images

"Hundreds of Yahoos have been working around the clock over the last several months to provide a more secure experience for our users and we want to do even more moving forward. Our goal is to encrypt our entire platform for all users at all times, by default," said Alex Stamos, chief information security officer at Yahoo, in a post on the company's blog on Wednesday.

The move comes as Yahoo attempts to protect its users' information from prying attempts by surveillance agencies. Last year's revelations that the U.S. National Security Agency (NSA) intercepted user data without the knowledge of major tech companies -- including Yahoo – prompted Yahoo CEO Marissa Mayer to announce the company intended to encrypt all of its products.

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In November, Mayer wrote on Yahoo's blog that the company had never willingly granted the U.S. government access to users' data.

"There have been a number of reports over the last six months about the U.S. government secretly accessing user data without the knowledge of tech companies, including Yahoo," Mayer said. "I want to reiterate what we have said in the past: Yahoo has never given access to our data centers to the NSA or to any other government agency."

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Professor Keith Martin, head of the information security group at Royal Holloway, University of London, said that encryption was one of the most basic techniques organizations could use to protect their data.

"You can never completely stop attackers from accessing data because there's a lot of clever tricks they can play ... (Encryption is) like locking your front door (to deter burglars), but there are other ways in," Martin told CNBC in a telephone interview.

Other tech companies are also using encryption to protect their products against surveillance. In March this year, Google revealed it was encrypting all emails sent or received on its Gmail email service.

"No one can listen in on your messages as they go back and forth between you and Gmail's servers – no matter if you're using public WiFi or logging in from your computer, phone or tablet," Nicholas Lidzborksi, Gmail security engineering lead at Google said in a blog post.

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Last year, Yahoo wrote an open letter to Washington in conjunction with other tech giants such as Google and Twitter, in which it argued for reforms to government practices and laws surrounding surveillance of individuals and access to their private information.

They also said they would deploy "the latest encryption technology" to protect users' privacy going forward, and "push back on government requests, to ensure they are legal and in reasonable scope."