Yahoo has added more layers of security in its effort to shield users' online lives from government spying and other snooping. Yahoo on Wednesday said that the traffic moving between the company's data centers has been fully encrypted since March 31.

In January, Yahoo also made browsing over HTTPS the default for Yahoo Mail, and also enabled encryption of mail between its servers and other mail providers that support the SMTPTLS standard.

Search requests made from Yahoo's home page are also now automatically encrypted, and the Sunnyvale, Calif., company is promising to make it more difficult for unauthorized intruders to hack into other services, including video chats, within the next few months.

However, Yahoo still lags behind Google's encryption efforts, mainly because many of its services rely on content and ads provided by other companies, including some that aren't convinced that they need to encrypt. For that reason, Yahoo users can initiate an encrypted session for Yahoo News, Yahoo Sports, Yahoo Finance, and Good Morning America on Yahoo (gma.yahoo.com) by typing "https" before the site URL in their web browser.

And a new, encrypted, version of Yahoo Messenger will be deployed in coming months.

Yahoo and other major technology companies such as Google and Microsoft have made online security a top priority during the last 10 months amid a series of revelations about U.S. government programs that have vacuumed up personal information about millions of Web surfers in an effort to thwart terrorism.