SAN FRANCISCO — Yahoo has added more layers of security in its effort to shield people’s online lives from government spying and other snooping.

The measures announced Wednesday include the completion of a system that encrypts all information being transmitted from one Yahoo data center to another. The technology is designed to make the emails and other digital information flowing through data centers indecipherable to outsiders.

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. Yahoo strengthened the security of its email in January.

“Whether or not our users understand it, I feel it’s our responsibility to keep them safe,” said Alex Stamos, Yahoo’s recently hired chief information of security.

Yahoo and other major technology companies such as Google and Microsoft have made online security a top priority during the past 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.

The surveillance has been outlined in documents leaked to the media by former National Security Agency contractor Edward Snowden.