By Jim Finkle
(Reuters) - Alphabet Inc's <GOOGL.O> Google, Facebook Inc <FB.O>, Microsoft Corp <MSFT.O> and about a dozen other Internet companies will file a joint legal brief on Thursday asking a judge to support Apple Inc <AAPL.O> in its encryption battle with the U.S. government, sources familiar with the companies' plans said.
The effort is a rare display of unity and support for the iPhone maker from companies which are competitors in many areas, and shows the breadth of Silicon Valley's opposition to the government's anti-encryption effort.
The group plans to file what is known as an amicus brief - a form of comment from outside groups common in complex cases - to the Riverside, California, federal judge Sheri Pym. She will rule on Apple's appeal of a court order that would force it to create software to unlock an iPhone associated with last December's shootings in San Bernardino.
Mozilla, maker of the Firefox web browser, said it was joining in the effort along with online planning tool maker Evernote and messaging app firms Snapchat and WhatsApp. Photo sharing service Pinterest and online storage firm Dropbox are also participating.
"We stand against the use of broad authorities to undermine the security of a company’s products," Dropbox General Counsel Ramsey Homsany said in a statement.
Networking leader Cisco Systems Inc <CSCO.O> said it expected to address the court on Apple's behalf, but did not say whether it was joining with the large group of companies.
Semiconductor maker Intel Corp <INTC.O> plans to file a brief of its own in support of Apple, said Chris Young, senior vice president and general manager for Intel Security Group.
“We believe that tech companies need to have the ability to build and design their products as needed, and that means that we can’t have the government mandating how we build and design our products,” Young said in an interview.
The Stanford Law School for Internet and Society filed a separate brief on Thursday morning on behalf of a group of well-known experts on iPhone security and encryption, including Charlie Miller, Dino Dai Zovi, Bruce Schneier and Jonathan Zdziarski.
"The dangers of forcing companies to denigrate the security of their products and of allowing law enforcement to commandeer consumer devices for surveillance purposes are too great," the brief said.
Privacy advocacy groups the American Civil Liberties Union, Access Now and the Wickr Foundation filed briefs on Wednesday in support of Apple before Thursday's deadline set by Pym.
Salihin Kondoker, whose wife Anies Kondoker was injured in the San Bernardino attack, also wrote on Apple's behalf, saying he shared the company's fear that the software the government wants Apple to create to unlock the phone could be used to break into millions of other phones.
"I believe privacy is important and Apple should stay firm in their decision," the letter said. "Neither I, nor my wife, want to raise our children in a world where privacy is the tradeoff for security."
Briefs are also expected in support of the government.
Stephen Larson, a former federal judge, told Reuters last week that he is working on a brief with victims of the San Bernardino shooting who want the U.S. Federal Bureau of Investigation to be able to access the data on the phone used by Rizwan Farook, one of the shooters. "They were targeted by terrorists, and they need to know why, how this could happen," Larson said.
The fight between Apple and the government became public last month when the FBI obtained a court order requiring Apple to write new software and take other measures to disable passcode protection and allow access to Farook's iPhone.
Apple has pushed back, arguing that such a move would set a dangerous precedent and threaten customer security. The clash has intensified a long-running debate over how much law enforcement and intelligence officials should be able to monitor digital communications.
Law enforcement officials have said that Farook and his wife, Tashfeen Malik, were inspired by Islamist militants when they shot and killed 14 people and wounded 22 others last Dec. 2 at a holiday party. Farook and Malik were later killed in a shootout with police and the FBI said it wants to read the data on Farook's phone to investigate any links with militant groups.
Earlier this week, a Brooklyn judge ruled that the government had overstepped its authority by seeking similar assistance from Apple in a drug case.
(Reporting by Jim Finkle in Boston; Additional reporting by Dustin Volz, Dan Levine, Heather Somerville, Sarah McBride, Julia Love in San Francisco; Editing by Jonathan Weber, Grant McCool and Bill Rigby)