Jessica Guynn

USA TODAY

SAN FRANCISCO — Former National Security Agency contractor Edward Snowden has backed Apple's refusal to comply with a federal court order to help the FBI unlock an iPhone used by one of the assailants in the mass shootings in San Bernardino, Calif., in December.

"The @FBI is creating a world where citizens rely on #Apple to defend their rights, rather than the other way around," Snowden tweeted.

Snowden called on Internet giant Google to stand with Apple, saying, "This is the most important tech case in a decade."

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Google CEO Sundar Pichai took a public stand in support of Apple in a series of tweets late Wednesday, saying "forcing companies to enable hacking could compromise users’ privacy" and would set a "troubling precedent."

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Apple CEO Tim Cook said late Tuesday that his company would oppose a federal judge's ruling ordering the technology giant to help investigators break into an iPhone belonging to San Bernardino shooter Syed Rizwan Farook.

"We have great respect for the professionals at the FBI, and we believe their intentions are good. Up to this point, we have done everything that is both within our power and within the law to help them," Cook wrote in a letter published on Apple's website.

"But now the U.S. government has asked us for something we simply do not have, and something we consider too dangerous to create. They have asked us to build a backdoor to the iPhone."

Apple and Google engineered their software so they cannot unlock devices in the wake of damaging revelations by Snowden that made the world suspicious they created "back doors" for American intelligence and law enforcement.

The fear: Unlocking the iPhone could hand law enforcement a master encryption key. The FBI hasn't been able to access the smartphone because it is passcode-protected.

"The technical changes the @FBI demands would make it possible to break into an iPhone (5C or older) in a half hour," Snowden tweeted.

Farook and his wife Tashfeen Malik killed 14 people in December in a mass shooting at a county public health facility. The pair died in a gun battle with police. An iPhone 5C was recovered from the scene.

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Snowden tweets from exile

Snowden has been living in exile in Russia to avoid facing prosecution in the United States for leaking government secrets. He joined Twitter last September. His Twitter profile reads: "I used to work for the government. Now I work for the public."

He has found a receptive audience on Twitter. Twitter has positioned itself as a digital bastion of free speech and a core group of Twitter users oppose government surveillance and intrusion.

Snowden and Pichai were not the only prominent voices in the tech world to commend Apple on Wednesday.

WhatsApp founder and Facebook board member Jan Koum posted on Facebook: "I have always admired Tim Cook for his stance on privacy and Apple's efforts to protect user data and couldn't agree more with everything said in their Customer Letter today. We must not allow this dangerous precedent to be set. Today our freedom and our liberty is at stake."

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Follow USA TODAY senior technology writer Jessica Guynn @jguynn