Discussing the growing role of Internet companies in the public sphere, Ellsberg said companies such as Google, Facebook and Twitter need to take a stand and push back on excessive requests for personal data.

"You're on the spot," he told a roomful of Silicon Valley executives at a Churchill Club event in Santa Clara, California, Wednesday night. "You are facing a challenge at this moment of profound implications for our democracy."

Ellsberg was on a panel talking about Wikileaks and the relationship between the U.S. government -- eager to shut it down -- and corporations such as Amazon, eBay, Visa and Mastercard -- who all recently severed ties with Wikileaks in response to government pressure.

Ellsberg's take: If companies don't push back, the government will get too much power as more and more of our private lives -- logged in photo uploads, status updates or online check-ins -- is recorded online.

As the government fights to keep its own secrets, it wants to know as much as possible about our lives, said Ellsberg, who was himself targeted by government investigators after he began leaking classified military documents that described what the U.S. government knew as it escalated its war in Vietnam.