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Experts on privacy and Internet security have blasted the National Security Agency over reports it has secretly been working with the British government to crack encryption technology that billions of Internet users rely upon to keep their electronic messages and confidential data secure.

The New York Times, Britain's Guardian newspaper and the nonprofit news website ProPublica reported Thursday that the NSA has bypassed or altogether cracked much of the digital encryption used by businesses and everyday Web users. The reports describe how the NSA invested billions of dollars since 2000 to make nearly everyone's secrets available for government consumption.

Bruce Schneier, a security expert who worked with the Guardian to reveal the NSA's secrets, said Thursday that the U.S. government had "betrayed the Internet."

"By subverting the Internet at every level to make it a vast, multi-layered and robust surveillance platform, the NSA has undermined a fundamental social contract," Schneier wrote in an essay for the British paper.

"We can no longer trust them to be ethical Internet stewards. This is not the Internet the world needs, or the Internet its creators envisioned. We need to take it back."

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The American Civil Liberties Union joined Schneier in criticizing the spy agency. Christopher Soghoian, principal technologist of the ACLU's Speech, Privacy and Technology Project, said late Thursday that the agency's alleged campaign against encryption is "is making the Internet less secure" and exposing Web users to "criminal hacking, foreign espionage, and unlawful surveillance."

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"The NSA's efforts to secretly defeat encryption are recklessly shortsighted and will further erode not only the United States' reputation as a global champion of civil liberties and privacy but the economic competitiveness of its largest companies," Soghoian said in a statement.

The reports state that the NSA built powerful supercomputers to break encryption codes and partnered with unnamed technology companies to insert "back doors" into their software. Such a practice would give the government access to users' digital information before it was encrypted and sent over the Internet.

"For the past decade, NSA has led an aggressive, multipronged effort to break widely used Internet encryption technologies," according to a 2010 briefing document about the NSA's accomplishments meant for its UK counterpart, Government Communications Headquarters, or GCHQ. Security experts told the news organizations such a code-breaking practice would ultimately undermine Internet security and leave everyday Web users vulnerable to hackers.

The revelations stem from documents leaked by former NSA contractor Edward Snowden, who sought asylum in Russia this summer. His leaks, first published by the Guardian, revealed a massive effort by the U.S. government to collect and analyze all sorts of digital data that Americans send at home and around the world.

Those revelations prompted a renewed debate in the United States about the proper balance between civil liberties and keeping the country safe from terrorists. President Barack Obama said he welcomed the debate and called it "healthy for our democracy" but meanwhile criticized the leaks; the Justice Department charged Snowden under the federal Espionage Act.

Thursday's reports described how some of the NSA's "most intensive efforts" focused on Secure Sockets Layer, a type of encryption widely used on the Web by online retailers and corporate networks to secure their Internet traffic. One document said GCHQ had been trying for years to exploit traffic from popular companies like Google, Yahoo, Microsoft and Facebook.

GCHQ, they said, developed "new access opportunities" into Google's computers by 2012 but said the newly released documents didn't elaborate on how extensive the project was or what kind of data it could access.

Even though the latest document disclosures suggest the NSA is able to compromise many encryption programs, Snowden himself touted using encryption software when he first surfaced with his media revelations in June.

During a Web chat organized by the Guardian on June 17, Snowden told one questioner that "encryption works." Snowden said that "properly implemented strong crypto systems" were reliable, but he then alluded to the NSA's capability to crack tough encryption systems. "Unfortunately, endpoint security is so terrifically weak that NSA can frequently find ways around it," Snowden said.

It was unclear if Snowden drew a distinction between everyday encryption used on the Internet — the kind described in Thursday's reports — versus more-secure encryption algorithms used to store data on hard drives and often requires more processing power to break or decode. Snowden used an encrypted email account from a now-closed private email company, Lavabit, when he sent out invitations to a mid-July meeting at Moscow's Sheremetyevo International Airport.

The operator of Lavabit LLC, Ladar Levison, suspended operations of the encrypted mail service in August, citing a pending "fight in the 4th (U.S.) Circuit Court of Appeals." Levison did not explain the pressures that forced him to shut the firm down but added that "a favorable decision would allow me to resurrect Lavabit as an American company."

The government asked the news organizations not to publish their stories, saying foreign enemies would switch to new forms of communication and make it harder for the NSA to break. The organizations removed some specific details but still published the story, they said, because of the "value of a public debate regarding government actions that weaken the most powerful tools for protecting the privacy of Americans and others."

Such tensions between government officials and journalists, while not new, have become more apparent since Snowden's leaks. Last month, Guardian editor Alan Rusbridger said that British government officials came by his newspaper's London offices to destroy hard drives containing leaked information. "You've had your debate," one UK official told him. "There's no need to write any more."

The Associated Press contributed to this report.