British and US intelligence officials say they are worried about a “doomsday” cache of highly classified, heavily encrypted material they believe former National Security Agency (NSA) contractor Edward Snowden has stored on a data cloud.
The cache contains documents generated by the NSA and other agencies and includes the names of US and allied intelligence personnel, seven current and former US officials and others, sources briefed on the matter said.
The information is protected with sophisticated encryption and multiple passwords are needed to open it, said two of the sources, who, like the others, spoke on condition of anonymity.
The passwords are in the possession of at least three different people and are valid for only a brief time window each day, they said. The identities of people who might have the passwords are unknown.
Spokespeople for both the NSA and the US Office of the Director of National Intelligence declined to comment.
One source described the cache of still unpublished material as Snowden’s “insurance policy” against arrest or physical harm.
US officials and other sources said only a small proportion of the classified material Snowden downloaded during stints as a contract systems administrator for the NSA has been made public. Some officials in the administration of US President Barack Obama have said privately that Snowden downloaded enough material to fuel two more years of news stories.
“The worst is yet to come,” said one former US official who follows the investigation closely.
Snowden, who is believed to have downloaded between 50,000 and 200,000 classified NSA and British government documents, is living under temporary asylum in Russia, where he fled after traveling to Hong Kong. He has been charged in the US under the Espionage Act.
Cryptome, a Web site which started publishing leaked secret documents years before WikiLeaks or Snowden surfaced, estimated that the total number of Snowden documents made public so far is more than 500.
Given Snowden’s presence in Moscow and the low likelihood that he will return to the US anytime soon, US and British authorities say they are focused more on dealing with the consequences of the material he has released than trying to apprehend him.
It is unclear whether US or allied intelligence agencies — or those of adversary services, such as Russia’s and China’s — know where the material is stored and, if so, have tried to unlock it.
One former senior US official said that the Chinese and Russians have cryptographers skilled enough to open the cache if they find it.
Snowden’s revelations of government secrets have brought to light extensive and previously unknown surveillance of telephone, e-mail and social media communications by the NSA and allied agencies. That has sparked several diplomatic rows between Washington and its allies, along with civil liberties debates in Europe, the US and elsewhere.
Among the material which Snowden acquired from classified government computer servers, but which has not been published by media outlets known to have had access to it, are documents containing names and resumes of employees working for the NSA’s British counterpart, the Government Communications Headquarters (GCHQ), sources familiar with the matter said.
The sources said Snowden started downloading some of it from a classified GCHQ Web site, known as GC-Wiki, when he was employed by Dell and assigned to the NSA last year.
Snowden made a calculated decision to move from Dell Inc to another NSA contractor, Booz Allen Hamilton, because he would have wide-ranging access to NSA data at the latter firm, one source with knowledge of the matter said.
Glenn Greenwald, who met with Snowden in Hong Kong and was among the first to report on the leaked documents for the Guardian, said the former NSA contractor had “taken extreme precautions to make sure many different people around the world have these archives to insure the stories will inevitably be published.”
“If anything happens at all to Edward Snowden, he has arranged for them to get access to the full archives,” Greenwald said in a June interview with the Daily Beast Web site. “I don’t know for sure whether he has more documents than the ones he has given me ... I believe he does.”
In an e-mail exchange with Reuters, Greenwald, who has said he remains in contact with Snowden, affirmed his statements about Snowden’s “precautions,” but said he had nothing to add.
Officials believe that the “doomsday” cache is stored and encrypted separately from any material that Snowden has provided to media outlets.
Conservative British politicians, including Louise Mensch, a former member of parliament, have accused the Guardian, one of two media outlets to first publish stories based on Snowden’s leaks, of “trafficking of GCHQ agents’ names abroad.”
No names of British intelligence personnel have been published by any media outlet. After British officials informed the Guardian it could face legal action, the newspaper disclosed it had destroyed computers containing Snowden material on GCHQ, but had provided copies of the data to the New York Times and the US nonprofit group ProPublica.
Sources familiar with unpublished material Snowden downloaded said it also contains information about the CIA — possibly including personnel names — as well as other US spy agencies such as the National Reconnaissance Office and the National Geospatial-Intelligence Agency, which operate US image-producing satellites and analyze their data.
US security officials have indicated in briefings they do not know what, if any, of the material is still in Snowden’s possession. Snowden himself has been quoted as saying he took no such materials with him to Russia.