The latest documents from the National Security Agency leaked by Edward Snowden show that government spies are capable of listening in on mobile phone calls that use a common form of encryption.
The Washginton Post on published confidential government documents provided by Snowden that show that the NSA can 'process' cellular phone calls on GSM networks, even if they are encrypted.
Observers have long known that military and law enforcement officials are capable of hacking into a suspect’s mobile phone.
GSM, which stands for Global System for Mobile communications, is the world's most widely used cellphone technology — though several large networks, notably Verizon and Sprint, rely on an older network technology called CDMA.
Calls that have been encrypted according to a common standard called A5/1 — which was developed in 1987.
The vulnerability comes into play on 2G networks, which modern cellphones may resort to it when 3G or 4G networks are not available or too congested.
More modern networks like 3G and 4G, found throughout the US and other wealthy nations, are more difficult to decode.
The Post found that more than 80 percent of cell phones used in the world use outdated and vulnerable technology.
David Wagner, a computer scientist at the University of California Berkley, said that type of encryption 'was designed 30 years ago, and you wouldn’t expect a 30-year-old car to have the latest safety mechanisms.'
Experts suggest that while it takes longer for analysts to decode and examine messages sent on higher systems, it is indeed possible.
Some carriers are already making the change to the newer A5/3 method of encryption, however, it doesn't matter how strong strong their encryption, the calls are automatically decoded upon reaching the carrier's internal network.
The NSA has repeatedly stated that it only snoops on conversations involving foreign citizens, as it has no legal basis by which to conduct such surveillance on Americans.
Current US law makes it illegal for the NSA to monitor phone conversations between American citizens without a court order, yet these documents reveal that the agency is capable of overriding encryption and listening in on international citizens.
The Post warned that the intelligence agencies of other nations likely have the same technology, and may even listen in on American phone calls.
This method of surveillance has made headlines recently because of the reported NSA tap on world leaders, including German Chancellor Angela Merkel.
'The scale of foreign surveillance has become so vast, the amount of information about Americans 'incidentally' captured may itself be approaching mass surveillance levels,'' said Elizabeth Goitein of the Brennan Center for Justice's Liberty and National Security Program.
'The government should be targeting its surveillance at those suspected of wrongdoing, not assembling massive associational databases that by their very nature record the movements of a huge number of innocent people,' said Catherine Crump, a staff attorney for the American Civil Liberties Union.