T-Mobile upgrades to A5/3 encryption on parts of GSM network in attempt to thwart eavesdropping

T-Mobile US (NYSE:TMUS) has upgraded parts of its 2G GSM network with enhanced encryption technology, which could provide a stronger defense against government eavesdropping and other network intrusions. The changes come after revelations of widespread surveillance of phone calls and Internet traffic by the National Security Agency.

According to the Washington Post, T-Mobile has moved to a new encryption method called A5/3 that is tougher to beat than earlier forms of encryption. The newspaper tested the carrier's networks in New York City, Washington, and Boulder, Colo., and found that the new encryption was present there rather than the older A5/1 standard. A5/1 has long been used in GSM networks, while UMTS and LTE networks use stronger encryption to secure the network. The tests were performed using an application known as Darshak, which was released at the Black Hat security conference in August.

T-Mobile declined to provide details on its network upgrades, telling the Post in statement, "T-Mobile is continuously implementing advanced security technologies in accordance with worldwide recognized and trusted standards."

The apparent push to improve network security comes after revelations by former NSA contractor Edward Snowden that the agency was collecting metadata such as the location and duration of massive amounts of U.S. phone calls, including wireless calls.

Deutsche Telekom, T-Mobile's parent, said it would make the A5/3 encryption a standard feature on its 2G network in Germany. That decision came after reports emerged that the NSA had wiretapped the cell phone of German Chancellor Angela Merkel, which outraged Germans.

Last month investigators for the German government said they would ask the leaders of German telecom companies about reports the NSA and its UK counterpart GCHQ were able to access data at will on their networks using a computer program named Treasure Map. The program reportedly offered the foreign intelligence agencies near real-time access to data on German routers, PCs, smartphones and tablets. While DT and NetCologne--a local telecoms service provider--denied finding evidence of the snooping, satellite operator Stellar PCS said it had.

As the Post notes, A5/3 encryption places hurdles in front of would-be network snoops because equipment that passively collects cell signals often cannot decode calls. However, if a third party was using a device known as an "IMSI catcher" they could still eavesdrop on individual calls by changing a phone's security settings.

AT&T Mobility (NYSE: T) said last year that it was using A5/3 encryption for parts of its network. "AT&T always protects its customers with the best encryption possible in line with what their device will support," the company said in a statement to the Post.

AT&T plans to shut down its 2G network by 2017, and T-Mobile has not said when it will shut off GSM service. However, both carriers--and most U.S. carriers generally--are migrating to LTE technology, which provides stronger security features. According to Cisco data cited by the Post, around 13 percent of U.S. cellular connections used 2G technology in 2013, a figure that is expected to drop to 7.2 percent by 2018. However, because much of the world has not migrated to LTE (or, in some cases, to 3G), 2G connections made up 68.4 percent of the worldwide market in 2013.

For more:
- see this Washington Post article

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