A security researcher says evidence suggests the U.S. military has been using an obscure GPS message field for nearly 20 years to broadcast encrypted key-distribution data, effectively turning GPS satellites into a global "numbers station." The hidden-looking 176-bit messages appear tied to the Pentagon's Over-the-Air Distribution system for remotely updating cryptographic keys, meaning ordinary GPS receivers may have been receiving the traffic all along without anyone outside the military noticing. The findings have been detailed by Steven Murdoch, an information security expert, in a new article in Inside GNSS. 404 Media reports: [...] From the beginning, he suspected that the subframe fie...