# GPS: The Covert 'Numbers Station' Broadcasting Military Encryption Keys for 20 Years A surprising discovery by security researcher **Steven Murdoch** indicates that the **U.S. military** has likely been using public **GPS** for nearly 20 years to broadcast codes for its global encryption network. This covert operation effectively turned each **GPS** satellite into a 'numbers station,' transmitting hidden government information to every **GPS**-enabled device globally, unbeknownst to the public. ## Unveiling the Hidden Broadcasts **Murdoch's** investigation revealed a specific 'sentinel' signal transmitted by all 31 operational **GPS** satellites within a few hours on May 26, 2011. This coordinated broadcast, he posits, likely signaled the activation of a new operational system. Cross-referencing declassified documents, including a 2015 presentation, **Murdoch** confirmed that this timeline perfectly aligned with the rollout of the military's **Over-the-Air Distribution (OTAD)** and **Over-the-Air Rekeying (OTAR)** systems. "There was a perfect match between the timeline and that presentation and the change points that were automatically identified from the data," **Murdoch** stated. "That was the smoking gun that made me think: This is what it’s for." ## The Evolution of Cryptographic Key Distribution These automated **OTAD** and **OTAR** systems represent a significant leap from the cumbersome manual distribution of cryptographic keying material. Prior to this, military **GPS** receivers worldwide required onsite procedures for rekeying. The new system allowed for remote rekeying through satellite broadcasts, streamlining a critical security process. The implications of this discovery are substantial, highlighting the dual-use nature of widely adopted technologies and the sophisticated methods employed by state actors for secure communication. While the public receives standard **GPS** positioning data, a parallel, encrypted information stream has likely been flowing beneath the surface for years.