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 field contained encrypted transmissions because the data was so random. "Random data is actually very unusual to get in nature," Murdoch said. "If you see it, either it's been carefully designed to be random -- but then, why is someone sending out random data? -- or it's encrypted data. I thought encrypted data is by far the most likely explanation." He returned to the subframe on and off over the years, and solicited guesses about its content on Stack Exchange in 2023. Ahmed Kamruddin, a master's student at UCL, developed the project further in 2025. Then, this year, Murdoch put the last pieces of the puzzle together over several weeks by analyzing open archive Global Navigation Satellite System (GNSS) recordings collected since 2007 and kept by GFZ Helmholtz Centre for Geosciences. This dataset included more than 12 million observations of Subframe 4, Page 17, yielding 3,994 unique 176-bit messages. Within this corpus, Murdoch pinpointed key-repeating "sentinels" including a pattern that appeared in February 2010 and was broadcast on and off across dozens of satellites for more than a decade. Murdoch discovered that this particular sentinel was transmitted by all 31 operational satellites within a window of a few hours on May 26, 2011, potentially heralding the activation of a new operational system. He confirmed that this timeline coincided with the rollout of the military's Over-the-Air Distribution (OTAD) and the Over-the-Air Rekeying (OTAR) by cross-referencing declassified documents, including a 2015 presentation about the dates of the operation. "There was a perfect match between the timeline and that presentation and the change points that were automatically identified from the data," Murdoch said. "That was the smoking gun that made me think: This is what it's for." These automated systems replaced the cumbersome manual distribution of cryptographic keying material, allowing military GPS receivers around the world to be rekeyed remotely through satellite broadcasts rather than through onsite procedures. For the next 11 years, this expansive rekeying operation was overlooked in public GPS data. In 2022, the system entered a new phase, according to Murdoch's analysis. The shift was characterized by a slowing in the message rotation rate. Later, in December 2023, broadcasts carrying a distinctive "TEXT" prefix emerged then gradually spread across the constellation. Murdoch isn't sure what explains the recent transition, though it could be a possible modernization of the infrastructure or the introduction of a new protocol. But to him, the bigger takeaway is that the signals were always available for anyone willing to take a closer look, a discovery that suggests that there could be more revelations hidden for the cryptographically curious among us. "Every receiver in the world decodes Subframe 4, Page 17," Murdoch said in his new article. "Almost none of them have ever looked at it. The lesson generalizes: There is more to learn from the bytes already arriving at our antennas than from the bytes we wish were specified differently. The data are publicly available. The signal is overhead, twice a day, every day."

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An anonymous reader quotes a report from Reuters: Elon Musk's Starlink and Amazon's low-earth-orbit satellite business may be able to acquire some European mobile satellite spectrum next year, two people with direct knowledge of the matter said on Tuesday. But they said two-thirds of the satellite spectrum that allows mobile devices and vehicles to communicate seamlessly even in remote locations, would be reserved for European companies. U.S. companies Viasat and EchoStar hold licenses that are due to expire in May 2027 and the European Commission has been considering how to allocate future spectrum at the same time as the bloc pushes to reduce reliance on U.S. tech. The European Union's IRIS2 multi-orbit array of 290 satellites, a response to Starlink, will be among the European companies to receive some spectrum, the sources said. British and Norwegian companies can also bid for a license, the people said. Details of the proposal, set to be announced on Wednesday, could still change at a meeting of commissioners on the day, one of the sources. Commission spokesman Thomas Regnier said EU-wide satellite connectivity was "synonymous with resilience, security, and capability" given the current geopolitical context. "Satellite connectivity is a key piece of our technological sovereignty, our security, and our defense, as also highlighted by IRIS2," he added.

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Europe is testing laser-based satellite communications through a new mountaintop ground station in Greece, aiming to deliver faster, more secure links than traditional radio systems as bandwidth demand grows. The Register reports: Lithuanian space and defense biz Astrolight says that it has commissioned a new optical ground station in Greece that will support ESA-backed CubeSat missions testing laser-based communications between satellites and Earth. The Holomondas Optical Ground Station was built through the PeakSat project, led by the Aristotle University of Thessaloniki with backing from the European Space Agency and Greece's Ministry of Digital Governance. Its job is to receive data from satellites via infrared laser links rather than the radio systems that space operators have relied on for decades. PeakSat and ERMIS-3, two Greek CubeSats launched in March under ESA's wider Greek IOD/IOV mission program, both carry Astrolight's ATLAS-1 optical communication terminal. Astrolight also built the ground segment, giving the project a fully integrated end-to-end optical communications setup. [...] The company says the station uses an 808-nanometer laser beacon and an optical C-band receiver capable of receiving data at up to 2.5 Gbps. Unlike traditional RF systems, optical links use tightly focused infrared beams that are harder to intercept or jam while also supporting significantly higher throughput.

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