The constellation of 31 GPS satellites, used by devices such as cell phones and smartwatches for location, has been used for two decades to transmit information beyond positioning signals.
The constellation of 31 GPS satellites, used by devices such as cell phones and smartwatches for location, has been used for two decades to transmit information beyond positioning signals.
Over the last twenty years, this network has also broadcast 3,994 secret codes, each containing 176 bits, with these codes being emitted on more than 12 million occasions.
This discovery was made by British engineer Steven Murdoch, affiliated with University College London. He analyzed signal recordings captured by the GFZ Helmholtz Centre for Geosciences, a German governmental research institution, covering the period between 2007 and the beginning of the current year.
Initially, the codes appeared to be mere random numerical sequences. However, Murdoch identified recurring patterns that coincide with dates when the US Army performed the rekeying process, which is the distribution of new cryptographic keys.
Based on this analysis, Murdoch determined the purpose of these codes: they function to allow United States military equipment to update its cryptography, thereby ensuring the continuity of communication without the risk of espionage.