Researchers from Cornell University claim to have cracked the codes used by the Galileo global navigation satellite GIOVE-A.
The signal transmitted from GIOVE-A (Galileo In-Orbit Validation Element-A) was broken after researchers intercepted the signals using a roof-mounted hemispherical patch antenna and a digital storage receiver.
The Cornell researchers claim that breaking the codes, which use "pseudo random numbers (PRNs)", will allow consumers free access to GIOVE-A, raising questions as to whether the project will be economically viable.
GIOVE-A is a prototype for satellites that will compose Galileo, a joint venture of the European Union, European Space Agency and private investors. The complete network will eventually consist of 30 satellites when it is completed in 2010, and will cost an estimated £2.2bn. This cost could potentially be recouped through the sale of PRN codes to subscribers.
However, the European Commission has dismissed Cornell's claims, saying that the code broken by the team is a prototype, and that the final code will be different.
The data stream that was intercepted had been broadcast over a wide range of frequencies, or spread spectrum, to encode it. The researchers, led by Mark Psiaki, professor of mechanical and aerospace engineering at Cornell, devised a computer algorithm and used statistical analyses to reassemble and so decode the data encoded and received as pseudo random numbers.
Security expert Bruce Schneier has cited the researcher's work as evidence of the perils of "security through obscurity", as once published the codes can no longer protect the system from being accessed by anyone with a navigation devices that use PRN codes.
Galileo is the European rival to the US military Global Positioning Satellite (GPS) system. Whereas GPS is funded by US tax-payers, the European project is expected to be monetised through charging for encrypted, precision signal services, with some services remaining free.
The EC insisted on Thursday that Galileo has not been compromised.
"This code had not been published since it was not intended to be used for commercial purposes (GIOVE-A is an experimental satellite), but the code was not secret either and it was not really an achievement to find it," said an EC spokeswoman.
"The codes which will be used for the Galileo operational satellites have been already published and can be found on www.galileoju.com," she added.
The EC has also indicated that the final code will be made freely available in the future, according to EETimes.