Signals transmitted from Giove-A, short for Galileo In-Orbit Validation Element A, were broken after the researchers intercepted them using a roof-mounted hemispherical patch antenna and a digital storage receiver.
The Cornell researchers claim that breaking the codes, which use pseudorandom numbers, or PRNs, will give 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, the European Space Agency and private investors. The complete network, costing an estimated 2.2 billion pounds ($4 billion), is designed to by 2010 consist of 30 satellites. Its cost could potentially be recouped through the sale of PRN codes to subscribers.
However, the European Commission has dismissed Cornell's claims, saying 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 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 PRNs.
Security expert Bruce Schneier has cited the researcher's work as evidence of the perils of "security through obscurity." Once published, codes can no longer protect the system from being accessed by anyone with navigation devices that use PRN codes.
Galileo is the European rival to the U.S. military Global Positioning System, or GPS navigation. Whereas GPS is funded by U.S. taxpayers, the European project is expected to be monetized through charging for encrypted, precision signal services, with some services remaining free.
The European Commission 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," a representative of the European Union's administrative arm said.
The codes, which will be used for the Galileo operational satellites, have already been published and can be found on the Galileo Joint Undertaking Web site, the representative added.
The Commission has also indicated that the final code will be made freely available in the future, according to EE Times.
Tom Espiner of ZDNet UK reported from London.