Catch up on stories from the past week (and beyond) at the Slashdot story archive


Forgot your password?
DEAL: For $25 - Add A Second Phone Number To Your Smartphone for life! Use promo code SLASHDOT25. Also, Slashdot's Facebook page has a chat bot now. Message it for stories and more. Check out the new SourceForge HTML5 Internet speed test! ×

Comment Cryptography doesn't help against GPS spoofing. (Score 1) 180

Our company is developing and producing some GPS based hardware (GPS GNSS OBUs). Even so I'm working in a different group, not involved in design/support of these, back in 2007 we had internal courses for R&D employes that was presented by a professor who is considered to be one of the leading authorities in design of GPS (unfortunately I don't remember his name right now). One of the thing that was said on these courses was that GPS spoofing is a problem that isn't possible to prevent by means of cryptography. Here is explanation why: Let say you have two directional antennas:
- the first antenna receives GPS satellite signal
- and second is retransmitting the same signal with higher effect in the direction of GPS receiver you want to spoof.
The only thing is required to spoof positioning of GPS receiver is to put a few microseconds delay in retransmitted signal. Having higher output effect from spoofing antenna can make original satellite signal to be completely invisible for spoofed GPS receiver (satellite signal is rather weak, so it would not be any problem in achieving this). The position is calculated by time difference between timestamped signals received from different satellites visible to GPS receiver. So, the satellite and receiver can encrypt and sign the signal whatever they want. But for as long as adversary is able to receive satellite signal and retransmit exact same signal with few microseconds delay, with higher effect - spoofing of GPS receiver is a done deal.

Submission + - Firefox: we'll tell websites what you're interested in (

Barence writes: Mozilla is proposing that the Firefox browser collects data on users' interests to pass on to websites. The proposal is designed to allow websites to personalise content to visitors' tastes, without sites having to suck up a user's browsing history, as they do currently.

"Let’s say Firefox recognises within the browser client, without any browsing history leaving my computer, that I’m interested in gadgets, comedy films, hockey and cooking," says Justin Scott, a product manager from Mozilla Labs. "Those websites could then prioritise articles on the latest gadgets and make hockey scores more visible. And, as a user, I would have complete control over which of my interests are shared, and with which websites."

Comment Re:And the numbers are... (Score 1) 326

Random number is just a short-hand for: a number chosen uniformly at random. I.e. there is a set of numbers that we can choose from and we want to pick one number from this set. A set could be for example: all numbers between 1 and 36, or all integer numbers.... if the procedure of picking the number from given set is truly random, then 999999 have the same probability of being picked by a true random number generator as 234162 or 874926 (or any other). And if your RNG never returns numbers like 999999, then it is a completely broken RNG because here we have a trivial distinguisher from true RNG. The term "random number" by itself (if we forget its shorthand notation) is a nonsense.

Comment Advantage... compared to what type of shoes? (Score 1) 199

The previous decision, where they claimed that he have an advantage, was based on estimations that: - His blades provides around 90% of energy returned, while as - Human leg provides around 60% of energy return (see around 13:10) I'm completely blank concerning the athletics and world-rank sports competitions, but I got several questions: How athlete's shoes could affect this energy return figures? What types of shoes were tested with this 60% energy return? What prevents athletes from using different types of shoes that provide higher energy return?

Comment Credits where credits are due (Score 1) 115

This is actually a part of CVIS (cooperative vehicle infrastructure systems) project for at least 6+ years. Currently CVIS is a part of ITS WC group The demo mentioned in the article was already demonstrated many-many times before in numerous European cities starting from late 2008/early 2009, but since it was mostly research organizations performing these demonstrations, it didn't generate sufficient publicity to attract /.

Slashdot Top Deals

Nothing is faster than the speed of light ... To prove this to yourself, try opening the refrigerator door before the light comes on.