Announcing: Slashdot Deals - Explore geek apps, games, gadgets and more. (what is this?)

Thank you!

We are sorry to see you leave - Beta is different and we value the time you took to try it out. Before you decide to go, please take a look at some value-adds for Beta and learn more about it. Thank you for reading Slashdot, and for making the site better!



GPS Spoofing With $3000 Worth of Equipment and a Laptop

valpr Re:Cryptography doesn't help against GPS spoofing. (180 comments)

You can't even receive the P(Y) code without the encryption key.

Why would you care about content when you can always simply retransmit the signal. Few microseconds delay in receiving signal by GPS receiver is sufficient to spoof it.

about a year ago

GPS Spoofing With $3000 Worth of Equipment and a Laptop

valpr Cryptography doesn't help against GPS spoofing. (180 comments)

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.

about a year ago

US Lawmakers Want Sanctions On Any Country Taking In Snowden

valpr disapointing... (650 comments)

only trade sanctions? Why not call it "War on Snowden", say that " We will starve Snowden of funding, turn everyone against him, drive him from place to place, until there is no refuge or no rest", and bomb them who dares to do anything against it...?

about a year ago

Physicist Uses Laser Light As Fast, True-Random Number Generator

valpr Re:And the numbers are... (326 comments)

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.

about 3 years ago

Ask Slashdot: Post-Quantum Asymmetric Key Exchange?

valpr lattice-based algorithms. (262 comments)

Even so I think 20 years estimate is way too optimistic... but for what it worth - lattice-based algorithms don't have know quantum computer attacks and Shor algorithm would not work for them.

more than 3 years ago

Of Diamond Planets, Climate Change, and the Scientific Method

valpr Re:Irrelevant comparison? (821 comments)

... Yes, the "method" of science is similar in the disciplines of astrology and climate science ...

Should the scientists who discovered the diamond planet (or star) feel them-self offended by someone referring them as "astrologist"? :)

more than 3 years ago

World's First Cybernetic Athlete To Compete

valpr Advantage... compared to what type of shoes? (199 comments)

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 http://www.youtube.com/watch?v=vUoIQ-KeZ1A 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?

more than 3 years ago

Ford Demonstrates Networked Cars

valpr Credits where credits are due (115 comments)

This is actually a part of CVIS (cooperative vehicle infrastructure systems) project http://www.cvisproject.org/ 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 /.

more than 3 years ago


valpr hasn't submitted any stories.


valpr has no journal entries.

Slashdot Login

Need an Account?

Forgot your password?