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GNSS Jamming and Spoofing – Galileo's Authentication Algorithm Part 3 (2020)

40 点作者 oritsnile超过 4 年前

7 条评论

throw0101a超过 4 年前
The OSNMA protocol discussed is based on Timed Efficient Stream Loss-Tolerant Authentication (TESLA):<p>&gt; <i>This document introduces Timed Efficient Stream Loss-tolerant Authentication (TESLA). TESLA allows all receivers to check the integrity and authenticate the source of each packet in multicast or broadcast data streams. TESLA requires no trust between receivers, uses low-cost operations per packet at both sender and receiver, can tolerate any level of loss without retransmissions, and requires no per-receiver state at the sender. TESLA can protect receivers against denial of service attacks in certain circumstances. Each receiver must be loosely time-synchronized with the source in order to verify messages, but otherwise receivers do not have to send any messages. TESLA alone cannot support non-repudiation of the data source to third parties.</i><p>* <a href="https:&#x2F;&#x2F;tools.ietf.org&#x2F;html&#x2F;rfc4082" rel="nofollow">https:&#x2F;&#x2F;tools.ietf.org&#x2F;html&#x2F;rfc4082</a><p>* A. Perrig, R. Canetti, J. Tygar and D. Song, “Efficient Authentication and Signing of Multicast Streams over Lossy Channels,” <i>IEEE Symposium on Security and Privacy</i>, pp. 56-73, May 2000.
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throw0101a超过 4 年前
&gt; <i>Military solutions will fall back to inertial, celestial or optical guidance, and people using GPS for navigation will at worst show up where they need to be somewhat later than planned.</i><p>The US Navy re-started celestial navigation a few years ago:<p>* <a href="https:&#x2F;&#x2F;www.npr.org&#x2F;2016&#x2F;02&#x2F;22&#x2F;467210492&#x2F;u-s-navy-brings-back-navigation-by-the-stars-for-officers" rel="nofollow">https:&#x2F;&#x2F;www.npr.org&#x2F;2016&#x2F;02&#x2F;22&#x2F;467210492&#x2F;u-s-navy-brings-bac...</a><p>This (1960s?) US government produced (45m) video video gives a pretty good overview:<p>* <a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=UV1V9-nnaAs" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=UV1V9-nnaAs</a><p>For those wanting to invest (substantially) more time, the two videos by &quot;Tippecanoe Boats&quot; are slightly rambling at times, but he does lay things out pretty well by the end of it (second is largely examples):<p>* <a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=-ARXW8InStY" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=-ARXW8InStY</a><p>* <a href="https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=yu5R5mrrGB0" rel="nofollow">https:&#x2F;&#x2F;www.youtube.com&#x2F;watch?v=yu5R5mrrGB0</a>
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knorker超过 4 年前
Another question for knowledgeable people here:<p>Can I not just run two GNSS receivers 10 meters apart (on a ship), and if they report as having the same position, then I know someone is spoofing?<p>It should be really hard to beamform the spoofing to spoof two different locations, at least from a distance because of the precise angles needed.<p>Yes, this assumes that my <i>real</i> GNSS signal is good enough that they normally are 10M apart.
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knorker超过 4 年前
So if I understand this right the signature is 32bits times 24 times 15 per full frame?<p>After the fact, why exactly can I not precalculate my spoofed data stream?<p>I just need to spend:<p><pre><code> 3*2^31*24*15*(spoof_seconds&#x2F;30) ops (on average)? </code></pre> (assuming 3 streams for position data)<p>Sure, not cheap, but hardly hard even for even a hobbyist.<p>So ~2^45 ops to spoof 10 minutes of data? That&#x27;s doable.<p>Is my math off?<p>I have more faith in the direction finding aspects. Here&#x27;s from the article, an understatement of the year:<p>&gt; To beat these simple tricks, a spoofer will need to have multiple transmitters that actually show the same parallax as the actual satellites. However, you can only do this by placing your transmitters next to the satellites - in space. This raises the bar significantly.
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PaulHoule超过 4 年前
Some people say that there isn&#x27;t much open literature on GPS anti-spoofing, but there are many patents filed by the likes of Lockheed-Martin, Boeing, BAE, etc.<p>I find the multiple antenna answers interesting.<p>For instance, one of the easier attack scenarios against an airplane is to have a directional antenna on the ground. Because airplanes broadcast their GPS position via ADS-B, you could also know that you&#x27;d succeeded.<p>In a case like that, however, the radio signal from the ground would be stronger than the signal from the sky and it would be obvious what was going on, unless the attacker managed to get the power level just right.<p>With multiple receivers you also will see very different results with spoofing than with a real signal. For instance if you had a receiver at the front of the airplane and one at the back of the airplane, the time delay for all the fake satellites would be the same (they all come from the same place) whereas the time delays (e.g. position) would be noticeably different from real sats.
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MayeulC超过 4 年前
Is there any cheap, open source alternative to GPS for navigation? I&#x27;m thinking of an electronic sextant (or star tracker) for rough position estimation, with a few km accuracy.
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aaron695超过 4 年前
Here&#x27;s a good map&#x2F;report on Russian in action GNSS spoofing - <a href="https:&#x2F;&#x2F;www.c4reports.org&#x2F;aboveusonlystars" rel="nofollow">https:&#x2F;&#x2F;www.c4reports.org&#x2F;aboveusonlystars</a>
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