asymetric warfare

On Thu, 18 Dec 2003 10:32:11 -0800, pervect wrote:

Processors and computing power are getting cheaper every year - and
there are a lot of US weapons with military GPS around - so it's
conceivable to me that someone could obtain one of these weapons and
reverse-engineer the GPS system on them.

If there is no sort of "auxiliary code input" to the weapon (i.e. some
sort of activation code that has to be input)

I would imagine there is and the USA has the ability to change the
codes from time to time. I would be very surprised if this is not
the case.

--
"It's easier to find people online who openly support the KKK than
people who openly support the RIAA" -- comment on Wikipedia
(Email: , but first subtract 275 and reverse
the last two letters).

"pervect" wrote in message
...
On Thu, 18 Dec 2003 08:21:03 GMT, "Kevin Brooks"
wrote:


That is a decent description of the selective availability (SA)
function of
GPS. SA renders the average (non-US military) receiver incapable of
determining a precise fix, and you need precision for the kind of
weapons
the poster was postulating. SA was shut down a couple of years back
so that
civil users (i.e., surveyors, commercial aircraft, etc.) could take
advantage of its precision (prior to that occuring surveyors had to
use what
is known as "differential GPS", a more time consuming method of
achieving a
precise location), but according to the official USG website on the
subject
it can be reinstituted over a particular region at will.


Denying the US use of GPS would have a negative impact on US
military
capability, but it would not eliminate it.

Actually, I don't think SA adversely affects US military systems.

Brooks

Processors and computing power are getting cheaper every year - and
there are a lot of US weapons with military GPS around - so it's
conceivable to me that someone could obtain one of these weapons and
reverse-engineer the GPS system on them.

They can, but the signal is encrypted. The military can change the key
at will. In fact, I suspect that the keys are changed at least daily.

Even if you know all about the lock, you won't get a thing if you don't
have the key.



If there is no sort of "auxiliary code input" to the weapon (i.e. some
sort of activation code that has to be input) the reverse engineered
weapons would work just as well as the US weapons, so the US would
have to make the choice of whether it was better for everyone to have
(accurate) GPS or nobody to have GPS.

Without knowing for sure, I would personally expect that current
weapons would have some sort of auxiliary code, and that this code
would have to be entered as part of the target programming process
(which is quite long according to news reports, though it's getting
shorter).

I'm sure it's a private key system. The US issues keys (probably 1k
bits or more) to all units that need them. Contingency keys are also
issued. If someone captures the keys for next month, the contingency
keys are used.



Ray Drouillard

pervect wrote:

:Processors and computing power are getting cheaper every year - and
:there are a lot of US weapons with military GPS around - so it's
:conceivable to me that someone could obtain one of these weapons and
:reverse-engineer the GPS system on them.

Which does them absolutely no good at all.

:If there is no sort of "auxiliary code input" to the weapon (i.e. some
:sort of activation code that has to be input) the reverse engineered
:weapons would work just as well as the US weapons, so the US would
:have to make the choice of whether it was better for everyone to have
accurate) GPS or nobody to have GPS.
:
:Without knowing for sure, I would personally expect that current
:weapons would have some sort of auxiliary code, and that this code
:would have to be entered as part of the target programming process
which is quite long according to news reports, though it's getting
:shorter).

They aren't 'auxiliary codes' at all. Military GPS data streams are
encrypted. You need keys to use them. Without keys you get nothing.
This is why copying a GPS weapon exactly does you no good.

:Assuming (as I suspect) that "auxiliary code input" to the weapon is
:required, things get more complicated. Basically the question is how
:long it would take for the enemy to figure out what the auxiliary code
:was to activate their weapons.

Longer than the key is good for. They change frequently, you see.

:Pessimistically assuming that the current military GPS system does get
:compromised, and that the code breaking process could be done in
:minutes, the US is of course free to build a better one with more
:modern (and longer) codes. Of course, retrofitting existing weapons
:to use the new GPS system might be a bit involved. OTOH, it could be
:as simple as pulling out a modular "black box", and replacing it with
:a new improved one.

Well, if you assume the enemy has magical powers (which is essentially
what you're doing above), then I suppose anything is possible. Just
by the way, even your "black box" replacement above isn't simple.
Examine the replacement of PPS-SM by SAASM, for example.

You know, if you want to keep speculating, you might want to learn a
bit of something about the GPS system before you continue. See
http://gps.losangeles.af.mil/user/pr...curity/hae.htm for a
very brief synopsis on GPS security.

--
"Millions for defense, but not one cent for tribute."
-- Charles Pinckney

On Sun, 21 Dec 2003 12:42:11 GMT, Fred J. McCall
wrote:

pervect wrote:



Well, if you assume the enemy has magical powers (which is essentially
what you're doing above), then I suppose anything is possible. Just
by the way, even your "black box" replacement above isn't simple.
Examine the replacement of PPS-SM by SAASM, for example.

You know, if you want to keep speculating, you might want to learn a
bit of something about the GPS system before you continue. See
http://gps.losangeles.af.mil/user/pr...curity/hae.htm for a
very brief synopsis on GPS security.

Another poster already pointed me at

http://www.globalsecurity.org/milita...nd-gps_faq.pdf

which was much better, IMO.

From my POV, the key point that I missed in my earlier post (the one
you just replied to, there have been a bunch since then) is that GPS
is spread spectrum.

Of course this has spawned yet another argument, where I point out
that if you know what the satellites are supposed to be sending, use
of encryption (rather than spread spectrum) would be unlikely to
provide much security. Other people have suggested that "good codes"
are harder to break than this. I haven't gotten around yet to
pointing out that all you'd have to do given that you would already
have the plaintext because you know what the satellites have to be
sending is to broadcast a signal that would provide a "lookup table".
Then someone else could point out that this would slow the response
time of the GPS system down. Then I could say, yes, but is that
really significant. And the argument could go on for quite some
time....

On Thu, 18 Dec 2003 00:04:21 -0800, pervect wrote:

How are you getting your position information?

A combination of dead reckoning, a ground-based LORAN-type system,
celestial navigation, and visual/IR identification of the target in
the end phase.

The cheap solution is to use GPS. But IIRC the US has complete
control over the GPS satellite system. So if you are at war with the
US, you can't count on your GPS working right.

Indeed.

--
"It's easier to find people online who openly support the KKK than
people who openly support the RIAA" -- comment on Wikipedia
(Email: , but first subtract 275 and reverse
the last two letters).

"pervect" wrote in message
...
On Thu, 18 Dec 2003 03:22:52 +0000, ess (phil
hunt) wrote:

What would be sensible strategies/weapons for a middle-ranking
country to employ if it thought it is likely to be involved in a war
against the USA or other Western countries, say in the next 10
years?

I think one strategy would be to use large numbers of low cost
cruise missiles (LCCM). The elements of a cruise missile are all
very simple, mature technology, except for the guidance system.
Modern computers are small and cheap, so guidance systems can be
made cheaply.

How are you getting your position information?

The cheap solution is to use GPS. But IIRC the US has complete
control over the GPS satellite system. So if you are at war with the
US, you can't count on your GPS working right.

I don't know the details of the system (one reason I'm free to post) -
but the absolute best case I can see is for you to force the US to
basically shut off the GPS system everywhere. Depending on your
weapons range, you may be able to force GPS nullification only in a
limited area (the US can probably scramble the timing when the
satellites are over the area threatened by your weapons, while leaving
the timing intact when the satellites are over "safe" areas.

Denying the US use of GPS would have a negative impact on US military
capability, but it would not eliminate it.

Even if the non-encrypted civilian access GPS is turned off, the
military system will work fine.



From a terrorist POV - naw, it's pretty obvious, but I'll defer
comment, no sense in making life easy for them.

On Thu, 18 Dec 2003 21:40:13 -0500, Ray Drouillard wrote:

"pervect" wrote in message

Denying the US use of GPS would have a negative impact on US military
capability, but it would not eliminate it.

Even if the non-encrypted civilian access GPS is turned off, the
military system will work fine.

Not entirely. Older military GPS receivers use the less
precise civilian signal to get a coarse position fix before
they lock onto and receive the military signal. If the
civilian signal was turned off entirely, these receivers would
either take an extremely long time to initialize after being
turned on, or would not be able to get a position at all.


ljd

On Thu, 18 Dec 2003 21:40:13 -0500, "Ray Drouillard"
wrote:



Even if the non-encrypted civilian access GPS is turned off, the
military system will work fine.

Yes, another poster pointed that out, so I stand corrected. Also,
because the signals coming from the satellites are apparently spread
spectrum, it will be much less easy to reverse-engineer the codes than
I anticipated. Because we know what the output of the atomic clocks
should be, we know what the "clear" signal has to be. So I expected
extreme difficulties in encoding these signals - it's like trying to
design a good code when you have someone with access to the plaintext
working on breaking it.

However, with the spread spectrum approach, the difficulty will be to
be able to detect the signal in the broad-band noise.

In article ,
pervect wrote:

Yes, another poster pointed that out, so I stand corrected. Also,
because the signals coming from the satellites are apparently spread
spectrum, it will be much less easy to reverse-engineer the codes than
I anticipated. Because we know what the output of the atomic clocks
should be, we know what the "clear" signal has to be. So I expected
extreme difficulties in encoding these signals - it's like trying to
design a good code when you have someone with access to the plaintext
working on breaking it.

Assuming that the GPS project was reasonably competent when it came to
encryption, the encryption alone should be an insurmountable challenge.
Encryption which can't be reverse-engineered (by which I mean, you can
publish everything about the system except the keys and it's still
perfectly secure) has been pretty much a solved problem for quite some
time, barring revolutionary new mathematical techniques. The only hard
part is the key distribution. So you'd have to steal a key close enough
to your launch time for that key to still be valid, and do it in such a
way that nobody catches on and changes the key sooner than usual. Having
the plaintext for a section of code text is not, afaik, very much help
when it comes to cracking modern codes.

Wasn't it pervect who wrote:
On Thu, 18 Dec 2003 03:22:52 +0000, ess (phil
hunt) wrote:

What would be sensible strategies/weapons for a middle-ranking
country to employ if it thought it is likely to be involved in a war
against the USA or other Western countries, say in the next 10
years?

I think one strategy would be to use large numbers of low cost
cruise missiles (LCCM). The elements of a cruise missile are all
very simple, mature technology, except for the guidance system.
Modern computers are small and cheap, so guidance systems can be
made cheaply.

How are you getting your position information?

The cheap solution is to use GPS. But IIRC the US has complete
control over the GPS satellite system. So if you are at war with the
US, you can't count on your GPS working right.

The last I heard, the projected date for the launch of the Galileo Next
Generation Global Navigation Satellite System was some time in 2005, so
after that date there could be an alternative to the American GPS.
However, anyone who's at war with the US is likely to be also disliked
by the Europeans behind Galileo, and might find that they can't get good
readings from either system.

--
Mike Williams
Gentleman of Leisure