asymetric warfare

pervect wrote:

: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.

Which really doesn't buy you much in the way of security. DS-SS
merely makes it easier for the receivers to do ranging functions.

: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
f encryption (rather than spread spectrum) would be unlikely to
rovide much security. Other people have suggested that "good codes"
:are harder to break than this. I haven't gotten around yet to
ointing 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....

It's actually easier than this (since figuring out what the plaintext
ought to be is NOT as trivial as you make out). Just use DGPS and
hope they don't take down your differential station(s).

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

On Mon, 22 Dec 2003 03:47:23 GMT, Fred J. McCall
wrote:

pervect wrote:

: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.

Which really doesn't buy you much in the way of security. DS-SS
merely makes it easier for the receivers to do ranging functions.

You're missing the forest for the trees - or maybe you just like to
argue? :-)

I'm going to give a reference of my own:
http://arxiv.org/pdf/gr-qc/9508043

for an overview of a more theoretical and high-level approach as to
how GPS works, and to support the following statements I'm going to
make as to how GPS works.

The very basic principles of GPS are that are it is a bunch of
orbiting clocks, all of which (in the simplest model) transmit their
own proper time.

An observer on the ground, at a fixed location, knows what the proper
time on the satellite must have been when it was sent, when he
recieves the signal, because he knows (or can directly observe) the
satellites orbit.

Therfore, ultimately, an approach based on encryption is going to boil
down to encrypting something that everybody already knows or can
figure out, which is not going to be terribly secure.

Spread spectrum tecniques are really crucial to making this system
have the level of security it actually does.

pervect wrote:

:On Mon, 22 Dec 2003 03:47:23 GMT, Fred J. McCall
wrote:
:
:pervect wrote:
:
::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.
:
:Which really doesn't buy you much in the way of security. DS-SS
:merely makes it easier for the receivers to do ranging functions.
:
:You're missing the forest for the trees - or maybe you just like to
:argue? :-)

Or maybe I know more about botany than you do?

:I'm going to give a reference of my own:
:http://arxiv.org/pdf/gr-qc/9508043
:
:for an overview of a more theoretical and high-level approach as to
:how GPS works, and to support the following statements I'm going to
:make as to how GPS works.

I would suggest a pair of alternative documents for more than just a
brief relativistic discussion: "NAVSTAR GPS User Equipment
Introduction" for an overview of the system and ICD-GPS-200C for a
description of what the signals actually look like and how they're
used (what you really want to look at are ICD-GPS-203, ICD-GPS-224,
and ICD-GPS-225, but those aren't really open to discussion here).

:The very basic principles of GPS are that are it is a bunch of
rbiting clocks, all of which (in the simplest model) transmit their
wn proper time.

Right so far.

:An observer on the ground, at a fixed location, knows what the proper
:time on the satellite must have been when it was sent, when he
:recieves the signal, because he knows (or can directly observe) the
:satellites orbit.

Well, not quite. There's a bit more to it than that.

:Therfore, ultimately, an approach based on encryption is going to boil
:down to encrypting something that everybody already knows or can
:figure out, which is not going to be terribly secure.

Except you don't know all of what you need to know, so you really
don't know what the clear text is supposed to be.

:Spread spectrum tecniques are really crucial to making this system
:have the level of security it actually does.

Ok, view it that way if you like. I'm really not going to talk about
it other than what I've already said.

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

On Tue, 23 Dec 2003 01:30:25 GMT, Fred J. McCall
wrote:



:Spread spectrum tecniques are really crucial to making this system
:have the level of security it actually does.

Ok, view it that way if you like. I'm really not going to talk about
it other than what I've already said.

OK, if you don't want to explain yourself, I can't force you to.

pervect wrote:

:On Tue, 23 Dec 2003 01:30:25 GMT, Fred J. McCall
wrote:
:
::Spread spectrum tecniques are really crucial to making this system
::have the level of security it actually does.
:
:Ok, view it that way if you like. I'm really not going to talk about
:it other than what I've already said.
:
:OK, if you don't want to explain yourself, I can't force you to.

That's right, you can't. Have your security department send my
security department your clearance and then call me on a STUIII.

--
"Rule Number One for Slayers - Don't die."
-- Buffy, the Vampire Slayer