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Re: battlefield Internet (was: Stryker/C-130 Pics)

> [regarding battlefield internet]

>> The signal must be such that the extended receiver can hear it. So >> others can too, in principle. (Though detecting the signal and >> knowing where it's from aren't the same thing). I'm not a radio >> engineer but I can imagine a few ways how direction-finding might >> work; for example place two (or 3) detectors a few meters apart >> and calculate the time delay between each one receiving the signal. > >No. Paul is correct, DF'ing a "frequency agile" (or "hopping") >transmitter is no easy task. For example, the standard US SINCGARS >radio changes frequencies about one hundred times per *second*,

Bear in mind that I'm talking about automated electronic gear here, not manual intervention. Electronics works in time spans a lot quicker than 10 ms.

over a >pretty wide band of freq's (this is why synchronization of the radios >on a time basis is critical to succesful operation of the net).

So the frequency changes are pre-determined on a time basis?

If there is a radio receiver, is it better able to detect/deceive a signal whgen it knows the frequency in advance? Or can it "sniff" for lots of frequencies at a time and pick out what looks interesting?

If two receivers, placed say 10 m aparet, both pick up a signal, how accurately can the time difference between the repetion of both signals be calculated? Light moves 30 cm in 1 ns, so if time differences can be calculated to an accuracy of 0.1 ns, then direction could be resolved to an accuracy of 3 cm/10 m ~= 3 mrad.

Alternately, would something like a pinhole camera work? What I mean here is: imagine a cubic metal box, 1 m on its side, with a vertical slit, about 1 cm wide down one of its vertical faces. On the opposite face, there are detectors for detecting radio waves. If the elevctromatnetic ratiation coming into the box can only go in through the slit, and goes in a straight line, then knowing which detectors are lit up would allow someone to tell where the radiation was coming from. It may be that, depending on the wavelength, the incoming radiation would be diffracted by the slit and would get spread all over the detectors. If this is the case, perehaps multiple slits could be used, and the diffraction pattern would differ dependent on the angle with which the radiation strikes the slitted face? (because the radation at each slit would be out-of-phase with the radiation at other slits). Has anything like this been tried?

It is >hard enough for the average "rest of the world" intel unit to DF an >old fashioned non-hopping transmitter if the radio operator uses good >RTO procedures--trying to pluck enough of these random >fractional-second bursts out of the ether to determine a direction is >more difficult by a few orders of magnitude.

What methods are used to do DF?

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Reply to
phil hunt
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So what? Unless you know the frequency hopping plan ahead of time (something that is rather closely guarded), you can't capture enough of the transmission to do you any good--they use a rather broad spectrum.

Yes.

Both radios have to be loaded with the same frequency hopping (FH) plan, and then they have to be synchronized by time. When SINGCARS first came out the time synch had to be done by having the net control station (NCS) perform periodic radio checks (each time your radio "talked" to the NCS, it resynchronized to the NCS time hack); failure to do this could result in the net "splitting", with some of your radios on one hack, and the rest on another, meaning the two could not talk to each other. I believe that the newer versions (known as SINCGARS EPLRS, for enhanced precision location system) may use GPS time data, ensuring that everyone is always on the same time scale.

Yes, you can set up to scan various nets (we did so for command post operations where we wanted to monitor multiple nets), but they all have to be on that same time hack, and you have to have each net's FH plan loaded; you can't just decide to operate it like a police scanner and listen in on whoever you choose to.

The fact is that the direction finding (DF'ing) of frequency agile commo equipment is extremely difficult for the best of the world's intel folks, and darned near impossible for the rest (which is most of the rest of the world); that is why US radio procedures are a bit more relaxed than they used to be before the advent of FH, back when we tried to keep our transmissions to no more than five seconds at a time with lots of "breaks" in long messages to make DF'ing more difficult.

Hey, I just *used* the critters and was fortunate enough to attend new equipment training from the manufacturer when we got it; suffice it to say that use of FH makes DF'ing a remote concern, pretty much eliminates any concern over jamming (even broad band jamming can only take down a small percentage of the available spectrum, making voice transmissions still very clear), and the use of FH combined with crypto key makes it darned near impossible for the bad guy to decypher it in any realistic timely manner.

You'd have to find a signals intel puke to answer that one (but you can rest assured that any really good methods/systems remain classified).

Brooks

Reply to
Kevin Brooks

OK, I now understand that DF generally relies on knowing the frequency in advance.

BTW, when you say a rather broad spectrum, how broad? And divided into how many bands, roughly?

That would make sense.

So transmissions of 5 seconds tend to be hard to DF? Of course, with the battlefield internet, a text transmission will typically be a lot less than 5 s (assuming the same bandwidth as for a voice transmission, i.e. somewhere in the region of 20-60 kbit/s).

Modern crypto is good enough to withstand all cryptanalytic attacks.

--
  "It's easier to find people online who openly support the KKK than 
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Reply to
phil hunt

Thank you Admiral Doenitz...

Reply to
L'acrobat

------------ He's right. Major breaththrough of all possible barriers, the RSA algorithm. Uncrackable in the lifetime of the serious user, and crack is entirely predictable with improved computing power and can be lengthened to compensate.

-Steve

--
-Steve Walz  rstevew@armory.com   ftp://ftp.armory.com/pub/user/rstevew
Electronics Site!! 1000's of Files and Dirs!!  With Schematics Galore!!
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Reply to
R. Steve Walz

decypher

The fact that you and I think it is unbeatable, doesn't mean it is.

"lifetime of the serious user" what bollocks, you and I have absolutely no idea what sort of tech/processing power will be available 10 years from now, let alone 30.

"and crack is entirely predictable with improved computing power" of course it is...

Ask the good Admiral how confident he was that his system was secure.

Damn near as confident as you are and that worked out so well, didn't it?

Reply to
L'acrobat

Ever heard of Moore's law?

I've got a pretty good idea. A typical PC now has a 2 GHz CPU, and about 256 MB RAM.

Assume these double every 18 months. 10 years is about 7 doublings so in 2003 we'll see PCs with 250 GHz CPUs and 32 GB of RAM.

--
  "It's easier to find people online who openly support the KKK than 
  people who openly support the RIAA" -- comment on Wikipedia
Reply to
phil hunt

It uses the entire normal military VHF FM spectrum, 30-88 MHz. ISTR that the steps in between are measured in 1 KHz increments, as opposed to the old 10 KHz increments found in older FM radios like the AN/VRC-12 family, so the number of different frequencies SINGCARS can use is 58,000.

ISTR the old guidance was to keep transmissions no longer than 5 to 7 seconds without a break (a break normally was announced as part of the message, followed by release of the mic key, then rekeying and continuing the message).

Only if it were so...but thank goodness it is not. Otherwise we would have lost the value of one of our largest and most valuable intel programs, and NSA would no longer exist. Even the cypher keys used by our modern tactical radios (said keys being generated by NSA at the top end, though we now have computers in the field capable of "key generation" using input from that source) are not unbreakable--instead, they are tough enough to break that we can be reasonably assured that the bad guys will not be able to gain any kind of *timely* tactical intel; enough computing power in the hands of the crypto-geeks and they can indeed break them, but it will probably take them a while, not to mention the time to get the data into their hands in the first place.

Brooks

Reply to
Kevin Brooks

That's a great idea, and I suspect tthat you're right in the general case. But a modern cryptosystem, badly implemented, will have all manner of vulnerabilities -- most of which are not particularly obvious.

Remember the competition for the successor to DES as the standard crypto algorithm? That was *quite* interesting.

--
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station.  These 'targets' can shoot back."
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Reply to
Mike Andrews

----------------- Nothing CAN magically guess extraordinarily long primes. That will never just magically become possible. This intrinsic truth resides in the very mathematics itself, a fact outside of time and progress, and not in any technology of any kind.

---------------------- Irrelevant. His system relied on technology, as any mathematician could have told him. He merely held his nose and trusted the allies weren't technically advanced enough to do it quick enough. He lost.

But the "bet" that RSA makes is totally different, in that it relies statistically upon the ABSOLUTE RANDOM unlikelihood of any absolute guessing of very large prime numbers by machines whose rate of guessing is limited and well-known as their intrinsic limit. This number is a VERY VERY VERY large prime number. In case you don't quite get it, the most used high security prime number size is greater than the number of atoms in the entire big-bang universe AND greater than even THAT by an even GREATER multiplier! See the writings of James Bidzos, CEO of RSA Tech. for these revelations.

------------------------ You have absolutely NO IDEA what the f*ck you're talking about.

-Steve

--
-Steve Walz  rstevew@armory.com   ftp://ftp.armory.com/pub/user/rstevew
Electronics Site!! 1000's of Files and Dirs!!  With Schematics Galore!!
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Reply to
R. Steve Walz

That's true now, but only to a point. That point is the advent of quantum computing, which allows you to effectively solve for all the possible factors in very little time (say 10^500 times faster than conventional computing for this sort of problem). If QC happens, large prime number encryption is crackable in a matter of seconds. And there is at least some reason to beleive that QC is achievable within a couple of decades.

OTOH, the real danger in the near- to mid-term is not crypto-system attack, but physical compromise of the crypto-system (the adversary getting hold of the both the mechanism and the keys themselves). If they have the actual keys, the eavesdroppers can decode RSA just as easily as the intended recipients.

-- Tom Schoene Replace "invalid" with "net" to e-mail "If brave men and women never died, there would be nothing special about bravery." -- Andy Rooney (attributed)

Reply to
Thomas Schoene

no

now,

Right. you are going to base national security matter on a rule of thumb that relates to a typical PC.

Good move.

Reply to
L'acrobat

no

now,

course

it?

See Mr Schoenes response.

It seems that you sir, have no idea what the f*ck you are talking about.

Again, ask the Good Admiral D how confident he was that his system was safe.

Reply to
L'acrobat

----------------------- Or DNA computing, sure.

Just an escalation, the power of operations easier one way than the other persists and an increase in length results in the same safety.

For it to be otherwise you need to postulate that the govt will be doing its own fundamental research, and it NEVER does, and that it will develop QC to that level BEFORE the market sells it or the people developing it steal it and spread it around to prevent a national monopoly on power, and that's pretty unlikely.

--------------------- Yes. Goes without saying.

-Steve

--
-Steve Walz  rstevew@armory.com   ftp://ftp.armory.com/pub/user/rstevew
Electronics Site!! 1000's of Files and Dirs!!  With Schematics Galore!!
http://www.armory.com/~rstevew or http://www.armory.com/~rstevew/Public
Reply to
R. Steve Walz

------------------- You're a lying shit and a bounder, and you're diddling yourself and delaying the inevitable.

---------------- You're blathering, hoping that line will sustain you while you try to bluster your way out of this, when the fact is that RSA is qualitatively different than any systematically crackable cipher.

-Steve

--
-Steve Walz  rstevew@armory.com   ftp://ftp.armory.com/pub/user/rstevew
Electronics Site!! 1000's of Files and Dirs!!  With Schematics Galore!!
http://www.armory.com/~rstevew or http://www.armory.com/~rstevew/Public
Reply to
R. Steve Walz

with

absolutely

from

secure.

could

guessing

of

didn't

Not trying to argue your already discredited position anymore Stevie?

Only an idiot would suggest that any code is "Uncrackable in the lifetime of the serious user" ands so you did.

safe.

As has already been shown, RSA isn't uncrackable, but you are.

What, exactly do you think the NSA is doing with all those 'puters they own? playing Doom?

Of course RSA is uncrackable, just like the good Admirals systems and I assume he had a lackwitted buffoon just like you telling him that there was no way anyone could be decrypting our stuff too...

Reply to
L'acrobat

More than one 1 kHz slot is likely to be in use at anyone time, since you need enough bandwidth for voice. Say 20, then about

1/3000th of the frequency space is in use at any one time.

Oh? So who can break AES/Rijndael?

True, but "enough" happens to be more than all the computers in existance right now, or likely to exist.

Assume: there are 1 billion computers, each of which can check 1 billion keys/second.

Then a brute-force search on a 128-bit keyspace would take about

10^60 years. 
--
  "It's easier to find people online who openly support the KKK than 
  people who openly support the RIAA" -- comment on Wikipedia
Reply to
phil hunt

Absolutely.

What was interesting about it?

--
  "It's easier to find people online who openly support the KKK than 
  people who openly support the RIAA" -- comment on Wikipedia
Reply to
phil hunt

It was cracked by brute force but only on a 64-bit key.

That was done by literally thousands of machines around the world, collaborating, using spare processor time (mine was one).

331,252 individuals participated (some were using multiple machines). 15,769,938,165,961,326,592 keys were tested

It took 1757 days.

Some guy in Japan is one happy bunny. He got the ten thousand buck prize from RSA Labs for the correct key.

2048 bit keys are a little more difficult :-) 
--
Then there's duct tape ... 
              (Garrison Keillor)
nofr@sbhevre.pbzchyvax.pb.hx
Reply to
Fred Abse

Maybe. And maybe QC will make possible other encryption techniques.

All good cryptosystems are still effective if the adversary knows the algorithm.

The most effective attacks aren't usually on the systems, but on the people -- e.g. getting an insider to divulge secrets.

--
  "It's easier to find people online who openly support the KKK than 
  people who openly support the RIAA" -- comment on Wikipedia
Reply to
phil hunt

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