Firegrounds getting encrypted but not Police Tacs?

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nec208

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ENCODING (which is what P25 is) is simply the conversion of voice into digital packets before they are sent over the air. There is no secretive-ness to it. Sure, initially, when P25 became popular, and there were no digital scanners on the market, it made monitoring these systems quite a chore. But it was NEVER meant to secure radio traffic. It's simply an alternative way to send voice over the radio waves.

Not if they go to non P25.


ENCRYPTION is a process of turning voice into digital packets, then "mixing them up" before sending them over the air. All radios must have the "key" to put the packets back into the right order, so they can be converted BACK into audio. There are hundreds of millions of combinations that can make up the "key" and most modern encryption systems can re-key over the air at any time, making it impossible to "break" the key and intercept the audio.


But what is to stop a programmer writting a software to scan key combinations .Computers can do millions of combinations in minutes, people doing it take long time.

No scanner can monitor an encrypted signal. Further, it is unlawful to monitor encrypted signal - in many cases, it's a federal crime.

True and that is why you will not see any scanner manufacture making a scanners how to do it.And most 98% of US people will not be picking them up.Unless you a engineer/programmer or former CIA spie or former KGB spie.
 
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nec208

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RedPenguin said:
I noticed in much of the RR database and forums, that many places have already or are in the process of encrypted there Fireground/Tac channels.

Why are fire channels being encrypted but many police tac are not? I mean police have dangerous and possibly in need of encryption stuff on their Tacs.

Also, are many Firegrounds different than my county? My county just uses unencrypted Tac channels, and all you hear is them going into the house/car or whatever, but mostly guys asking for equipment. Why would that need to be encrypted?

Same reason it is becoming a cool thing for fire to use cell phones and the police using the MDT and cell phones more and more now.
 

slicerwizard

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nec208 said:
But what is to stop a programmer writting a software to scan key combinations .Computers can do millions of combinations in minutes, people doing it take long time.
Hey Einstein, how many combinations does a 128 bit key support? What about a 256 bit key? Do you have any idea?
 

gmclam

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Digital processing power

slicerwizard said:
Hey Einstein, how many combinations does a 128 bit key support?
About 3.4 to the power of 38.

What about a 256 bit key? Do you have any idea?
About 1.158 to the power of 77.

So what? Do you know how many MIPS your current PC process at? And how many MIPS would be required (with well written code) to test each key combination?
 

ocguard

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gmclam said:
About 3.4 to the power of 38.

About 1.158 to the power of 77.

So what? Do you know how many MIPS your current PC process at? And how many MIPS would be required (with well written code) to test each key combination?

So what are we getting at? I am right, right? Virtually unbreakable? NEC208 is wrong?

ANd sure, a computer can go through lots of combincations really quick. But you have to apply each combination to see if it's the right one, too. Which means the encrypted carrier has to be on the air. THAT would really add to the time abd hassle!
 
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nec208

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slicerwizard said:
Hey Einstein, how many combinations does a 128 bit key support? What about a 256 bit key? Do you have any idea?

No the question is how many combinations can a program scan in one minute a thousand or million? Or a billion in one minute ?

It would be up to how well the programmer can write the program to scan the combinations in one minute , remember computers can count and work with big numbers , but people have a hard time.
 

Alarms50

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Just an FYI for this topic. The Phoenix,AZ FD along with the National Institute of Standards and Technology(NIST) conducted a study of Fireground Radios.

Phoenix Fire Department - Radio System Safety Project http://www.phoenix.gov/FIRE/radioreport.pdf.

On page five of this report it states "Based on testing conducted within buildings in Phoenix, and the experience of other fire departments, we recommend the use of 700 or 800MHz SIMPLEX channels with ANALOG modulation specifically for firefighting during hot zone operations. Simplex channels provide incident commanders and firefighters a safe and consistant communication system that is not dependent on infrastructure in order to speak to other units on the incident."

In other words "KISS", Keep It Simple 'Sir', no fancy crap, Simpex and Analog for Fireground!!
 

slicerwizard

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ocguard said:
So what are we getting at? I am right, right? Virtually unbreakable? NEC208 is wrong?
nec208 is usually wrong. And certainly is this time. I have no idea why gmclam is defending him.

If you had a computer that could test a trillion (1,000,000,000,000) keys per second, it would run for about a million billion years before brute forcing the key.

Cracking 128 bit (or better) encryption requires methods other than brute force (such as exploiting flaws in the algorithms used), but that's not what nec208 is claiming.
 
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nec208

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slicerwizard said:
nec208 is usually wrong. And certainly is this time. I have no idea why gmclam is defending him.

If you had a computer that could test a trillion (1,000,000,000,000) keys per second, it would run for about a million billion years before brute forcing the key.

Cracking 128 bit (or better) encryption requires methods other than brute force (such as exploiting flaws in the algorithms used), but that's not what nec208 is claiming.

So a 128 bit is way over a trillion ?So is it the hardware or software? So you are saying computers are not fast enough?

It would take million billion years using a $3,000 computer at the store? What would the combinations number be? You saying it is way over a trillion combinations .

Sorry I thought the combinations was no more than a trillion .
 

RKG

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Alarms50 said:
Just an FYI for this topic. The Phoenix,AZ FD along with the National Institute of Standards and Technology(NIST) conducted a study of Fireground Radios.

Phoenix Fire Department - Radio System Safety Project http://www.phoenix.gov/FIRE/radioreport.pdf.

On page five of this report it states "Based on testing conducted within buildings in Phoenix, and the experience of other fire departments, we recommend the use of 700 or 800MHz SIMPLEX channels with ANALOG modulation specifically for firefighting during hot zone operations. Simplex channels provide incident commanders and firefighters a safe and consistant communication system that is not dependent on infrastructure in order to speak to other units on the incident."

In other words "KISS", Keep It Simple 'Sir', no fancy crap, Simpex and Analog for Fireground!!


NFPA 1221, the standard guidelines for Fire Department communications, published the identical recommendation several years ago.
 

Alarms50

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RKG said:
NFPA 1221, the standard guidelines for Fire Department communications, published the identical recommendation several years ago.
I knew NFPA had something in one of their standards, but I did not have access to this one and didn't need to spend the $ for it. thanks.
 

slicerwizard

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nec208 said:
So a 128 bit is way over a trillion ?So is it the hardware or software? So you are saying computers are not fast enough?

It would take million billion years using a $3,000 computer at the store? What would the combinations number be? You saying it is way over a trillion combinations .
A 128 bit key has 340,282,366,920,938,463,463,374,607,431,768,211,456 combinations.

A 256 bit key has 115,792,089,237,316,195,423,570,985,008,687,907,853,269,984,665,640,564,039,457,584,007,913,129,639,936 combinations.

Computers are not fast enough to do brute force testing of that many combinations.
 

GTR8000

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Alarms50 said:
I knew NFPA had something in one of their standards, but I did not have access to this one and didn't need to spend the $ for it. thanks.

All the NFPA standards are viewable for free on their website. You just can't print or copy/paste text, but if you need to look things up, it's a great resource.

http://www.nfpa.org/aboutthecodes/list_of_codes_and_standards.asp

Click on the standard you want to view, then scroll down to the bottom of the page and click the View the YYYY edition of this document
 

Alarms50

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res6cue_dot_com said:
All the NFPA standards are viewable for free on their website. You just can't print or copy/paste text, but if you need to look things up, it's a great resource.
Thanks Res6cue, I've done that before, just too lazy to do it when I had the Phoenix Report in my favorites.
 

ka5lqj

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Hmmm,

Now,

I thought the whole purpose of this "encryption" thing was to prevent "terrorist", criminals, etc. from intercepting police traffic and making use of the information....getting away.

ANYTHING the Government "touches" turns to "brown fertilizer". They've become "paranoid" about "Terrorist" and "bad guys" overunning the country. They've got to keep things "secret". So, they use OUR hard-earned money to buy "toys" for the police and fire departments. Our local cops, use cell 'phones to talk about 10-35 stuff and I could care less where a drug dealer is, LOL!

All I want to do is to be able to hear OTHER area's agencies during bad wx, to hear if they report tornado's, straight-line winds, storm damage, and electrical lines down. Some are too busy handling the situation to call the National Wx Service office (WXJ97) to report it.

Yeah, I'm an "Ol' Fart" and I have a "thing" about bad wx. I'm not afraid of it, like some old folks. Because of medical problems, I'm not likely to jump in my F-150 and "chase storms", like I used to, either. But, I'd rather listen and warn others, if they are in the path of storms.

Well, I'm going back to bed, 'cause I can, LOL!

Respectfully,
73,

Don/KA5LQJ
 

gmclam

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...and I could care less where a drug dealer is...

slicerwizard said:
nec208 is usually wrong. And certainly is this time. I have no idea why gmclam is defending him.
I wasn't defending anyone or taking sides, I was simply answering some basic (basic to me) math questions. The fact is if anyone did break this encryption, they'd be pretty stupid to say so. :)

ka5lqj said:
I thought the whole purpose of this "encryption" thing was to prevent "terrorist", criminals, etc. from intercepting police traffic and making use of the information....getting away.
No, I think it is about keeping people with scanners from listening. Apparently a lot of people must think drug dealers/etc listen in.

All I want to do is to be able to hear OTHER area's agencies during bad wx...
And we're not the only people who want to hear other nearby agencies; this is a common use by people in LE & FF business!
 

TheZach

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The local city fire department encrypts everything on the 800 digital side, but they also patch over the VHF in the clear....

sometimes it makes me wonder.
 

Raccon

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When a firefighter calls for help it seems to me that more people are likely to hear and understand him/her if their radio signal only has to travel a few dozen yards. And when marginal, there's a good chance someone will make it out if in analog.
The quality of the signal and thus if someone can actually hear you depends on a few more things than just the distance between the users.

Furthermore there might be other reasons, even a need that the signal travels via the system, e.g. so that the dispatcher can listen in and directly communicate with the users (and vice versa of course), voice recording of the event, direct access to PABX/PSTN by user etc.
To me it seems people are pissed off due to (the optional) encryption and thus are against digital, rather than having some hard facts that speak against digital, which anyway in most cases revolves around a particular digital system only, i.e. it does not apply to digital signals in general.

But what is to stop a programmer writting a software to scan key combinations .Computers can do millions of combinations in minutes, people doing it take long time.
The encryption is usually so strong that it would take years to break the key by means of a brute-force attack (which is what you are describing). During that time the key has probably changed, so you would need to start from scratch - which means you will never have enough time unless you get really lucky.
Even you break the key it's only that of one particular radio - if it were known the key was compromised all you need to do is kill that radio and you are "out" again.
 

jim202

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Where are you getting your info that a digital signal takes up less spectrum than an analog signal?

If both are using the same deviation, they both are going to take up the same bandwidth. You may
be getting confused in that some digital systems have moved to a 12.5 KHz channel which uses
a lower level of deviation. The old standard 25 KHz channel does use 5 Khz of deviation. The new
12.5 KHz channel uses 2.5 KHz of deviation. This might be what your trying to imply.

Jim



Well I guess the digital transition for TV is a waste too. Even though it's freeing up gobs of usable spectrum for additional public safety. The airwaves are congested beyond belief. Analog signals take up 300% greater spectrum than the same signal digitally encoded. This frees up a huge amount of spectrum for additional capacity, not only for public safety, but for other wireless media, such as wireless broadband internet, cellular phone, etc.
 
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