Legally Breaking Encryption

[N_Jay]

Everything has encryption as an option. Simple conventional FM used CVSD prior to P25 CAI.

Not everything.

 

[INDY72]

If your intercepting foriegn signals that are outside the US then youd need to talk to the Government and let them handle it. If its a signal from inside the USA you first need to prove its not friendly, and that its hostile intent to the safety of this nation.... Not easy to begin with. And if it happened to not be a threat then you violated federal law by intercepting "secure" comms in this country. Again, its just asking for trouble.

 

[victorspencer5]

Go buy an OpenSky, DES, or other encryption package of your choice since you are now legal to possess and use it

 

[MattSR]

Let me preface this by saying I have no intention of cracking anyones encryption. My question is this, what is the most basic type of equipment you would need to even recieve, record, and analyze a transmission to determine what type of encryption you were looking at? It seems to me even this first step would present difficulties.

Nope, all that is easy.

And its available as a free download too. (for APCO25 anyway)

Lots of people in here talkin' - very few actually doing.

 

[N_Jay]

And its available as a free download too. (for APCO25 anyway)

Lots of people in here talkin' - very few actually doing.

Maybe because those who know how, also understand it is effort worthless.

and those who don't know and don't understand keep talking!

 

[MattSR]

All well and good, but radio system are open networks by definition, so the KEY and the ALGORITHMS are almost as important as "good security practices"

P25 blurts out the algorithm and key ID info out in the clear - check the ALGID and KEYID in the HDU and LDU1/2 frames. Radios that are loaded with the the correct key and algorithm have to have some way of knowing which key/algo to select

 

[MattSR]

Maybe because those who know how, also understand it is effort worthless.

Keep in mind a brute force takes only 7 days with current FPGAs. I know for a fact there's at least one agency near me that changes keys every 6 months or so.

 

[MattSR]

^^^ For DES-OFB, of course.

AES = forget it

 

[N_Jay]

P25 blurts out the algorithm and key ID info out in the clear - check the ALGID and KEYID in the HDU and LDU1/2 frames. Radios that are loaded with the the correct key and algorithm have to have some way of knowing which key/algo to select

But you still need to know the Key. KeyID is just a pointer.

 

[KC9NCF]

I thought you left this thread. You stated you were finished with it more than once. Although you started the topic, your OP has been answered and the topic has grown past your original and ill considered (read wrong) assumptions; therefore, unless you can contribute at the level of those who know of what they speak or can ask relevant questions, further comments like the one quoted above will be considered as disruptions and dealt with appropriately.

To all others, there have been some good points made here in relation to encryption, its relationship to the law and its application in both fixed text and audio signals. Let's consider the legality of attempting to monitoring encrypted transmissions (at least in the US) to be settled and stay on the more technical matters at least until this thread dies out.

I was finished with it until I saw some really good posts by people here and the enrtire idea of the post was constructed with an eye towards becoming educated about something I know nothing about! Sometimes, one has to construct a theory and test it with their peers (in this case, other hobbyists) to learn something new. Something I enjoy doing.

A couple people hinted towards self-study...which books are good to read on this subject? Referrals for reliable material?

 

[MattSR]

But you still need to know the Key. KeyID is just a pointer.

Duh. Gee I'm glad there's experts like you on teh intarwebs to educated all us silly people

 

[N_Jay]

Duh. Gee I'm glad there's experts like you on teh intarwebs to educated all us silly people

I am glad everyone is as smart and well informed as you.

I thought, just perhaps, one or more of the people reading this thread could possibly be confused and mistake what you said to mean that the key is sent over the air.

But now looking at it I see that there is no way that could happen. :roll:

 

[MattSR]

lol, good point!

 

[rvictor]

A couple people hinted towards self-study...which books are good to read on this subject? Referrals for reliable material?

There were two good suggestions in post #53 in this thread. I've got the 1967 version of the Kahn book. It's almost 1200 pages and was $60.00 when I bought it years ago. It only covers up to 1967, of course. A later edition, published in 1996 includes a chapter on the developments between 1967 and 1996. Obviously, it doesn't cover that period nearly as well as the history from the beginning to 1967.

Either one will keep you busy for some time. Come back and look at this thread when you're done. I think you'll see why people have been responding to you as they have.

Dick

 

[KC9NCF]

Thanks rvictor!

I'm gonna get a hold of those books. I was recently at the Museum at the U-505 exhibit and got to take a look at the old form of encryption via a digital display which explained the basics of how it worked on a three or four wheel system and 26 letter alphabet minus any special characters and any special characters had to be spelled out if ever they were used.

Then, I went over to a page over on the Batlabs site that Google directed me to and learned a ton more, but am just starting to scratch the surface. I am starting to see what the more irate posters here were trying to tell me. Sorry for having posted a stupid idea that is truly not workable. That's how some of us learn though! Thanks everyone for your patience!