Decoding Encryption with Permission...

[mancow]

It would make and interesting defcon challenge, that's for sure!

 

[JnglMassiv]

The point is (AGAIN) . . . . . .
TEXT:
You could try a key and run the file, if you get lots of invalid ASCII characters, try the next key. all automatically at computer like speed.
This will probably sort out all but a few false positives.
Fast process, computer intensive.

AUDIO:
Try a key and run the file, search the audio for some very basic pass/fail test.
THEN listen to LOTS of false positive audio samples until you hear a voice.
SLOWWWWW Process, human intensive.

GET IT!!!!!!!:roll:

I mentioned this earlier in the thread but I still maintain that there's some sort of tone (or header?..) injected into the signal prior to encryption. When a secure capable and keyloaded radio receives the encrypted signal, it 'knows' whether the incoming transmit is the same key. If there wasn't some sort of simple test, you'd hear hash from an on-freq radio with a wrong key. Which you don't.

This would obviously make the test for successful decode much, much easier.

 

[crayon]

I mentioned this earlier in the thread but I still maintain that there's some sort of tone (or header?..) injected into the signal prior to encryption. When a secure capable and keyloaded radio receives the encrypted signal, it 'knows' whether the incoming transmit is the same key. If there wasn't some sort of simple test, you'd hear hash from an on-freq radio with a wrong key. Which you don't.

This would obviously make the test for successful decode much, much easier.

Agreed. As stated, the radio needs some way to compare the incoming encrypted data stream against what it expects the encryption to be. How else can it decode? Is there a PKI type preamble CRC check? If so, then you would not need to worry about a false decode ...

 

[rescue161]

If you turn an analog radio on in the middle of an encrypted DES transmission, the receiving radio will not pick up the transmission.

DES using digital radios is different. You can turn them on in the middle of a transmission and it will start receiving the transmission immediately.

The above instances have been my experience using Systems Sabers for analog and Astro Sabers and an XTS5000 for the digital tests.

 

[hotdjdave]

Got it?

I GOT IT !!!!!!!!!!

THE ANSWER IS : DRINK MORE OVALTINE !!!!!!

So did he get it or is this just a joke? If so, where is the "how?"

 

[rescue161]

He was joking.

The real message is three (3) sentences long and only mentions DES once... :-;

 

[loumaag]

Dave, Dave, Dave...
You need to know your movie trivia a little better, next Christmas season, see "A Christmas Story". :wink:

 

[hotdjdave]

Dave, Dave, Dave...
You need to know your movie trivia a little better, next Christmas season, see "A Christmas Story". :wink:

LOL - Didn't think of that. A Little Orphan Annie secret decoder ring is what we need to make this work. :lol:

 

[rescue161]

Well, crap, I didn't win the lottery, so I guess I won't be offering up the $100,000.00 prize... :evil:

Maybe next week...

 

[scannerfreak]

ya me neither, but 2 other lucky souls did..Oh well..

 

[902]

If you turn an analog radio on in the middle of an encrypted DES transmission, the receiving radio will not pick up the transmission.

DES using digital radios is different. You can turn them on in the middle of a transmission and it will start receiving the transmission immediately.

The above instances have been my experience using Systems Sabers for analog and Astro Sabers and an XTS5000 for the digital tests.

Periodic resync in XL takes care of late entry, but degrades audio quality.

 

[paulrrulon]

Code Breaker

http://www.top500.org/news/2006/11/...percomputers_shows_major_shakeup_among_top_10

This computer might be helpfull in cracking a cipher or code. 280 trillion calculations per second. Wow thats a lot of power I bet that baby could heat a small city hehe. Some thought the Enigma would never be broken . Seems like as technology changes new codes are constantly getting overhauled or redesigned . Then the supercomputers get faster and the codes get redesigned Etc... I remember the guy who sold me my first mobile phone many years ago telling me how safe and secure they are , we all know the rest of that story. I have to admit you had a very generous offer to all , you were willing to give up a radio to any and all takers , my hats off to you. I do not understand any of this code breaking but it makes for good reading.
Thanks

 

[gregmoss]

Yep! My eyes are glued too this tread. Very interesting indeed. Now I'm wondering if it's even possible within a week. I highly doubt it.

 

[wannabescannist]

Skip brute-force...anyone can do that....I'm gonna get into cryptanalysis later on down the line.

 

[kb2vxa]

No wonder this has turned into a joke thread, by now you've figured out the time decryption takes depends on how many layers there are and what is used to decrypt it. That in itself may be considered as an infinite number of occasional tables.

BTW, the answer is 42 but the mice are dead.

 

[rescue161]

Why is it a joke thread? I wasn't joking when I offered up my Pro-96 and still am not joking about the Systems Saber.

The whole point of this thread was to prove to the "DES has been cracked croud" that it still hasn't been done as far as radio is concerned. She me proof or better yet, crack my DES transmission and I'll step down. It's that simple.

After Saturday, I'll even post some more info to help folks along, but the SS1 won't be offered after that.

 

[MattSR]

A couple of points..

Recoding the discriminator audio with MP3 ruins the bit stream. remember that MP3 is a lossy codec and the data is probably not recoverable from those files. Wave format would be ideal.

Here is a Motorola internal training document for securenet systems that I found elsewhere on the web:- http://users.757.org/~telmnstr/pics/pdf/securenet2.PDF

as Jnglmassiv alludes to there is a mechanism in there to check for the validity of the key (its called proper code detect) that pdf breifly touches on the topic.

Enjoy!!

 

[SCPD]

Recoding the discriminator audio with MP3 ruins the bit stream. remember that MP3 is a lossy codec and the data is probably not recoverable from those files. Wave format would be ideal.

It depends upon the quality settings at the time of encoding. A "hi fi" or CD audio quality mono recording is adequate for low-speed data (and much quicker to transfer). As long as the original signal is decent, it works. In the case of Scott's MP3 file - I was able to get a waveform consistent with the type of data claimed.
-rick

 

[SKEYGEN]

Where would one find software and or equipment to even start to try and decode the data stream and so on???

R6

You'd record the IF output of the receiver to an instrumentation tape recorder (e.g. Sony DIR-1000, or for P25 you could safely use DAT.) You'd then load the contents of that tape into a program like PCscan III on a PC, and export the data to the signal analysis package of your choice under a program like Mathematica.

From your signal analysis package, you'd have a raw bitstream which you would then process to identify individual frames etc (trivial.) You'd then write a program to attempt a DES decryption against a group of sample frames for each key using your special DES cracker, now worth no more than about $10,000, containing heaps of FPGAs that can search the entire keyspace in a week or so, determine a method of detecting valid audio (Motorola radios do this easily enough!), and Bob's your auntie.

 

[SKEYGEN]

VSELP?

All my documents say it's CVSD Continuously Variable Slope Delta modulation. The waveform generator is a device that produces a steadily increasing or decreasing voltage at a known rate. The 0 or 1 data bit tells it to produce a negative or positive output. If the incoming digital stream is a steady 0101010 there is no output at all.


Or, at least that's how I read it.

That's the gist of it.

VSELP came along many, many years later. The signal processing capability to encode/decode VSELP didn't exist in a two way radios back in the seventies.