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Secure Digital Voice Communications In World War II
mercury7 writes: "Saw this one on Memepool. A very interesting paper from the U.S. National Security Agency site on the first digital encyrpted voice communication system. It is incredible how hard it was to manipulate data before the existence of computers."
"All of the elements of this system were developed by the Bell Telephone Laboratories in the interests of advancing the art of telephony. . . . When it had reached the point where its principles could be demonstrated, the Signal Corps took prompt steps for its procurement."
It appears to me that the NSA has, to a limited degree, tried to make their mammoth budgets and spare-no-expense approach more palatable to the American taxpayer by claiming to develop technology way ahead of its time. "Hey, our job is American security but even if you think that's not a big problem these days, look at the tech spinoffs and innovation we create." To me this seems a little disingenuous.
As this article, among others indicates, the NSA et al may be a nice mechanism *funding* innovation (although VCs are arguably better, with a more attractive upside economically) they don't actually *do* much innovation (outside of say, crypto research).
--LP
You can listen to examples of vocoder audio on this web page.
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That's because of the GCHQ challenge - try it here!
While this is certainly funny, and I wish I could mod it up further, the original first use of a vocoder in music was done by the Alan Parsons Project around 1976 or so (does anyone remember the album/track - I can't remember if it was Stereotomy, or Tales/Raven)...
Worldcom - Generation Duh!
Reason is the Path to God - Anon
"Two turntables and a microphooooone..."
Burris
"It is incredible how hard it was to manipulate data before the existence of computers."
Yes, back then they couldn't just run it through a computer and have it scramble it. To do this they would have to run it through some sort of mechanical device.
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where the reciever broadcast 'noise' at the same frequency as the incoming message. As the reciver knew exactly what noise he was broadcasting he could then subtract that quite easily. So you don't NEED digital encryption.
Obviously this would only be effective on point-point (cable) connections, as the noise would become insignificant when broadcast by an arial.
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I very highly recommend everyone read the paper, which was published in the Bell Systems Technical Journal under the title "Communication Theory of Secrecy Systems" in 1949. It's pretty accessible, you don't need to be a crypto weenie to understand it. However, you can't even pretend to know anything about cryptology without having read that paper.
Shannon is the MAN.
Burris
Note that many politicians and spin doctor seem to have this done to a fine art.
The reverse is slightly more difficult, which is the fine art of taking something indistinguishable from noise, and try to extract intelligible speech from it.
How similar this is to public forums such as slashdot, etc is left as a exercise for the reader.
;-)
"It is a greater offense to steal men's labor, than their clothes"
Ok, there's probably something here that I'm not getting, and maybe someone can explain it to me. But after reading their description, I don't really understand why they went to the trouble to digitize the signal at all. I wondered that, too. I got the impression, though, that they wanted the signal to be undetectable in the relatively-broadband HF receivers of the day, not just undecodable. That meant they needed to distribute the frequency content over a larger chunk of the spectrum, making it sound more like random noise in the AF bandwidth of a conventional monitoring receiver. Wideband linear FM modulation would have been a real hassle in those days (no varactor diodes, for instance), so it may actually have been more convenient for them to drive six separate transmitters with the results of the "digitization." OTOH I'm pretty sure that contemporary telephone gear was already using frequency-division multiplexing without any digitization at all, so I don't see why they couldn't have accomplished the same thing with an analog filter bank and mixdown scheme.
Dahlmann tightly grips the knife, which he may have no idea how to use, and steps out into the plain.
I knew it. We need to criminalise the production and possession of vinyl as a munition. :-)
The technical hurdles they had to overcome for this first "digital" voice system were pretty impressive. And each station weighed in at a mere 55 tons. I'd love to hear a recording of what the recovered speech sounded like.
the AC
Hemos is like...sci-fi fans;he thinks technology is cool, but he hasn't bothered to understand the science it's based on
Another thing that was tough in this age was aiming artillery. If you know the distance, the characteristic of the gun, the characteristics of the shell, and the windspeed, physics equations tell you how to aim the gun to hit your target. Realistically, the equations cannot be solved in battlefield conditions where time is a factor and competent mathematicians are in short supply.
The solution to this problem was to issue huge books of pre-computed tables to artillery gunners. Each new gun and new shell needed a new book generated. That involved many hours of computation to be done by a small army of geeks. Because the guy-geeks were busy cracking codes, inventing atomic weapons, running logistics and stopping lead, a cadre of girl geeks was assembled in Annapolis and tasked with generating these artillery tables. The women were brought up to speed on Calculus and Physics (if they needed to be) and they were know as (you guessed it) "Computers."
While the lady Computers toiled, some other geeks were trying to automate their task using analog and digital electronic systems. Because the first automated calculation machines were targetted to the labor-intensive task of generating artillery tables, these devices were called "electronic computers."
Every time I see a flame session about the lack of women in computer engineering, I find it ironic that the word "computer" itself is an artifact of a group of geek girls.
Because the signal that is transmitted will be subjected to additional noise. This has a much greater effect on the encrypted signal, if the encryption is of any reliable level at all, than it does on plaintext sound. The digitization had the same advantage then it does in modern systems, noise can be completely removed which is a necessary first step toward reconstructing the plaintext.
Brackets contain world's first nanosig, highly magnified:[.]
Or ~55 years for those of us who aren't stuck in the 80's...
Pax Digitalia
If you want to look at cool modern-day intel. stuff, the GCHQ website is actually pretty detailed.
The largest LAN in Europe, one of the highest data storage capacities in the world, and free healthcare =)
Also, they seem to think they can pass secret instructions to spies the world over by inserting 'random' bold tags on one of their pages
Ben^3The Slashdot Paradox: "100% Overrated"
Now, as Klingon was likely contrived by English speakers I would imagine it would have a fairly simple to decode structure, idioms (if there even are any), and all verbs and nouns would probably have 1:1 equivalents, with the exception of stupid star trek shit.
As such, I doubt Klingon speakers would make very good code talkers. Although putting them in the line of fire is not necessarily an entirely unattractive proposition.
Now once again, to reiterate, I may be wrong, as I do not know any Klingon, nor do I ever intend to.
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Bob Fucking Costas. Does anyone else hate that motherfucker?
A vocoder converts an analog voice signal to a digital bit stream, which can easily be encrypted by any number of devices. The advantage of a vocoder, in comparison to the PCM encoding techniques used in the telephone system, is a much lower bit rate. A vocoder constructs a model of the human vocal tract, and transmits the parameters of the model at a periodic rate. The receiver uses these parameters to construct an electronic replica of the speaker's vocal tract, which produces the audio that the other party hears.
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Burris