
SIGSALY – Secure Speech System Used in WWII by the Allies - notlukesky
https://www.cryptomuseum.com/crypto/usa/sigsaly/index.htm
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Animats
More technical information: [1]

This gives a sense of how much 1940s equipment it took to do something every
mobile phone does today.

This is another device from the "if only we had memory" era of early
computing. IBM had a digital vacuum tube multiplier before WWII, and semi-
programmable electromechanical computing machines. Good memory devices were in
the future. The 1940s and early 1950s saw quite a collection of strange memory
devices, all big, expensive, or slow. Often all three. SIGSALY had massive
synchronized phonograph turntables as key storage.

Memory took quite a while to get cheap. Core memory was still around a million
dollars a megabyte in 1970. Memory didn't get cheap until the 1990s.

[1] [https://www.nsa.gov/about/cryptologic-heritage/historical-
fi...](https://www.nsa.gov/about/cryptologic-heritage/historical-figures-
publications/publications/wwii/sigsaly-start-digital/)

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tasty_freeze
A site with far more information about it:
[https://www.cryptomuseum.com/crypto/usa/sigsaly/index.htm](https://www.cryptomuseum.com/crypto/usa/sigsaly/index.htm)

~~~
dang
Ok, changed to that from
[https://en.wikipedia.org/wiki/SIGSALY](https://en.wikipedia.org/wiki/SIGSALY).
Thanks!

Edit: there's also [https://www.nsa.gov/about/cryptologic-heritage/historical-
fi...](https://www.nsa.gov/about/cryptologic-heritage/historical-figures-
publications/publications/wwii/sigsaly-story/), via
[https://hn.algolia.com/?sort=byDate&dateRange=all&type=story...](https://hn.algolia.com/?sort=byDate&dateRange=all&type=story&storyText=false&prefix=false&page=0&query=sigsaly).

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kristaps
Would really love to hear what the final output sounded like. Some light
googling found no recordings, did anyone else have more luck?

~~~
joezydeco
The 99%PI podcast does a little simulation:

[https://99percentinvisible.org/episode/vox-ex-
machina/](https://99percentinvisible.org/episode/vox-ex-machina/)

Scroll down "Below you can hear an example of what a SIGSALY communication
would’ve sounded like"

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ganoushoreilly
If you're ever in the D.C / Maryland area, Fort Meade has a pretty cool museum
with all of these on display.

[https://www.nsa.gov/about/cryptologic-
heritage/museum/](https://www.nsa.gov/about/cryptologic-heritage/museum/)

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Ken_Adler
A great book to read on this topic is 'How To Wreck A Nice Beach"

[https://www.amazon.com/How-Wreck-Nice-Beach-
Vocoder/dp/16121...](https://www.amazon.com/How-Wreck-Nice-Beach-
Vocoder/dp/1612190928)

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modoc
Very cool to read all the details beyond the one-time-pad records described in
Cryptonomicon!

~~~
BuildTheRobots
Solitaire Cyphers are the one that stuck with me from Cryptonomicon. iirc,
there's supposed to be enough combinations in a shuffled deck of cards that
every time anyone shuffles a deck, it should be a unique ordering.

[https://www.schneier.com/academic/solitaire/](https://www.schneier.com/academic/solitaire/)

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belltyler
First learned about this on a highly-recommended episode of 99% Invisible:
[https://99percentinvisible.org/episode/vox-ex-
machina/](https://99percentinvisible.org/episode/vox-ex-machina/)

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madengr
Interesting that they added the code (random noise) to the data rather than
multiply (XOR). I assume this was safe to do since averaging won’t recover
much signal when the signal rate and code rate are the same.

Also interesting that the basement in that department store went down 200
feet. Was this to get a good foundation? The link does not say.

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Aloha
Isn't an add much cheaper than a multiply?

~~~
madengr
Sure, but typically bit-wise multiply by XOR is used, at least with spread
spectrum and many forward error correction.

~~~
ncmncm
Using base-6 signaling, modulo addition per digit position is a close
equivalent to XOR for binary.

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meatsock
as a record collector, the idea that top secret military phonographs filled
with white noise may have once existed sure is exiting. can there possibly be
any rarer record than one that required it's own destruction after use?

