SIGSALY – Secure Speech System Used in WWII by the Allies | Hacker News Reader

SIGSALY – Secure Speech System Used in WWII by the Allies

cryptomuseum.com

56 pointsnotlukesky18 comments

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...

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

Ok, changed to that from https://en.wikipedia.org/wiki/SIGSALY. Thanks!

Edit: there's also https://www.nsa.gov/about/cryptologic-heritage/historical-fi..., via https://hn.algolia.com/?sort=byDate&dateRange=all&type=story....

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

The 99%PI podcast does a little simulation:

https://99percentinvisible.org/episode/vox-ex-machina/

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

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/

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...

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

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/

This technology (SIGSALY) also features in Cryptonomicon.

Lawrence Waterhouse uses it while he stationed in Brisbane to talk chat to Turing on the other other side of the planet.

It is not a major plot device, but it is used.

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

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.

Isn't an add much cheaper than a multiply?

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

They weren't using base 2.

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

”Also interesting that the basement in that department store went down 200 feet. Was this to get a good foundation?”

It’s not as much as “below Selfridge’s” as “effectively in the cabinet war rooms”. https://en.wikipedia.org/wiki/Military_citadels_under_London...: ”There was a telephone room down the corridor that provided a direct line to the White House in Washington, DC, via a special scrambler in an annexe basement of Selfridges department store.”

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?

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