What Defcon Sounds Like: Skyking Emergency Action Messages (2016)

that EAM had a weird number of repeated characters in it, more than I'd expect by chance if my ears aren't deceiving me. I thought they used a one-time pad, don't they?

I was thinking this might have been a primary source for the Storm Trooper helmet design.

Fond memories of watching that show.

HF-GCS (High Frequency Global Communications System) uses a variety of frequencies, but if memory serves, the two primary frequencies that are always used are 8992 kHz (better for night propagation) and 11175 kHz (day propagation). If you're using one of the receivers listed at websdr.org you might try those for a start.

If you're in northern California and in need of a day trip, drive on Interstate 80 to the town of Dixon and head south on Highway 113 towards Rio Vista. Eventually you'll see a pair of very tall antenna towers. I'm pretty sure those are the "West Coast" HF-GCS transmitting towers, with the receiving antennas located further east near Lincoln.

(And if you're up for a great burger and shake, Dave's Giant Hamburger in nearby Fairfield will set you straight. (Be sure to ask for the hot sauce.))

I think the real lesson is how much effort we put into making bomber crews believe they would return from their bombing runs alive, to functioning airfields, to be used again if necessary.

They’re also a reminder of the hidden infrastructure and communications that will be unseen and unheard by the world but is at the ready to handle this contingency.

You then consider that this infrastructure (ie the googles) has been duplicated by at least two other world superpowers, with each having had a slightly different variations on implementation which inherently reflects the values of the nation.

I think the writers of the film WarGames liked it too. They seemed to imitate the call with the phrase "Skybird calling Dropkick" in an impressive radio DJ voice.

I noticed that GMRS radio IDs also have these effects on people sometimes. When I call with my ID in a place like Yosemite I'll hear other people on their FRS radios ask if they have a cool ID too. (Not that I think it is cool, but it's certainly different...and I think most prefer it to calling family and friends by name on a public radio band)

These googles? PLZT (Polarized Lead Zirconium Titanate)

https://www.thedrive.com/the-war-zone/7975/this-is-what-usaf...

Just like TLS, the payload is encrypted. The skyking stuff is just header. It has the advantage that there’s less to go wrong and doesn’t take sophisticated equipment to receive.

But they do:

"Salutation, trigraph, timestamp, authentication, and then a series of letters comprising the coded message."

"The messages are simply a series of letters, relayed in NATO phonetics, and encrypted with a one-time cypher. The receiver would need a code book (by varying reports refreshed daily, weekly, or monthly and inches thick) to identify the key and decrypt the message."

The article implies that the nuclear forces have already been deployed and targets set - this would be the final instruction to launch (the "go/no go" on that USAF cheat sheet).

At that point there's not much to hide or encrypt.

Well, the payload is encrypted using OTPs. But if the gist of the question was really "why use such old tech when newer tech is available?":

I suspect these methods of communication remain because of their robustness against attack and simplicity to implement. It's a guarantee that even if all the modern networks go down, commands can still be issued from anyone, to anyone using off-the-shelf hardware.

The content is encrypted with one-time pads that are constantly refreshed, which is entirely undecipherable through cryptanalysis. Encrypting the radio signal itself would require a much more extensive infrastructure than binders and radio receivers: specialized hardware that might be compromised or flawed, or simply break down, rendering you unable to listen to the channel over which your critical orders might come; harder to audit as well with more moving parts and components that aren't easily inspected or tested.

This seems like a case of a very simple and robust system being more than sufficient for the task, and anything more complex is a waste of time and money.

Sometimes you want a communication to be public, loud, and undeniable, even if you don't want it to be understood by all.

It makes it difficult to later deny that the order was given, it'll be recorded many times over by friend and foe alike. Recipients can possibly confirm that their counterparts are also receiving consistent orders.

That cheatsheet is not accurate. The number of "skyking"s do not have anything to do with priority/severity. Further, SIOP was not strictly speaking retired — it was renamed, most recently to OPLAN 8010-12. I would take the linked page with a very large grain of salt.

Presumably the adversary has already launched an easily detectable nuclear attack themselves so they know something is up

For a good explanation on why you don't want these things to be too high-tech and too encrypted, see "Doctor Strangelove", and take particular notice about the roles played by CRM-114.

The salutation is not encrypted because it's designed to attract the attention of the radio operators on the plane. They need a few moments to grab their pens to write down the message that follows so they aren't going to miss any characters.

So far as leaking information - by the time these are sent as real-world communications (i.e. not as a test or during training), the planes are nearing their target. So it won't matter for much longer if the enemy knows, since the positions of the planes are (hopefully) unknown.

> Why don't they use encryption? Wouldn't it be preferable for your messages to be completely inscrutable?

They don't? The letters read out in a phonetic alphabet are most certainly a code that's completely inscrutable without a codebook, which is probably rotated frequently. Encryption like we use it (e.g. encode arbitrary messages) is probably unnecessary and too complicated. All they're probably trying to do is transmit an authenticated order to execute an action that's been agreed upon ahead of time.

Its a number station of sorts, more can be found explaining them on wiki (https://en.wikipedia.org/wiki/Numbers_station) and youtube (https://www.youtube.com/watch?v=SQbQTv3aMkU) (loads on youtube)

I think the reason they have disappeared is because of the satellite coverage seen today, so people need to look in new places to find them.

A clearly defined format probably prevents something like "Where is Task Force 34 the world wonders" from happening.

The "echo" is actually from multiple spatially separated stations simultaneously transmitting the same message. You're hearing the differences in time of flight. The overlapping signals don't interfere as one might expect because they use single sideband modulation.

> interesting interference

There is a lot of interesting interference at these low frequencies. I didn't hear anything I wouldn't expect to hear on HF. Also, echo is a complex and somewhat mysterious topic. Long Path echo is easily grasped; the same signal is received twice due to two paths around the Earth which happens when band conditions are favorable. Other forms of echo (Long delayed echo[1], for example) are less easily explained.

[1] https://en.wikipedia.org/wiki/Long_delayed_echo

This USAF HF system uses a lot of power (4+ kilowatts) and very good antennas, so they're prone to experience these effects.