> Here, we demonstrate a covert communications method in which photon emission is rapidly electrically modulated both above and below the level of a passive blackbody at the emitter temperature. The time-averaged emission can be designed to be identical to the thermal background, realizing communications with zero optical signature for detectors with bandwidth lower than the modulation frequency
It sounds like maybe they're modulating the emissivity of a diode up and down so that over time, its IR spectrum looks like black body radiation. Only someone looking at the intensity of the thermal radiation coming from the diode at really fast timescales (kilohertz or megahertz) would notice that there was a signal being transmitted.
dustfinger 2 hours ago [-]
> Only a receiver with the right equipment can pick up the hidden message.
So all an eavesdropper has to do is setup the right equipment then? I guess it is only invisible until the technology becomes more widely available.
behehebd 1 hours ago [-]
As invisible as radio signals then.
Hobadee 16 minutes ago [-]
Now now... Let's be fair...
Radio broadcasts to everyone.
Light you can block off to a single direction.
Oh wait, directional radio antennas exist. Nevermind, yes. Exactly like radio waves.
TheOtherHobbes 3 hours ago [-]
Maybe I'm missing something, but this reads like a complicated way to say "We made an IR diode that gets cold as well as hot."
RobotToaster 1 hours ago [-]
Yeah, but saying that doesn't get the military to give you money.
JellyBeanThief 39 minutes ago [-]
I would much rather have been called a computerologist than a computer scientist.
thewanderer1983 1 hours ago [-]
Yep.
Retr0id 1 hours ago [-]
> We do have encryption methods, but at the same time we’re always having to create new encryption methodologies when bad actors find new decryption strategies.
> But if someone doesn’t even know the data is being transferred, then it’s really very hard for them to hack into it. If you can send information secretly then it definitely helps to prevent it being acquired by people you don’t want to access it.
Very strange framing. Symmetric cryptography has been "unhackable" for a while now, for all intents and purposes. The real advantage is surely that nobody notices you're transmitting data at all?
nine_k 1 hours ago [-]
The cypher may be prefectly impenetrable, but the software running on the transmitter or receiver may be more brittle. You cannot attack what you don't even know exists nearby.
Retr0id 1 hours ago [-]
A secure cipher is indistinguishable from random data, you can't infer what software is on either end just by eavesdropping.
nine_k 57 minutes ago [-]
But once you've located the device, you can use a number of electronic warfare approaches to crack into it, not necessarily through its main radio interface. For instance, electromagnetic interference, heating, etc, all can inject a subtle hardware failure that the software is not ready to handle.
Retr0id 54 minutes ago [-]
Hence, "the real advantage is surely that nobody notices you're transmitting data at all?"
scottyah 3 hours ago [-]
It's impressive how this article made this sound like a breakthrough, didn't even mention the entire historied field of steganography once.
jkhdigital 2 hours ago [-]
The paper itself mentions steganography in the second sentence at least.
nyc_data_geek1 45 minutes ago [-]
Makes me look at steganography in slips on sunglasses an entirely new light.
8 minutes ago [-]
charcircuit 3 hours ago [-]
It seems simpler to use a secure radio protocol instead of relying on security by obscurity for communication.
StevenWaterman 3 hours ago [-]
A covert signal is still beneficial even if the signal is secure. The existence of the signal is valuable metadata.
For a contrived example, imagine I'm in a warzone:
- Secure = Enemies can't read my messages. Good. But they can still triangulate my position.
- Covert = Enemies don't know I exist
TeMPOraL 6 minutes ago [-]
Also even if they know you are transmitting, it may still be beneficial to prevent them from knowing how much you are transmitting.
Imagine the enemy detects some of your transmission, even knowing it's encrypted, they can still look at the data rate (or estimate order of it):
- 5 bps = probably a random transmitter, maybe audio spy device, maybe remote detonated weapon
- 5 Mbps = probably a feed from military hardware or personnel
Similar inferences can be made about volume, if they can identify distinct transmissions. Etc. If tricks like these can make the enemy confuse 5 Mbps TX for a 5 bps one, it has obvious tactical utility.
applfanboysbgon 2 hours ago [-]
Another example: in some regimes merely using Tor is illegal, or say in the US using it is enough to justify a search warrant for probable cause, with no evidence of any actual wrongdoing. The EU Chat Control lobby is also trying very hard to criminalize encryption. The simple act of trying to communicate privately is taken as indicative of criminal wrongdoing in the modern world. Being able to communicate without adversarial parties knowing you're communicating is a boon.
pinkmuffinere 3 hours ago [-]
+1. As another example see https://en.wikipedia.org/wiki/Numbers_station -- people can't decipher the messages, but they strongly suspect something spy-y is going on. If they couldn't even detect it, there would be no suspicion.
Also hi StevenWaterman, I recognize you from previous comments! I think this is the first time that's happened to me on HN
mvrckhckr 1 hours ago [-]
Unless they have "the right equipment". Then you are right back at the same situation.
bob1029 2 hours ago [-]
DSSS is sort of both security and obscurity at the same time. The very act of spreading your spectrum out via a secret key also has the effect of reducing the amplitude of your transmission, ideally below the noise floor. A receiver on the other side wouldn't see anything except noise unless they had the same key.
jkhdigital 2 hours ago [-]
Secure channels can still be jammed. Undetectability is a fundamentally different goal than secrecy.
hmmokidk 2 hours ago [-]
I am sure you could encrypt the warmth message somehow.
esseph 2 hours ago [-]
Unless your adversary is scanning for RF emissions, which is getting more and more common.
Rendered at 00:04:49 GMT+0000 (Coordinated Universal Time) with Vercel.
From the abstract:
> Here, we demonstrate a covert communications method in which photon emission is rapidly electrically modulated both above and below the level of a passive blackbody at the emitter temperature. The time-averaged emission can be designed to be identical to the thermal background, realizing communications with zero optical signature for detectors with bandwidth lower than the modulation frequency
It sounds like maybe they're modulating the emissivity of a diode up and down so that over time, its IR spectrum looks like black body radiation. Only someone looking at the intensity of the thermal radiation coming from the diode at really fast timescales (kilohertz or megahertz) would notice that there was a signal being transmitted.
So all an eavesdropper has to do is setup the right equipment then? I guess it is only invisible until the technology becomes more widely available.
Radio broadcasts to everyone.
Light you can block off to a single direction.
Oh wait, directional radio antennas exist. Nevermind, yes. Exactly like radio waves.
> But if someone doesn’t even know the data is being transferred, then it’s really very hard for them to hack into it. If you can send information secretly then it definitely helps to prevent it being acquired by people you don’t want to access it.
Very strange framing. Symmetric cryptography has been "unhackable" for a while now, for all intents and purposes. The real advantage is surely that nobody notices you're transmitting data at all?
For a contrived example, imagine I'm in a warzone:
- Secure = Enemies can't read my messages. Good. But they can still triangulate my position.
- Covert = Enemies don't know I exist
Imagine the enemy detects some of your transmission, even knowing it's encrypted, they can still look at the data rate (or estimate order of it):
- 5 bps = probably a random transmitter, maybe audio spy device, maybe remote detonated weapon
- 5 Mbps = probably a feed from military hardware or personnel
Similar inferences can be made about volume, if they can identify distinct transmissions. Etc. If tricks like these can make the enemy confuse 5 Mbps TX for a 5 bps one, it has obvious tactical utility.
Also hi StevenWaterman, I recognize you from previous comments! I think this is the first time that's happened to me on HN