Signal Spoofing Protection - Do you need a way to modulate the signal at a low level so that packets cannot be spoofed?

Question

Electronics

This is not about how to protect a computer or ARP, but about methods of protection using a modulated signal.
Sorry if the question looks a bit vague, it's just hard to formulate it precisely enough.
What does it mean: for example, we create two network devices that exchange packets between each other,
which are a certain combination of ones and zeros, roughly speaking, a modulated signal
according to some algorithm.
The modulation algorithm turns out to be "direct" i.e. what sequence of ones and zeros will be sent to the network device, such a signal will be modulated and sent to the second device. The algorithm itself is calculated in the ALU of the device that pushes the data into the network device.
So here is my question:
Is it possible without data encryption, i.e. completely discarding any computers, alu, all sorts of goodies, etc. and taking a purely network device to modulate the signal in such a way that, in addition to the data itself, it builds them in an algorithm that could recognize the second network device?
For example, if you take a regular radio - there is FM, useful data is obtained by changing the frequency, and if, for example, you combine it with AM / PWM (for example) which will build identification information about the sender and will obey a certain algorithm, so that only the second network device can recognize them?
Then the device can be sure that the package is not spoofed.
And also put some kind of random into the algorithm so that only two network devices know how it will change with every 5 or 10 bits? And without having to transfer encryption keys, etc.? Crazy idea, right?
I've been scratching my head for a week, so there are probably so many letters, maybe someone has an idea

Answer 1

For example, if you take a regular radio - there is FM, useful data is obtained by changing the frequency, and if, for example, you combine it with AM / PWM (for example) which will build identification information about the sender and will obey a certain algorithm, so that only the second network device can recognize them?
Then the device can be sure that the package is not spoofed.
And also put some kind of random into the algorithm so that only two network devices know how it will change with every 5 or 10 bits?

This is called security through obscurity and is considered bad practice.

Answer 2

Such a method will be hacked with a bang.
Encrypt with SSL and be happy!

Answer 3

optical communication line, and indeed look into the field of quantum cryptography

Answer 4

is it possible without data encryption, i.e. completely discarding any computers, alu, all sorts of goodies, etc. and taking a purely network device to modulate the signal in such a way that, in addition to the data itself, it builds them in an algorithm that could recognize the second network device?

And in your network device, in your opinion, there is no "computer, alu, all sorts of goodies"?

For example, if you take a regular radio - there is FM, useful data is obtained by changing the frequency, and if, for example, you combine it with AM / PWM (for example) which will build identification information about the sender and will obey a certain algorithm, so that only the second network device can recognize them?

If you are interested in a low-level implementation of something like this, then look towards frequency-hopping spread spectrum (FHSS) and parallel technologies (Time-hopping spread spectrum, Direct sequence spread spectrum).

Then the device can be sure that the package is not spoofed.

I understand that your question is rather theoretical, but if the hypothetical task is to protect against data spoofing, then, in my opinion, it is much more productive to use one of the MAC schemes .

Crazy idea, right?

In my opinion, your question, rather, is a consequence of insufficient knowledge of the subject.