Cryptographic keyed gdss

[Hakun_the_eril]

Hello,

I am a Norwegian with an interest in privacy and open source software. I
have no formal background in cryptography or signal processing, so that is
mentioned.

I have read an open access paper from 2023 about Gaussian-Distributed
Spread-Spectrum (GDSS) for covert communication:

Shakeel et al., Sensors 2023, doi:10.3390/s23084081

The paper describes a spread spectrum scheme that makes radio transmissions
largely statistically indistinguishable from thermal white noise.

The masking in the original scheme uses the transmitter's own thermal noise
as a random source. My question is whether it would improve the signal's
masking - or whether it has already been tried - to replace the random
source with a cryptographically keyed source: specifically a ChaCha20
keystream derived from a BrainpoolP256r1 ECDH key exchange via GnuPG, which
was passed through a Box-Muller transform to produce Gaussian-distributed
masking values.

My reasoning is that this would make the masking sequence cryptographically
secret rather than just random - so that an adversary could not remove the
masking without the session key, even if they knew the full algorithm. It
would also make traffic analysis more difficult, since each session's
masking sequence would be unique.

The practical implementation will use GNU Radio with gr-qradiolink (which
has GDSS blocks) and gr-linux-crypto (which provides Brainpool and
ChaCha20), both open source.

I'm not sure if this method is already known, already tried, or if there is
an obvious reason why it wouldn't work that I'm overlooking.

Does anyone know anything about this ? Is it viable?
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