Maybe it’s the servers that is the problem.
The encryption probably won't be owned up to the point where it is practical to decrypt traffic in bulk, but it's a valid thing to look at.
Note that this is what we are discussing in the above messages, not the "strength" of Signal's encryption. I get that it is largely hypothetical risk, but it's a real difference.
For their use case, which requires communication between two (or more) arbitrary users who never communicated before among millions of users, running on cheap commodity hardware over wireless connectivity to the internet.
Leaving encryption aside, looking only at the network level, the DoD is capable of using a dedicated fiber line. Or rather a parallel fiber infrastructure.
Is this device using DoD PKI [0]?
If not, then how is DoD managing access to it? Or is there a post-it with a local password stuck to it?
[0] https://en.m.wikipedia.org/wiki/Common_Access_Card#Integrate...
Edit: I didn't state something perhaps I should have. Symmetric key is considered more secure because public key is more complicated so more room for side channel mistakes, and the computation needes to break public keys doesn't scale as fast with key size. I am not an expert but that is what I've read.
Forcing the reader to parse thru the literary devices in order to get to the argument weakens the argument.
Approximately 30,000 people go to work in the Pentagon every day. There are areas in the building that are SCIFs and they don't allow cell phones and laptops. But the majority of the building is an office building used for office building type stuff. Employees and contractors bring their personal cellphones and mobile devices in there every day.
About a month ago there was a discussion here saying Signal is preinstalled and widely used at the CIA.
https://news.ycombinator.com/item?id=43478091
It's also recommended by the government's cybersecurity agency CISA.
https://www.cisa.gov/sites/default/files/2024-12/guidance-mo...
Also, to be clear, Signal doesn't use public-key cryptography in the naive way (i.e. to encrypt/decrypt messages) as was/is possible with RSA. It uses asymmetric key pairs to first do a Diffie-Hellman key exchange, i.e. generate ephemeral symmetric keys, which are then used for encryption/decryption. This then also guarantees forward secrecy, see https://signal.org/blog/asynchronous-security/ . (Add to that they incorporate an additional post-quantum cryptographic scheme these days, and I'm probably omitting a lot of other details.)