Signal provides:
- Excellent protection against third party interception of communications (wiretapping).
- Limited protection against compromised (hacked) or lost devices
- No protection against certain common usage mistakes (accidentally including a reporter in your large group war planning chat).
If you look at the systems that are supposed to be used for classified communications, the underlying cryptography isn’t particularly different from Signal (the AES cipher can be used to protect classified material). That’s not what failed here.
The difference is that systems like Signal are designed to *facilitate* communication with anyone. Classified systems are designed to *limit* communication to authorized recipients.
Both are sensible for their respective - very different - purposes.
Infodump follows aimed at nobody in particular:
AES is the symmetric cipher, Signal uses ECC (on Curve25519 & derivatives: So X25519 and Ed25519) for the DR protocol, and ML-KEM as the KEM for the initial key exchange.
ECC is not quantum-safe: You can recover a private key from the public key and decrypt communication if you have a quantum computer. The protection from using a PQC (post-quantum) KEM for the initial key exchange is limited.
Additionally, Signal has a specific threat model, which can make using it insecure for a lot of usecases. For one, it is not anonymous. This means that it does not protect your identity, it only protects your messages. Aka it is fine for chatting with trusted parties, but dangerous for chatting with untrusted parties.
@mattblaze I am starting to feel like I said something wrong here ?
If there's any mistakes in what I said feel free to correct me, I am always eager to learn ^^
Matt Blaze is a well know academic security expert, so he's poking fun at being lectured on systems he understands very well lol
@ity Additional context you might be missing: He was commenting specifically on this breaking news story wherein top level US government people accidentally added a journalist to their signal loop planning military strikes, so the quantum safety (or lack thereof) of signal and the lack of anonymity is pretty irrelevant to this specific issue. Your post might have come off as lecture-y for this reason
@void_turtle Ah, yea I was missing that context completely :(
I don't keep up with US news anymore, it's too depressing
Matt Blaze
ity [unit X-69]
Void Turtle
blausand 🐟