The French government doesn't consider WhatsApp, Signal or Telegram secure enough, replaced by Olvid (Google translate link in post text)
The French government doesn't consider WhatsApp, Signal or Telegram secure enough, replaced by Olvid (Google translate link in post text)

Les ministres français invités à désinstaller WhatsApp, Signal et Telegram

Another article, much better and presents in more detail that Olvid was audited on an older version and chosen because it was French and they applied for it (French) https://www.numerama.com/tech/1575168-pourquoi-les-ministres-vont-devoir-renoncer-a-whatsapp-signal-et-telegram.html
Google translate link original post : https://www-lepoint-fr.translate.goog/high-tech-internet/les-ministres-francais-invites-a-desinstaller-whatsapp-signal-et-telegram-29-11-2023-2545099_47.php?_x_tr_sl=fr&_x_tr_tl=en&_x_tr_hl=fr&_x_tr_pto=wapp
The translation has some mistakes but good enough to understand the context.
Here is a short summary :
Olvid passed a 35d intrusion test by Anssi (French cybersecurity state organisation) experts or designated experts, with code examination without finding any security breach. Which is not the case of all other 3 messaging apps (either because they didn't do any test, or because they didn't pass).
This makes WhatsApp, signal and telegram unreliable for state security.
And so government members and ministerial offices will have to use Olvid or Tchap (French state in house messaging app).
More detail in the article.
I'm sure there are more attack vectors than that though
Exactly. "Security assuming nobody fucked up" isn't enough
Signal does store the decryption keys in the cloud. Using their SGX enclaves. Which have their own issues. Signal SVR I believe they call it.
You can turn off signal pins, which still stores the decryption keys in the cloud, but then they're signed with a very long pin which is good enough.
From a government perspective, signals a no-go, the SGX enclaves are completely exploitable at the state actor level. You just have to look at all of the security vulnerabilities to date for SGX enclaves.
Do you have a reference for Signal using SGX for keys?
Everything I could find was about metadata and private data, e.g. contact lists (which is what the SVR thing that you mention is), but nothing about keys.