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.
Lol at military stuff being secure. Most often it’s not, it’s just hidden. There was an Ars Technica article about the “secure” devices used at military bases being full of holes for example: https://arstechnica.com/security/2023/08/next-gen-osdp-was-supposed-to-make-it-harder-to-break-in-to-secure-facilities-it-failed/
When code is hidden all you know for sure is that you don’t know anything about it. You certainly can’t say it’s secure.
If a piece of code or a system is really secure then it does not care if the code is open because the security lays in the quality of its algorithms and the strength of the keys.