I have a vaguely related question about Signal. People say it’s secure and encrypted but it was widely publicised that Sam Bankman Fried’s Signal messages were inspected by authorities. How did this happen?
There are many ways to get to those messages, like getting access to your unlocked phone/unlocking your phone, if your signal is not password locked (and if they can't break that password), or doing this with your recipient.
OpSec is a process, not single tools!
The authorities asked for them and, possibly after consulting a lawyer, he handed them over.
The only way I can think to intercept prior to encryption would be Key logger, so this would require an already compromised device. Alternatively the government could force a vulnerability state (e.g., the Perseus text message of doom). Is this also your understanding?