Ontimp

Depends. A basically old wood fire? No. But here is other nasty stuff that does not ‘burn’ as we think of it but still produces enormous heat in exothermic reactions that do not need oxygen to sustain themselves.

If you plan to securely store such material look at appropriate chemical supply storage, not safes.

Yea but if you worry about CPU bugs there is no such thing as trust, no matter who owns the infrastructure. Any software can have critical bugs and any system that can be accessed remotely can be compromised. Personally I’d trust the people at Signal that they have made a reasonable architecture section to balance availability and privacy