109
Signal under fire for storing encryption keys in plaintext
(stackdiary.com)
If it's free and open source and it's also software, it can be discussed here. Subcommunity of Technology.
This community's icon was made by Aaron Schneider, under the CC-BY-NC-SA 4.0 license.
You would probably use a recovery key that exists exclusively elsewhere like on paper in a vault. Like bitlocker.
I have no idea if signal uses TPM or not but generally keys in TPM are non-exportable which is a very good thing and IMO the primary reason to use TPM at all.