In the end signal and imessage (with backups off) provide roughly the same claimed guarantee here (on a technical level at least). They both promise not to secr

In the end signal and imessage (with backups off) provide roughly the same claimed guarantee here (on a technical level at least). They both promise not to secretly inject additional client keys into your account, (to at least obtain a forward-operating 'wire tap'), but the software you're running is all opaque and could certainly do so if they wanted (or were compelled) to.