What would be great would be a stand-alone account manager, like a local Boincstats BAM! on your computer, so you'd be in charge of all your own keys.
It would be another "app" the user have to install. But what if we think a bit further. Imagine a Secure Boinc Manager which encapsulate the native BOINC Manager in a secure environment that uses the Project Manager interface from the Boinc Manager - like a virtual machine. It's open source. So instead of one App u install another app including Password Manager and multi machine remote management like boinc task. Than the dev has nearly unlimited possibilities.
Potential candidate software: https://www.projectatomic.io/