Interesting idea. The Software Heritage project (https://www.softwareheritage.org/) has the goal of doing this for all software source code; perhaps they might be interested in extending that to binaries as well? That seems compatible with their goal of preservation.
Software Heritage looks excellent, but it sounds like the two projects may have different goals. It sounds like Software Heritage is focused on collecting, preserving, and sharing code (and, as you say, potentially compiled software), whereas codehash.db is focused on allowing people to securely authenticate it after they've obtained it through some other means.
