please explain the exact making of the digest
See https://github.com/kfogel/OneTime/issues/18.
(OneTime has moved over here to code.librehq.com GitLab, but there are still some open issue tickets and PRs over at GitHub. I haven't ported them all over; we'll just improvisatorily refer to them from here until they're closed. New tickets should be filed here, of course.)