Well, what shall I say: thanks a lot! I was somehow confused about the downloads, lost somewhere on [that github.io page](https://utelle.github.io/SQLite3MultipleCiphers/) and on the [System.Data.SQLite](http://system.data.sqlite.org/index.html/doc/trunk/www/downloads.wiki) pages. The releases on their Github pages indeed have sqlite3-32/64.dll's with that `sqlite3_user_authenticate()` method.