New answers tagged play-by-post
Hamate meets most of your requirements, if in a roundabout way. A dice log can be opened per-player or I believe for a campaign, with registered users being able to roll in the log and keep records. Unregistered users cannot access the dice logs but can make individual rolls with verification numbers a GM can use to make sure the rolls are legitimate. ...
Myth-Weavers is an RPG Play-by-Post site which meets all but one of your listed criteria. With wide support for a variety of game systems and dice mechanics, this seems like your best option. In addition to a robust built-in dice roller, it also provides everything else you would need for a PbP game: message board, character sheets, and even has some nifty ...
A guy I know has this site. It might not be as good and versatile as the invisible castle, but it's open source and you can run your own version, where only your campaign's rolls are stored (and it will never go down as long as you keep it operative yourself).
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