Oh,it's so simple!"as" here is a noun,it means "Roman copper coin" [its plural form is "asses"] Your sentence is right and it is a passive voice! (you can find it easily in any Oxfort dictionary)

It means that the fact or subject matter was known by everyone.

as here means LIKE like (it) is known to all.. google search or googling, as it is known to all... hope this helps :)