Keep in mind you're also ensuring the integrity of the document is kept and the user has (to some degree) a good idea that the document is actually from you. Co

Keep in mind you're also ensuring the integrity of the document is kept and the user has (to some degree) a good idea that the document is actually from you. Confidentiality is only one aspect. I think a couple of ISPs in the US were injecting ads/content at one point into pages served over HTTP.