Is there a mechanism to use HTTPS to
preencrypt web pages so that they
are encrypted on the server (and so the
server does not have the keys to decrypt
them!)
Not using HTTPS per-se, but you can use SSL to encrypt files.
My initial constraints are that once the data
is put on the server that no one except for
the intended recipient could decrypt it,
including the original poster, server admin...
Or, to basically do with HTTP what GPG does with email. The original
poster would necessarily need to have access to the plaintext, as they
would need to encrypt it with the end-user's public keys (each of them
individually).
I'm not a mathematician, but it can't be wise to store multiple copies
of the same plaintext encrypted by the same cipher using different keys
.. much crypto has historically been broken that way.
~Mike.