sftp-server file encryption

[Jürgen Weber]

Hi,

I wonder if sftp-server could encrypt files before writing to disc. This
would make sshd a poor man's alternative for an encrypting filesystem on a
server.

How to get the crypto key from a client to be used by sftp-server? Upload
the key to a /well/defined/key.pem virtual location? Or can you access the
ssh client certificate from sftp-server?

Can sftp-server call a filter?
Or would one write a sftp-server replacement?

Juergen