@lnxw48 owncloud supports some encryption, by the server app though, so not meeting your requirements. The problem I had with it though is, it generates the encryption key from the user password. And if a user changes password reencrypts the data. (Or the user master enc key). So far so good. But if you are using a third party authentication source (eg LDAP) owncloud never sees the pwd change, so it becomes impossible to decrypt your data