[Mimedefang] patch to add blocking of encrypted email via uvscan

[Lucas Albers]

> Huh? Where does the passphrase come from? It can't be good encryption if
> the
> virus scanner can get into it.
>
> OTOH, if the encrypted payload is identical each time, then the scanner
> can
> recognize it without decrypting it. But then we don't care if the payload
> is
> encrypted, because we already know it's hostile without opening it.
Beats me.

Encrypt a file.
zip -e virus.zip virus.

Then clamscan|f-prot it (with unarchive option), and it will see the virus.
Uvscan will not.

--Luke