Zitat von Martijn Brinkers <[email protected]>:

> On 10/31/2011 07:31 PM, Stefan Michael Guenther wrote:
>> Hello,
>>
>> let' s think of the following scenario:
>>
>> Our client has 5 employees and uses Djigzo
>>
>> E1, E2, E3, E4, E5
>>
>> His business contact hat 5 employess, too, but doesn't use an  
>> encryption gateway (encryption is performed by the email client) :
>>
>> e1, e2, e3, e4, 5
>>
>> E1 exchanges emails with e1, e3, e5
>> E2 exchanges emails with e1, e2, e3
>> E3 echanges emails with e2,e3,e5
>> and so on.
>>
>> Is it really necessary, that the IT admin on the other side runs  
>> around and distributes all required user certificates?
>> Or is it possible to have a wildcard domain certificate, which only  
>> has to be installed once? The web interface accepts "*@abc.com" as  
>> an "email address".
>>
>> The problem in our real world scenario is, that our client has 250  
>> employees and the other side is a governmental organization with  
>> some 3000+ employees.
>> Therefore, running around and distributing certifocates  would only  
>> be an option for marathon runners. ;-))
>
> The recipients can in principle use just one certificate to decrypt
> incoming email. Most (if not all) S/MIME email clients will use any
> available certificate (with private key) to decrypt the message with.
> So, from Djigzo gateway -> recipient(s) this would work since with the
> Djigzo gateway you can select a certificate for a particular domain. All
> email sent to that domain will then be encrypted with that particular
> domain certificate.

But this will require to install this particular certificate on any  
recipient mail client, no?

> Although the recipient can decrypt the message, with most S/MIME email
> clients the recipient cannot however reply encrypted. Outlook for
> example refuses to use a certificate with a non-matching email address
> (although I haven't tried a wildcard address). So, if the recipient need
> to reply, the recipient need it's own valid and trusted certificate with
> matching email address. This is a shortcoming of the email clients in my
> opinion. S/MIME encryption would have been a lot easier if the email
> clients would allow more manual overrides.

That is the problem indeed. Mail clients rely to a big extend on  
matching mail addresses, so this would not work well. Even if it would  
be configurable, it does not make a big difference to configure  
"something" on all clients versus to install a matchnig  
certificate/key on every client.

After all that's why the S/MIME Gateways were invented ;-)

> About distributing certificates, there are ways to make it somewhat
> easier to distribute a lot of client certificates. However, if a lot of
> client certificates are required, it might be *a lot* easier for them to
> install a gateway as well (unless client side encryption is a requirement).

That said if the recipient are a german governmental organization they  
nearly for sure have a S/MIME Gateway, you only have to convince them  
to use it.

Regards

Andreas


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