Digital signed mail- certificate issuing

[Jeffrey Goldberg]

On Apr 25, 2007, at 11:10 AM, David Southwell wrote:

> Can anyone please tell me the simplest way I can issue my customers  
> a means of
> digitally signing emails they transmit to us via our server. I need  
> the
> chosen method to be compatible with most popular email clients and  
> popular
> webmail services.

As someone said, PGP and S/MIME are really the two choices.  Neither  
will be simple enough to go smoothly with all of your users,  
particular your webmail users.  Both involve understanding some  
apparently tricky concepts, although your users (but not you) can be  
spared from many of them.  Particularly if you wish to issue  
certificates (either client certificates or a self-signed server  
certificate) you need to develop a good understanding of how things  
are supposed to work.

> Every customer has their identity and email addresses stored on our  
> mysql
> database.
>
> Essentially my target is , as far as possible, to ensure that emails
> purporting to come from my customers are indeed from them and noone  
> else.

Do you need to know that it really is from such and such person, or  
can you get by with knowing that it really is from such and such  
email address?  If the latter will be enough, then you can use the  
same sort of confirmation mechanism that is used by mailing list  
management systems.  Simply require a response sent to a confirmation  
request sent to the email address you are trying to authenticate.

Also, why does this have to be an email based system instead of a web  
based one?  For the latter users can authenticate with a simple  
username and password.

-j

-- 
Jeffrey Goldberg                        http://www.goldmark.org/jeff/