RE: [pki-tc] Extranet S/MIME?

["Skyberg, David" <dskyberg@rsasecurity.com>]

Two comments.  First, exchanging keys by sending signed emails only
works in single key systems.  For enterprises, I would recommend a dual
key system so that encryption keys can be escrowed to safeguard the
availability of corporate IP.

Second, you really need to check the IT security constraints of the
partner enterprises.  Some enterprises do not allow encrypted email
through because of the obvious security risks.  See Anders' email for
ways around that issue that do not entail deploying PKI to the end user.

> -----Original Message-----
> From: Arshad Noor [mailto:arshad.noor@strongauth.com]
> Sent: Wednesday, January 05, 2005 6:12 PM
> To: licather@wellsfargo.com
> Cc: pki-tc@lists.oasis-open.org
> Subject: Re: [pki-tc] Extranet S/MIME?
> 
> Catherine,
> 
> Encryption in S/MIME works counter-intuitively to what one expects -
> the decryption of encrypted S/MIME messages does not require the
> sender to have a digital certificate at all (he/she does need to
> have the RECIPIENT's certificate though, to encrypt the message in
> the first place).  The recipient need only have the private key to
> their encryption certificate to decrypt the S/MIME contents.
> 
> If your goal is only encrypted S/MIME, then you do need to setup a
> repository (typically, an LDAP directory) where the encryption cert
> of the recipient is available to senders.  If setting up such a
> repository is not feasible, an alternate way to ensure that senders
> have the recipients' encryption certificate is to have the recipients
> send a digitally signed e-mail to all senders.  This automatically
> sends the the signers' digital certificates in the S/MIME object.
> Compliant S/MIME tools - such as Netscape's Messenger, Outlook
> Express, (haven't tested Thunderbird yet - but will probably work)
> will automatically import the senders' digital certificates into the
> local address book.
> 
> The next time the sender wants to send the recipient an encrypted
> message, the recipients' encryption cert will already be available
> to them locally to perform the encryption, thus obviating the need
> to access a repository for the encryption cert.
> 
> Hope that helps.
> 
> Arshad Noor
> StrongAuth, Inc.
> 
> licather@wellsfargo.com wrote:
> > Hi All,
> >
> >
> >
> > I'm seeking expert opinions and recommendations how to support
S/MIME
> > communications in an extranet. Specially, decrypting an encrypted
email
> > from another company, i.e., the recipient needs to get hold of the
> > certificate of the email author's. Does that mean, there needs to be
an
> > extranet directory service to facilitate obtaining certificates? If
not,
> > what service needs to be setup to facilitate that?
> >
> >
> >
> > Thank you in advance,
> >
> > Catherine Li
> >
> > CAST PKI Development
> >
> > Wells Fargo Services
> >
> > Office:   415.243.6228
> >
> > Fax:      415.975.6780
> >
> > MAC:    A0186-056
> >
> > Email:   licather@wellsfargo.com
> >
> >
> >
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> 
> 
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