RE: AS2-SMIME : has the certificate to be included inside thesignatu re?

Response or two in line.

	-----Original Message-----
	From: Paul V Ford-Hutchinson [mailto:[email protected]] 
	Sent: Thursday, June 05, 2003 9:02 AM
	To: Rishel,Wes
	Cc: [email protected]
	Subject: RE: AS2-SMIME : has the certificate to be included
inside thesignatu re?
	
	

	No , that's one of the main points of X.509 certificates. 
	
	[Unless you are discussing self-signed certificates (the X.509
equivalent of "trust me, because I say so - signed me")] 
	
	so ..... 
	
	Is there a published way for an AS-2 implementation to map the
"AS2-From" field to an X.509 DN ?  
	 
	Not in IETF spec. Maybe someone has profiled AS2 for some
community/vertical but I have not heard of one.
	 
	Or does AS2 assume that there is always some OOB mechanism for
establishing identity (AS2-To/From) to certificate mappings ?  
	 
	SMIME/CMS/PKCS7 has in its SignerInfo structure fields that
allow determination of the relevant signature used in producing the
signature.
	So the value for the AS2-From field is not involved in finding
the certificate. Actually, the AS2-From value should not be considered a
highly trusted piece of information-- no signature over it. Generally
spoofing would be a lot harder if you use SSL though. 
	
	If the former - who needs to bloat messages with certificates?  
	AS2 follows the CMS/PKCS7 approach on identifying the
certificate used in signing.  So you are right, cert chain can be
omitted.
	If the latter - why ?  
	 
	Not applicable. If there were a mapping, then people might
wonder what to do if the AS2-from value did not match up with the X.509
DN.
	Should we discard the whole thing? 
	 
	We avoid this. What we have now is that the signed info is what
counts only. So trust that the payload is OK if you accept the signature
as one that checks out with respect to a certificate that chains up to
one of your trust anchors (which will be itself if using self-signed
certs.) 
	 
	Dale 
	
	Paul
	--
	Paul Ford-Hutchinson :  eCommerce application security :
[email protected]
	MPT-6, IBM , PO Box 31, Birmingham Rd, Warwick, CV34 5JL +44
(0)1926 462005
	http://www.ford-hutchinson.com/~fh-1-pfh/ftps-ext.html
	
	
	
	
	"Rishel,Wes" <[email protected]> 
Sent by: [email protected] 

05/06/2003 15:23 


        
        To:        "Jess Sightler" <[email protected]>,
<[email protected]> 
        cc:        <[email protected]> 
        Subject:        RE: AS2-SMIME : has the certificate to be
included inside thesignatu re? 

       




	What is the benefit of sending the cert with the message? If you
truly want to authenticate the originator you have to acquire the cert
by independent, trusted means, don't you?
	
	-----Original Message-----
	From: [email protected]
	[mailto:[email protected]]On Behalf Of Jess
Sightler
	Sent: Thursday, June 05, 2003 6:36 AM
	To: [email protected]
	Cc: [email protected]
	Subject: Re: AS2-SMIME : has the certificate to be included
inside
	thesignatu re?
	
	
	
	I can't speak 100% from the spec on this, but I know that iSoft
makes
	sending the Certificate with a signature optional.
	
	Based on that, I believe that it is an option to not send the
cert.  I
	believe that sending the Cert would be a good practice, however.
	
	Thanks,
	Jess
	
	
	On Thu, 2003-06-05 at 09:58, [email protected] wrote:
	> Hello,
	>
	>
	>
	> I am new on this list - and I need your help.
	>
	>
	>
	> AS2: when sending a signed message (the original message which
can
	> also be signed, or a signed MDN), has the signer's certificate
to be
	> included inside of the signature MIME part?
	>
	> Is it mandatory or should AS2 compliant products accept both?
(signed
	> messages containing the cert, or not containing it, in which
case they
	> would try to find a certificate on the local key store etc.)
	>
	>
	>
	> Regards,
	>
	> -----------------------------------------
	> Ludan STOECKLE
	> DSI Groupe Casino - Etudes
	>
	> 04 77 45 48 01
	>
	> [email protected]
	> -----------------------------------------
	>
	>
	>
	>
	>
	>
	--
	=======================================
	Jess Sightler
	Senior Developer
	Exim Technologies
	131 Falls Street
	Greenville SC 29601
	Phone: 864-679-4651
	=======================================