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RE: I-D ACTION:draft-ietf-smime-escertid-01.txt

2006-08-15 11:26:01


-----Original Message-----
From: owner-ietf-smime(_at_)mail(_dot_)imc(_dot_)org 
[mailto:owner-ietf-smime(_at_)mail(_dot_)imc(_dot_)org] On Behalf Of Denis 
Sent: Wednesday, May 03, 2006 4:55 PM
To: ietf-smime(_at_)imc(_dot_)org
Subject: Re: I-D ACTION:draft-ietf-smime-escertid-01.txt

I have several problems with draft-ietf-smime-escertid-01.txt.

In RFC 2634, we have section "5.4 called Signing Certificate 
Attribute Definition"

The proposal is to add a section 5.4.1 to define the v2 
version first (!) and then the current version (with SHA-1). 
This should be done in the reverse way:

 - first a section 5.4.1 to define the current version (with SHA-1),
 - then a section 5.4.2 to define the v2 version.

I prefer the existing ordering.  I would rather have the items that people
are to be using occur first and then obsolete items rather than the other
way around.  I have not changed this.

After this restructuring, I have some problems with the text itself :

Issue 1 (page 4):

   "Applications SHOULD recognize both attributes as long as
   they consider SHA-1 to be sufficiently descriminating".

"descriminating" is not crystal clear for me. Would it be 
possible to have the same idea expressed using a different wording ?


Issue 2 (pages 4 & 5):

There is a duplication of the same paragraph (one is enough):

   "The signing certificate attribute is designed to prevent 
the simple
   substitution and re-issue attacks, and to allow for a 
restricted set
   of authorization certificates to be used in verifying a signature".

I believe that not having any descriptive text at these locations and
jumping directly into the ASN.1 to be a poor choice.  I have not changed

Issue 3 (page 7):

   "The issuer/serial number pair would therefore normally be 
   to identify the correct signing certificate.  (This 
assumes the same 
   issuer name is not re-used from the set of trust anchors.)"

The assumption between the parenthesis is insufficient to 
correctly identify the correct signing certificate. The 
sentence needs to be changed.

I do not understand your statement.  If the statement in parenthesis is
true, then it is sufficent.  If the statement in the parenthesis is not
true, then issuer/serial number is not sufficent.  Please re-read the text
and explain better what your problem is.

Issue 4 (page 7):

   "In the cases
   where the issuer/serial number pair is not used in the sid or the
   issuer/serial number need to be signed, they should be 
placed in the
   issuerSerial field of the ESSCertIDv2 structure."

The issuer/serial number pair can be used in the sid, but 
since it is unsigned, it is insufficient to correctly 
identify the correct signing certificate. 
So this rational is incorrect. The sentence needs to be changed.

I have no idea what you are trying to state here.  My sentence and your
comment do not seem to be coming from the same context.  Please re-read the

Finally, I would propose that the next draft proposes a 
global replacement 
for section 5.4 to make sure that the whole section is consistent 
(and that the text in it is not redondant).

I can understand your concern, however I believe that the current layout is
better and more explicit for the RFC editor.





A New Internet-Draft is available from the on-line 
Internet-Drafts directories.
This draft is a work item of the S/MIME Mail Security 
Working Group of the IETF.

    Title           : ESS Update: Adding CertID Algorithm Agility
    Author(s)       : J. Schaad
    Filename        : draft-ietf-smime-escertid-01.txt
    Pages           : 18
    Date            : 2006-4-18
In the original Enhanced Security Services for S/MIME draft, a
structure for cryptographically linking the certificate to be used in
validation with the signature was introduced, this structure was
hardwired to use SHA-1.  This document allows for the structure to
have algorithm agility and defines new attributes to deal with the

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Denis Pinkas

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