Subject: Logos: 04: ~editorial comments

From: "Manger, James H" <[email-masked]>
Date: Thu, 5 Sep 2002 19:27:18 +1000

1.
The URI fields (imageURI, audioURI and refStructURI) are all a SEQUENCE OF
IA5String.  There is no mention about why multiple URIs can be included or
how they should be handled.  I am guessing that they are supposed to be
alternative URIs for exactly the same item.  Consequently, a client can use
any URI from the sequence.  If a URI fails, the client should try another.
If so, a sentence to that affect would help.

2.
Renaming the imageFormat and audioFormat fields to imageSubtype and
audioSubtype should make it clearer (in code, not just an ASN.1 comment)
that the fields hold MIME subtypes.

3.
Community, issuer, subject & loyalty types tell you what a logo is related
to.  Whether a logo can be used as a background image is a different style
of information.  Instead of defining id-logo-background, how about including
a flag in LogotypeImageInfo.
	LogotypeImageInfo ::= SEQUENCE {
		...
		background	BOOLEAN DEFAULT FALSE }

	If background is true it indicates that the image is appropriate
	for use as a background image for other certificate details, in
which case
	it MUST allow black text placed over the image to be clearly
readable.

4.
That logos can - to some degree - circumvent name constraints is understood
and explained in the Security considerations section.  A client can take
steps to minimise this risk by, for instance, consistently displaying logos
in a separate, clearly delineated, section of the screen -- so at least a
careful user would not be fooled.  Using a logo as a background image seems
to make this much harder -- now the client would need to, say, make the logo
wobble for a careful user to be able to distinguish what come from the logo
and what is generated by the (trusted) client.  Perhaps background images
should not be supported.

> ----------
> From:	[email-masked] [SMTP:[email-masked]]
> Sent:	Wednesday, 4 September 2002 9:57 pm
> 
> 	Title		: Internet X.509 Public Key Infrastructure Logotypes
> in X.509 certificates
> 	Author(s)	: S. Santesson, R. Housley, T. Freeman
> 	Filename	: draft-ietf-pkix-logotypes-04.txt
> 	Pages		: 19
> 	Date		: 2002-9-3
> 	
> This document specifies a certificate extension for including logotypes in
> public key certificates and attribute certificates.
> 
> http://www.ietf.org/internet-drafts/draft-ietf-pkix-logotypes-04.txt
>

---

From: "Housley, Russ" <[email-masked]>
Date: Thu, 12 Sep 2002 12:15:04 -0400

James:

Thanks for your careful reading of the document.  These are all good 
comments, and I agree with all of them except the background.  I do not 
think that you proposal allows the inclusion of both a foreground and a 
background logotypes.

Russ