WDIFF

draft-ietf-pkix-logotypes-00.txt --> draft-ietf-pkix-logotypes-01.txt

PKIX Working Group S. Santesson (AddTrust)
INTERNET-DRAFT R. Housley (RSA Laboratories)
Expires January, August 2002 February 2002

Internet X.509 Public Key Infrastructure

Logotypes in X.509 certificates

<draft-ietf-pkix-logotypes-00.txt>

<draft-ietf-pkix-logotypes-01.txt>

Status of this Memo

This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.

Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that other
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The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt

The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.

Abstract

This document contains an initial outline of a standard for inclusion
of attaching
logotypes in to certificates. The draft includes background discussions
around different aspects of problems and solutions, forming a
starting point for the creation of a complete standard.

Please send comments on this document to the ietf-pkix@imc.org
mailing list.

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Table of Contents

1 Introduction ................................................. 3
1.1 Are human recognition concepts relevant ................... 4
1.2 Combination of verification techiques ..................... 5
2 Different types of logotypes in certificates.................. 5
3 Technical solutions .......................................... 6
3.1 General ....................................... 6
3.2 Type of certificates ...................................... 7
3.3 Logotype placement ........................................ 8
3.3.1 Qualifier .............................................. 8
3.3.2 Issuer and Subject Alt Names ........................... 8
3.3.3 New extension .......................................... 9
3.3.4 Conclusion ............................................. 10
4 Use in Clients ............................................... 10
5 Security considerations ...................................... 10
6 References ................................................... 12
7 Intellectual Property Right .................................. 12

Appendices

A. ASN.1 definitions ........................................... 13
B. Author Addresses ............................................ 13
C. Full Copyright Statement .................................... 13

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1 Rationale Introduction

The basic function of a certificate is to bind a public key to the
identity of an entity (subject). From a strict strictly technical viewpoint that would viewpoint,
this goal could be
satisfied achieved by just signing the identity of the subject
together with its public key. The However, the art of PKI have however has developed
certificates far beyond this functionality in order to meet the needs
from modern global networks and heterogeneous IT structures.

A primary

One driver of the evolution from simple certificate formats to more
complex structures is the need to distinguish between different
certificate concepts, defining everything from such as assurance level,
policies policies, appropriate
key usage, and procedures, fields of usage to name forms and semantics. form constraints. Before a relying party can make
an informed decision whether a particular certificate is trustworthy
and relevant for its intended usage, a large number of aspects of the certificate may have to be
processed.

All of these aspects of certificates do mainly concern systematic examined
from several different perspectives.

Systematic processing in order to deliver a distinct Yes or No answer is necessary to the
question determine whether the a particular
certificate match meets the predefined prerequisites and
thereby is regarded as appropriate for its an intended usage.
Even though these the information objects in certificates are appropriate
and effective for machine processing, they are poor instruments for a
corresponding human trust and recognition process.

The human mind prefer prefers to structure information into categories and
symbols. Complex Most humans associate complex structures of reality are encapsulated in with
easy recognizable logotypes and marks. The human trust process is Humans tend to a
smaller extent based on trust things
that they recognize from previous experiences. Humans may examine
information and to a greater extent based on
recognition and experience. confirm their initial reaction. Very few consumers
actually read all terms and conditions they accept when accepting a
service, instead they most commonly act in trust based on previous
experience and recognition.

A big part of this process is branding, where service branding. Service providers and product
vendors invest a lot of money and resources into creating a strong
relation between positive user experiences and easily recognizable
trademarks and logotypes.

This reality

Branding is also extends to the realm of concepts, services and
instruments for identification, ranging from ID-cards, passports and pervasive in identification instruments, including
identification cards, passports, driver's licenses to licenses, credit cards,
gasoline cards cards, and loyalty cards
etc, whose function is to cards. Identification instruments are
intended identify an entity either the holder as a particular person or as member of community, subscriber
community. The community may represent the subscribers of a service, etc. These concepts and
instruments of identification service
or any other group. Identification instruments, in physical form have in common the form,
commonly use logotypes and symbols, solely aimed to enhance human
recognition and trust in the underlying concept.

As identification instrument itself.

Since certificates play an equivalent role in electronic exchange, to
the use of physical ID's in physical exchange, some important
questions deserves closer attention in the investigation whether exchanges,
we examine the
use inclusion of logotypes in certificates are relevant or not. certificates.

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1.1 Are human recognition concepts relevant in electronic forms of
identification? relevant?

The answer depends on the answer to the fundamental underlying
question whether manner in which certiciates are used. Are
certificates should be visible or invisible to human
users and if users? Will the
certificates will be used in open environments. environments?

If certificates are to be used in open environments and in
applications that brings the user in conscious contact with the
result of a certificate based certificate-based identification process, then human
recognition of concept is highly relevant, and it may even be a necessity.

Examples of sucha applications of these types are: include:

- Web server identification where a user identifies the owner of the
web site.

- Peer entity e-mail exchange (in in B2B, B2C B2C, and private communication
exchange). communications.

- Other profession information processing and message exchange
systems (such as Exchange of medical records handling, records, and system for medical
prescriptions) prescriptions.

- Unstructured e-business applications (i.e. non EDI applications) non-EDI applications).

Most applications that offer provide the human user with an opportunity to view
the result results of a
certificate based successful certificate-based identification process do this by allowing process.
When the user takes the steps necessary to view these results, the certificate
user is presented with a view of the identified entity. a certificate. This solution has
however two major problems.

1) The function to view a certificate is often rather hard to find
for a non-technical user.

2) The presentation of the certificate is rather technical and not
user friendly. Further it contains no graphic symbols and
logotypes to enhance human recognition.

Many investigations have shown that users in current of today's applications
don't "click" do
not take the steps necessary to view certificates. There is however a distinct
possibility that this fact is This could be due
to how poor user interfaces. However, many applications are structured
and due to very poor user interfaces, much more than a proof that
hide certificates should from users. The application designers do not be exposed want
to expose certificates to users at all.

1.2 Combination of verification techiques

Can the concepts of systematic certification path verification processing and
human recognition be combined in any sensible manner?

Systematic verification of a certificate (including systematic
verification of all certificates in the certification path built up to a trusted
root) will at most give a user/system either the result "Verified
according to defined policy" or "Failed verification determines whether the
end-entity certificate can be verified according to defined policy". policy.

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The systematic processing has in this case provided the user/system
with provides assurance that the certificate is
a valid document, but document. It does not who indicate whether the subject of the certificate in fact is or what that entity is
entitled/trusted
entitled to do. The latter is any particular information, or whether the task of an subject ought
to be trusted to perform a particular service. These are access
control
function, which function decisions. Some access control decisions may again be made
by a systematic process or in fact a human
recognition process, all dependent but others, depending on the application context.

So in
context, involve the human user.

In some situations a situations, the human person will be user is the sole handler of the post
certification path verification process of identification and authorization. It may
in access control decisions. In the end,
the end be a human decision to accept, act on will decide whether or not to accept an executable email
attachment, to release
information personal information, or follow the
instructions displayed by a web browser. As we have seen, this
decision will often be based on who and/or what the opponent is recognition and whom he/she
represents. previous experience.

The conclusion is that the distinction between systematic processing and human processing
is rather straightforward and clear and has the
character of being complementary rather than interfering. straightforward. They can be complementary. While the
systematic process is focused on certification path processing construction and
verification, the human acceptance process is focused on identification, recognition
and authorization.

Some interference related previous experience.

There are some situations where systematic processing and human
processing interfer with each other. These issues do however exist as handled under security
considerations are discussed in
the Security Considerations section.

1.3 Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [STDWORDS].

2 Different types of logotypes in certificates

This report recommends standardized supported usage draft suggests standardization of 3 types of
logotypes in certificates. logotype types.

1) Concept logotype
2) Issuer organization logotype
3) Subject organization logotype

The concept logotype - is the general mark for a service concept for
entity identification and certificate issuance. Many issuers may use
the concept logotypes to co-brand with a global concept in order to
gain global recognition of its local service provision. This type of
concept branding is very common in credit card business where local
independent card issuers issue cards within a globally branded
concept (such as VISA and. MasterCard etc.). and MasterCard).

Issuer organization logotype - is a logotype representing the

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organization identified as part of the issuer name in the
certificate.

Subject organization logotype - is a logotype representing the
organization identified in the subject name in the certificate.

3 Technical solutions solution

3.1 General
A general conclusion is that there

There is no need to include any significantly increase the size of the
certificate by including logotype image data in a certificate.

The same function may be achieved by including a hash of the logotype
image in the certificate together with
Rather, a URI/ URL URI identifying the location of to the logotype image data. and a
one-way hash of the referenced data is included in the certificate.

Applications may enhance processing and off-line functionality by
cashing logotype data.

Other minor aspects are:
- that the URL also

The URI defines the file format for the image data.
- that the logotype image.

The solution includes algorithm information about explicitly identifies the
employed one-way hash algorithm. function
employed.

The initially proposed general structure for logotype data is:

LogotypeData ::= SEQUENCE {
typeOfLogotype TypeOflogotype, TypeOfLogotype,
hashAlgorithm AlgorithmIdentifier,
logotypeDataHash OCTET STRING,
sourceDataUri
logotypeDataUri IA5String OPTIONAL }

TypeOflogotype ::= CHOICE {
predefinedLogotypeType PredefinedLogotypeType,
LogotypeTypeID
logotypeTypeID OBJECT IDENTIFIER }

PredefinedLogotypeType ::= INTEGER {
subject-organization-logotype(0),
issuer-organization-logotype(1)
concept-logotype(2)}
(subject-organization-logotype|
issuer-organization-logotype|
concept-logotype,...)
concept-logotype(2) }

The predefined logotype types are are:

subject-organization-logotype, if used, SHALL be used to include a
logotype of the subject organization. The logotype SHALL be
consistent with, and require the presence of, an organization name
stored in the organization attribute in the subject field.

issuer-organization-logotype, if used, SHALL be used to include a

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logotype of the issuer organization. The logotype SHALL be consistent
with, and require the presence of, an organization name stored in the
organization attribute in the issuer field.

Concept-logotype, if used, SHALL be used to include a logotype
representing the concept under which the issuer claims to issue this
certificate.

A concept may be shared within a network of CA certification authority
(CA) services, provided by one or several independent CA
organizations.

The relationship between the subject organization and the subject
organization logotype and the relationship between the issuer and
either the issuer organization logotype or the concept logotype, are
relationships claimed by the issuer. The policy under which the
issuer checks these logotypes is outside the scope of this standard.

Any URI pointing to a file containing the logotype data SHALL include
a file extension defining the image file format (i.e. .GIF, .TIF, .JPG
etc.)
.TIFF, .JPG, .JPEG, etc.).

3.2 Type of certificates

Logotypes according to the present model may be used in 3 types of
certificates:

- Selfsigned Self-signed CA certificates (root certificates)
- Intermediate CA certificates
- End entity End-entity certificates

A reason to constrain inclusion of logotypes to end entity end-entity
certificates would be to exclude the aspect of logotypes from path
processing issues, where a path validating service would want to
check consistency of logotypes in a chain. certification path.

However, as discussed in the rationale, above, logotypes are not aimed to be part of
certification path validation or any type of systematic processing
since its sole purpose is to enhance display of a single particular
certificate to a user regardless of its position or function in a
path construct.

The conclusions are:
-
certification path.

Logotypes should not be an active component in path processing.
- Logotypes processing, and
logotypes should be allowed in all types of certificates, by at the
choice
discretion of the CA.

3.2 Place of inclusion

3.3 Logotype placement

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So far far, there has have been 3 solutions discussed regarding where to store the placement
of the logotype data in certificates.

- Inclusion in a policy qualifier
- Inclusion in Issuer and Subject Alternative names extensions
- Inclusion in a separate private extension

3.2.1

3.3.1 Qualifier

This solution would include logotype data as a newly defined policy
qualifier.

Pros:

- This solution provides a mechanism to directly control the use and
display of logotypes under a particular policy

Cons:

- Current practice and standards (RFC 2459) recommends against use of
qualifiers

- This is generally considered to be a major hack and stretch of
semantics, since this type of data doesn't qualify a policy in any
way.

3.2.2

3.3.2 Issuer and Subject Alt Names

This solution would use the other name form to include;

- issuer and concept logotypes in the issuer alt name extension; and
and,
- subject organization logo in the subject alt name extension.

Pros:

- This mechanism could possibly enable cross certifying CAs to deny
any subordinate CA the right to include logotypes in descending end
entity certificates by listing the logotypes name form in
excludedSubtrees.

Cons:

- Logotypes are not a name form and can't should not be treated as a
displayable name.

- It is generally understood that it should be possible to apply
general name constraint mechanisms (as described in RFC 2459 as

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well as son of RFC 2459) son-of-2459) to names in the subject and issuer alt name ext.
extension. This is however not possible to do with logotypes due to
it's non-name since it is
not a name form.

- This split storage of logotype data into 2 different locations,
which may make life worse for applications with no interest in
logotypes.

- It is generally agreed that inclusion of logotype data by no means
should be regarded as critical data. This may interfere with the
criticality policy of the alt name extensions, especially if the
certificate has no attributes in the subject field, forcing the
subject alt name to be set to critical.

- This usage would possibly interfere with the resolution between
IETF and ITU-T regarding use of permitted subtrees.

- Since this solution may break current implementations it would
possibly block adoption of logotypes.

3.2.3

3.3.3 New extension
This solution would create a new private (non critical) extension.

logotypeInfo EXTENSION ::= {
SYNTAX LogotypeSyntax
IDENTIFIED BY id-pe-logotypeInfo }

id-pe-logotypeInfo OBJECT IDENTIFIER ::= {id-pe XX}

LogotypeSyntax ::= SEQUENCE OF LogotypeData

Pros:

- This is the cleanest solution.

- Do not impact on legacy implementations.

Cons:

- This solution activates the issue whether this extension may be
abused by a CA who include logotypes (in EE certificates) that
violates the intention of a name constraints set by a chaining CA.
This issue is addressed in the security consideration section
below.

3.2.4

3.3.4 Conclusion
The criteria for selecting a solution

We must be that it doesn't not destroy current structures and doesn't structures. We must not create problems
and confusion.

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Only the private extension solution meets this criterion and satisfies both of these desires.
Therefore, the private extension should
therefore be selected.

4 Use in Clients

All PKI implementations require that relying party software to have some
mechanism to determine whether a trusted CA issues a particular
certificate. This is an issue for certification path validation of the certificate
chain from a trusted root, validation,
including consistent policy and name checking.

After passing this process, a certificatin path is successfully validated, the general assumption replying
party must be trust the information that the CA is trusted to certify the information carried includes in the
certificate, including any certificate
extensions, given that the extensions. The client decides
software can choose to make use that information.
The assumption is regarded as general due to of such information, or the fact that current client
software can ignore it. Current standards do not provide any
mechanism for cross-certifying CAs to constrain subordinate CAs from
including private extensions (see security considerations).

Consequently, if relying party software accepts a CA, then it should
be prepared to (unquestioningly) display the associated logos to its
human user, given that it is configured to do so.

5 Security considerations

Logotypes are even worse than names regarding the possibility to
securely and accurately define what is, and what is not, a legitimate
logotype of an organization. There is a whole legal structure around
this issue that doesn't need repetition in this document.

As logotypes are hard (and sometimes expensive) to verify, this
increases the possibility of errors related to falsely assigning
wrong logotypes to organizations.

This is however not a new issue for electronic identification
instruments, but rather a well known problem that instruments.
It is already dealt with in numerous of similar situations in the
physical world, including physical employment ID employee identification cards. Secondly
Secondly, there are situations where identification of logotypes is
rather simple and straight
forward, straightforward, such as logotypes for well-known
industries and institutes. These issues should not be stopping stop those service
providers wanting who want to go into the issue of logotypes from doing so, where this is relevant.

The

There is a new problem related to electronic identification
instruments in the form of certificates are however that certificate chains certificates. Certification paths may
impose constraints that are systematically checked in during
certification path processing
algorithms, which processing, which, in theory theory, may be violated by
logotypes.

Path

Certification path processing algorithms does not, should not, and will never be

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able to control if any the inclusion of logotype included data in any certificate violates
any such constraints. I.e. certificates. That
is, a chaining parent CA may constraint subordinate CAs to only issue
certificates to end entities end-entities within a limited name space. A
potentially bad CA may comply with this name constraint in
included names but may and still
include a subject organization logotype
that gives a relying party the impression that the subject is part of
another organization or being part of a group of companies, which
exceeds the freedom in the name constraint. logotype. The problem here is that the chaining parent CA has no
means of preventing
this logotype data inclusion since there is no
mechanism to prevent subordinate CAs from including new extensions.

This is however nothing not unique with a to the logotype extension, but a
general problem with X.509. The fact is that a chaining CA has no
absolute extension. No technical control over means are
provides for constraining subordinate CAs behaviour with
respect to inclusion of new private extensions that may violate any
policy or constraint set in a chaining certificate. particular certificate
profile.

The controls available to a chaining parent CA to protect itself against bad from rogue
subordinate CAs are mainly: nontechnical. They include:

- Contractual agreements of suitable behaviour, including
terms of liability and severance pay in case of material
breach.

- Control mechanisms and procedures to monitor and
follow-up behaviour of subordinate CAs CAs.

- Use of certificate policies to declare assurance level
of logotype data as well as to guide applications on how
to treat and display logotypes.

- Use of revocation functions to revoke any misbehaving CA.

This may not be an issue that can cannot be given an easy and absolute technical solution.
Maybe the correct response is to surrender to the fact that involved
parties must settle some aspects of PKI outside the scope of
technical controls, and to clearly identify and communicate the
associated risks risks.

6 References

[STDWORDS] S. Bradner, "Key words for use in RFCs to Indicate
Requirement Levels", March 1997.

[RFC 2459] R. Housley, W. Ford, W. Polk, and D.Solo, "Internet X.509
Public Key Infrastructure: Certificate and CRL Profile", January
1999.

7 Intellectual Property Rights

The IETF takes no position regarding the validity or scope of any
intellectual property or other rights that might be claimed to
pertain to the implementation or use of the technology described in

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this document or the extent to which any license under such rights
might or might not be available; neither does it represent that it
has made any effort to identify any such rights. Information on the
IETF's procedures with that. respect to rights in standards-track and
standards related documentation can be found in BCP-11. Copies of
claims of rights made available for publication and any assurances of
licenses to be made available, or the result of an attempt made to
obtain ageneral license or permission for the use of such proprietary
rights by implementors or users of this specification can be obtained
from the IETF Secretariat.

The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights which may cover technology that may be required to practice
this standard. Please address the information to the IETF Executive
Director.

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APPENDICES

A. ASN.1 definitions

TBD

B. Author Addresses

Stefan Santesson
AddTrust AB
P.O. Box 465
S-201 24 Malmoe
Sweden
stefan@addtrust.com

Russell Housley
RSA Laboratories
918 Spring Knoll Drive
Herndon, VA 20170
USA
rhousley@rsasecurity.com

C. Full Copyright Statement

This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph
are included on all such copies and derivative works. In addition,
the ASN.1 modules presented in Appendices A and B may be used in
whole or in part without inclusion of the copyright notice.
However, this document itself may not be modified in any way, such
as by removing the copyright notice or references to the Internet
Society or other Internet organizations, except as needed for the
purpose of developing Internet standards in which case the
procedures for copyrights defined in the Internet Standards process
shall be followed, or as required to translate it into languages
other than English.

The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assigns. This
document and the information contained herein is provided on an "AS

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IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK
FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN
WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

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