< draft-ietf-pkix-logotypes-01.txt		draft-ietf-pkix-logotypes-02.txt >
	PKIX Working Group S. Santesson (AddTrust)		PKIX Working Group S. Santesson (AddTrust)
	INTERNET-DRAFT R. Housley (RSA Laboratories)		INTERNET-DRAFT R. Housley (RSA Laboratories)
	Expires August 2002 February 2002		Expires August 2002 T. Freeman (Microsoft)
			April 2002
	Internet X.509 Public Key Infrastructure		Internet X.509 Public Key Infrastructure
	Logotypes in X.509 certificates		Logotypes in X.509 certificates
	<draft-ietf-pkix-logotypes-01.txt>		<draft-ietf-pkix-logotypes-02.txt>
	Status of this Memo		Status of this Memo
	This document is an Internet-Draft and is in full conformance with		This document is an Internet-Draft and is in full conformance with
	all provisions of Section 10 of RFC2026.		all provisions of Section 10 of RFC2026.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF), its areas, and its working groups. Note that other		Task Force (IETF), its areas, and its working groups. Note that other
	groups may also distribute working documents as Internet-Drafts.		groups may also distribute working documents as Internet-Drafts.
	skipping to change at page 1, line 37 ¶		skipping to change at page 1, line 38 ¶
	The list of current Internet-Drafts can be accessed at		The list of current Internet-Drafts can be accessed at
	http://www.ietf.org/ietf/1id-abstracts.txt		http://www.ietf.org/ietf/1id-abstracts.txt
	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html.		http://www.ietf.org/shadow.html.
	Copyright (C) The Internet Society (2002). All Rights Reserved.		Copyright (C) The Internet Society (2002). All Rights Reserved.
	Abstract		Abstract
	This document contains an initial outline of a standard for attaching		This document specifies a certificate extension for including
	logotypes to certificates. The draft includes background discussions		logotypes in public key certificates and attribute certificates.
	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		Please send comments on this document to the ietf-pkix@imc.org
	mailing list.		mailing list.
	Table of Contents		Table of Contents
	1 Introduction ................................................. 3		1 Introduction ................................................. 3
	1.1 Are human recognition concepts relevant ................... 4		1.1 Certificate-based Identification .......................... 4
	1.2 Combination of verification techiques ..................... 5		1.2 Selection of Certificates ................................. 4
	2 Different types of logotypes in certificates.................. 5		1.3 Combination of Verification Techniques .................... 5
	3 Technical solutions .......................................... 6		1.4 Terminology ............................................... 6
	3.1 General ....................................... 6		2 Different types of logotypes in Certificates ................. 6
	3.2 Type of certificates ...................................... 7		3 Image formats ................................................ 6
	3.3 Logotype placement ........................................ 8		4 Logotype extension ........................................... 7
	3.3.1 Qualifier .............................................. 8		5 Type of certificates ......................................... 9
	3.3.2 Issuer and Subject Alt Names ........................... 8		6 Use in Clients ............................................... 9
	3.3.3 New extension .......................................... 9		7 Security considerations ...................................... 10
	3.3.4 Conclusion ............................................. 10		8 References ................................................... 11
	4 Use in Clients ............................................... 10		9 Intellectual Property Rights ................................. 12
	5 Security considerations ...................................... 10
	6 References ................................................... 12
	7 Intellectual Property Right .................................. 12
	Appendices		Appendices
	A. ASN.1 definitions ........................................... 13		A. ASN.1 definitions ........................................... 13
	B. Author Addresses ............................................ 13		B. Logotype placement .......................................... 13
	C. Full Copyright Statement .................................... 13		B.1 Qualifier ................................................. 13
			B.2 Issuer and Subject Alt Names .............................. 13
			B.3 New extension ............................................. 14
			B.4 Conclusion ................................................ 14
			C. Author Addresses ............................................ 15
			D. Full Copyright Statement .................................... 16
	1 Introduction		1. Introduction
	The basic function of a certificate is to bind a public key to the		The basic function of a certificate is to bind a public key to the
	identity of an entity (subject). From a strictly technical viewpoint,		identity of an entity (the subject). From a strictly technical
	this goal could be achieved by signing the identity of the subject		viewpoint, this goal could be achieved by signing the identity of the
	together with its public key. However, the art of PKI has developed		subject together with its public key. However, the art of PKI has
	certificates far beyond this functionality in order to meet the needs		developed certificates far beyond this functionality in order to meet
	from modern global networks and heterogeneous IT structures.		the needs of modern global networks and heterogeneous IT structures.
	One driver of the evolution from simple certificate formats to more		Certificate users must be able to determine certificate policies,
	complex structures is the need to distinguish between different		appropriate key usage, assurance level, and name form constraints.
	certificate concepts, such as assurance level, policies, appropriate		Before a relying party can make an informed decision whether a
	key usage, and name form constraints. Before a relying party can make		particular certificate is trustworthy and relevant for its intended
	an informed decision whether a particular certificate is trustworthy		usage, a certificate may be examined from several different
	and relevant for its intended usage, a certificate may be examined		perspectives.
	from several different perspectives.
	Systematic processing is necessary to determine whether a particular		Systematic processing is necessary to determine whether a particular
	certificate meets the predefined prerequisites for an intended usage.		certificate meets the predefined prerequisites for an intended usage.
	Even though the information objects in certificates are appropriate		Much of the information contained in certificates is appropriate and
	and effective for machine processing, they are poor instruments for a		effective for machine processing; however, this information is not
	corresponding human trust and recognition process.		suitable for a corresponding human trust and recognition process.
	The human prefers to structure information into categories and		Humans prefer to structure information into categories and symbols.
	symbols. Most humans associate complex structures of reality with		Most humans associate complex structures of reality with easy
	easy recognizable logotypes and marks. Humans tend to trust things		recognizable logotypes and marks. Humans tend to trust things that
	that they recognize from previous experiences. Humans may examine		they recognize from previous experiences. Humans may examine
	information to confirm their initial reaction. Very few consumers		information to confirm their initial reaction. Very few consumers
	actually read all terms and conditions they accept when accepting a		actually read all terms and conditions they accept when accepting a
	service, instead they most commonly act in trust based on previous		service, rather they commonly act on trust derived from previous
	experience and recognition.		experience and recognition.
	A big part of this process is branding. Service providers and product		A big part of this process is branding. Service providers and product
	vendors invest a lot of money and resources into creating a strong		vendors invest a lot of money and resources into creating a strong
	relation between positive user experiences and easily recognizable		relation between positive user experiences and easily recognizable
	trademarks and logotypes.		trademarks, servicemarks, and logotypes.
	Branding is also pervasive in identification instruments, including		Branding is also pervasive in identification instruments, including
	identification cards, passports, driver's licenses, credit cards,		identification cards, passports, driver's licenses, credit cards,
	gasoline cards, and loyalty cards. Identification instruments are		gasoline cards, and loyalty cards. Identification instruments are
	intended identify the holder as a particular person or as member of		intended to identify the holder as a particular person or as member
	community. The community may represent the subscribers of a service		of community. The community may represent the subscribers of a
	or any other group. Identification instruments, in physical form,		service or any other group. Identification instruments, in physical
	commonly use logotypes and symbols, solely to enhance human		form, commonly use logotypes and symbols, solely to enhance human
	recognition and trust in the identification instrument itself.		recognition and trust in the identification instrument itself. They
			may also include a registered trademark to allow legal recourse for
			unauthorized duplication.
	Since certificates play an equivalent role in electronic exchanges,		Since certificates play an equivalent role in electronic exchanges,
	we examine the inclusion of logotypes in certificates.		we examine the inclusion of logotypes in certificates. We consider
			certificate-based identification and certificate selection.
	1.1 Are human recognition concepts relevant?
	The answer depends the manner in which certiciates are used. Are		1.1. Certificate-based Identification
	certificates visible or invisible to human users? Will the
	certificates be used in open environments?
	If certificates are to be used in open environments and in		The need for human recognition depends on the manner in which
	applications that brings the user in conscious contact with the		certificates are used and whether certificates need to be visible to
			human users. If certificates are to be used in open environments and
			in applications that bring the user in conscious contact with the
	result of a certificate-based identification process, then human		result of a certificate-based identification process, then human
	recognition is highly relevant, and it may be a necessity.		recognition is highly relevant, and it may be a necessity.
	Examples of sucha applications include:		Examples of such applications include:
	- Web server identification where a user identifies the owner of the
	web site.
	- Peer e-mail exchange in B2B, B2C, and private communications.
	- Exchange of medical records, and system for medical prescriptions.
	- Unstructured e-business applications (i.e. non-EDI applications).		- Web server identification where a user identifies the owner
			of the web site.
			- Peer e-mail exchange in B2B, B2C, and private communications.
			- Exchange of medical records, and system for medical
			prescriptions.
			- Unstructured e-business applications (i.e., non-EDI
			applications).
			- Wireless client authenticating to a service provider.
	Most applications provide the human user with an opportunity to view		Most applications provide the human user with an opportunity to view
	the results of a successful certificate-based identification process.		the results of a successful certificate-based identification process.
	When the user takes the steps necessary to view these results, the		When the user takes the steps necessary to view these results, the
	user is presented with a view of a certificate. This solution has		user is presented with a view of a certificate. This solution has two
	however two major problems.		major problems. First, the function to view a certificate is often
			rather hard to find for a non-technical user. Second, the
	1) The function to view a certificate is often rather hard to find		presentation of the certificate is too technical and, it is not user
	for a non-technical user.		friendly. It contains no graphic symbols or logotypes to enhance
			human recognition.
	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 of today's applications do		Many investigations have shown that users of today's applications do
	not take the steps necessary to view certificates. This could be due		not take the steps necessary to view certificates. This could be due
	to poor user interfaces. However, many applications are structured to		to poor user interfaces. Further, many applications are structured to
	hide certificates from users. The application designers do not want		hide certificates from users. The application designers do not want
	to expose certificates to users at all.		to expose certificates to users at all.
	1.2 Combination of verification techiques		1.2. Selection of Certificates
	Can the concepts of systematic certification path verification and		One situation where software applications must expose human users to
	human recognition be combined in any sensible manner?		certificates is when the user must select a single certificate from a
			portfolio of certificates. In some cases, the software application
			can use information within the certificates to filter the list for
			suitability; however, the user must be queried if more than one
			certificate is suitable. The human user must select one of them.
			This situation is comparable to a person selecting a suitable plastic
			card from his wallet. In this situation, substantial assistance is
			provided by card color, location, and branding.
			In order to provide similar support for certificate selection, the
			users need tools to easily recognize and distinguish certificates.
			Introduction of logotypes into certificates provides the necessary
			graphic.
			1.3. Combination of Verification Techniques
			The use of logotypes will in many cases affect the users decision to
			trust and use a certificate. It is therefore important that there is
			a distinct and clear architectural and functional distinction between
			the processes and objectives of the systematic certificate
			verification and human recognition.
	Systematic certification path verification determines whether the		Systematic certification path verification determines whether the
	end-entity certificate can be verified according to defined policy.		end-entity certificate can be verified according to defined policy.
			The algorithm for this verification is specified in RFC <TBD>
			[PKIX-1].
	The systematic processing provides assurance that the certificate is		The systematic processing provides assurance that the certificate is
	a valid document. It does not indicate whether the subject is		valid. It does not indicate whether the subject is entitled to any
	entitled to any particular information, or whether the subject ought		particular information or whether the subject ought to be trusted to
	to be trusted to perform a particular service. These are access		perform a particular service. These are access control decisions.
	control function decisions. Some access control decisions may be made		Automatic processing will make some access control decisions, but
	by a systematic process, but others, depending on the application		others, depending on the application context, involve the human user.
	context, involve the human user.
	In some situations, the human user is the sole handler of the post		In some situations, where automated procedures have failed to
	certification path verification access control decisions. In the end,		establish the suitability of the certificate to the task, the human
	the human will decide whether or not to accept an executable email		user is the final arbitrator of the post certificate verification
	attachment, to release personal information, or follow the		access control decisions. In the end, the human will decide whether
	instructions displayed by a web browser. As we have seen, this		or not to accept an executable email attachment, to release personal
	decision will often be based on recognition and previous experience.		information, or follow the instructions displayed by a web browser.
			This decision will often be based on recognition and previous
			experience.
	The distinction between systematic processing and human processing		The distinction between systematic processing and human processing is
	is rather straightforward. They can be complementary. While the		rather straightforward. They can be complementary. While the
	systematic process is focused on certification path construction and		systematic process is focused on certification path construction and
	verification, the human acceptance process is focused on recognition		verification, the human acceptance process is focused on recognition
	and related previous experience.		and related previous experience.
	There are some situations where systematic processing and human		There are some situations where systematic processing and human
	processing interfer with each other. These issues are discussed in		processing interfere with each other. These issues are discussed in
	the Security Considerations section.		the Security Considerations section.
	1.3 Terminology		1.4. Terminology
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [STDWORDS].		document are to be interpreted as described in RFC 2119 [STDWORDS].
	2 Different types of logotypes in certificates		2. Different Types of Logotypes in Certificates
	This draft suggests standardization of 3 logotype types.		This specification defines the inclusion of three predefined logotype
			types.
	1) Concept logotype		1) Community logotype
	2) Issuer organization logotype		2) Issuer organization logotype
	3) Subject organization logotype		3) Subject organization logotype
	The concept logotype - is the general mark for a service concept for		The community logotype - is the general mark for a community. It
	entity identification and certificate issuance. Many issuers may use		identifies a service concept for entity identification and
	the concept logotypes to co-brand with a global concept in order to		certificate issuance. Many issuers may use a community logotype to
	gain global recognition of its local service provision. This type of		co-brand with a global community in order to gain global recognition
	concept branding is very common in credit card business where local		of its local service provision. This type of community branding is
	independent card issuers issue cards within a globally branded		very common in the credit card business where local independent card
	concept (such as VISA and MasterCard).		issuers include a globally recognized brand (such as VISA and
			MasterCard).
	Issuer organization logotype - is a logotype representing the		Issuer organization logotype - is a logotype representing the
	organization identified as part of the issuer name in the		organization identified as part of the issuer name in the
	certificate.		certificate.
	Subject organization logotype - is a logotype representing the		Subject organization logotype - is a logotype representing the
	organization identified in the subject name in the certificate.		organization identified in the subject name in the certificate.
	3 Technical solution		3. Image formats
	3.1 General
	There is no need to significantly increase the size of the
	certificate by including logotype image data in a certificate.
	Rather, a URI identifying the location to the logotype image 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.
	The URI defines the file format for the logotype image.
	The solution explicitly identifies the one-way hash function
	employed.
	The general structure for logotype data is:
	LogotypeData ::= SEQUENCE {
	typeOfLogotype TypeOfLogotype,
	hashAlgorithm AlgorithmIdentifier,
	logotypeDataHash OCTET STRING,
	logotypeDataUri IA5String OPTIONAL }
	TypeOflogotype ::= CHOICE {
	predefinedLogotypeType PredefinedLogotypeType,
	logotypeTypeID OBJECT IDENTIFIER }
	PredefinedLogotypeType ::= INTEGER {		This specification defines two image format types:
	subject-organization-logotype(0),
	issuer-organization-logotype(1)
	concept-logotype(2) }
	The predefined logotype types are:		- High Resolution (included by reference)
			- Low Resolution (icon-sized image embedded in the extension)
	subject-organization-logotype, if used, SHALL be used to include a		Format restrictions:
	logotype of the subject organization. The logotype SHALL be		High Resolution Low Resolution
	consistent with, and require the presence of, an organization name		+-----------------+---------------------+--------------------+
	stored in the organization attribute in the subject field.		| Image format | JPEG or GIF | JPEG or GIF |
			+-----------------+---------------------+--------------------+
			| Size | Max 150 x 50 pixels | 20 x 20 pixels |
			+-----------------+---------------------+--------------------+
			| Color palette | Unlimited | 256 colors (8-bit) |
			+-----------------+---------------------+--------------------+
	issuer-organization-logotype, if used, SHALL be used to include a		A high resolution image SHOULD include a black border. Exceptions are
	logotype of the issuer organization. The logotype SHALL be consistent		such things as arrows or X's. These images SHOULD be fairly flat in
	with, and require the presence of, an organization name stored in the		appearance with little dimensioning or shading.
	organization attribute in the issuer field.
	Concept-logotype, if used, SHALL be used to include a logotype		There is no need to significantly increase the size of the
	representing the concept under which the issuer claims to issue this		certificate by including image data of logotypes in high quality
			format. Rather, a URI identifying the location to the logotype image
			and a one-way hash of the referenced data is included in the
	certificate.		certificate.
	A concept may be shared within a network of certification authority		To enhance functionality for off-line and low bandwidth situations
	(CA) services, provided by one or several independent CA		where reasonable access to high quality logotypes are not available,
	organizations.		the icon-sized version of the logotype may optionally be stored
			directly in the certificate extension.
	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,
	.TIFF, .JPG, .JPEG, etc.).
	3.2 Type of certificates
	Logotypes according to the present model may be used in 3 types of
	certificates:
	- Self-signed CA certificates (root certificates)
	- Intermediate CA certificates
	- End-entity certificates
	A reason to constrain inclusion of logotypes to 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 certification path.
	However, as discussed 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
	certification path.
	Logotypes should not be an active component in path processing, and
	logotypes should be allowed in all types of certificates, at the
	discretion of the CA.
	3.3 Logotype placement
	So far, there have been 3 solutions discussed regarding 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
	3.3.1 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:		Applications may also enhance processing and off-line functionality
			by cashing the higher quality logotype data.
	- Current practice and standards (RFC 2459) recommends against use of		4. Logotype extension
	qualifiers
	- This is generally considered to be a major hack and stretch of		The logotype extension MAY be included in public key certificates
	semantics, since this type of data doesn't qualify a policy in any		[PKIX-1] or attribute certificates [PKIX-AC]. The logotype extension
	way.		MUST be identified by the following object identifier:
	3.3.2 Issuer and Subject Alt Names		id-pe-logotypeInfo OBJECT IDENTIFIER ::= {id-pe XX}
	This solution would use the other name form to include;		The logotype extension MUST have the following syntax:
	- issuer and concept logotypes in the issuer alt name extension;		LogotypeInfo ::= SEQUENCE {
	and,		communityLogo [0] LogotypeData OPTIONAL,
	- subject organization logo in the subject alt name extension.		issuerLogo [1] LogotypeData OPTIONAL,
			subjectLogo [2] LogotypeData OPTIONAL,
			otherLogos [3] SEQUENCE OF OtherLogotypeData OPTIONAL }
	Pros:		OtherLogotypeData ::= SEQUENCE {
			logotypeTypeID OBJECT IDENTIFIER,
			logotypeData LogotypeData }
	- This mechanism could possibly enable cross certifying CAs to deny		LogotypeData ::= SEQUENCE {
	any subordinate CA the right to include logotypes in descending end		highRes LogotypeReference OPTIONAL,
	entity certificates by listing the logotypes name form in		lowRes EmbeddedLogotype OPTIONAL }
	excludedSubtrees.
	Cons:		LogotypeReference ::= SEQUENCE {
			hashAlgorithm AlgorithmIdentifier,
			logotypeHash OCTET STRING,
			logotypeUri IA5String }
	- Logotypes are not a name form and should not be treated as a		EmbeddedLogotype ::= SEQUENCE {
	displayable name.		imageFileExtn IA5String, -- MUST be "JPEG" or "JPG" or "GIF"
			image OCTET STRING }
	- It is generally understood that it should be possible to apply		This extension MUST NOT be marked critical.
	general name constraint mechanisms (as described in RFC 2459 as
	well as son-of-2459) to names in the subject and issuer alt name
	extension. This is not possible to do with logotypes since it is
	not a name form.
	- This split storage of logotype data into 2 different locations,		At least one of the optional elements in the LogotypeInfo structure
	which may make life worse for applications with no interest in		MUST be present. Whenever possible, the use of otherLogos should be
	logotypes.		avoided.
	- It is generally agreed that inclusion of logotype data by no means		The LogotypeReference structure explicitly identifies the one-way
	should be regarded as critical data. This may interfere with the		hash function employed. Implementations MUST support the SHA-1 [FIPS
	criticality policy of the alt name extensions, especially if the		180-1] algorithm, and implementations MAY support other one-way hash
	certificate has no attributes in the subject field, forcing the		functions.
	subject alt name to be set to critical.
	- This usage would possibly interfere with the resolution between		The predefined logotype types are:
	IETF and ITU-T regarding use of permitted subtrees.
	- Since this solution may break current implementations it would		Community Logotype. If communityLogo is present, the logotype MUST
	possibly block adoption of logotypes.		represent the community to which the certificate issuer is a
			member. The communityLogo MAY be present in an end entity
			certificate or an attribute certificate. The communityLogo MUST
			NOT be present in a CA certificate.
	3.3.3 New extension		Issuer Organization Logotype. If issuerLogo is present, the
			logotype MUST represent the issuer's organization. The logotype
			MUST be consistent with, and require the presence of, an
			organization name stored in the organization attribute in the
			issuer field (for either a public key certificate or attribute
			certificate). The issuerLogo MAY be present in an end entity
			certificate, a CA certificate, or an attribute certificate.
	logotypeInfo EXTENSION ::= {		Subject Organization Logotype. If subjectLogo is present, the
	SYNTAX LogotypeSyntax		logotype MUST represent the subject's organization. The logotype
	IDENTIFIED BY id-pe-logotypeInfo }		MUST be consistent with, and require the presence of, an
			organization name stored in the organization attribute in the
			subject field (for either a public key certificate or attribute
			certificate). The subjectLogo MAY be present in an end entity
			certificate, a CA certificate, or an attribute certificate.
	id-pe-logotypeInfo OBJECT IDENTIFIER ::= {id-pe XX}		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 community logotype,
			are relationships claimed by the issuer. The policy under which the
			issuer checks these logotypes is outside the scope of this standard.
	LogotypeSyntax ::= SEQUENCE OF LogotypeData		Any URI pointing to a file containing the logotype data MUST include
			a file extension defining the image file format. The file extension
			is the last three or four letters of the file name, immediately
			following a period. Implementations MUST support both the JPEG and
			GIF image formats. The JPEG image format MUST be identifier using a
			file extension of "JPG" or "JPEG". The GIF image format MUST be
			identified using the "GIF" file extension.
	Pros:		The same three file extension strings ("JPG," "JPEG," and "GIF") are
			used to identify the format of embedded images.
	- This is the cleanest solution.		To ensure that certificates are not greatly enlarged by including
			embedded logotypes, restrictions are imposed on image size and color
			definition. Embedded images MUST NOT exceed 20 pixels by 20 pixels.
			Embedded images MUST use a 256-color (8-bit) palette. The size of an
			image conforming to these restrictions is about 750 octets.
	- Do not impact on legacy implementations.		5. Type of certificates
	Cons:		Logotypes MAY be present in three types of certificates:
	- This solution activates the issue whether this extension may be		- CA certificates
	abused by a CA who include logotypes (in EE certificates) that		- End-entity certificates
	violates the intention of a name constraints set by a chaining CA.		- Attribute certificates
	This issue is addressed in the security consideration section
	below.
	3.3.4 Conclusion		CA certificates include self-signed certificates (often used to
			represent trust anchors) or Intermediate CA certificates.
	We must not destroy current structures. We must not create problems		Some types of logotypes are not permitted in CA certificates. This
	and confusion.		ensures that logotypes are excludes from all aspects of certification
			path processing. As discussed above, logotypes are not intended to be
			part of certification path validation or any type of systematic
			processing. The sole purpose of logotypes is to enhance display of a
			particular certificate, regardless of its position in a certification
			path.
	Only the private extension solution satisfies both of these desires.		Logotypes MUST NOT be an active component in certification path
	Therefore, the private extension should be selected.		processing, and they are included in public key certificates and
			attribute certificates at the discretion of the certificate issuer.
	4 Use in Clients		6. Use in Clients
	All PKI implementations require relying party software to have some		All PKI implementations require relying party software to have some
	mechanism to determine whether a trusted CA issues a particular		mechanism to determine whether a trusted CA issues a particular
	certificate. This is an issue for certification path validation,		certificate. This is an issue for certification path validation,
	including consistent policy and name checking.		including consistent policy and name checking.
	After a certificatin path is successfully validated, the replying		After a certification path is successfully validated, the replying
	party must trust the information that the CA includes in the		party must trust the information that the CA includes in the
	certificate, including any certificate extensions. The client		certificate, including any certificate extensions. The client
	software can choose to make use of such information, or the client		software can choose to make use of such information, or the client
	software can ignore it. Current standards do not provide any		software can ignore it. Current standards do not provide any
	mechanism for cross-certifying CAs to constrain subordinate CAs from		mechanism for cross-certifying CAs to constrain subordinate CAs from
	including private extensions (see security considerations).		including private extensions (see the security considerations
			section).
	Consequently, if relying party software accepts a CA, then it should		Consequently, if relying party software accepts a CA, then it should
	be prepared to (unquestioningly) display the associated logos to its		be prepared to (unquestioningly) display the associated logotypes to
	human user, given that it is configured to do so.		its human user, given that it is configured to do so.
	5 Security considerations		However, if the relying party software is unable to successfully
			validate a particular certificate, then it MUST NOT display any
			associated logotype graphics.
	Logotypes are even worse than names regarding the possibility to		7. Security considerations
	securely and accurately define what is, and what is not, a legitimate
			Logotypes are very difficult to securely and accurately define. Names
			are also difficult in this regard, but logotypes are even worse. It
			is quite difficult to specify what is, and what is not, a legitimate
	logotype of an organization. There is a whole legal structure around		logotype of an organization. There is a whole legal structure around
	this issue that doesn't need repetition in this document.		this issue, and it will not be repeated here. However, issuers should
			be aware of the implications of including images associated with a
			trademark or servicemark before doing so.
	As logotypes are hard (and sometimes expensive) to verify, this		As logotypes can be difficult (and sometimes expensive) to verify,
	increases the possibility of errors related to falsely assigning		this increases the possibility of errors related to assigning wrong
	wrong logotypes to organizations.		logotypes to organizations.
	This is not a new issue for electronic identification instruments.		This is not a new issue for electronic identification instruments.
	It is already dealt with in numerous of similar situations in the		It is already dealt with in numerous of similar situations in the
	physical world, including physical employee identification cards.		physical world, including physical employee identification cards.
	Secondly, there are situations where identification of logotypes is		Secondly, there are situations where identification of logotypes is
	rather simple and straightforward, such as logotypes for well-known		rather simple and straightforward, such as logotypes for well-known
	industries and institutes. These issues should not stop those service		industries and institutes. These issues should not stop those service
	providers who want to issue logotypes from doing so, where relevant.		providers who want to issue logotypes from doing so, where relevant.
	There is a new problem related to electronic identification		The premise used for the logotype work is that logotype graphics in a
	instruments in the form of certificates. Certification paths may		certificate are trusted only if the certificate is successfully
	impose constraints that are systematically checked during		validated within a valid path. It is however impossible to prevent
	certification path processing, which, in theory, may be violated by		fraudulent creation of certificates by non-validated issuers,
	logotypes.		containing names and logotypes that the issuer has no claim to. Such
			certificates could be created in an attempt to socially engineer a
			user into accepting a certificate. It is thus imperative that the
			representation of any certificate that fails to validate is not
			enhanced in any way by using the logotype graphic.
	Certification path processing does not, should not, and will never be		Certification paths may also impose name constraints that are
	able to control the inclusion of logotype data in certificates. That		systematically checked during certification path processing, which,
	is, a parent CA may constraint subordinate CAs to only issue		in theory, may be circumvented by logotypes.
	certificates to end-entities within a limited name space. A
	potentially bad CA may comply with this name constraint and still
	include a subject organization logotype. The the parent CA has no
	means of preventing logotype data inclusion since there is no
	mechanism to prevent subordinate CAs from including new extensions.
	This is not unique to the logotype extension. No technical means are		Certificate path processing does not constrain the inclusion of
	provides for constraining subordinate CAs to a particular certificate		logotype data in certificates. A parent CA can constrain
	profile.		certification path validation such that subordinate CAs cannot issue
			valid certificates to end-entities outside a limited name space or
			outside specific certificate polices. A malicious CA can comply with
			these name and policy requirements and still include inappropriate
			logotypes in the certificates that it issues. These certificates will
			pass the certification path validation algorithm, which means the
			client will trust the logotypes in the certificates. Since there is
			no technical mechanism to prevent or control subordinate CAs from
			including the logotype extension or its contents, where appropriate,
			a parent CA could employ a legal agreement to impose a suitable
			restriction on the subordinate CA. This situation is not unique to
			the logotype extension.
	The controls available to a parent CA to protect itself from rogue		The controls available to a parent CA to protect itself from rogue
	subordinate CAs are nontechnical. They include:		subordinate CAs are non-technical. They include:
	- Contractual agreements of suitable behaviour, including		- Contractual agreements of suitable behavior, including
	terms of liability and severance pay in case of material		terms of liability and severance pay in case of material
	breach.		breach.
	- Control mechanisms and procedures to monitor and		- Control mechanisms and procedures to monitor and
	follow-up behaviour of subordinate CAs.		follow-up behavior of subordinate CAs.
	- Use of certificate policies to declare assurance level		- Use of certificate policies to declare assurance level
	of logotype data as well as to guide applications on how		of logotype data as well as to guide applications on how
	to treat and display logotypes.		to treat and display logotypes.
	- Use of revocation functions to revoke any misbehaving CA.		- Use of revocation functions to revoke any misbehaving CA.
	This issue cannot be given an easy and absolute technical solution.		There is not a simple, straightforward, and absolute technical
	Maybe the correct response is to surrender to the fact that involved		solution. Rather, involved parties must settle some aspects of PKI
	parties must settle some aspects of PKI outside the scope of		outside the scope of technical controls. As such, issuers need to
	technical controls, and to clearly identify and communicate the		clearly identify and communicate the associated risks.
	associated risks.
	6 References		8. References
	[STDWORDS] S. Bradner, "Key words for use in RFCs to Indicate		[FIPS 180-1] Federal Information Processing Standards Publication
	Requirement Levels", March 1997.		(FIPS PUB) 180-1, Secure Hash Standard, 17 April 1995.
			[Supersedes FIPS PUB 180 dated 11 May 1993.]
	[RFC 2459] R. Housley, W. Ford, W. Polk, and D.Solo, "Internet X.509		[OLD-PKIX-1] R. Housley, W. Ford, W. Polk, and D. Solo, "Internet
	Public Key Infrastructure: Certificate and CRL Profile", January		X.509 Public Key Infrastructure: Certificate and
	1999.		CRL Profile", January 1999.
	7 Intellectual Property Rights		[PKIX-1] R. Housley, W. Ford, W. Polk, and D. Solo, "Internet
			X.509 Public Key Infrastructure: Certificate and
			CRL Profile", January 1999.
			{Replace with Son-of-2459 as soon as it is published.}
			[STDWORDS] S. Bradner, "Key words for use in RFCs to Indicate
			Requirement Levels", March 1997.
			9. Intellectual Property Rights
	The IETF takes no position regarding the validity or scope of any		The IETF takes no position regarding the validity or scope of any
	intellectual property or other rights that might be claimed to		intellectual property or other rights that might be claimed to
	pertain to the implementation or use of the technology described in		pertain to the implementation or use of the technology described in
	this document or the extent to which any license under such rights		this document or the extent to which any license under such rights
	might or might not be available; neither does it represent that it		might or might not be available; neither does it represent that it
	has made any effort to identify any such rights. Information on the		has made any effort to identify any such rights. Information on the
	IETF's procedures with respect to rights in standards-track and		IETF's procedures with respect to rights in standards-track and
	standards related documentation can be found in BCP-11. Copies of		standards related documentation can be found in BCP-11. Copies of
	claims of rights made available for publication and any assurances 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		licenses to be made available, or the result of an attempt made to
	obtain ageneral license or permission for the use of such proprietary		obtain a general license or permission for the use of such
	rights by implementors or users of this specification can be obtained		proprietary rights by implementers or users of this specification can
	from the IETF Secretariat.		be obtained from the IETF Secretariat.
	The IETF invites any interested party to bring to its attention any		The IETF invites any interested party to bring to its attention any
	copyrights, patents or patent applications, or other proprietary		copyrights, patents or patent applications, or other proprietary
	rights which may cover technology that may be required to practice		rights which may cover technology that may be required to practice
	this standard. Please address the information to the IETF Executive		this standard. Please address the information to the IETF Executive
	Director.		Director.
	APPENDICES		APPENDICES
	A. ASN.1 definitions		A. ASN.1 definitions
	TBD		TBD
	B. Author Addresses		B. Logotype Placement
			This Appendix documents reasons and rationales behind the technical
			solution selected in this standard.
			Three alternatives for the placement of the logotypes in a
			certificate have been considered. They are:
			1. Inclusion in a policy qualifier;
			2. Inclusion in Issuer and Subject Alternative names extensions; and
			3. Inclusion in a separate certificate extension.
			B.1 Qualifier
			This alternative 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:
			- RFC <TBD> [PKIX-1] 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.
			B.2 Issuer and Subject Alt Names
			This solution would use the other name form to include the issuer and
			community logotypes in the issuer alt name extension, 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 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
			well as RFC <TBD> [PKIX-1]) to names in the subject and issuer
			alt name extension. This is not possible to do with logotypes
			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.
			B.3 New extension
			This solution places logotype data in a new extension.
			Pros:
			- This is the cleanest solution.
			- This does 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.
			B.4 Conclusion
			We must not destroy current structures. We must not create problems
			or confusion.
			Only the private extension solution satisfies both of these criteria.
			Therefore, the private extension was selected to carry logotype
			information.
			While the syntax and semantics of the X.509 public key certificate
			were used in this analysis, the logotype private extension can also
			be included in an X.509 attribute certificate.
			C. Author Addresses
	Stefan Santesson		Stefan Santesson
	AddTrust AB		AddTrust AB
	P.O. Box 465		P.O. Box 465
	S-201 24 Malmoe		S-201 24 Malmoe
	Sweden		Sweden
	stefan@addtrust.com		stefan@addtrust.com
	Russell Housley		Russell Housley
	RSA Laboratories		RSA Laboratories
	918 Spring Knoll Drive		918 Spring Knoll Drive
	Herndon, VA 20170		Herndon, VA 20170
	USA		USA
	rhousley@rsasecurity.com		rhousley@rsasecurity.com
	C. Full Copyright Statement		Trevor Freeman
			Microsoft Corporation
			One Microsoft Way
			Redmond WA 98052
			USA
			trevorf@microsoft.com
			D. Full Copyright Statement
	Copyright (C) The Internet Society (2002). All Rights Reserved.		Copyright (C) The Internet Society (2002). All Rights Reserved.
	This document and translations of it may be copied and furnished to		This document and translations of it may be copied and furnished to
	others, and derivative works that comment on or otherwise explain it		others, and derivative works that comment on or otherwise explain it
	or assist in its implementation may be prepared, copied, published		or assist in its implementation may be prepared, copied, published
	and distributed, in whole or in part, without restriction of any		and distributed, in whole or in part, without restriction of any
	kind, provided that the above copyright notice and this paragraph		kind, provided that the above copyright notice and this paragraph are
	are included on all such copies and derivative works. In addition,		included on all such copies and derivative works. In addition, the
	the ASN.1 modules presented in Appendices A and B may be used in		ASN.1 modules presented in Appendices A and B may be used in whole or
	whole or in part without inclusion of the copyright notice.		in part without inclusion of the copyright notice. However, this
	However, this document itself may not be modified in any way, such		document itself may not be modified in any way, such as by removing
	as by removing the copyright notice or references to the Internet		the copyright notice or references to the Internet Society or other
	Society or other Internet organizations, except as needed for the		Internet organizations, except as needed for the purpose of
	purpose of developing Internet standards in which case the		developing Internet standards in which case the procedures for
	procedures for copyrights defined in the Internet Standards process		copyrights defined in the Internet Standards process shall be
	shall be followed, or as required to translate it into languages		followed, or as required to translate it into languages other than
	other than English.		English.
	The limited permissions granted above are perpetual and will not be		The limited permissions granted above are perpetual and will not be
	revoked by the Internet Society or its successors or assigns. This		revoked by the Internet Society or its successors or assigns. This
	document and the information contained herein is provided on an "AS		document and the information contained herein is provided on an "AS
	IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK		IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK
	FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT		FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT
	NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN		LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL
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