Internet DRAFT - draft-ietf-lamps-rfc3709bis
draft-ietf-lamps-rfc3709bis
Network Working Group S. Santesson
Internet-Draft IDsec Solutions
Obsoletes: 3709, 6170 (if approved) R. Housley
Intended status: Standards Track Vigil Security
Expires: 14 June 2023 T. Freeman
Amazon Web Services
L. Rosenthol
Adobe
11 December 2022
Internet X.509 Public Key Infrastructure: Logotypes in X.509
Certificates
draft-ietf-lamps-rfc3709bis-10
Abstract
This document specifies a certificate extension for including
logotypes in public key certificates and attribute certificates.
This document obsoletes RFC 3709 and RFC 6170.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on 14 June 2023.
Copyright Notice
Copyright (c) 2022 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
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extracted from this document must include Revised BSD License text as
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Certificate-based Identification . . . . . . . . . . . . 4
1.2. Selection of Certificates . . . . . . . . . . . . . . . . 5
1.3. Combination of Verification Techniques . . . . . . . . . 5
1.4. Terminology . . . . . . . . . . . . . . . . . . . . . . . 6
2. Different Types of Logotypes in Certificates . . . . . . . . 6
3. Logotype Data . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Logotype Extension . . . . . . . . . . . . . . . . . . . . . 8
4.1. Extension Format . . . . . . . . . . . . . . . . . . . . 8
4.2. Conventions for LogotypeImageInfo . . . . . . . . . . . . 12
4.3. Embedded Images . . . . . . . . . . . . . . . . . . . . . 13
4.4. Other Logotypes . . . . . . . . . . . . . . . . . . . . . 13
4.4.1. Loyalty Logotype . . . . . . . . . . . . . . . . . . 14
4.4.2. Certificate Background Logotype . . . . . . . . . . . 14
4.4.3. Certificate Image Logotype . . . . . . . . . . . . . 14
5. Type of Certificates . . . . . . . . . . . . . . . . . . . . 16
6. Use in Clients . . . . . . . . . . . . . . . . . . . . . . . 16
7. Image Formats . . . . . . . . . . . . . . . . . . . . . . . . 17
8. Audio Formats . . . . . . . . . . . . . . . . . . . . . . . . 19
9. Security Considerations . . . . . . . . . . . . . . . . . . . 20
10. Privacy Considerations . . . . . . . . . . . . . . . . . . . 22
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 24
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 25
12.1. Acknowledgments from RFC 3709 . . . . . . . . . . . . . 25
12.2. Acknowledgments from RFC 6170 . . . . . . . . . . . . . 25
12.3. Additional Acknowledgments . . . . . . . . . . . . . . . 25
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 25
13.1. Normative References . . . . . . . . . . . . . . . . . . 25
13.2. Informative References . . . . . . . . . . . . . . . . . 27
Appendix A. ASN.1 Modules . . . . . . . . . . . . . . . . . . . 29
A.1. ASN.1 Modules with 1988 Syntax . . . . . . . . . . . . . 29
A.2. ASN.1 Module with 2002 Syntax . . . . . . . . . . . . . . 32
Appendix B. Examples . . . . . . . . . . . . . . . . . . . . . . 35
B.1. Example from RFC 3709 . . . . . . . . . . . . . . . . . . 35
B.2. Issuer Logotype Example . . . . . . . . . . . . . . . . . 36
B.3. Embedded Image Example . . . . . . . . . . . . . . . . . 37
B.4. Embedded Certificate Image Example . . . . . . . . . . . 39
B.5. Full Certificate Example . . . . . . . . . . . . . . . . 42
Appendix C. Changes Since RFC 3709 and RFC 6170 . . . . . . . . 45
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 46
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1. Introduction
This specification supplements [RFC5280], which profiles public-key
certificates and certificate revocation lists (CRLs) for use in the
Internet, and it supplements [RFC5755] which profiles attribute
certificates for use in the Internet.
This document obsoletes RFC 3709 [RFC3709] and RFC 6170 [RFC6170].
Appendix C provides a summary of the changes since the publication of
RFC 3709 and RFC 6170.
The basic function of a certificate is to bind a public key to the
identity of an entity (the subject). From a strictly technical
viewpoint, this goal could be achieved by signing the identity of the
subject together with its public key. However, the art of Public Key
Infrastructure (PKI) has developed certificates far beyond this
functionality in order to meet the needs of modern global networks
and heterogeneous information and operational technology structures.
Certificate users must be able to determine certificate policies,
appropriate key usage, assurance level, and name form constraints.
Before a relying party can make an informed decision whether a
particular certificate is trustworthy and relevant for its intended
usage, a certificate may be examined from several different
perspectives.
Systematic processing is necessary to determine whether a particular
certificate meets the predefined prerequisites for an intended usage.
Much of the information contained in certificates is appropriate and
effective for machine processing; however, this information is not
suitable for a corresponding human trust and recognition process.
Humans prefer to structure information into categories and symbols.
Most humans associate complex structures of reality with easily
recognizable logotypes and marks. Humans tend to trust things that
they recognize from previous experiences. Humans may examine
information to confirm their initial reaction. Very few consumers
actually read all terms and conditions they agree to in accepting a
service, rather they commonly act on trust derived from previous
experience and recognition.
A big part of this process is 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, servicemarks, and logotypes.
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Branding is also pervasive in identification instruments, including
identification cards, passports, driver's licenses, credit cards,
gasoline cards, and loyalty cards. Identification instruments are
intended to identify the holder as a particular person or as a member
of the community. The community may represent the subscribers of a
service or any other group. Identification instruments, in physical
form, commonly use logotypes and symbols, solely to enhance human
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,
we examine the inclusion of logotypes in certificates. We consider
certificate-based identification and certificate selection.
1.1. Certificate-based Identification
The need for human recognition depends on the manner in which
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
recognition is highly relevant, and may be a necessity.
Examples of such applications include:
* Web server identification where a user identifies the owner of the
website.
* Peer e-mail exchange in business-to-business (B2B), business-to-
consumer (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
the results of a successful certificate-based identification process.
When the user takes the steps necessary to view these results, the
user is presented with a view of a certificate. This solution has
two major problems. First, the function to view a certificate is
often rather hard to find for a non-technical user. Second, the
presentation of the certificate is too technical and is not user
friendly. It contains no graphic symbols or logotypes to enhance
human recognition.
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Many investigations have shown that users of today's applications do
not take the steps necessary to view certificates. This could be due
to poor user interfaces. Further, many applications are structured
to hide certificates from users. The application designers do not
want to expose certificates to users at all.
1.2. Selection of Certificates
One situation where software applications must expose human users to
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
be a distinct and clear architectural and functional distinction
between the processes and objectives of the automated certificate
verification and human recognition.
Since logotypes are only aimed for human interpretation and contain
data that is inappropriate for computer based verification schemes,
the logotype extension MUST NOT be an active component in automated
certification path validation as specified in Section 6 of [RFC5280].
Automated certification path verification determines whether the end-
entity certificate can be verified according to defined policy. The
algorithm for this verification is specified in [RFC5280].
The automated processing provides assurance that the certificate is
valid. It does not indicate whether the subject is entitled to any
particular information, or whether the subject ought to be trusted to
perform a particular service. These are authorization decisions.
Automatic processing will make some authorization decisions, but
others, depending on the application context, involve the human user.
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In some situations, where automated procedures have failed to
establish the suitability of the certificate to the task, the human
user is the final arbitrator of the post certificate verification
authorization decisions. In the end, the human will decide whether
or not to accept an executable email attachment, to release personal
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 is
rather straightforward. They can be complementary. While the
systematic process is focused on certification path construction and
verification, the human acceptance process is focused on recognition
and related previous experience.
There are some situations where systematic processing and human
processing interfere with each other. These issues are discussed in
the Section 9.
1.4. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
2. Different Types of Logotypes in Certificates
This specification defines the inclusion of three standard logotype
types:
* Community logotype
* Issuer organization logotype
* Subject organization logotype
The community logotype is the general mark for a community. It
identifies a service concept for entity identification and
certificate issuance. Many issuers may use a community logotype to
co-brand with a global community in order to gain global recognition
of its local service provision. This type of community branding is
very common in the credit card business, where local independent card
issuers include a globally recognized brand (such as VISA and
MasterCard). Certificate issuers may include more than one community
logotype to indicate participation in more than one global community.
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Issuer organization logotype is a logotype representing the
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.
In addition to the standard logotype types, this specification
accommodates inclusion of other logotype types where each class of
logotype is defined by an object identifier. The object identifier
can be either locally defined or an identifier defined in Section 4.4
of this document.
3. Logotype Data
This specification defines two types of logotype data: image data and
audio data. Implementations MUST support image data; however,
support for audio data is OPTIONAL.
Image and audio data for logotypes can be provided by reference by
including a URI that identifies the location to the logotype data and
a one-way hash of the referenced data in the certificate. The
privacy-related properties for remote logotype data depend on four
parties: the certificate relying parties that use the information in
the certificate extension to fetch the logotype data, the certificate
issuers that populate the certificate extension, certificate
subscribers that request certificates that include the certificate
extension, and server operators that provide the logotype data.
Alternatively, embedding the logotype data in the certificate with
direct addressing (as defined in Section 4.3) provides improved
privacy properties and depends upon fewer parties. However, this
approach can significantly increase the size of the certificate.
Several image objects, representing the same visual content in
different formats, sizes, and color palates, may represent each
logotype image. At least one of the image objects representing a
logotype SHOULD contain an image with a width between 60 pixels and
200 pixels and a height between 45 pixels and 150 pixels.
Several instances of audio data may further represent the same audio
sequence in different formats, resolutions, and languages. At least
one of the audio objects representing a logotype SHOULD provide text-
based audio data suitable for processing by text-to-speech software.
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A typical use of text based audio data is inclusion in web
applications where the audio text is placed as the "alt" atttribute
value of an HTML image (img) element and the language value obtained
from LogotypeAudioInfo is included as the "lang" attribute of that
image.
If a logotype of a certain type (as defined in Section 2) is
represented by more than one image object, then each image object
MUST contain variants of roughly the same visual content. Likewise,
if a logotype of a certain type is represented by more than one audio
object, then the audio objects MUST contain variants of the same
audio information. A spoken message in different languages is
considered a variation of the same audio information. When more than
one image object or more than one audio object for the same logotype
type is included in the certificate, the certificate issuer is
responsible for ensuring that the objects contain roughly the same
content. Compliant applications MUST NOT display more than one of
the image objects and MUST NOT play more than one of the audio
objects for any logotype type (see Section 2) at the same time.
A client MAY simultaneously display multiple logotypes of different
logotype types. For example, it may display one subject organization
logotype while also displaying a community logotype, but it MUST NOT
display multiple image variants of the same community logotype.
Each logotype present in a certificate MUST be represented by at
least one image data object.
Client applications SHOULD enhance processing and off-line
functionality by caching logotype data.
4. Logotype Extension
This section specifies the syntax and semantics of the logotype
certificate extension.
4.1. Extension Format
The logotype extension MAY be included in public key certificates
[RFC5280] or attribute certificates [RFC5755]. The logotype
extension MUST be identified by the following object identifier:
id-pe-logotype OBJECT IDENTIFIER ::=
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-pe(1) 12 }
This extension MUST NOT be marked critical.
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Logotype data may be referenced through either direct or indirect
addressing. Client applications SHOULD support both direct and
indirect addressing. Certificate issuing applications MUST support
direct addressing, and certificate issuing applications SHOULD
support indirect addressing.
The direct addressing includes information about each logotype in the
certificate, and URIs point to the image and audio data object.
Multiple URIs MAY be included for locations for obtaining the same
logotype object. Multiple hash values MAY be included, each computed
with a different one-way hash function. Direct addressing supports
cases where just one or a few alternative images and audio objects
are referenced.
The indirect addressing includes one or more references to an
external hashed data structure that contains information on the type,
content, and location of each image and audio object. Indirect
addressing supports cases where each logotype is represented by many
alternative audio or image objects.
Both direct and indirect addressing accommodate alternative URIs to
obtain exactly the same logotype data. This opportunity for
replication is intended to improve availability. Therefore, if a
client is unable to fetch the item from one URI, the client SHOULD
try another URI in the sequence. All direct addressing URIs SHOULD
use the HTTPS scheme (https://...) or the HTTP scheme (http://...) or
the DATA scheme (data://...) [RFC3986]. However, the "data" URI
scheme MUST NOT be used with the indirect addressing. Clients MUST
support retrieval of referenced LogoTypeData with the HTTP [RFC9110]
and the HTTP with TLS [RFC8446], or subsequent versions of these
protocols. Client applications SHOULD also support the "data" URI
scheme [RFC2397] for direct addressing with embedded logotype data
within the extension.
Note that the HTTPS scheme (https://...) requires the validation of
other certificates to establish a secure connection. For this
reason, the HTTP scheme (http://...) may be easier for a client to
handle. Also, the hash of the logotype data provides data integrity.
The logotype extension MUST have the following syntax:
LogotypeExtn ::= SEQUENCE {
communityLogos [0] EXPLICIT SEQUENCE OF LogotypeInfo OPTIONAL,
issuerLogo [1] EXPLICIT LogotypeInfo OPTIONAL,
subjectLogo [2] EXPLICIT LogotypeInfo OPTIONAL,
otherLogos [3] EXPLICIT SEQUENCE OF OtherLogotypeInfo
OPTIONAL }
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LogotypeInfo ::= CHOICE {
direct [0] LogotypeData,
indirect [1] LogotypeReference }
LogotypeData ::= SEQUENCE {
image SEQUENCE OF LogotypeImage OPTIONAL,
audio [1] SEQUENCE OF LogotypeAudio OPTIONAL }
LogotypeImage ::= SEQUENCE {
imageDetails LogotypeDetails,
imageInfo LogotypeImageInfo OPTIONAL }
LogotypeAudio ::= SEQUENCE {
audioDetails LogotypeDetails,
audioInfo LogotypeAudioInfo OPTIONAL }
LogotypeDetails ::= SEQUENCE {
mediaType IA5String, -- MIME media type name and optional
-- parameters
logotypeHash SEQUENCE SIZE (1..MAX) OF HashAlgAndValue,
logotypeURI SEQUENCE SIZE (1..MAX) OF IA5String }
LogotypeImageInfo ::= SEQUENCE {
type [0] LogotypeImageType DEFAULT color,
fileSize INTEGER, -- In octets, 0=unspecified
xSize INTEGER, -- Horizontal size in pixels
ySize INTEGER, -- Vertical size in pixels
resolution LogotypeImageResolution OPTIONAL,
language [4] IA5String OPTIONAL } -- RFC 5646 Language Tag
LogotypeImageType ::= INTEGER { grayScale(0), color(1) }
LogotypeImageResolution ::= CHOICE {
numBits [1] INTEGER, -- Resolution in bits per pixel
tableSize [2] INTEGER } -- Number of colors or grey tones
LogotypeAudioInfo ::= SEQUENCE {
fileSize INTEGER, -- In octets, 0=unspecified
playTime INTEGER, -- In milliseconds, 0=unspecified
channels INTEGER, -- 0=unspecified,
-- 1=mono, 2=stereo, 4=quad
sampleRate [3] INTEGER OPTIONAL, -- Samples per second
language [4] IA5String OPTIONAL } -- RFC 5646 Language Tag
OtherLogotypeInfo ::= SEQUENCE {
logotypeType OBJECT IDENTIFIER,
info LogotypeInfo }
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LogotypeReference ::= SEQUENCE {
refStructHash SEQUENCE SIZE (1..MAX) OF HashAlgAndValue,
refStructURI SEQUENCE SIZE (1..MAX) OF IA5String }
-- Places to get the same LogotypeData
-- image or audio object
HashAlgAndValue ::= SEQUENCE {
hashAlg AlgorithmIdentifier,
hashValue OCTET STRING }
When using indirect addressing, the URI (refStructURI) pointing to
the external data structure MUST point to a resource that contains
the DER-encoded data with the syntax LogotypeData.
At least one of the optional elements in the LogotypeExtn structure
MUST be present.
When using direct addressing, at least one of the optional elements
in the LogotypeData structure MUST be present.
The LogotypeReference and LogotypeDetails structures explicitly
identify one or more one-way hash functions employed to authenticate
referenced image or audio objects. CAs MUST include a hash value for
each referenced object, calculated on the whole object. CAs MUST use
the one-way hash function that is associated with the certificate
signature to compute one hash value, and CAs MAY include other hash
values. Clients MUST compute a one-way hash value using one of the
identified functions, and clients MUST discard the logotype data if
the computed hash value does not match the hash value in the
certificate extension.
A MIME type is used to specify the format of the image or audio
object containing the logotype data. The mediaType field MUST
contain a string that is constructed according to the ABNF [RFC5234]
provided in Section 4.2 of [RFC6838]. MIME types MAY include
parameters.
Image format requirements are specified in Section 7, and audio
format requirements are specified in Section 8.
When language is specified, the language tag MUST use the [RFC5646]
syntax.
Logotype types defined in this specification are:
Community Logotype: If communityLogos is present, the logotypes
MUST represent one or more communities with which the certificate
issuer is affiliated. The communityLogos MAY be present in an end
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entity certificate, a CA certificate, or an attribute certificate.
The communityLogos contains a sequence of Community Logotypes,
each representing a different community. If more than one
Community logotype is present, they MUST be placed in order of
preferred appearance. Some clients MAY choose to display a subset
of the present community logos; therefore the placement within the
sequence aids the client selection. The most preferred logotype
MUST be first in the sequence, and the least preferred logotype
MUST be last in the sequence.
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.
Subject Organization Logotype: If subjectLogo is present, the
logotype MUST represent the subject's organization. The logotype
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.
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 asserted by the issuer. The policies and practices
employed by the issuer to check subject organization logotypes or
claims its issuer and community logotypes is outside the scope of
this document.
4.2. Conventions for LogotypeImageInfo
When the optional LogotypeImageInfo is included with a logotype
image, the parameters MUST be used with the following semantics and
restrictions.
The xSize and ySize fields represent the recommended display size for
the logotype image. When a value of 0 (zero) is present, no
recommended display size is specified. When non-zero values are
present and these values differ from corresponding size values in the
referenced image object, then the referenced image SHOULD be scaled
to fit within the size parameters of LogotypeImageInfo, while
preserving the x and y ratio. Dithering may produce a more
appropriate image than linear scaling.
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The resolution field is redundant for all logotype image formats
listed in Section 7. The optional resolution field SHOULD be omitted
when the image format already contains this information.
4.3. Embedded Images
If the logotype image is provided through direct addressing, then the
image MAY be stored within the logotype certificate extension using
the "data" scheme [RFC2397]. The syntax of the "data" URI scheme
defined is included here for convenience:
dataurl := "data:" [ mediatype ] [ ";base64" ] "," data
mediatype := [ type "/" subtype ] *( ";" parameter )
data := *urlchar
parameter := attribute "=" value
When including the image data in the logotype extension using the
"data" URI scheme, the following conventions apply:
* The value of mediaType in LogotypeDetails MUST be identical to the
media type value in the "data" URL.
* The hash of the image MUST be included in logotypeHash and MUST be
calculated over the same data as it would have been, had the image
been referenced through a link to an external resource.
NOTE: As the "data" URI scheme is processed as a data source rather
than as a URL, the image data is typically not limited by any URL
length limit settings that otherwise apply to URLs in general.
NOTE: Implementations need to be cautious about the size of images
included in a certificate in order to ensure that the size of the
certificate does not prevent the certificate from being used as
intended.
4.4. Other Logotypes
Logotypes identified by otherLogos (as defined in Section 4.1) can be
used to enhance the display of logotypes and marks that represent
partners, products, services, or any other characteristic associated
with the certificate or its intended application environment when the
standard logotype types are insufficient.
The conditions and contexts of the intended use of these logotypes
are defined at the discretion of the local client application.
Three other logotype types are defined in the follow subsections.
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4.4.1. Loyalty Logotype
When a loyalty logotype appears in the otherLogos, it MUST be
identified by the id-logo-loyalty object identifier.
id-logo OBJECT IDENTIFIER ::= { id-pkix 20 }
id-logo-loyalty OBJECT IDENTIFIER ::= { id-logo 1 }
A loyalty logotype, if present, MUST contain a logotype associated
with a loyalty program related to the certificate or its use. The
relation between the certificate and the identified loyalty program
is beyond the scope of this document. The logotype extension MAY
contain more than one Loyalty logotype.
If more than one loyalty logotype is present, they MUST be placed in
order of preferred appearance. Some clients MAY choose to display a
subset of the present loyalty logotype data; therefore the placement
within the sequence aids the client selection. The most preferred
loyalty logotype data MUST be first in the sequence, and the least
preferred loyalty logotype data MUST be last in the sequence.
4.4.2. Certificate Background Logotype
When a certificate background logotype appears in the otherLogos, it
MUST be identified by the id-logo-background object identifier.
id-logo-background OBJECT IDENTIFIER ::= { id-logo 2 }
The certificate background logotype, if present, MUST contain a
graphical image intended as a background image for the certificate,
and/or a general audio sequence for the certificate. The background
image MUST allow black text to be clearly read when placed on top of
the background image. The logotype extension MUST NOT contain more
than one certificate background logotype.
4.4.3. Certificate Image Logotype
When a certificate image logotype appears in the otherLogos, it MUST
be identified by the id-logo-certImage object identifier.
id-logo-certImage OBJECT IDENTIFIER ::= { id-logo 3 }
The certificate image logotype, if present, aids human interpretation
of a certificate by providing meaningful visual information to the
user interface (UI). The logotype extension MUST NOT contain more
than one certificate image logotype.
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Typical situations when a human needs to examine the visual
representation of a certificate are:
* A person establishes a secured channel with an authenticated
service. The person needs to determine the identity of the
service based on the authenticated credentials.
* A person validates the signature on critical information, such as
signed executable code, and needs to determine the identity of the
signer based on the signer's certificate.
* A person is required to select an appropriate certificate to be
used when authenticating to a service or Identity Management
infrastructure. The person needs to see the available
certificates in order to distinguish between them in the selection
process.
The display of certificate information to humans is challenging due
to lack of well-defined semantics for critical identity attributes.
Unless the application has out-of-band knowledge about a particular
certificate, the application will not know the exact nature of the
data stored in common identification attributes such as serialNumber,
organizationName, country, etc. Consequently, the application can
display the actual data, but faces the problem of labeling that data
in the UI and informing the human about the exact nature (semantics)
of that data. It is also challenging for the application to
determine which identification attributes are important to display
and how to organize them in a logical order.
When present, the certificate image MUST be a complete visual
representation of the certificate. This means that the display of
this certificate image represents all information about the
certificate that the issuer subjectively defines as relevant to show
to a typical human user within the typical intended use of the
certificate, giving adequate information about at least the following
three aspects of the certificate:
* Certificate Context
* Certificate Issuer
* Certificate Subject
Certificate Context information is visual marks and/or textual
information that helps the typical user to understand the typical
usage and/or purpose of the certificate.
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It is up to the issuer to decide what information -- in the form of
text, graphical symbols, and elements -- represents a complete visual
representation of the certificate. However, the visual
representation of Certificate Subject and Certificate Issuer
information from the certificate MUST have the same meaning as the
textual representation of that information in the certificate itself.
Applications providing a Graphical User Interface (GUI) to the
certificate user MAY present a certificate image as the only visual
representation of a certificate; however, the certificate user SHOULD
be able to easily obtain the details of the certificate content.
5. Type of Certificates
Logotypes MAY be included in public key certificates and attribute
certificates at the discretion of the certificate issuer; however,
the relying party MUST NOT use the logotypes as part of certification
path validation or automated trust decision. The sole purpose of
logotypes is to enhance the display of a particular certificate,
regardless of its position in a certification path.
6. Use in Clients
All PKI implementations require 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,
including consistent policy and name checking.
After a certification path is successfully validated, the replying
party trusts the information that the CA includes in the certificate,
including any certificate extensions. The client software can choose
to make use of such information, or the client software can ignore
it. If the client is unable to support a provided logotype, the
client MUST NOT report an error, rather the client MUST behave as
though no logotype extension was included in the certificate.
Current standards do not provide any mechanism for cross-certifying
CAs to constrain subordinate CAs from including private extensions
(see Section 9).
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Consequently, if relying party software accepts a CA, then it should
be prepared to (unquestioningly) display the associated logotypes to
its human user, given that it is configured to do so. Information
about the logotypes is provided so that the replying party software
can select the one that will best meet the needs of the human user.
This choice depends on the abilities of the human user, as well as
the capabilities of the platform on which the replaying party
software is running. If none of the provided logotypes meets the
needs of the human user or matches the capabilities of the platform,
then the logotypes can be ignored.
A client MAY, subject to local policy, choose to display none, one,
or any number of the logotypes in the logotype extension. In many
cases, a client will be used in an environment with a good network
connection and also used in an environment with little or no network
connectivity. For example, a laptop computer can be docked with a
high-speed LAN connection, or it can be disconnected from the network
altogether. In recognition of this situation, the client MUST
include the ability to disable the fetching of logotypes. However,
locally cached logotypes can still be displayed when the user
disables the fetching of additional logotypes.
A client MAY, subject to local policy, choose any combination of
audio and image presentation for each logotype. That is, the client
MAY display an image with or without playing a sound, and it MAY play
a sound with or without displaying an image. A client MUST NOT play
more than one logotype audio sequence at the same time.
The logotype is to be displayed in conjunction with other identity
information contained in the certificate. The logotype is not a
replacement for this identity information.
Care is needed when designing replying party software to ensure that
an appropriate context of logotype information is provided. This is
especially difficult with audio logotypes. It is important that the
human user be able to recognize the context of the logotype, even if
other audio streams are being played.
If the relying party software is unable to successfully validate a
particular certificate, then it MUST NOT display any logotype data
associated with that certificate.
7. Image Formats
Animated images SHOULD NOT be used.
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The following table lists many common image formats and the
corresponding MIME type. The table also indicates the support
requirements for these image formats. The filename extensions
commonly used for each of these formats is also provided.
Implementations MAY support other image formats.
+========+==============+===========+============+============+
| Format | MIME Type | Extension | References | Implement? |
+========+==============+===========+============+============+
| JPEG | image/jpeg | .jpg | [JPEG] | MUST |
| | | .jpeg | [RFC2046] | support |
+--------+--------------+-----------+------------+------------+
| GIF | image/gif | .gif | [GIF] | MUST |
| | | | [RFC2046] | support |
+--------+--------------+-----------+------------+------------+
| SVG | image/ | .svg | [SVGT] | SHOULD |
| | svg+xml | | [SVGR] | support |
+--------+--------------+-----------+------------+------------+
| SVG + | image/ | .svgz | [SVGT] | MUST |
| GZIP | svg+xml+gzip | .svg.gz | [SVGZR] | support |
+--------+--------------+-----------+------------+------------+
| PNG | image/png | .png | [ISO15948] | SHOULD |
| | | | [PNGR] | support |
+--------+--------------+-----------+------------+------------+
| PDF | application/ | .pdf | [ISO32000] | MAY |
| | pdf | | [ISO19005] | support |
| | | | [RFC8118] | |
+--------+--------------+-----------+------------+------------+
Table 1: Image Formats
NOTE: The image/svg+xml-compressed media type is widely implemented,
but it has not yet been registered with IANA.
When a Scalable Vector Graphics (SVG) image is used, whether the
image is compressed or not, the SVG Tiny profile [SVGT] MUST be
followed, with these additional restrictions:
* The SVG image MUST NOT contain any Internationalized Resource
Identifier (IRI) references to information stored outside of the
SVG image of type B, C, or D, according to Section 14.1.4 of
[SVGT].
* The SVG image MUST NOT contain any 'script' element, according to
Section 15.2 of [SVGT].
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* The XML structure in the SVG file MUST use linefeed (0x0A) as the
end-of-line (EOL) character when calculating a hash over the SVG
image.
When a GZIP-compressed SVG image is fetched with HTTP, the client
will receive a response that includes these headers:
Content-Type: image/svg+xml
Content-Encoding: gzip
In this case, the octet stream of type image/svg+xml is compressed
with GZIP [RFC1952] as specified in [SVGR].
When an uncompressed SVG image is fetched with HTTP, the client will
receive a response with the same Content-Type header, but no Content-
Encoding header.
Whether the SVG image is GZIP-compressed or uncompressed, the hash
value for the SVG image is calculated over the uncompressed SVG
content with canonicalized EOL characters as specified above.
When an SVG image is embedded in the certificate extension using the
"data" URL scheme, the SVG image data MUST be provided in GZIP-
compressed form, and the XML structure, prior to compression, SHOULD
use linefeed (0x0A) as the end-of-line (EOL) character.
When a bitmap image is used, the PNG [ISO15948] format SHOULD be
used.
When a Portable Document Format (PDF) document according to
[ISO32000] is used, it MUST also be formatted according to the
profile PDF/A [ISO19005].
8. Audio Formats
Implementations that support audio MUST support the MP3 audio format
[MP3] with a MIME type of "audio/mpeg" [RFC3003]. Implementations
SHOULD support text-based audio data with a MIME type of "text/
plain;charset=UTF-8". Implementations MAY support other audio
formats.
Text-based audio data using the MIME type of "text/plain;charset=UTF-
8" is intended to be used by text-to-speech software. When this
audio type is used, the following requirements apply:
* LogotypeAudioInfo MUST be present and specify the language of the
text.
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* The fileSize, playTime, and channels elements of LogotypeAudioInfo
MUST have the value of 0.
* The sampleRate element of LogotypeAudioInfo MUST be absent.
9. Security Considerations
Implementations that simultaneously display multiple logotype types
(subject organization, issuer, community, or other), MUST ensure that
there is no ambiguity as to the binding between the image and the
type of logotype that the image represents. "Logotype type" is
defined in Section 1.1, and it refers to the type of entity or
affiliation represented by the logotype, not the of binary format of
the image or audio.
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 an entire legal
structure around 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 can be difficult (and sometimes expensive) to verify,
the possibility of errors related to assigning wrong logotypes to
organizations is increased.
This is not a new issue for electronic identification instruments.
It is already dealt with in a number of similar situations in the
physical world, including physical employee identification cards. In
addition, there are situations where identification of logotypes is
rather simple and straightforward, such as logotypes for well-known
industries and institutes. These issues should not stop those
service providers who want to issue logotypes from doing so, where
relevant.
It is impossible to prevent fraudulent creation of certificates by
dishonest or badly performing issuers, containing names and logotypes
that the issuer has no claim to or has failed to check correctly.
Such certificates could be created in an attempt to socially engineer
a user into accepting a certificate. The premise used for the
logotype work is thus that logotype graphics in a certificate are
trusted only if the certificate is successfully validated within a
valid path. It is thus imperative that the representation of any
certificate that fails to validate is not enhanced in any way by
using the logotype data.
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This underlines the necessity for CAs to provide reliable services,
and the relying party's responsibility and need to carefully select
which CAs are trusted to provide public key certificates.
This also underlines the general necessity for relying parties to use
up-to-date software libraries to render or dereference data from
external sources, including logotype data in certificates, to
minimize risks related to processing potentially malicious data
before it has been adequately verified and validated. Implementers
should review the guidance in Section 7 of [RFC3986].
Referenced image objects are hashed in order to bind the image to the
signature of the certificate. Some image types, such as SVG, allow
part of the image to be collected from an external source by
incorporating a reference to an external file that contains the
image. If this feature were used within a logotype image, the hash
of the image would only cover the URI reference to the external image
file, but not the referenced image data. Clients SHOULD verify that
SVG images meet all requirements listed in Section 7 and reject
images that contain references to external data.
CAs issuing certificates with embedded logotype images should be
cautious when accepting graphics from the certificate requestor for
inclusion in the certificate if the hash algorithm used to sign the
certificate is vulnerable to collision attacks such as [RFC6151]. In
such a case, the accepted image may contain data that could help an
attacker to obtain colliding certificates with identical certificate
signatures.
Certification paths may also impose name constraints that are
systematically checked during certification path processing, which,
in theory, may be circumvented by logotypes.
Certificate path processing as defined in [RFC5280] does not
constrain the inclusion of logotype data in certificates. A parent
CA can constrain 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.
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When a relying party fetches remote logotype data, a mismatch between
the media type provided in the mediaType field of the LogotypeDetails
and the Content-Type HTTP header of the retrieved object MUST be
treated as a failure and the fetched logotype data should not be
presented to the user. However, if more than one location for the
remote logotype data is provided in the certificate extension, the
relying party MAY try to fetch the remote logotype data from an
alternate location to resolve the failure.
When a subscriber requests the inclusion of remote logotype data in a
certificate, the CA cannot be sure that any logotype data will be
available at the provided URI for the entire validity period of the
certificate. To mitigate this concern, the CA may provide the
logotype data from a server under its control, rather than a
subscriber-controlled server.
The controls available to a parent CA to protect itself from rogue
subordinate CAs are non-technical. They include:
* Contractual agreements of suitable behavior, including terms of
liability in case of material breach.
* Control mechanisms and procedures to monitor and follow the
behavior of subordinate CAs, including Certificate Transparency
[RFC9162].
* Use of certificate policies to declare an 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.
There is not a simple, straightforward, and absolute technical
solution. Rather, involved parties must settle some aspects of PKI
outside the scope of technical controls. As such, issuers need to
clearly identify and communicate the associated risks.
10. Privacy Considerations
Certificates are commonly public objects, so the inclusion of
privacy-sensitive information in certificates should be avoided. The
more information that is included in a certificate, the greater the
likelihood that the certificate will reveal privacy-sensitive
information. The inclusion of logotype data needs to be considered
in this context.
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Logotype data might be fetched from a server when it is needed. By
watching activity on the network, an observer can determine which
clients are making use of certificates that contain particular
logotype data. Since clients are expected to locally cache logotype
data, network traffic to the server containing the logotype data will
not be generated every time the certificate is used. Further, when
logotype data is not cached, activity on the network might reveal
certificate usage frequency. Even when logotype data is cached,
regardless of whether direct or indirect addressing is employed,
network traffic monitoring could reveal when logotype data is fetched
for the first time. Implementations MAY encrypt fetches of logotype
data using HTTPS, padding the data to a common size to reduce
visibility into the data that is being fetched. Likewise, servers
MAY reduce visibility into the data that is being returned by
encrypting with HTTPS and padding to a few common sizes.
Similarly, when fetching logotype data from a server, the server
operator can determine which clients are making use of certificates
that contain particular logotype data. As above, locally caching
logotype data will eliminate the need to fetch the logotype data each
time the certificate is used, and lack of caching would reveal usage
frequency. Even when implementations cache logotype data, regardless
of whether direct or indirect addressing is employed, the server
operator could observe when logotype data is fetched for the first
time.
In addition, the use of an encrypted DNS mechanism, such as DoT
[RFC7858] or DoH [RFC9230], hides the name resolution traffic
associated fetching remote logotype objects from third parties.
When the "data" URI scheme is used with direct addressing, there is
no network traffic to fetch logotype data, which avoids the
observations of network traffic or server operations described above.
To obtain this benefit, the certificate will be larger than one that
contains a URL. Due to the improved privacy posture, the "data" URI
scheme with direct addressing will be the only one that is supported
by some CAs. Privacy-aware certificate subscribers MAY wish to
insist that logotype data is embedded in the certificate with the
"data" URI scheme with direct addressing.
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In cases where logotype data is cached by the relying party, the
cache index should include the hash values of the associated logotype
data with the goal of fetching the logotype data only once, even when
it is referenced by multiple URIs. The index should include hash
values for all supported hash algorithms. The cached data should
include the media type as well as the logotype data. Implementations
should give preference to logotype data that is already in the cache
when multiple alternatives are offered in the LogotypeExtn
certificate extension.
When the "data" URI scheme is used, the relying party MAY add the
embedded logotype data to the local cache, which could avoid the need
to fetch the logotype data if it is referenced by a URL in another
certificate.
When fetching remote logotype data, relying parties should use the
most privacy-preserving options that are available to minimize the
opportunities for servers to "fingerprint" clients. For example,
avoid cookies, e-tags, and client certificates.
When a relying party encounters a new certificate, the lack of
network traffic to fetch logotype data might indicate that a
certificate with references to the same logotype data has been
previously processed and cached.
TLS 1.3 [RFC8446] includes the ability to encrypt the server's
certificate in the TLS handshake, which helps hide the server's
identity from anyone that is watching activity on the network. If
the server's certificate includes remote logotype data, the client
fetching that data might disclose the otherwise protected server
identity.
11. IANA Considerations
For the new ASN.1 Module in Appendix A.2, IANA is requested to assign
an object identifier (OID) for the module identifier. The OID for
the module should be allocated in the "SMI Security for PKIX Module
Identifier" registry (1.3.6.1.5.5.7.0).
For the existing entries in the Structure of Management Information
(SMI) Numbers registry that refer to RFC 3709 or RFC 6170, IANA is
requested update the entries to refer to this document. These
entries are:
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1.3.6.1.5.5.7.0.22 id-mod-logotype
1.3.6.1.5.5.7.0.68 id-mod-logotype-certimage
1.3.6.1.5.5.7.1.12 id-pe-logotype
1.3.6.1.5.5.7.20.1 id-logo-loyalty
1.3.6.1.5.5.7.20.2 id-logo-background
1.3.6.1.5.5.7.20.3 id-logo-certImage
12. Acknowledgments
12.1. Acknowledgments from RFC 3709
This document is the result of contributions from many professionals.
The authors appreciate contributions from all members of the IETF
PKIX Working Group. We extend a special thanks to Al Arsenault,
David Cross, Tim Polk, Russel Weiser, Terry Hayes, Alex Deacon,
Andrew Hoag, Randy Sabett, Denis Pinkas, Magnus Nystrom, Ryan Hurst,
and Phil Griffin for their efforts and support.
Russ Housley thanks the management at RSA Laboratories, especially
Burt Kaliski, who supported the development of this specification.
The vast majority of the work on this specification was done while
Russ was employed at RSA Laboratories.
12.2. Acknowledgments from RFC 6170
The authors recognize valuable contributions from members of the PKIX
working group, the CA Browser Forum, and James Manger, for their
review and sample data.
12.3. Additional Acknowledgments
Combining RFC 3709 and RFC 6170 has produced an improved
specification. The authors appreciate contributions from all members
of the IETF LAMPS Working Group. We extend a special thanks to
Alexey Melnikov for his guidance on media types. We extend a special
thanks to Tim Geiser for his careful checking of the new examples in
Appendix B.4 and B.5. We extend a special thanks to Corey Bonnell,
Daniel Kahn Gillmor, Roman Danyliw, Paul Wouters, Paul Kyzivat,
Shuping Peng, Sheng Jiang, Rob Wilton, Eric Vyncke, Donald Eastlake,
and Dan Harkins for their careful review and helpful comments.
13. References
13.1. Normative References
[GIF] CompuServe Incorporated, "Graphics Interchange Format",
Version 89a, 31 July 1990,
<https://www.w3.org/Graphics/GIF/spec-gif89a.txt>.
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[ISO15948] ISO/IEC, "Information technology -- Computer graphics and
image processing -- Portable Network Graphics (PNG):
Functional specification", ISO/IEC 15948:2004, 2004.
[JPEG] ITU-T, "Information technology -- Digital compression and
coding of continuous-tone still images: JPEG File
Interchange Format (JFIF)", ITU-T Recommendation T.871,
ISO/IEC 10918-5:2013, May 2011.
[MP3] ISO/IEC, "Information technology -- Generic coding of
moving pictures and associated audio information -- Part
3: Audio", ISO/IEC 13818-3:1998, 1998.
[NEW-ASN1] ITU-T, "Information technology -- Abstract Syntax Notation
One (ASN.1): Specification of basic notation", ITU-T
Recommendation X.680, ISO/IEC 8824-1:2021, February 2021,
<https://www.itu.int/rec/T-REC-X.680>.
[RFC1952] Deutsch, P., "GZIP file format specification version 4.3",
RFC 1952, DOI 10.17487/RFC1952, May 1996,
<https://www.rfc-editor.org/info/rfc1952>.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046,
DOI 10.17487/RFC2046, November 1996,
<https://www.rfc-editor.org/info/rfc2046>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2397] Masinter, L., "The "data" URL scheme", RFC 2397,
DOI 10.17487/RFC2397, August 1998,
<https://www.rfc-editor.org/info/rfc2397>.
[RFC3003] Nilsson, M., "The audio/mpeg Media Type", RFC 3003,
DOI 10.17487/RFC3003, November 2000,
<https://www.rfc-editor.org/info/rfc3003>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
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[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/info/rfc5234>.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
<https://www.rfc-editor.org/info/rfc5280>.
[RFC5646] Phillips, A., Ed. and M. Davis, Ed., "Tags for Identifying
Languages", BCP 47, RFC 5646, DOI 10.17487/RFC5646,
September 2009, <https://www.rfc-editor.org/info/rfc5646>.
[RFC5755] Farrell, S., Housley, R., and S. Turner, "An Internet
Attribute Certificate Profile for Authorization",
RFC 5755, DOI 10.17487/RFC5755, January 2010,
<https://www.rfc-editor.org/info/rfc5755>.
[RFC6838] Freed, N., Klensin, J., and T. Hansen, "Media Type
Specifications and Registration Procedures", BCP 13,
RFC 6838, DOI 10.17487/RFC6838, January 2013,
<https://www.rfc-editor.org/info/rfc6838>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[RFC9110] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
Ed., "HTTP Semantics", STD 97, RFC 9110,
DOI 10.17487/RFC9110, June 2022,
<https://www.rfc-editor.org/info/rfc9110>.
[SVGT] World Wide Web Consortium, "Scalable Vector Graphics (SVG)
Tiny 1.2 Specification", W3C PR-SVGTiny12-20081117, 17
November 2008,
<https://www.w3.org/TR/2008/PR-SVGTiny12-20081117>.
13.2. Informative References
[ISO19005] ISO, "Document management -- Electronic document file
format for long-term preservation -- Part 1: Use of PDF
1.4 (PDF/A-1)", ISO 19005-1:2005, 2005.
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[ISO32000] ISO, "Document management -- Portable document format --
Part 1: PDF 1.7", ISO 32000-1:2008, 2008.
[OLD-ASN1] CCITT, "Specification of Abstract Syntax Notation One
(ASN.1)", CCITT Recommendation X.208, November 1988,
<https://www.itu.int/rec/T-REC-X.208/en>.
[PNGR] World Wide Web Consortium, "Media Type Registration for
image/png",
<https://www.iana.org/assignments/media-types/image/png>.
[RFC3709] Santesson, S., Housley, R., and T. Freeman, "Internet
X.509 Public Key Infrastructure: Logotypes in X.509
Certificates", RFC 3709, DOI 10.17487/RFC3709, February
2004, <https://www.rfc-editor.org/info/rfc3709>.
[RFC5912] Hoffman, P. and J. Schaad, "New ASN.1 Modules for the
Public Key Infrastructure Using X.509 (PKIX)", RFC 5912,
DOI 10.17487/RFC5912, June 2010,
<https://www.rfc-editor.org/info/rfc5912>.
[RFC6151] Turner, S. and L. Chen, "Updated Security Considerations
for the MD5 Message-Digest and the HMAC-MD5 Algorithms",
RFC 6151, DOI 10.17487/RFC6151, March 2011,
<https://www.rfc-editor.org/info/rfc6151>.
[RFC6170] Santesson, S., Housley, R., Bajaj, S., and L. Rosenthol,
"Internet X.509 Public Key Infrastructure -- Certificate
Image", RFC 6170, DOI 10.17487/RFC6170, May 2011,
<https://www.rfc-editor.org/info/rfc6170>.
[RFC6268] Schaad, J. and S. Turner, "Additional New ASN.1 Modules
for the Cryptographic Message Syntax (CMS) and the Public
Key Infrastructure Using X.509 (PKIX)", RFC 6268,
DOI 10.17487/RFC6268, July 2011,
<https://www.rfc-editor.org/info/rfc6268>.
[RFC7858] Hu, Z., Zhu, L., Heidemann, J., Mankin, A., Wessels, D.,
and P. Hoffman, "Specification for DNS over Transport
Layer Security (TLS)", RFC 7858, DOI 10.17487/RFC7858, May
2016, <https://www.rfc-editor.org/info/rfc7858>.
[RFC8118] Hardy, M., Masinter, L., Markovic, D., Johnson, D., and M.
Bailey, "The application/pdf Media Type", RFC 8118,
DOI 10.17487/RFC8118, March 2017,
<https://www.rfc-editor.org/info/rfc8118>.
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[RFC9162] Laurie, B., Messeri, E., and R. Stradling, "Certificate
Transparency Version 2.0", RFC 9162, DOI 10.17487/RFC9162,
December 2021, <https://www.rfc-editor.org/info/rfc9162>.
[RFC9216] Gillmor, D. K., Ed., "S/MIME Example Keys and
Certificates", RFC 9216, DOI 10.17487/RFC9216, April 2022,
<https://www.rfc-editor.org/info/rfc9216>.
[RFC9230] Kinnear, E., McManus, P., Pauly, T., Verma, T., and C.A.
Wood, "Oblivious DNS over HTTPS", RFC 9230,
DOI 10.17487/RFC9230, June 2022,
<https://www.rfc-editor.org/info/rfc9230>.
[SVGR] World Wide Web Consortium, "Media Type Registration for
image/svg+xml", <https://www.iana.org/assignments/media-
types/image/svg+xml>.
[SVGZR] "A separate MIME type for svgz files is needed",
<https://github.com/w3c/svgwg/issues/701>.
Appendix A. ASN.1 Modules
A.1. ASN.1 Modules with 1988 Syntax
This appendix contains two ASN.1 modules, both using the old syntax
[OLD-ASN1].
The first ASN.1 module provides the syntax for the Logotype
certificate extension. Only comments have changed in the module from
RFC 3709, and the IMPORTS now come from [RFC5280].
The second ASN.1 module provides the Certificate Image object
identifier. The module is unchanged from RFC 6170.
<CODE BEGINS>
LogotypeCertExtn
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-logotype(22) }
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
IMPORTS
AlgorithmIdentifier FROM PKIX1Explicit88 -- RFC 5280
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-pkix1-explicit(18) };
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-- Logotype Extension OID
id-pe-logotype OBJECT IDENTIFIER ::=
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-pe(1) 12 }
-- Logotype Extension Syntax
LogotypeExtn ::= SEQUENCE {
communityLogos [0] EXPLICIT SEQUENCE OF LogotypeInfo OPTIONAL,
issuerLogo [1] EXPLICIT LogotypeInfo OPTIONAL,
subjectLogo [2] EXPLICIT LogotypeInfo OPTIONAL,
otherLogos [3] EXPLICIT SEQUENCE OF OtherLogotypeInfo
OPTIONAL }
-- Note: At least one of the OPTIONAL components MUST be present
LogotypeInfo ::= CHOICE {
direct [0] LogotypeData,
indirect [1] LogotypeReference }
LogotypeData ::= SEQUENCE {
image SEQUENCE OF LogotypeImage OPTIONAL,
audio [1] SEQUENCE OF LogotypeAudio OPTIONAL }
-- Note: At least one of the OPTIONAL components MUST be present
LogotypeImage ::= SEQUENCE {
imageDetails LogotypeDetails,
imageInfo LogotypeImageInfo OPTIONAL }
LogotypeAudio ::= SEQUENCE {
audioDetails LogotypeDetails,
audioInfo LogotypeAudioInfo OPTIONAL }
LogotypeDetails ::= SEQUENCE {
mediaType IA5String, -- MIME media type name and optional
-- parameters
logotypeHash SEQUENCE SIZE (1..MAX) OF HashAlgAndValue,
logotypeURI SEQUENCE SIZE (1..MAX) OF IA5String }
LogotypeImageInfo ::= SEQUENCE {
type [0] LogotypeImageType DEFAULT color,
fileSize INTEGER, -- In octets, 0=unspecified
xSize INTEGER, -- Horizontal size in pixels
ySize INTEGER, -- Vertical size in pixels
resolution LogotypeImageResolution OPTIONAL,
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language [4] IA5String OPTIONAL } -- RFC 5646 Language Tag
LogotypeImageType ::= INTEGER { grayScale(0), color(1) }
LogotypeImageResolution ::= CHOICE {
numBits [1] INTEGER, -- Resolution in bits per pixel
tableSize [2] INTEGER } -- Number of colors or grey tones
LogotypeAudioInfo ::= SEQUENCE {
fileSize INTEGER, -- In octets, 0=unspecified
playTime INTEGER, -- In milliseconds, 0=unspecified
channels INTEGER, -- 0=unspecified,
-- 1=mono, 2=stereo, 4=quad
sampleRate [3] INTEGER OPTIONAL, -- Samples per second
language [4] IA5String OPTIONAL } -- RFC 5646 Language Tag
OtherLogotypeInfo ::= SEQUENCE {
logotypeType OBJECT IDENTIFIER,
info LogotypeInfo }
LogotypeReference ::= SEQUENCE {
refStructHash SEQUENCE SIZE (1..MAX) OF HashAlgAndValue,
refStructURI SEQUENCE SIZE (1..MAX) OF IA5String }
-- Places to get the same LogotypeData
-- image or audio object
-- Note: The referenced LogotypeData binary file contains a
-- DER-encoded LogotypeData type
HashAlgAndValue ::= SEQUENCE {
hashAlg AlgorithmIdentifier,
hashValue OCTET STRING }
-- Other logotype type OIDs
id-logo OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) pkix(7) 20 }
id-logo-loyalty OBJECT IDENTIFIER ::= { id-logo 1 }
id-logo-background OBJECT IDENTIFIER ::= { id-logo 2 }
END
CERT-IMAGE-MODULE { iso(1) identified-organization(3) dod(6)
internet(1) security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-logotype-certimage(68) }
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DEFINITIONS EXPLICIT TAGS ::=
BEGIN
EXPORTS ALL; -- export all items from this module
id-logo-certImage OBJECT IDENTIFIER ::=
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-logo(20) 3 }
END
<CODE ENDS>
A.2. ASN.1 Module with 2002 Syntax
Some developers like to use the latest version of ASN.1 standards.
This appendix provides an ASN.1 module to assist in that goal. It
uses the ASN.1 syntax defined in [NEW-ASN1], and it follows the
conventions established in [RFC5912] and [RFC6268].
This ASN.1 module incorporates the module from RFC 3709 and the
module from RFC 6170.
Note that [NEW-ASN1] was published in 2021, and all of the features
used in this module are backward compatible with the specification
that was published in 2002.
<CODE BEGINS>
LogotypeCertExtn
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-logotype(TBD) }
DEFINITIONS IMPLICIT TAGS ::=
BEGIN
IMPORTS
EXTENSION
FROM PKIX-CommonTypes-2009 -- RFC 5912
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-pkixCommon-02(57) }
AlgorithmIdentifier{}, DIGEST-ALGORITHM
FROM AlgorithmInformation-2009
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-mod(0)
id-mod-algorithmInformation-02(58) } ;
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-- Logotype Extension
ext-logotype EXTENSION ::= {
SYNTAX LogotypeExtn
IDENTIFIED BY id-pe-logotype }
-- Logotype Extension OID
id-pe-logotype OBJECT IDENTIFIER ::=
{ iso(1) identified-organization(3) dod(6) internet(1)
security(5) mechanisms(5) pkix(7) id-pe(1) 12 }
-- Logotype Extension Syntax
LogotypeExtn ::= SEQUENCE {
communityLogos [0] EXPLICIT SEQUENCE OF LogotypeInfo OPTIONAL,
issuerLogo [1] EXPLICIT LogotypeInfo OPTIONAL,
subjectLogo [2] EXPLICIT LogotypeInfo OPTIONAL,
otherLogos [3] EXPLICIT SEQUENCE OF OtherLogotypeInfo
OPTIONAL }
-- At least one of the OPTIONAL components MUST be present
( WITH COMPONENTS { ..., communityLogos PRESENT } |
WITH COMPONENTS { ..., issuerLogo PRESENT } |
WITH COMPONENTS { ..., subjectLogo PRESENT } |
WITH COMPONENTS { ..., otherLogos PRESENT } )
LogotypeInfo ::= CHOICE {
direct [0] LogotypeData,
indirect [1] LogotypeReference }
LogotypeData ::= SEQUENCE {
image SEQUENCE OF LogotypeImage OPTIONAL,
audio [1] SEQUENCE OF LogotypeAudio OPTIONAL }
-- At least one image component MUST be present
( WITH COMPONENTS { ..., image PRESENT } )
LogotypeImage ::= SEQUENCE {
imageDetails LogotypeDetails,
imageInfo LogotypeImageInfo OPTIONAL }
LogotypeAudio ::= SEQUENCE {
audioDetails LogotypeDetails,
audioInfo LogotypeAudioInfo OPTIONAL }
LogotypeDetails ::= SEQUENCE {
mediaType IA5String, -- MIME media type name and optional
-- parameters
logotypeHash SEQUENCE SIZE (1..MAX) OF HashAlgAndValue,
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logotypeURI SEQUENCE SIZE (1..MAX) OF IA5String }
LogotypeImageInfo ::= SEQUENCE {
type [0] LogotypeImageType DEFAULT color,
fileSize INTEGER, -- In octets, 0=unspecified
xSize INTEGER, -- Horizontal size in pixels
ySize INTEGER, -- Vertical size in pixels
resolution LogotypeImageResolution OPTIONAL,
language [4] IA5String OPTIONAL } -- RFC 5646 Language Tag
LogotypeImageType ::= INTEGER { grayScale(0), color(1) }
LogotypeImageResolution ::= CHOICE {
numBits [1] INTEGER, -- Resolution in bits
tableSize [2] INTEGER } -- Number of colors or grey tones
LogotypeAudioInfo ::= SEQUENCE {
fileSize INTEGER, -- In octets, 0=unspecified
playTime INTEGER, -- In milliseconds, 0=unspecified
channels INTEGER, -- 0=unspecified
-- 1=mono, 2=stereo, 4=quad
sampleRate [3] INTEGER OPTIONAL, -- Samples per second
language [4] IA5String OPTIONAL } -- RFC 5646 Language Tag
OtherLogotypeInfo ::= SEQUENCE {
logotypeType OBJECT IDENTIFIER,
info LogotypeInfo }
LogotypeReference ::= SEQUENCE {
refStructHash SEQUENCE SIZE (1..MAX) OF HashAlgAndValue,
refStructURI SEQUENCE SIZE (1..MAX) OF IA5String }
-- Places to get the same LogotypeData
-- image or audio object
-- Note: The referenced LogotypeData binary file contains a
-- DER-encoded LogotypeData type
HashAlgAndValue ::= SEQUENCE {
hashAlg AlgorithmIdentifier{DIGEST-ALGORITHM, {...}},
hashValue OCTET STRING }
-- Other logotype type OIDs
id-logo OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
dod(6) internet(1) security(5) mechanisms(5) pkix(7) 20 }
id-logo-loyalty OBJECT IDENTIFIER ::= { id-logo 1 }
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id-logo-background OBJECT IDENTIFIER ::= { id-logo 2 }
id-logo-certImage OBJECT IDENTIFIER ::= { id-logo 3 }
END
<CODE ENDS>
Appendix B. Examples
B.1. Example from RFC 3709
The following example displays a logotype extension containing one
Issuer logotype using direct addressing. The issuer logotype image
is of the type image/gif. The logotype image is referenced through
one URI and the image is hashed with SHA-256. This example is
changed from RFC 3709 to use SHA-256 instead of SHA-1.
The values on the left are the ASN.1 tag (in hexadecimal) and the
length (in decimal).
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30 122: SEQUENCE {
06 8: OBJECT IDENTIFIER logotype (1 3 6 1 5 5 7 1 12)
04 110: OCTET STRING, encapsulates {
30 108: SEQUENCE {
A1 106: [1] {
A0 104: [0] {
30 102: SEQUENCE {
30 100: SEQUENCE {
30 98: SEQUENCE {
16 9: IA5String 'image/gif'
30 49: SEQUENCE {
30 47: SEQUENCE {
30 11: SEQUENCE {
06 9: OBJECT IDENTIFIER
: sha-256 (2 16 840 1 101 3 4 2 1)
: }
04 32: OCTET STRING
: 6A 58 50 2E 59 67 F9 DD D1 8A FE BD 0D B1 FE 60
: A5 13 1B DF 0F B2 BE F0 B5 73 45 50 BA 1B BF 19
: }
: }
30 34: SEQUENCE {
16 32: IA5String 'http://logo.example.com/logo.gif'
: }
: }
: }
: }
: }
: }
: }
: }
: }
B.2. Issuer Logotype Example
The following example displays a logotype extension containing one
Issuer logotype using direct addressing. The issuer logotype image
is of the type image/jpeg. The logotype image is referenced through
one URI and the image is hashed with SHA-256.
The values on the left are the ASN.1 tag (in hexadecimal) and the
length (in decimal).
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30 124: SEQUENCE {
06 8: OBJECT IDENTIFIER logotype (1 3 6 1 5 5 7 1 12)
04 112: OCTET STRING, encapsulates {
30 110: SEQUENCE {
A1 108: [1] {
A0 106: [0] {
30 104: SEQUENCE {
30 102: SEQUENCE {
30 100: SEQUENCE {
16 10: IA5String 'image/jpeg'
30 49: SEQUENCE {
30 47: SEQUENCE {
30 11: SEQUENCE {
06 9: OBJECT IDENTIFIER
: sha-256 (2 16 840 1 101 3 4 2 1)
: }
04 32: OCTET STRING
: 1E 8F 96 FD D3 50 53 EF C6 1C 9F FC F0 00 2E 53
: B4 9C 24 9A 32 C5 E9 0C 2C 39 39 D3 AD 6D A9 09
: }
: }
30 35: SEQUENCE {
16 33: IA5String 'http://logo.example.com/logo.jpeg'
: }
: }
: }
: }
: }
: }
: }
: }
: }
B.3. Embedded Image Example
The following example displays a logotype extension containing one
Subject logotype using direct addressing. The subject logotype image
uses image/svg+xml-compressed. The logotype image is embedded in the
certificate extension with a "data:" URI and the image is hashed by
SHA-256. This technique produces a large certificate extension, but
offers reduced latency and improved privacy.
The values on the left are the ASN.1 tag (in hexadecimal) and the
length (in decimal).
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30 2160: SEQUENCE {
06 8: OBJECT IDENTIFIER logotype (1 3 6 1 5 5 7 1 12)
04 2146: OCTET STRING, encapsulates {
30 2142: SEQUENCE {
A2 2138: [2] {
A0 2134: [0] {
30 2130: SEQUENCE {
30 2126: SEQUENCE {
30 2122: SEQUENCE {
16 24: IA5String 'image/svg+xml-compressed'
30 49: SEQUENCE {
30 47: SEQUENCE {
30 11: SEQUENCE {
06 9: OBJECT IDENTIFIER
: sha-256 (2 16 840 1 101 3 4 2 1)
: }
04 32: OCTET STRING
: C5 AC 94 1A 0A 25 1F B3 16 6F 97 C5 52 40 9B 49
: 9E 7B 92 61 5A B0 A2 6C 19 BF B9 D8 09 C5 D9 E7
: }
: }
30 2041: SEQUENCE {
16 2037: IA5String
: 'data:image/svg+xml-compressed;base64,H4sICIGpy2E'
: 'AA2xvZ28tY29weS5zdmcApVbbbhs3EH3nV0y3Lw2Q9fK2JLe'
: 'wHDROUBRo2iBxW+RRlTa2UFkypIWV5ut7zlB2UqF9cuLlUkt'
: 'yLmfOzPD8xafbtdyPu/1qu5k17sw2sp/mm+V8vd2Ms2azbV5'
: 'cmPNvXv16efXh7WvZ31/L299e/vzTpTRt1/0RLrvu1dUref/'
: '7j+KtdXawsete/9IYaW6m6e77rjscDmeHcLbdXXdX7zpu6t6'
: '9vmxxon08AREdRDt7tpyWDRRSz7+tgp2b/ew/hEKI5WGoPKy'
: 'W082s8SmeWf13NzVyM66ub6ZZk+xXH+9X4+Hl9tOssWLly35'
: '53ARpd7txP+7uxx/2d+NiejefVttZ8+nNavkBj9yO40RLb8d'
: 'pvpxP8wtzuRvn07iUP/+Wu+20my9GcWfOPpfDbjVN44YLb8d'
: 'p3Mn7cb3aXGNCAICCc+a8+yLo/FpwfLP/uN3dzhqdriH5uwf'
: 'bnj9a+Uz2i/maK66utA+zZ435uFqvZ823R38Q1t32Lw3pZqT'
: 'hd/PpRpaz5o2LNkocvCzaIm0vrQvSpog359lLy3my0ga+e3H'
: 'p+B4InjVFPD9awdhnrGEFW30Sl/Pnpvta2QBVxUEVxFbJ2VU'
: 'FfYC01pUs+O4GK84V/k6CHUFyhvhiDVQF8Y5aPDbmnsrXbS7'
: '4DANjguwgENZLPwjUYVTRJQgEpiLR0ctiWj+Ig8rCvZAArxK'
: 'ExEEWMJLqMA1F+ggnsQDXgpQeomJPCVhtCRycNrAWxgAI+g1'
: 'Qsr6IUxlomBswjydYBEgOeVCDoRreBjiFjX2SdSA60BP5DgQ'
: 'M63xoPlWHbNq+egAEeAzxyNAdCQz+sDEMOhaGisKJdSlS6gt'
: 'WWm4M1rQwP0egEBIhhFLoXuCJhR4mT5RJBaiLKqqFROUEzYr'
: '1idG0gahwCzEnk+AMJLdp0FevQQ6VZ+SKOwGlOIJOh1MVjo0'
: 'eB6DRA10SRpSY6il/eFFKAm+MKSIWNFqSo4OFnORfwH5wJHC'
: 'MNM0qlDRlcIwUEkDlgiSBhiEpBgMKOx5FdAYqI3KYewKKkAI'
: 'tTABTkp5khI86kgbOgRywEBR0VGcwAjf8t9wqvdUMG6gLAbI'
: '0QQ8CbzCTtCSn/DEhCbm++duQaiRG1mQkdWHnminHA+r5wpL'
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: 'vsJbCALUKsDW5NAj43J+AD5vpfamUzJqiRJACmCWwIMhQq4H'
: 'mYGKaiiJPmIvpS80UzTtAjdSraApQZogslgFcJHw0y5WoEXD'
: 'Yr/aTqfxk2qhcg3z6ETQL+S18llvHOZQvlEOVEVpzqCozE9V'
: '6JZhh/lCslg7mUFY4AR7IlcApmgV6gz3DCSDe56fQ0SRS7el'
: '0NJWO8mQ6mkc6ylPpaL7QUZ5IR/M/dEwoJiEp+L6iT4cdSyI'
: 'p4ljDkoaZpQlgMoz0ApahjTiTWbZYu9v+MUqVjY61j2Bxr68'
: 'bPF3uS1232qAyAQDMhr4MRyVZq5l2QcuwgY/oTozbgoIKycH'
: '+yQxhzQsPJQ/ne9OmRKvYH1AeKA/EQRtzrmaYUiHUhpJOW4b'
: 'reSaxZ/TVc3ZAQJKOagAJiw6pRHVkBMIBa5E+SUMWi0ZNW1R'
: 'fn/xQXywHXyMHN5G8WF6gZ2IVjANHMIJQ1lAJQE8MJjZHJiU'
: 'tQZAWzmkisDywTVWSqLkkQG2NNB3wwyaerqRGLNKpvwUOhaQ'
: 'FiYcqviSjvp1n8WnRRzXFs9IXDxiiDd8HU/ROoAGn9+QgTPE'
: 'Vu6HaN6i0VPuv1SCzwyZeHwBA1EjFYoAk2jJ3OFeJ5Gp1E+3'
: 'Dlf3Aj70bbvmag5oyKHunVyGPq6+EnvTua/JUn3iadMHlqUa'
: 'psK2T8SwCBJUF1JnEmhu0ntBthJoQpZqumsBk5mA1hRc0LR5'
: 'ZFerdjksaCqt3IUWXcXW16vb6xdWyHLTgCaKXWKUKK1kOp9H'
: 'K5B3ELjSdXb0loB5RYtS01L6h9yTPW51Wpqwgosr5I927aw6'
: '401+YfwDria4WoQwAAA=='
: }
: }
: }
: }
: }
: }
: }
: }
: }
B.4. Embedded Certificate Image Example
The following example displays a logotype extension containing one
Certificate Image logotype using direct addressing. The Certificate
Image logotype uses image/svg+xml-compressed. The logotype image is
embedded in the certificate extension with a "data:" URI and the
image is hashed by SHA-256. This example contains the image from
Appendix B of RFC 6170, however, the media type used here is explicit
about the use of GZIP compression [RFC1952].
The values on the left are the ASN.1 tag (in hexadecimal) and the
length (in decimal).
30 2914: SEQUENCE {
06 8: OBJECT IDENTIFIER logotype (1 3 6 1 5 5 7 1 12)
04 2900: OCTET STRING, encapsulates {
30 2896: SEQUENCE {
A3 2892: [3] {
30 2888: SEQUENCE {
30 2884: SEQUENCE {
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06 8: OBJECT IDENTIFIER '1 3 6 1 5 5 7 20 3'
A0 2870: [0] {
30 2866: SEQUENCE {
30 2862: SEQUENCE {
30 2858: SEQUENCE {
16 24: IA5String 'image/svg+xml-compressed'
30 49: SEQUENCE {
30 47: SEQUENCE {
30 11: SEQUENCE {
06 9: OBJECT IDENTIFIER
: sha-256 (2 16 840 1 101 3 4 2 1)
: }
04 32: OCTET STRING
: 83 14 B3 26 9B D3 8B 0B 2A E6 6E 42 74 E2 A7 57
: 7A 40 B7 E1 2E 53 42 44 CC 7C AE 14 68 1B 0E B6
: }
: }
30 2777: SEQUENCE {
16 2773: IA5String
: 'data:image/svg+xml-compressed;base64,H4sICLXutU0'
: 'AA0NlcnRJbWFnZURlbW8uc3ZnANVaW2/bOBZ+n19BqBigwdo'
: 'S7xK9jmeapB0EWHQHzez2WZZoR1tZMiQ5jvvr95CSL7Gl1Em'
: '8C9d9iERSPOd85+O5EB3+9jhL0YMuyiTPLh3iYgfpLMrjJJt'
: 'eOv/661M/cFBZhVkcpnmmL50sd34b/TIsH6YoiS+da11UySS'
: 'Jwkqj21k41Q6CDbNyUMSTS+e+quYDz1sul+6SuXkx9YhSysP'
: 'Uo7QPK/rlKqvCx35Wvmu+a/uGYow9EOigh0Qvr/LHSwcjjDj'
: 'GiGHQ914n0/sKlMf4Vwctk7i6X7/sGEYdNA5L/WeRT5IUDKm'
: 'SbLVWNoo2cqNCh1XyoKN8Nsuz0iqwVW8Qb1fOF0Vqp+PI06m'
: 'e6awqPeISzxn9goYzXYVxWIUWpfWLCMwcGoLpgy83n8wzGkb'
: 'R4GtefENmMBznC7DEroKpOBpM8mIWVqPEYGtA+BvoMfS2E5u'
: 'F1Wqu7R6FLvNFEelWReNolpiV3l2VpGntMW9nk6RKdf0+9Br'
: 'FrMbeVuWhtzbHvMR6UlobPyVpBWjXBk7six2vH5nCwY6nXCo'
: '5xb7YusvFVPqCOGh16fSxSxglmPkScLfvmDDmC4FlDc1wov8'
: 'IF2WZhNlVumgEPRliimDD3PhGPyTgUUMC6lKqKAjxaptq1bo'
: 'UJvQFsvi+LOJyxZkPE/vCwHuAmXmoj1AarnRBatzqkbv7cK5'
: 'Ls2ORfwM/vsOG5lURZqXxOnDXPKZw5t5jVzIhFKO0B6D6hAR'
: 'SXDR6Fzqq7H7mQeJAOQiUSPvFIrUHOfuui3zrFI5dYVeAmpc'
: 'OcOb9u63vLjae4kYX4yRifYPrTa2SlMigYdO+cEWeGADMLZL'
: 'H96SH4R9xRYApl6q3Y02f+NzlRAl+cZSKhB6qSIVa80fsqMn'
: 'WOqZJpmsXwAPoyNaQ95uNIGasKPwhxGzQzOXzMIIzBKabmLI'
: 'il470zfSjWWn+kvpvLQ9g1l3yRIc8gukz0uysEcakcDfy3KM'
: 'k+l0SOXlOopltJL7EPtUlzZfP4tnM70k8xkKCySt92MwfIXP'
: 'oTe0pnu4dYbp7hJ/kxWySN0ey0o/1qbiCsxDXJMWWo37QekB'
: 'cAUFPSGkPCnUJF5wwBacDK5cGlEp4BC2lYoJcrNNGVc7DzIq'
: 'xT4CKsPlrAG8mL8whRejiQe9EmImIAoz3sds9NxP4RZEzugq'
: 'zb7c3Q89u3WQKY9aegbsA/AUJB/bJs6pfJt9BHFEuk5DWITz'
: 'OH5uZSThLUsDjQ5GE6RMsyihMTaQLfA6BIiAQMAhnHHN1sd6'
: '1WtUhDVJiuhkrdBXd740+hLB9Vm1HjQe4ywLOBLWOMMiyQAX'
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: 'NB8sm9Gx2qdGgGkMG6wY8aLfqgH4dfnmrVc+pPrE/Z/QnZOs'
: '8C1Okb2/ggwLdxlDC1D6DFPZDD98txv8xQf5TEc7Ax6ZyaDf'
: '6BC4SylWKCMqtizp80+UMchATal63qHq0M3ZTs83Ob/XO6LY'
: 'sFzpGVY5+iLxdWvwY+NaKoR/0iJIXL3dBjT2hG+wO+NXm53X'
: 'StSh1eogfeojV35BTOaqh/cmPUe2Mdp91pQp2CjWOO2k7Oam'
: 'hjU1HB3DLGm66n6iajz4bqn2oICmNFxDR/x2mC5s+rKhlkUA'
: '3Ne3P8lgP0qJfjf9uvu+HWXSfFwNoH4uqGUmTadYMtOc7yjE'
: 'Ed9EUhkwEEOcDSHKQ+yhnSvUYRH8miQo2FK5TCjWZZGWKB8i'
: 'HPud16wApnCvTOzjIFAj9TQdCxa+ddOTizaa1xJvD0qMrKx+'
: 'Ydaj6iwJQG0vaSdYWpTv4HwVRAP3Z6ONjOJunEIeKRVmhujp'
: 'A2+wPmQR9WFQAFhh9bGQzFEXX+WwOnXq8pV35P2Acdn0pGeb'
: 'cMg7OgQKaEdOKEAkFlk/9HuEKGBVwucc4AjnJ/LBYU09hVwW'
: 'Y1F0HlBUC2lbyIuYF58O8p+adMwUt9YAoX/IwRtAC9NAdBAy'
: 'GuEB3VR59u8/TGYx9/Xjz8bPB/Z/F9B0SghBK+4xxfiwtr0G'
: 'XECqedQQ9PRVpEAQ+26MidbGSmPm8RwRzcQsT17EPSmoorH3'
: '+av4Jcj78O/vIp/uzMEkHKAE6/F7VHHSj8HddR0Q3ymcGZfR'
: 'VjwfmOnNn3GuWR+FzhcPmPqiptHcayacT28T8j3Cs0/LQCwo'
: '6J2iYxP4R58AsobjFegusoJhuq7VNS2evRPcqASvQki+gbkB'
: 'YwETNPt/1A2pT6UErR1zMzUITZRvF5Lp5basO1fk2U4aBSjk'
: 'ji8quL3cDyW7TpI3unxezMcSTNhQJhfpGctKgKN2Amo7/7Sh'
: 'Sev4oXicPSYS+6GkCm9a1Qw3VEchCUA+z5HtTcbQhK6F14YF'
: 'Up+Yn7WgmzwpZCDf5DDiXT9B7U6RdHAHpdb7IqmLVjqZSLnT'
: 'W61zjQ7/G7D3hm9E846uTDZoNMADmLlm7IG2ieXfUtu1US9T'
: 'eNGUHibE9Nv//2jRJGZfQmK3v7ykJJOv1IXjBsDCPpmgWppe'
: '6sHxR3KVSQKqp+WIqammuJbtqkxZmMHry4oS/9pLhdCXKq8u'
: 'R0R+LDEqCKRxqc5VXdvPvIP+ggwR0RkyBfO9iKZvrWGAKVdz'
: '31cuocvoO/qemClFMYEFEH7oI+vpkek4s4bCMBqK+5mHQUlD'
: 'pE/oylpy+2/6pWXK31PEYagP04epV1cE50UMy6IQZeQM7+Ol'
: '74Z+eHfpHNc7OjffQ/HeV0X8BopoDkGEkAAA='
: }
: }
: }
: }
: }
: }
: }
: }
: }
: }
: }
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B.5. Full Certificate Example
The following example contains a certificate for Alice; it is
essentially a renewal of the certificate that appears in [RFC9216].
Of course, the serial number and issue dates are different. In
addition, Alice's certificate now has a logotype extension. The
extension contains URLs for two community logotype images, both at
fictional URLs. The extension also contains URLs for two subject
logotype images, both at fictional URLs. An implementation would
display at most three of these images, both of the community logotype
images and one of the subject logotype images. Direct addressing is
used for all of the images, and the images are hashed by SHA-256.
-----BEGIN CERTIFICATE-----
MIIFpTCCBI2gAwIBAgITN0EFee11f0Kpolw69Phqzpqx1zANBgkqhkiG9w0BAQ0F
ADBVMQ0wCwYDVQQKEwRJRVRGMREwDwYDVQQLEwhMQU1QUyBXRzExMC8GA1UEAxMo
U2FtcGxlIExBTVBTIFJTQSBDZXJ0aWZpY2F0aW9uIEF1dGhvcml0eTAgFw0yMjA2
MTUxODE4MThaGA8yMDUyMDkyNzA2NTQxOFowOzENMAsGA1UEChMESUVURjERMA8G
A1UECxMITEFNUFMgV0cxFzAVBgNVBAMTDkFsaWNlIExvdmVsYWNlMIIBIjANBgkq
hkiG9w0BAQEFAAOCAQ8AMIIBCgKCAQEAtPSJ6Fg4Fj5Nmn9PkrYo0jTkfCv4TfA/
pdO/KLpZbJOAEr0sI7AjaO7B1GuMUFJeSTulamNfCwDcDkY63PQWl+DILs7GxVwX
urhYdZlaV5hcUqVAckPvedDBc/3rz4D/esFfs+E7QMFtmd+K04s+A8TCNO12DRVB
DpbP4JFD9hsc8prDtpGmFk7rd0q8gqnhxBW2RZAeLqzJOMayCQtws1q7ktkNBR2w
ZX5ICjecF1YJFhX4jrnHwp/iELGqqaNXd3/Y0pG7QFecN7836IPPdfTMSiPR+peC
rhJZwLSewbWXLJe3VMvbvQjoBMpEYlaJBUIKkO1zQ1Pq90njlsJLOwIDAQABo4IC
hDCCAoAwDAYDVR0TAQH/BAIwADAXBgNVHSAEEDAOMAwGCmCGSAFlAwIBMAEwHgYD
VR0RBBcwFYETYWxpY2VAc21pbWUuZXhhbXBsZTATBgNVHSUEDDAKBggrBgEFBQcD
BDAOBgNVHQ8BAf8EBAMCBsAwHQYDVR0OBBYEFLv2zLItHQYSHJeuKWqQENMgZmZz
MB8GA1UdIwQYMBaAFJEwjnwHFwyn8QkoZTYaZxxodvRZMIIB0AYIKwYBBQUHAQwE
ggHCMIIBvqCB4zCB4KBvMG0wazBpFgppbWFnZS9qcGVnMDEwLzALBglghkgBZQME
AgEEIK/8EBZGy1YltJl95Yk+rjqEb1oC04LW2o7U7vh8vR3tMCgWJmh0dHA6Ly93
d3cuZXhhbXBsZS5uZXQvaW1hZ2VzL2xvZ28uanBnoG0wazBpMGcWCWltYWdlL2dp
ZjAxMC8wCwYJYIZIAWUDBAIBBCCIkIGBrftmri9m0EmgTY6g7E6oZEI4WzZKvyyL
0unpZjAnFiVodHRwOi8vd3d3LmV4YW1wbGUub3JnL2xvZ28taW1hZ2UuZ2lmooHV
oIHSMIHPMGUwYxYJaW1hZ2UvZ2lmMDEwLzALBglghkgBZQMEAgEEIGpYUC5ZZ/nd
0Yr+vQ2x/mClExvfD7K+8LVzRVC6G78ZMCMWIWh0dHA6Ly93d3cuc21pbWUuZXhh
bXBsZS9sb2dvLmdpZjBmMGQWCmltYWdlL2pwZWcwMTAvMAsGCWCGSAFlAwQCAQQg
vct7dXJtjBszpCzerHly2krZ8nmEClhYas4vAoDq16UwIxYhaHR0cDovL3d3dy5z
bWltZS5leGFtcGxlL2xvZ28uanBnMA0GCSqGSIb3DQEBDQUAA4IBAQBbjdCNVFA/
emCc5uKX5WSPrdvRFZSs57SEhE0odxvhTrOs13VM8Om0TxhNJ0Pl6d9CJdbUxtFw
SSnSu9fnghDO7OZDJnPiIYLNY5eTTzY6sx85mde9TLaBTE7RZf0W7NV0hqDqcfM+
9HnQrU4TtPSvtPS5rr5SvqkaMM0k89bpbkgZlh9HH14+x+DIeT0dLythiXJvkVod
qEfyZTcdplQHQ4szWO7lsjmvHrUIbS1tdAJnah8AZRZfqiJEFeiUp06hvAWnPc3y
1TMwYI8onfwPIVzyT6YLgjiT6PuLwSB/wtlhI+vWfdINaHdotegjawLm/3jZ+ceN
tu39FvbV0uKJ
-----END CERTIFICATE-----
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The following displays the logotype extension from Alice's
certificate. The values on the left are the ASN.1 tag (in
hexadecimal) and the length (in decimal).
30 464: SEQUENCE {
06 8: OBJECT IDENTIFIER logotype (1 3 6 1 5 5 7 1 12)
04 450: OCTET STRING, encapsulates {
30 446: SEQUENCE {
A0 227: [0] {
30 224: SEQUENCE {
A0 111: [0] {
30 109: SEQUENCE {
30 107: SEQUENCE {
30 105: SEQUENCE {
16 10: IA5String 'image/jpeg'
30 49: SEQUENCE {
30 47: SEQUENCE {
30 11: SEQUENCE {
06 9: OBJECT IDENTIFIER
: sha-256 (2 16 840 1 101 3 4 2 1)
: }
04 32: OCTET STRING
: AF FC 10 16 46 CB 56 25 B4 99 7D E5 89 3E AE 3A
: 84 6F 5A 02 D3 82 D6 DA 8E D4 EE F8 7C BD 1D ED
: }
: }
30 40: SEQUENCE {
16 38: IA5String 'http://www.example.net/images/logo.jpg'
: }
: }
: }
: }
: }
A0 109: [0] {
30 107: SEQUENCE {
30 105: SEQUENCE {
30 103: SEQUENCE {
16 9: IA5String 'image/gif'
30 49: SEQUENCE {
30 47: SEQUENCE {
30 11: SEQUENCE {
06 9: OBJECT IDENTIFIER
: sha-256 (2 16 840 1 101 3 4 2 1)
: }
04 32: OCTET STRING
: 88 90 81 81 AD FB 66 AE 2F 66 D0 49 A0 4D 8E A0
: EC 4E A8 64 42 38 5B 36 4A BF 2C 8B D2 E9 E9 66
: }
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: }
30 39: SEQUENCE {
16 37: IA5String 'http://www.example.org/logo-image.gif'
: }
: }
: }
: }
: }
: }
: }
A2 213: [2] {
A0 210: [0] {
30 207: SEQUENCE {
30 101: SEQUENCE {
30 99: SEQUENCE {
16 9: IA5String 'image/gif'
30 49: SEQUENCE {
30 47: SEQUENCE {
30 11: SEQUENCE {
06 9: OBJECT IDENTIFIER
: sha-256 (2 16 840 1 101 3 4 2 1)
: }
04 32: OCTET STRING
: 6A 58 50 2E 59 67 F9 DD D1 8A FE BD 0D B1 FE 60
: A5 13 1B DF 0F B2 BE F0 B5 73 45 50 BA 1B BF 19
: }
: }
30 35: SEQUENCE {
16 33: IA5String 'http://www.smime.example/logo.gif'
: }
: }
: }
30 102: SEQUENCE {
30 100: SEQUENCE {
16 10: IA5String 'image/jpeg'
30 49: SEQUENCE {
30 47: SEQUENCE {
30 11: SEQUENCE {
06 9: OBJECT IDENTIFIER
: sha-256 (2 16 840 1 101 3 4 2 1)
: }
04 32: OCTET STRING
: BD CB 7B 75 72 6D 8C 1B 33 A4 2C DE AC 79 72 DA
: 4A D9 F2 79 84 0A 58 58 6A CE 2F 02 80 EA D7 A5
: }
: }
30 35: SEQUENCE {
16 33: IA5String 'http://www.smime.example/logo.jpg'
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: }
: }
: }
: }
: }
: }
: }
: }
: }
Appendix C. Changes Since RFC 3709 and RFC 6170
This appendix summarizes the changes since RFC 3709. The changes
are:
* Combine RFC 3709 and RFC 6170 into one document, and encourage
implementers to support the "data" URI scheme (data:...) that was
originally specified in RFC 6170. Merging RFC 3709 and RFC 6170
lead to many editoral changes throughout the document.
* Drop SHA-1 as the mandatory-to-implement hash algorithm, and
encourage use of the one-way hash function that is employed by the
certificate signature algorithm.
* RFC 3709 required client applications to support both direct and
indirect addressing. This requirement is changed to SHOULD
support both direct and indirect addressing to allow
implementations to be more privacy preserving.
* Update the reference for language tags to be RFC 5646 instead of
the now obsolete RFC 3066.
* Update the reference for the URI Generic Syntax to be RFC 3986
instead of the now obsolete RFC 2396.
* Update the reference for the application/pdf media type to be RFC
8118 instead of the now obsolete RFC 3778.
* No longer require support for the FTP scheme (ftp://...) URI.
* Require support for the HTTP scheme (http://...) URI and the HTTPS
scheme (https://...) URI.
* Require support for the compressed SVG image format with the
image/svg+xml+gzip media type.
* Media types MUST follow the ABNF [RFC5234] that is provided in
Section 4.2 of [RFC6838]. This change resolves Errata ID 2679.
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* Remove the requirement that the LogotypeData file name have a file
extension of ".LTD". This change resolves Errata ID 2325.
* Encourage, instead of requiring, each logotype to be represented
by at least one image.
* Encourage the inclusion of text-based audio data suitable for
processing by a text-to-speech software using the MIME type of
"text/plain;charset=UTF-8".
* Encourage the use of dithering if an image needs to be scaled.
* Require that the logotype extension not contain more than one
certificate image logotype.
* Privacy-related topics that were previously discussed in the
Security Considerations section are now covered in a separate
Privacy Considerations section. Additional topics are covered in
both sections.
* Provide ASN.1 modules for both the older syntax [OLD-ASN1] and the
most recent ASN.1 syntax [NEW-ASN1].
* Provide additional references.
* Provide additional examples.
* Several editorial changes to improve clarity.
* The example in Appendix B.1 was changed to use SHA-256 instead of
SHA-1.
Authors' Addresses
Stefan Santesson
IDsec Solutions AB
Forskningsbyn Ideon
SE-223 70 Lund
Sweden
Email: sts@aaa-sec.com
Russ Housley
Vigil Security, LLC
516 Dranesville Road
Herndon, VA, 20170
United States of America
Email: housley@vigilsec.com
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Trevor Freeman
Amazon Web Services
1918 8th Ave
Seattle, WA, 98101
United States of America
Email: frtrevor@amazon.com
Leonard Rosenthol
Adobe
345 Park Avenue
San Jose, CA, 95110
United States of America
Email: lrosenth@adobe.com
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