Internet DRAFT - draft-housley-lamps-rfc3709bis

draft-housley-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: 29 July 2022                                         T. Freeman
                                                     Amazon Web Services
                                                         25 January 2022


      Internet X.509 Public Key Infrastructure: Logotypes in X.509
                              Certificates
                   draft-housley-lamps-rfc3709bis-00

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 29 July 2022.

Copyright Notice

   Copyright (c) 2022 IETF Trust and the persons identified as the
   document authors.  All rights reserved.











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   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
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   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 . . . . . . . . . . . . . . . . . . . . .  12
     4.4.  Other Logotypes . . . . . . . . . . . . . . . . . . . . .  13
       4.4.1.  Loyalty Logotype  . . . . . . . . . . . . . . . . . .  13
       4.4.2.  Certificate Background Logotype . . . . . . . . . . .  13
       4.4.3.  Certificate Image Logotype  . . . . . . . . . . . . .  14
   5.  Type of Certificates  . . . . . . . . . . . . . . . . . . . .  15
   6.  Use in Clients  . . . . . . . . . . . . . . . . . . . . . . .  15
   7.  Image Formats . . . . . . . . . . . . . . . . . . . . . . . .  17
   8.  Audio Formats . . . . . . . . . . . . . . . . . . . . . . . .  18
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  18
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  21
   11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  21
     11.1.  Acknowledgments from RFC 3709  . . . . . . . . . . . . .  21
     11.2.  Acknowledgments from RFC 6170  . . . . . . . . . . . . .  22
     11.3.  Additional Acknowledgments . . . . . . . . . . . . . . .  22
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  22
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  22
     12.2.  Informative References . . . . . . . . . . . . . . . . .  24
   Appendix A.  ASN.1 Modules  . . . . . . . . . . . . . . . . . . .  25
     A.1.  ASN.1 Modules with 1988 Syntax  . . . . . . . . . . . . .  25
     A.2.  ASN.1 Module with 1997 Syntax . . . . . . . . . . . . . .  28
   Appendix B.  Examples . . . . . . . . . . . . . . . . . . . . . .  30
     B.1.  Example from RFC 3709 . . . . . . . . . . . . . . . . . .  31
     B.2.  Issuer Logotype Example . . . . . . . . . . . . . . . . .  32
     B.3.  Embedded Image Example  . . . . . . . . . . . . . . . . .  33
     B.4.  Embedded Certificate Image Example  . . . . . . . . . . .  34
   Appendix C.  Changes Since RFC 3709 . . . . . . . . . . . . . . .  37



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   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  37

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 and RFC 6170.  Appendix C provides a
   summary of the changes since the publication of RFC 3709.

   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 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
      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
   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.

   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 access control decisions.
   Automatic processing will make some access control 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
   access control 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).





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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.

   There is no need to significantly increase the size of the
   certificate by including image and audio data of logotypes when a URI
   identifying the location to the logotype data and a one-way hash of
   the referenced data is included in the certificate.  Embedding the
   logotype in the certificate (as defined in Section 4.3) 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 within the size range of 60 pixels
   wide by 45 pixels high, and 200 pixels wide by 150 pixels high.

   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 have a play
   time between 1 and 30 seconds.

   If a logotype of a certain type (as defined in Section 1.1) is
   represented by more than one image object, then the image objects
   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.  Compliant
   applications MUST NOT display more than one of the image objects and
   MUST NOT play more than one of the audio object for any logotype type
   at the same time.




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   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.

   Logotype data may be referenced through either direct or indirect
   addressing.  Client applications MUST 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.
   Direct addressing supports cases where just one or a few alternative
   images and audio objects are referenced.

   The indirect addressing includes one reference 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 item.  This opportunity for replication is
   intended to improve availability.  Therefore, if a client is unable



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   to fetch the item from one URI, the client SHOULD try another URI in
   the sequence.  All direct addressing URIs SHOULD use either the HTTP
   scheme (http://...) or the HTTPS scheme (https://...) or the DATA
   scheme (data://...) [RFC2396]; however, the "data" URI scheme MUST
   NOT be used with the indirect addressing.  Clients MUST support
   retrieval of referenced LogoTypeData with the HTTP/2 [RFC7540] and
   the HTTPS/2 with TLS [RFC8740].  Client applications SHOULD also
   support the "data" URI scheme [RFC2397] for direct addressing with
   embedded logotype data within the extension.

   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 }

   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
      xSize           INTEGER,  -- Horizontal size in pixels
      ySize           INTEGER,  -- Vertical size in pixels
      resolution      LogotypeImageResolution OPTIONAL,
      language        [4] IA5String OPTIONAL }  -- RFC 5646 Language Tag



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   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
      playTime        INTEGER,  -- In milliseconds
      channels        INTEGER,  -- 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

   HashAlgAndValue ::= SEQUENCE {
      hashAlg         AlgorithmIdentifier,
      hashValue       OCTET STRING }

   When using indirect addressing, the URI (refStructURI) pointing to
   the external data structure MUST point to a binary file containing
   the DER-encoded data with the syntax LogotypeData.

   At least one of the optional elements in the LogotypeExtn structure
   MUST be present.  Avoid the use of otherLogos whenever possible.

   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 SHOULD
   include a hash value that computed with the one-way hash function
   associated with the certificate signature, 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.




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   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 [RFC4288].  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
      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.









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   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.

   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.




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   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.

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.

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 }








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   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-background 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).  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



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   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.

   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 according to this
   standard in any given application interface, as the only visual
   representation of a certificate.

5.  Type of Certificates

   Logotypes MAY be included in public key certificates and attribute
   certificates at the discretion of the certificate issuer; however,
   logotypes MUST NOT be part of certification path validation or any
   type of automated processing.  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



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   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).

   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.




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7.  Image Formats

   Animated images SHOULD NOT be used.

   The following table lists many commons image formats and their
   corresponding MIME type.  The table also indicates which of the image
   formats must be supported by implementations.  The filename
   extensions commonly used for each of these formats is also provided.
   Implementations MAY support other image formats.

    +========+====================+=========+============+============+
    | Format | MIME Type          | .ext    | References | Implement? |
    +========+====================+=========+============+============+
    | JPEG   | image/jpeg         | .jpg    | [JPEG]     | MUST       |
    |        |                    | .jpeg   | [RFC2046]  | support    |
    +--------+--------------------+---------+------------+------------+
    | GIF    | image/gif          | .gif    | [GIF]      | MUST       |
    |        |                    |         | [RFC2046]  | support    |
    +--------+--------------------+---------+------------+------------+
    | SVG    | image/svg+xml      | .svg    | [SVGT]     | SHOULD     |
    |        |                    |         | [SVGR]     | support    |
    +--------+--------------------+---------+------------+------------+
    | SVG +  | image/svg+xml-     | .svgz   | [SVGT]     | MUST       |
    | GZIP   | compressed         | .svg.gz | [SVGZR]    | support    |
    +--------+--------------------+---------+------------+------------+
    | PNG    | image/png          | .png    | [ISO15948] | SHOULD     |
    |        |                    |         | [PNGR]     | support    |
    +--------+--------------------+---------+------------+------------+
    | PDF    | application/pdf    | .pdf    | [ISO32000] | MAY        |
    |        |                    |         | [ISO19005] | support    |
    |        |                    |         | [RFC3778]  |            |
    +--------+--------------------+---------+------------+------------+

                           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].





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   *  The SVG image MUST NOT contain any 'script' element, according to
      Section 15.2 of [SVGT].

   *  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 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 a uncompressed SVG image is fetched with HTTP, the client will
   receive 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 a 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 bitmapped image is used, the PNG [ISO15948] format SHOULD be
   used.

8.  Audio Formats

   Implementations that support audio MUST support the MP3 audio format
   [MP3] with a MIME type of "audio/mpeg" [RFC3003].  Implementations
   MAY support other audio formats.

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 if
   the image or audio.




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   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.

   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.











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   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.

   Logotype data is 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.  This observation can potentially introduce privacy
   issues.  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.  In cases where
   logotype data is not cashed, monitoring would reveal usage frequency.
   In cases where logotype data is cached, monitoring would reveal when
   a certain logotype image or audio sequence is used for the first
   time.

   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.  In such a case, the
   accepted image may contain data that could help an attacker to obtain
   colliding certificates with identical certificate signatures.

   Certificates, and hence their logotype images, are commonly public
   objects and as such usually will not contain privacy-sensitive
   information.  However, when a logotype image that is referenced from
   a certificate contains privacy-sensitive information, appropriate
   security controls should be in place to protect the privacy of that
   information.  Details of such controls are outside the scope of this
   document.

   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



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   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
   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-up
      behavior of subordinate CAs.

   *  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.  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).

11.  Acknowledgments

11.1.  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.






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   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.

11.2.  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.

11.3.  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 Corey
   Bonnell for his carefule review and comments.

12.  References

12.1.  Normative References

   [GIF]      CompuServe Incorporated, "Graphics Interchange Format",
              Version 89a, 31 July 1990,
              <https://www.w3.org/Graphics/GIF/spec-gif89a.txt>.

   [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>.




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   [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>.

   [RFC2396]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifiers (URI): Generic Syntax", RFC 2396,
              DOI 10.17487/RFC2396, August 1998,
              <https://www.rfc-editor.org/info/rfc2396>.

   [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>.

   [RFC4288]  Freed, N. and J. Klensin, "Media Type Specifications and
              Registration Procedures", RFC 4288, DOI 10.17487/RFC4288,
              December 2005, <https://www.rfc-editor.org/info/rfc4288>.

   [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>.





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   [RFC7540]  Belshe, M., Peon, R., and M. Thomson, Ed., "Hypertext
              Transfer Protocol Version 2 (HTTP/2)", RFC 7540,
              DOI 10.17487/RFC7540, May 2015,
              <https://www.rfc-editor.org/info/rfc7540>.

   [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>.

   [RFC8740]  Benjamin, D., "Using TLS 1.3 with HTTP/2", RFC 8740,
              DOI 10.17487/RFC8740, February 2020,
              <https://www.rfc-editor.org/info/rfc8740>.

   [SVGT]     World Wide Web Consortium, "Scalable Vector Graphics (SVG)
              Tiny 1.2 Specification", W3C PR-SVGTiny12-20081117, 17
              November 2008,
              <http://www.w3.org/TR/2008/PR-SVGTiny12-20081117>.

12.2.  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.

   [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>.

   [RFC3778]  Taft, E., Pravetz, J., Zilles, S., and L. Masinter, "The
              application/pdf Media Type", RFC 3778,
              DOI 10.17487/RFC3778, May 2004,
              <https://www.rfc-editor.org/info/rfc3778>.

   [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>.







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   [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>.

   [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) };

   -- 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 }




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   -- 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
      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



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   LogotypeAudioInfo ::= SEQUENCE {
      fileSize        INTEGER,  -- In octets
      playTime        INTEGER,  -- In milliseconds
      channels        INTEGER,  -- 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 contain 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) }

   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 }



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   END
   <CODE ENDS>

A.2.  ASN.1 Module with 1997 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.

   <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) } ;


   -- 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 }




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   -- 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 of the OPTIONAL components MUST be present
         ( WITH COMPONENTS { ..., image PRESENT } |
           WITH COMPONENTS { ..., audio 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
      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) }



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   LogotypeImageResolution ::= CHOICE {
      numBits         [1] INTEGER,   -- Resolution in bits
      tableSize       [2] INTEGER }  -- Number of colors or grey tones

   LogotypeAudioInfo ::= SEQUENCE {
      fileSize        INTEGER,  -- In octets
      playTime        INTEGER,  -- In milliseconds
      channels        INTEGER,  -- 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 contain 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 }

   id-logo-background OBJECT IDENTIFIER ::= { id-logo 2 }

   id-logo-certImage  OBJECT IDENTIFIER  ::= { id-logo 3 }

   END
   <CODE ENDS>

Appendix B.  Examples








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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-1.  This example is
   unchanged from RFC 3709, except that shallow indenting is used to
   keep the example within traditional margins.  The use of SHA-1 was
   reasonable at the time that RFC 3709 was published, but many better
   choices are available today.

   The values on the left are the ASN.1 tag (in hexadecimal) and the
   length (in decimal).

   30 106: SEQUENCE {
   06   8:  OBJECT IDENTIFIER logotype (1 3 6 1 5 5 7 1 12)
   04  94:  OCTET STRING, encapsulates {
   30  92:   SEQUENCE {
   A1  90:    [1] {
   A0  88:     [0] {
   30  86:      SEQUENCE {
   30  84:       SEQUENCE {
   30  82:        SEQUENCE {
   16   9:         IA5String 'image/gif'
   30  33:         SEQUENCE {
   30  31:          SEQUENCE {
   30   7:           SEQUENCE {
   06   5:            OBJECT IDENTIFIER sha1 (1 3 14 3 2 26)
         :             }
   04  20:           OCTET STRING
         :            8F E5 D3 1A 86 AC 8D 8E 6B C3 CF 80 6A D4 48 18
         :            2C 7B 19 2E
         :            }
         :           }
   30  34:         SEQUENCE {
   16  32:          IA5String 'http://logo.example.com/logo.gif'
         :           }
         :          }
         :         }
         :        }
         :       }
         :      }
         :     }
         :    }
         :   }






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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).

   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'
         :           }
         :          }
         :         }
         :        }
         :       }
         :      }
         :     }
         :    }
         :   }









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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).

   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'



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          :          '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'
          :          '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



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   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 2910: SEQUENCE {
   06    8:  OBJECT IDENTIFIER logotype (1 3 6 1 5 5 7 1 12)
   04 2896:  OCTET STRING, encapsulates {
   30 2892:   SEQUENCE {
   A3 2888:    [3] {
   30 2884:     SEQUENCE {
   30 2880:      SEQUENCE {
   06    8:       OBJECT IDENTIFIER '1 3 6 1 5 5 7 20 3'
   A0 2866:       [0] {
   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'



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          :          'OcOb9u63vLjae4kYX4yRifYPrTa2SlMigYdO+cEWeGADMLZL'
          :          'H96SH4R9xRYApl6q3Y02f+NzlRAl+cZSKhB6qSIVa80fsqMn'
          :          'WOqZJpmsXwAPoyNaQ95uNIGasKPwhxGzQzOXzMIIzBKabmLI'
          :          'il470zfSjWWn+kvpvLQ9g1l3yRIc8gukz0uysEcakcDfy3KM'
          :          'k+l0SOXlOopltJL7EPtUlzZfP4tnM70k8xkKCySt92MwfIXP'
          :          'oTe0pnu4dYbp7hJ/kxWySN0ey0o/1qbiCsxDXJMWWo37QekB'
          :          'cAUFPSGkPCnUJF5wwBacDK5cGlEp4BC2lYoJcrNNGVc7DzIq'
          :          'xT4CKsPlrAG8mL8whRejiQe9EmImIAoz3sds9NxP4RZEzugq'
          :          'zb7c3Q89u3WQKY9aegbsA/AUJB/bJs6pfJt9BHFEuk5DWITz'
          :          'OH5uZSThLUsDjQ5GE6RMsyihMTaQLfA6BIiAQMAhnHHN1sd6'
          :          '1WtUhDVJiuhkrdBXd740+hLB9Vm1HjQe4ywLOBLWOMMiyQAX'
          :          '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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          :    }
          :   }

Appendix C.  Changes Since RFC 3709

   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.

   *  Update the reference for language tags to be RFC 5646 instead of
      the now obsolete RFC 3066.

   *  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-compressed media type.

   *  Media types MUST follow the ABNF [RFC5234] that is provided in
      Section 4.2 of [RFC4288].  This change resolves Errata ID 2679.

   *  Remove the requirement that the LogotypeData file name have a file
      extension of ".LTD".  This change resolves Errata ID 2325.

   *  Provide ASN.1 modules for the older syntax [OLD-ASN1] and most
      recent syntax [NEW-ASN1].

   *  Provide additional references.

   *  Provide additional examples.

Authors' Addresses

   Stefan Santesson
   IDsec Solutions AB
   Forskningsbyn Ideon
   SE-223 70 Lund




Santesson, et al.         Expires 29 July 2022                 [Page 37]

Internet-Draft       Logotypes in X.509 Certificates        January 2022


   Email: sts@aaa-sec.com


   Russ Housley
   Vigil Security, LLC
   516 Dranesville Road
   Herndon, VA,  20170
   United States of America

   Email: housley@vigilsec.com


   Trevor Freeman
   Amazon Web Services
   1918 8th Ave
   Seattle, WA,  98101
   United States of America

   Email: frtrevor@amazon.com
































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