Network Working Group                                            S. Raza
Internet-Draft                                 J. Hoeglund Preuss Mattsson
Internet-Draft                                               G. Selander
Intended status: Standards Track                                 RISE                             Ericsson AB
Expires: November 26, 2021                                   G. Selander January 13, 2022                                        S. Raza
                                                             J. Preuss Mattsson
                                                             Ericsson Hoeglund
                                                                 RISE AB
                                                              M. Furuhed
                                                             Nexus Group
                                                            May 25,
                                                           July 12, 2021

          CBOR Encoded X.509 Certificates (C509 Certificates)
                  draft-ietf-cose-cbor-encoded-cert-01
                  draft-ietf-cose-cbor-encoded-cert-02

Abstract

   This document specifies a CBOR encoding of X.509 certificates.  The
   resulting certificates are called C509 Certificates.  The CBOR
   encoding supports a large subset of RFC 5280 and all certificates
   compatible with the RFC 7925, IEEE 802.1AR (DevID), CNSA, RPKI, GSMA
   eUICC, and CA/
   Browser CA/Browser Forum Baseline Requirements profiles.  When
   used to re-encode DER encoded X.509 certificates, the CBOR encoding
   can in many cases reduce the size of RFC 7925 profiled certificates
   with over 50%.  The CBOR encoded structure can alternatively be
   signed directly ("natively signed"), which does not require re-encoding re-
   encoding for the signature to be verified.  The document also
   specifies C509 COSE headers
   as well as headers, a C509 TLS certificate type for type, and a C509 certificates.
   file format.

Status of This Memo

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   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on November 26, 2021. January 13, 2022.

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   document authors.  All rights reserved.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Notational Conventions  . . . . . . . . . . . . . . . . . . .   4
   3.  CBOR Encoding . .  C509 Certificate  . . . . . . . . . . . . . . . . . . . . . .   5
     3.1.  Message Fields  . . . . . . . . . . . . . . . . . . . . .   5
     3.2.  Encoding of subjectPublicKey and issuerSingatureValue issuerSignatureValue . .   8
     3.3.  Encoding of Extensions  . . . . . . . . . . . . . . . . .   9
   4.  Compliance Requirements for Constrained IoT  C509 Certificate Signing Request  . . . . . . . . .  12 . . . . .  14
   5.  C509 Certificate Revocation List  . . . . . . . . . . . . . .  15
   6.  C509 Online Certificate Status Protocol . . . . . . . . . . .  16
   7.  C509 Processing and Certificate Issuance  . . . . . . . . . .  16
   8.  Legacy Considerations . . . . . . . . . . . . . . . . . . . .  12
   6.  17
   9.  Expected Certificate Sizes  . . . . . . . . . . . . . . . . .  12
   7.  17
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  13
   8.  18
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
     8.1.  19
     11.1.  C509 Certificate Types Registry  . . . . . . . . . . . . .  14
     8.2.  19
     11.2.  C509 Certificate Attributes Registry . . . . . . . . . .  15
     8.3. . . . . . .  20
     11.3.  C509 Certificate Extensions Registry . . . . . . . . . .  17
     8.4. . . . . . .  23
     11.4.  C509 Certificate Certificate Policies Registry . . . . .  19
     8.5. . . . . . .  26
     11.5.  C509 Policies Qualifiers Registry  . . . . . . . . . . .  29
     11.6.  C509 Information Access Registry . . . . . . . . . . . .  29
     11.7.  C509 Certificate Extended Key Usages Registry  . . . . . .  20
     8.6. . . . . .  32
     11.8.  C509 Certificate General Names Registry  . . . . . . . . .  21
     8.7. . . . . .  33
     11.9.  C509 Certificate Signature Algorithms Registry . . . . .  22
     8.8. . . . . . .  35
     11.10. C509 Certificate Public Key Algorithms Registry  . . . . .  25
     8.9. . . . . .  38
     11.11. COSE Header Parameters Registry  . . . . . . . . . . . . .  27
     8.10.  41
     11.12. TLS Certificate Types Registry . . . . . . . . . . . . .  28
     8.11.  42
     11.13. CBOR Tags Registry . . . . . . . . . . . . . . . . . . .  29
   9.  43
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  29
     9.1.  43
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  29
     9.2.  43
     12.2.  Informative References . . . . . . . . . . . . . . . . .  30  44
   Appendix A.  Example C509 Certificates  . . . . . . . . . . . . .  32  47
     A.1.  Example RFC 7925 profiled X.509 Certificate . . . . . . .  32  47
     A.2.  Example IEEE 802.1AR profiled X.509 Certificate . . . . .  36  50
     A.3.  Example CAB Baseline ECDSA HTTPS X.509 Certificate  . . .  36  50
     A.4.  Example CAB Baseline RSA HTTPS X.509 Certificate  . . . .  39  54
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  42  57
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  42  57

1.  Introduction

   One of the challenges with deploying a Public Key Infrastructure
   (PKI) for the Internet of Things (IoT) is the size and parsing of
   X.509 public key certificates [RFC5280], since those are not
   optimized for constrained environments [RFC7228].  Large certificate
   chains are also problematic in non-constrained protocols such as EAP-
   TLS [I-D.ietf-emu-eap-tls13] [I-D.ietf-emu-eaptlscert] where
   authenticators typically drop an EAP session after only 40 - 50
   round-trips and
   round-trips, QUIC [I-D.ietf-quic-transport] [RFC9000] where the latency increases significantly
   unless the server sends less than three times as many bytes as
   received prior to validating the client address.
   More compact certificate address, and RPKI [RFC6487]
   where a single certificate can be very large.  More compact
   certificate representations are therefore desirable in many use
   cases.  Due to the current PKI usage of DER encoded X.509
   certificates, keeping compatibility with DER encoded X.509 is
   necessary at least for a transition period.  However, the use of a
   more compact encoding with the Concise Binary Object Representation
   (CBOR) [RFC8949] reduces the certificate size significantly which has
   known performance benefits in terms of decreased communication
   overhead, power consumption, latency, storage, etc.

   CBOR is a data format designed for small code size and small message
   size.  CBOR builds on the JSON data model but extends it by e.g.
   encoding binary data directly without base64 conversion.  In addition
   to the binary CBOR encoding, CBOR also has a diagnostic notation that
   is readable and editable by humans.  The Concise Data Definition
   Language (CDDL) [RFC8610] provides a way to express structures for
   protocol messages and APIs that use CBOR.  [RFC8610]  RFC 8610 also extends the
   diagnostic notation.

   CBOR data items are encoded to or decoded from byte strings using a
   type-length-value encoding scheme, where the three highest order bits
   of the initial byte contain information about the major type.  CBOR
   supports several different types of data items, in addition to
   integers (int, uint), simple values (e.g. null), byte strings (bstr),
   and text strings (tstr), CBOR also supports arrays [] of data items,
   maps {} of pairs of data items, and sequences of data items.  For a
   complete specification and examples, see [RFC8949], [RFC8610], and
   [RFC8742].  We recommend implementors to get used to CBOR by using
   the CBOR playground [CborMe].

   CAB Baseline Requirements [CAB-Baseline], [CAB-TLS], RFC 7925 [RFC7925], IEEE 802.1AR
   [IEEE-802.1AR], and CNSA [RFC8603] specify certificate profiles which
   can be applied to certificate based authentication with, e.g., TLS
   [RFC8446], QUIC [I-D.ietf-quic-transport], [RFC9000], DTLS [I-D.ietf-tls-dtls13], COSE
   [RFC8152], EDHOC [I-D.ietf-lake-edhoc], or Compact TLS 1.3
   [I-D.ietf-tls-ctls].  RFC 7925 [RFC7925], RFC7925bis
   [I-D.ietf-uta-tls13-iot-profile], and IEEE 802.1AR [IEEE-802.1AR]
   specifically target Internet of Things deployments.  This document
   specifies a CBOR encoding based on [X.509-IoT], which can support
   large parts of [RFC5280]. RFC 5280.  The encoding support supports all
   [RFC7925] and RFC 7925, IEEE 802.1AR [IEEE-802.1AR] and
   802.1AR, CAB Baseline
   [CAB-Baseline] [CAB-TLS], [CAB-Code], RPKI [RFC6487], eUICC
   [GSMA-eUICC] profiled X.509 certificates.  The resulting certificates
   are called C509 Certificates.  This document does not specify a
   certificate profile.  Two variants are defined using the same CBOR
   encoding and differing only in what is being signed:

   1.  An invertible CBOR re-encoding of DER encoded X.509 certificates
       [RFC5280], which can be reversed to obtain the original DER
       encoded X.509 certificate.

   2.  Natively signed C509 certificates, where the signature is
       calculated over the CBOR encoding instead of over the DER
       encoding as in 1.  This removes the need for ASN.1 and DER
       parsing and the associated complexity but they are not backwards
       compatible with implementations requiring DER encoded X.509.

   Natively signed C509 certificates can be applied in devices that are
   only required to authenticate to natively signed C509 certificate
   compatible servers, which is not a major restriction for many IoT
   deployments where the parties issuing and verifying certificates can
   be a restricted ecosystem.

   This document specifies COSE headers for use of the C509 certificates
   with COSE, see Section 8.9. 11.11.  The document also specifies a TLS
   certificate type for use of the C509 certificates with TLS and QUIC
   (with or without additional TLS certificate compression), see
   Section 8.10. 11.12.

2.  Notational Conventions

   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.

   This specification makes use of the terminology in [RFC5280],
   [RFC7228], [RFC8610], and [RFC8949].  When referring to CBOR, this
   specification always refer refers to Deterministically Encoded CBOR as
   specified in Sections 4.2.1 and 4.2.2 of [RFC8949].

3.  CBOR Encoding  C509 Certificate

   This section specifies the content and encoding for C509
   certificates, with the overall objective to produce a very compact
   representation supporting large parts of [RFC5280], and everything in
   [RFC7925], [IEEE-802.1AR], RPKI [RFC6487], GSMA eUICC [GSMA-eUICC],
   and CAB Baseline [CAB-Baseline]. [CAB-TLS] [CAB-Code].  In the CBOR encoding, static
   fields are elided, elliptic curve points and time values are
   compressed, OID are replaced with short integers, and redundant
   encoding is removed.  Combining these different components reduces
   the certificate size significantly, which is not possible with
   general purpose compression algorithms, see Figure 3. 5.

   The C509 certificate can be either a CBOR re-encoding of a DER
   encoded X.509 certificate, in which case the signature is calculated
   on the DER encoded ASN.1 data in the X.509 certificate, or a natively
   signed C509 certificate, in which case the signature is calculated
   directly on the CBOR encoded data.  In both cases the certificate
   content is adhering to the restrictions given by [RFC5280].  The re-
   encoding is known to work with DER encoded certificates but might
   work with other canonical encodings.  The re-encoding does not work
   for BER encoded certificates.

   In the encoding described below, the order of elements in arrays are
   always encoded in the same order as the elements or the corresponding
   SEQUENCE or SET in the DER encoding.

3.1.  Message Fields

   The X.509 fields and their CBOR encodings are listed below, and used
   in the definition of C509 certificates, see Figure 1.

   C509 certificates are defined in terms of DER encoded [RFC5280] X.509
   certificates:

   o  version.  The 'version' field is encoded in the
      'c509CertificateType' CBOR int.  The field 'c509CertificateType'
      also indicates the type of the C509 certificate.  Currently, the
      type can be a natively signed C509 certificate following X.509 v3
      (c509CertificateType = 0) or a CBOR re-encoded X.509 v3 DER
      certificate (c509CertificateType = 1), see Section 8.1. 11.1.

   o  serialNumber.  The 'serialNumber' INTEGER value field is encoded
      as the unwrapped CBOR unsigned bignum (~biguint)
      'certificateSerialNumber'.  Any leading 0x00 byte (to indicate
      that the number is not negative) is therefore omitted.

   o  signature.  The 'signature' field is always the same as the
      'signatureAlgorithm' field and therefore omitted from the CBOR
      encoding.

   o  issuer.  In the general case, the sequence of
      'RelativeDistinguishedName' is encoded as a CBOR array of CBOR
      arrays of Attributes.  Typically  Typically, each RelativeDistinguishedName
      only contains a single attribute and the sequence is then encoded
      as a CBOR array of Attributes.  Each Attribute is encoded as a
      (CBOR int, CBOR text string) pair or as a (unwrapped CBOR OID,
      CBOR bytes) pair.  The absolute value of the CBOR int (see
      Figure 5) 7) encodes the attribute type and the sign is used to
      represent the character string type; positive for Utf8String,
      negative for PrintableString.  The Attribute Email Address is
      always an IA5String.  In natively signed C509 certificates all
      text strings are UTF-8 encoded and all attributes attributeType SHALL have a positive sign. be
      non-negative.  Text strings SHALL still adhere to any X.509
      restrictions, i.e. i.e., serialNumber SHALL only contain the 74
      character subset of ASCII allowed by PrintableString and
      countryName SHALL have length 2.  The string types teletexString,
      universalString, and bmpString are not supported.  If Name
      contains a single Attribute containing an utf8String encoded
      'common name' it is encoded as a CBOR text string.  If the text
      string contains an EUI-64 of the form "HH-HH-HH-HH-HH-HH-HH-HH"
      where 'H' is one of the symbol symbols '0'-'9' or 'A'-'F' it is encoded
      as a CBOR byte string of length 8 instead.  EUI-64 mapped from a
      48-bit MAC address (i.e. (i.e., of the form "HH-HH-HH-FF-FE-HH-HH-HH) is
      encoded as a CBOR byte string of length 6.

   o  validity.  The 'notBefore' and 'notAfter' fields are encoded as
      unwrapped CBOR epoch-based date/time (~time) where the tag content
      is an unsigned integer.  In POSIX time, leap seconds are ignored,
      with a leap second having the same POSIX time as the second before
      it.  Compression of X.509 certificates with the time 23:59:60 UTC
      is therefore not supported.  Note that RFC 5280 mandates encoding
      of dates through the year 2049 as UTCTime, and later dates as
      GeneralizedTime.  The value "99991231235959Z" (no expiration date)
      is encoded as CBOR null.

   o  subject.  The 'subject' is encoded exactly like issuer.

   o  subjectPublicKeyInfo.  The 'AlgorithmIdentifier' field including
      parameters is encoded as the CBOR int 'subjectPublicKeyAlgorithm'
      (see Section 8.8) 11.10) or as an array with an unwrapped CBOR OID tag
      [I-D.ietf-cbor-tags-oid] optionally followed by the parameters
      encoded as a CBOR byte string.  In general, the 'subjectPublicKey'
      BIT STRING value field is encoded as a CBOR byte string.  This
      specification assumes the BIT STRING has zero unused bits and the
      unused bits byte is omitted.  For rsaEncryption and id-
      ecPublicKey, the encoding of subjectPublicKey is further optimized
      as described in Section 3.2.

   o  issuerUniqueID.  Not supported.

   o  subjectUniqueID.  Not supported.

   o  extensions.  The 'extensions' field is encoded as a CBOR array
      where each extension is encoded as either a CBOR int (see
      Section 8.3) 11.3) followed by an optional CBOR item of any type or an
      unwrapped CBOR OID tag [I-D.ietf-cbor-tags-oid] followed by a CBOR
      bool encoding 'critical' and the DER encoded value of the
      'extnValue' encoded as a CBOR byte string.  If the array contains
      exactly two ints and the absolute value of the first int is 2, 2
      (corresponding to keyUsage), the array is omitted and the
      extensions is encoded as a single CBOR int with the absolute value
      of the second int and the sign of the first int.  Extensions are
      encoded as specified in Section 3.3.  The extensions mandated to
      be supported by [RFC7925] and [IEEE-802.1AR] are given special
      treatment.  An omitted 'extensions' field is encoded as an empty
      CBOR array.

   o  signatureAlgorithm.  The 'signatureAlgorithm' field including
      parameters is encoded as a CBOR int (see Section 8.7) 11.9) or as an
      array with an unwrapped CBOR OID tag [I-D.ietf-cbor-tags-oid]
      optionally followed by the parameters encoded as a CBOR byte
      string.

   o  signatureValue.  In general, the 'signatureValue' BIT STRING value
      field is encoded as the CBOR byte string issuerSignatureValue.
      This specification assumes the BIT STRING has zero unused bits and
      the unused bits byte is omitted.  For natively signed C509
      certificates the signatureValue is calculated over the CBOR
      sequence TBSCertificate.  For ECDSA, the encoding of
      issuerSignatureValue is further optimized as described in
      Section 3.2

   The following Concise Data Definition Language (CDDL) defines the
   CBOR array C509Certificate and the CBOR sequence [RFC8742]
   TBSCertificate.  The member names therefore only have documentary
   value.  Applications not requiring a CBOR item MAY represent C509
   certificates with the CBOR sequence ~C509Certificate (unwrapped
   C509Certificate).

    C509Certificate = [
       TBSCertificate,
       issuerSignatureValue : any,
    ]

    ; The elements of the following group are to be used in a CBOR Sequence:
    TBSCertificate = (
       c509CertificateType: int,
       certificateSerialNumber: CertificateSerialNumber,
       issuer: Name,
       validityNotBefore: Time,
       validityNotAfter: Time,
       subject: Name,
       subjectPublicKeyAlgorithm: AlgorithmIdentifier,
       subjectPublicKey: any,
       extensions: Extensions,
       issuerSignatureAlgorithm: AlgorithmIdentifier,
    )

    CertificateSerialNumber = ~biguint

    Name = [ * RelativeDistinguishedName ] / text / bytes

    RelativeDistinguishedName = Attribute / [ 2* Attribute ]

    Attribute = ( attributeType: int, attributeValue: text ) //
                ( attributeType: ~oid, attributeValue: bytes )

    Time = ~time / null

    AlgorithmIdentifier = int / ~oid /
                        [ algorithm: ~oid, parameters: bytes ]

    Extensions = [ * Extension ] / int

    Extension = ( extensionID: int, extensionValue: any ) //
                ( extensionID: ~oid, ? critical: true,
                  extensionValue: bytes )

                    Figure 1: CDDL for C509Certificate.

3.2.  Encoding of subjectPublicKey and issuerSingatureValue issuerSignatureValue

3.2.1.  Encoding of subjectPublicKey

   For RSA public keys (rsaEncryption), the SEQUENCE and INTEGER type
   and length fields are omitted and the two INTEGER value fields
   (modulus, exponent) are encoded as an array of two unwrapped CBOR
   unsigned bignum (~biguint), i.e. [ modulus : ~biguint, exponent :
   ~biguint ].  If the exponent is 65537, the array and the exponent is
   omitted and subjectPublicKey consist of only the modulus encoded as
   an unwrapped CBOR unsigned bignum (~biguint).

   For elliptic curve public keys in Weierstrass form (id-ecPublicKey),
   uncompressed keys are point compressed as defined in Section 2.3.3 of
   [SECG].  If a DER encoded certificate with a point compressed public
   key of type id-ecPublicKey is CBOR encoded, the octets 0xfe and 0xfd
   are used instead of 0x02 and 0x03 in the CBOR encoding to represent
   even and odd y-coordinate, respectively.

3.2.2.  Encoding of issuerSingatureValue issuerSignatureValue

   For ECDSA signatures, the SEQUENCE and INTEGER type and length fields
   as well as the any leading 0x00 byte (to indicate that the number is
   not negative) are omitted.  If the two INTEGER value fields have
   different lengths, the shortest INTEGER value field is padded with
   zeroes so that the two fields have the same length.  The resulting
   byte string is encoded as a CBOR byte string.

3.3.  Encoding of Extensions

   This section details the encoding of the 'extensions' field.  The
   'extensions' field is encoded as a CBOR array where each extensionID
   is encoded as either a CBOR int or an unwrapped CBOR OID tag.  If
   'extensionID' is encoded an int (see Section 8.3), 11.3), the sign is used
   to encode if the extension is critical and the 'critical' field is
   omitted.  Critical extensions are encoded with a negative sign and
   non-critical extensions are encoded with a positive sign.

   The 'extnValue' OCTET STREAM STRING value field is encoded as the CBOR byte
   string 'extensionValue' except for the extensions mandated to be
   supported by [RFC7925], [IEEE-802.1AR], and [CAB-Baseline] which are
   encoded as specified below.
   For some extensions, only commonly used parts are supported by the
   CBOR encoding.  If unsupported parts are used, the CBOR encoding
   cannot be used.

   CBOR encoding of the following extension values are fully supported:

   o  subjectKeyIdentifier.  Subject Key Identifier (subjectKeyIdentifier).  The extensionValue
      is the value of the
      'keyIdentifier' field encoded as a CBOR byte string. follows:

      KeyIdentifier = bytes
      SubjectKeyIdentifier = KeyIdentifier

   o  keyUsage.  Key Usage (keyUsage).  The 'KeyUsage' BIT STRING is interpreted as
      an unsigned integer in network byte order and encoded as a CBOR
      int.  See Section 3.1 for special encoding in case keyUsage is the
      only extension present.

      KeyUsage = int

   o  Policy Mappings (policyMappings). extensionValue is encoded as
      follows:

      PolicyMappings = [
        + (issuerDomainPolicy: ~oid, subjectDomainPolicy: ~oid)
      ]

   o  basicConstraints.  Basic Constraints (basicConstraints).  If 'cA' = false then
      extensionValue = -2, if 'cA' = true and 'pathLenConstraint' is not
      present then extensionValue = -1, and if 'cA' = true and
      'pathLenConstraint' is present then extensionValue =
      pathLenConstraint.

      BasicConstraints = int

   o  Policy Constraints (policyConstraints). extensionValue is encoded
      as follows:

      PolicyConstraints = [
        requireExplicitPolicy: uint / null,
        inhibitPolicyMapping: uint / null,
      ]

   o  extKeyUsage.  Extended Key Usage (extKeyUsage). extensionValue is encoded as an
      array of CBOR ints (see Section 8.5) 11.7 or unwrapped CBOR OID tags
      [I-D.ietf-cbor-tags-oid] where each int or OID tag encodes a key
      usage purpose.  If the array contains a single int, KeyPurposeId, the
      array is omitted.

      ExtValueEKU

      KeyPurposeId = [ + int / ~oid
      ExtKeyUsageSyntax = [ 2* KeyPurposeId ] / int KeyPurposeId

   o  Inhibit anyPolicy (inhibitAnyPolicy). extensionValue is encoded as
      follows:

      InhibitAnyPolicy = uint

   CBOR encoding of the following extension values are partly supported:

   o  subjectAltName.  Subject Alternative Name (subjectAltName).  If the subject alternatice
      alternative name only contains general names registered in
      Section 8.6 11.8 the extension value can be CBOR encoded.
      extensionValue is encoded as an array of (int, any) pairs where
      each pair encodes a general name (see Section 8.6). 11.8).  If
      subjectAltName contains exactly one dNSName, the array and the int
      are omitted and extensionValue is the dNSName encoded as a CBOR
      text string.  In addition to the general names defined in
      [RFC5280], the hardwareModuleName type of otherName has been given
      its own int due to its mandatory use in IEEE 802.1AR.  When
      'otherName + hardwareModuleName' is used, then [ oid, bytes ] is
      used to identify the pair ( hwType, hwSerialEntries ) directly as
      specified in [RFC4108].  Only the general names in Section 8.6 11.8
      are supported.

      ExtValueSAN = [ + GeneralName ] / text

      GeneralName = ( GeneralNameType : int, GeneralNameValue : any )
      GeneralNames = [ + GeneralName ]
      SubjectAltName = GeneralNames / text

   o  cRLDistributionPoints.  Issuer Alternative Name (issuerAltName). extensionValue is encoded
      exactly like subjectAltName.

      IssuerAltName  = GeneralNames / text

   o  CRL Distribution Points (cRLDistributionPoints).  If the CRL
      Distribution Points is a sequence of DistributionPointName, where
      each DistributionPointName only contains a single uniformResourceIdentifier,
      uniformResourceIdentifiers, the extension value can be CBOR
      encoded.  The extensionValue is encoded as an array of CBOR text strings where each CBOR text
      string encodes a uniformResourceIdentifier.  If the array contains
      exactly one text string, the array is omitted.

      ExtValueCDP follows:

      DistributionPointName = [ 2* text ] / text
      CRLDistributionPoints = [ + DistributionPointName ]

   o  Freshest CRL (freshestCRL). extensionValue is encoded exactly like
      cRLDistributionPoints.

      FreshestCRL = CRLDistributionPoints

   o  certificatePolicies.  Authority Information Access (authorityInfoAccess).  If each PolicyInformation contains at most
      one PolicyQualifierInfo, where all present policyQualifierId are
      of type id-qt-cps and all present qualifiers the
      GeneralNames in authorityInfoAccess are of type cPSuri,
      uniformResourceIdentifier, the extension value can be CBOR
      encoded.  OIDs registered in  Each accessMethod is encoded as an CBOR ints (see
      Section 8.4 11.6) or unwrapped CBOR OID tags [I-D.ietf-cbor-tags-oid].
      The uniformResourceIdentifiers are encoded as an int.

      ExtValueCP CBOR text strings.

      AccessDescription = [ + ( CertPolicyId: oid accessMethod: int / int, ? CPSuri: ~oid , uri: text )
      AuthorityInfoAccessSyntax = [ + AccessDescription ]

   o  authorityKeyIdentifier.  Subject Information Access (subjectInfoAccess).  Encoded exactly
      like authorityInfoAccess.

      SubjectInfoAccessSyntax = AuthorityInfoAccessSyntax

   o  Authority Key Identifier (authorityKeyIdentifier).  If the
      authority key identifier contains all of keyIdentifier,
      certIssuer, and certSerialNumberm or if only keyIdentifier is
      present the extension value can be CBOR encoded.  If all three are
      present a CBOR array is used, if only keyIdentifier is present a CBOR byte string present,
      the array is used.

      ExtValueAKI omitted:

      KeyIdentifierArray = [
        keyIdentifier: bytes,
                      certIssuer: KeyIdentifier,
        authorityCertIssuer: GeneralNames,
                      certSerialNumber:
        authorityCertSerialNumber: CertificateSerialNumber
      ]
      AuthorityKeyIdentifier = KeyIdentifierArray / bytes KeyIdentifier

   o  authorityInfoAccess.  Certificate Policies (certificatePolicies).  If all the GeneralNames in
      authorityInfoAccess noticeRef is not
      used and any explicitText are of type uniformResourceIdentifier, encoded as UTF8String, the extension
      value can be CBOR encoded.  OIDs registered in Section 11.4 are
      encoded as an int.  The accessMethod policyQualifierId is encoded as an CBOR
      int (1 for ocsp and 2 for caIssuers).  The
      uniformResourceIdentifiers are encoded as (see Section 11.5) or an unwrapped CBOR text strings.

      ExtValueAIA OID tag
      [I-D.ietf-cbor-tags-oid].

      PolicyIdentifier = int / ~oid
      PolicyQualifierInfo = (
        policyQualifierId: int / ~oid,
        qualifier: text,
      )
      CertificatePolicies = [
        + ( accessMethod : 1 / 2 , uri : text PolicyIdentifier, ? [ + PolicyQualifierInfo ] )
      ]

   o  signedCertificateTimestamp.  Name Constraints (nameConstraints).  If all the SCTs are version 1, name constraints only
      contains general names registered in Section 11.8 the extension
      value can be CBOR encoded.

      GeneralSubtree = [ GeneralName, minimum: uint, ? maximum: uint ]
      NameConstraints = [
        permittedSubtrees: GeneralSubtree,
        excludedSubtrees: GeneralSubtree,
      ]

   o  Subject Directory Attributes (subjectDirectoryAttributes).
      Encoded as attributes in issuer and subject with the difference
      that there are no SCT extensions, can be more than one attributeValue.

      Attributes = ( attributeType: int, attributeValue: [+text] ) //
                   ( attributeType: ~oid, attributeValue: [+bytes] )
      SubjectDirectoryAttributes = Attributes

   o  AS Resources (autonomousSysIds).  If rdi is not present, the
      extension value can be CBOR encoded.  LogIDs are  Each ASId is encoded as CBOR byte strings, an
      uint.  With the timestamp exception of the first ASId, the ASid is encoded
      as and CBOR int (milliseconds since validityNotBefore),
      and the signature is encoded with an (AlgorithmIdentifier, any)
      pair in difference to the same way as issuerSignatureAlgorithm and
      issuerSignatureValue.

      ExtValueSCT previous ASid.

      AsIdsOrRanges = uint / [uint, uint]
      ASIdentifiers = [ + ( LogID : bstr, timestamp : int,
                          alg : AlgorithmIdentifier, signature : any ) AsIdsOrRanges ]

3.3.1.  Example Encoding of Extensions

   The examples below use values / null

   o  AS Resources v2 (id-pe-ipAddrBlocks-v2).  Encoded exactly like
      autonomousSysIds.

   o  IP Resources (id-pe-ipAddrBlocks).  If rdi and SAFI is not
      present, the extension value can be CBOR encoded.  Each
      AddressPrefix is encoded as a CBOR bytes string (without the
      unused bits octet) followed by the number of unused bits encoded
      as a CBOR uint.  Each AddressRange is encoded as an array of two
      CBOR byte strings.  The unused bits for min and max are omitted,
      but the unused bits in max IPAddress is set to ones.  With the
      exception of the first Address, if the byte string has the same
      length as the previous ASid, the Addess is encoded as an uint with
      the the difference to the previous Addess.

      Address = bytes / uint,
      AddressPrefix = (Address, unusedBits: uint)
      AddressRange =  [Address, Address]
      IPAddressOrRange = AddressPrefix / AddressRange
      IPAddressChoice = [ + IPAddressOrRange ] / null
      IPAddrBlocks = [ AFI: uint, IPAddressChoice ]

   o  IP Resources v2 (id-pe-ipAddrBlocks-v2).  Encoded exactly like id-
      pe-ipAddrBlocks.

   o  Signed Certificate Timestamp.  If all the SCTs are version 1, and
      there are no SCT extensions, the extension value can be CBOR
      encoded.  LogIDs are encoded as CBOR byte strings, the timestamp
      is encoded as and CBOR int (milliseconds since validityNotBefore),
      and the signature is encoded with an (AlgorithmIdentifier, any)
      pair in the same way as issuerSignatureAlgorithm and
      issuerSignatureValue.

      SignedCerticateTimestamp = (
        logID: bytes,
        timestamp: int,
        sigAlg: AlgorithmIdentifier,
        sigValue: any,
      )
      SignedCertificateTimestamps = [ + SignedCerticateTimestamp ]

3.3.1.  Example Encoding of Extensions

   The examples below use values from Section 8.3, 11.3, Section 8.5, 11.7, and
   Section 8.6: 11.8:

   o  A critical basicConstraints ('cA' = true) without
      pathLenConstraint is encoded as the two CBOR ints -4, -1.

   o  A non-critical keyUsage with digitalSignature and keyAgreement
      asserted is encoded as the two CBOR ints 2, 17 (2^0 + 2^4 = 17).

   o  A non-critical extKeyUsage containing id-kp-codeSigning and id-kp-
      OCSPSigning is encoded as the CBOR int 8 followed by the CBOR
      array [ 3, 6 ].

   o  A non-critical subjectAltName containing only the dNSName
      example.com is encoded as the CBOR int 3 followed by the CBOR text
      string "example.com".

   Thus, the extension field of a certificate containing all of the
   above extensions in the given order would be encoded as the CBOR
   array [ -4, -1, 2, 17, 8, [ 3, 6 ], 3, "example.com" ].

4.  Compliance Requirements for Constrained IoT

   For general purpose applications, the normative requirements of
   [RFC5280] applies.  This  C509 Certificate Signing Request

   The section describes defines the mandatory to implement
   algorithms C509 Certificate Signing Request (CSR) format
   based on and OIDs for constrained IoT application; the values of compatible with RFC 2986 [RFC2986] reusing the OIDs including certificate fields and extensions, time format,
   attributes in distinguished names, etc.

   TODO: Write this section

5.  Legacy Considerations
   formatting for C509 certificates can be deployed with legacy X.509 certificates and
   CA infrastructure.  In order to verify the signature, the defined in Section 3.  There are
   currently two c509CertificateSigningRequestType values defined,
   c509CertificateSigningRequestType = 0 requests a c509CertificateType
   = 0 and c509CertificateSigningRequestType = 1 requests a
   c509CertificateType = 1 . subjectProofOfPossessionAlgorithm can be a
   C509
   certificate is used to recreate signature algorithm or a non-signature Proof-of-Possession
   Algorithm as defined in e.g.  RFC 6955.  CSR attributes other than
   extensionRequest are not supported.

    C509CertificateSigningRequest = [
       TBSCertificateSigningRequest,
       subjectProofOfPossessionValue: any,
    ]

    ; The elements of the original X.509 data structure to
   be able to verify following group are used in a CBOR Sequence:
    TBSCertificateSigningRequest = (
       c509CertificateSigningRequestType: int,
       subject: Name,
       subjectPublicKeyAlgorithm: AlgorithmIdentifier,
       subjectPublicKey: any,
       extensionsRequest : Extensions,
       subjectProofOfPossessionAlgorithm: AlgorithmIdentifier,
    )

             Figure 2: CDDL for C509CertificateSigningRequest.

   After verifying the signature.

   For protocols like TLS/DTLS 1.2, where subjectProofOfPossessionValue, the handshake is sent
   unencrypted, CA MAY
   transform the actual encoding C509CertificateSigningRequest into a RFC 2985
   CertificationRequestInfo for compatibility with existing procedures
   and compression can be done at
   different locations depending code.

5.  C509 Certificate Revocation List

   The section defines the C509 Certificate Revocation List (CRL) format
   based on and compatible with [RFC5280] reusing the deployment setting.  For
   example, formatting for
   C509 certificates defined in Section 3.

    C509CertificateRevocationList = [
       TBSCertificateRevocationList,
       issuerSignatureValue : any,
    ]

    ; The elements of the mapping between following group are used in a CBOR Sequence:
    TBSCertificateSigningRequest = (
       C509CertificateRevocationListType: int,
       issuer: Name,
       thisUpdate: Time,
       nextUpdate: Time,
       revokedCertificates: RevokedCertificates,
       crlExtensions: Extensions,
       issuerSignatureAlgorithm: AlgorithmIdentifier,
    )

    RevokedCertificates = [
        userCertificate: CertificateSerialNumber,
        revocationDate: Time,
        crlEntryExtensions: Extensions,
    ]

             Figure 3: CDDL for C509CertificateRevocationList.

6.  C509 certificate Online Certificate Status Protocol

   TODO

7.  C509 Processing and standard Certificate Issuance

   It is straightforward to integrate the C509 format into legacy X.509
   processing during certificate issuance.  C509 processing can take place in be
   performed as an isolated function of the CA, or as a 6LoWPAN border gateway which allows separate
   function trusted by the server side to stay unmodified.  This case gives CA.

   The CSR format defined in Section 4 follows the advantage of PKCS#10 format to
   enable a direct mapping to the low overhead certification request information, see
   Section 4.1 of [RFC2986].

   When a certificate request is received the CA, or function trusted by
   the CA, needs to perform some limited C509 processing and verify the
   proof of possession of the public key, before normal certificate
   generation can take place.

   In the reverse direction, in case c509CertificateType = 1 was
   requested, a separate C509 processing function can perform the
   conversion from a generated X.509 certificate to C509 as a bump-in-
   the-wire.  In case c509CertificateType = 0 was requested, the C509
   processing needs to be performed before signing the certificate, in
   which case a tighter integration with CA may be needed.

8.  Legacy Considerations

   C509 certificates can be deployed with legacy X.509 certificates and
   CA infrastructure.  In order to verify the signature, the C509
   certificate is used to recreate the original X.509 data structure to
   be able to verify the signature.

   For protocols like TLS/DTLS 1.2, where the handshake is sent
   unencrypted, the actual encoding and compression can be done at
   different locations depending on the deployment setting.  For
   example, the mapping between C509 certificate and standard X.509
   certificate can take place in a 6LoWPAN border gateway which allows
   the server side to stay unmodified.  This case gives the advantage of
   the low overhead of a C509 certificate over a constrained wireless
   links.  The conversion to X.509 within an IoT device will incur a
   computational overhead, however, measured in energy this is likely to
   be negligible compared to the reduced communication overhead.

   For the setting with constrained server and server-only
   authentication, the server only needs to be provisioned with the C509
   certificate and does not perform the conversion to X.509.  This
   option is viable when client authentication can be asserted by other
   means.

   For protocols like IKEv2, TLS/DTLS 1.3, and EDHOC, where certificates
   are encrypted, the proposed encoding needs to be done fully end-to-
   end, through adding the encoding/decoding functionality to the
   server.

6.

9.  Expected Certificate Sizes

   The CBOR encoding of the sample certificate chains given in
   Appendix A results in the numbers shown in Figure 2 4 and Figure 3. 5.
   COSE_X509 is defined in [I-D.ietf-cose-x509] and COSE_C509 is defined
   in Section 11.11.  After [RFC7925] RFC 7925 profiling, most duplicated
   information has been removed, and the remaining text strings are
   minimal in size.  Therefore, the further size reduction reached with
   general compression mechanisms such as Brotli will be small, mainly
   corresponding to making the ASN.1 encoding more compact.  CBOR
   encoding can however significantly compress RFC 7925 profiled
   certificates.  For the example HTTPS certificate chains (www.ietf.org
   and tools.ietf.org) both C509 and Brotli perform well complementing
   each other.  C509 use dedicated information to compress individual
   certificates, while Brotli can compress duplicate information in the
   entire chain.  Note that C509 certificates of type 0 and 1 have the
   same size.  For Brotli [RFC7932], the Rust crate Brotli 3.3.0 was
   used with compression level 11 and window size 22.

     +---------------------------------------+-----------+-----------+
     |                                       | COSE_X509 | COSE_C509 |
     +---------------------------------------+-----------+-----------+
     | RFC 7925 profiled IoT Certificate (1) |       317 |       139 |
     +---------------------------------------+-----------+-----------+
     | ECDSA HTTPS Certificate Chain (2)     |      2193 |      1394 |
     +---------------------------------------+-----------+-----------+
     | RSA HTTPS Certificate Chain (4)       |      5175 |      3934 |
     +---------------------------------------+-----------+-----------+

    Figure 2: 4: Comparing Sizes of Certificate Chains in COSE (bytes)

    +-------------------+------+---------------+------+---------------+ COSE.  Number of
                   bytes (length of certificate chain).

   +-------------------+-------+---------------+------+---------------+
   |                   |  X509 | X509 + Brotli | C509 | C509 + Brotli |
    +-------------------+------+---------------+------+---------------+
   +-------------------+-------+---------------+------+---------------+
   | RFC 7925 Cert (1) |   327 |           324 |  151 |           167 |
    +-------------------+------+---------------+------+---------------+
   +-------------------+-------+---------------+------+---------------+
   | RPKI Cert (1)     | 20991 |          9134 | 8660 |          5668 |
   +-------------------+-------+---------------+------+---------------+
   | ECDSA HTTPS Chain (2)   |  2204 |          1455 | 1409 1414 |          1058          1063 |
    +-------------------+------+---------------+------+---------------+
   +-------------------+-------+---------------+------+---------------+
   | RSA HTTPS Chain (4)   |  5190 |          3244 | 3957 3958 |          2845 |
   +-------------------+-------+---------------+------+---------------+
   | HTTPS Bag (8)     | 11578 |          2841          3979 |
    +-------------------+------+---------------+------+---------------+ 8882 |          3519 |
   +-------------------+-------+---------------+------+---------------+

   Figure 3: 5: Comparing Sizes of Certificate Chains TLS (bytes)

7.  Security Considerations

   The CBOR profiling with TLS.  Number of X.509 certificates does not change the security
   assumptions needed when deploying
    bytes (length of certificate chain).  X509 and C509 are Certificate
   messages.  X509 + Brotli and C509 + Brotli are CompressedCertificate
                                 messages.

10.  Security Considerations

   The CBOR profiling of X.509 certificates does not change the security
   assumptions needed when deploying standard X.509 certificates but
   decreases the number of fields transmitted, which reduces the risk
   for implementation errors.

   The use of natively signed C509 certificates removes the need for
   ASN.1 encoding, which is a rich source of security vulnerabilities.

   Conversion between the certificate formats can be made in constant
   time to reduce risk of information leakage through side channels.

   The mechanism in this draft does not reveal any additional
   information compared to X.509.  Because of difference in size, it
   will be possible to detect that this profile is used.  The gateway
   solution described in Section 5 8 requires unencrypted certificates and
   is not recommended.

8.

11.  IANA Considerations

   This document creates several new registries under the new heading
   "C509 Certificate".  For all items, the 'Reference' field points to
   this document.

   The expert reviewers for the registries defined in this document are
   expected to ensure that the usage solves a valid use case that could
   not be solved better in a different way, that it is not going to
   duplicate one that is already registered, and that the registered
   point is likely to be used in deployments.  They are furthermore
   expected to check the clarity of purpose and use of the requested
   code points.  Experts should take into account the expected usage of
   entries when approving point assignment, and the length of the
   encoded value should be weighed against the number of code points
   left that encode to that size and how constrained the systems it will
   be used on are.  Values in the interval [-24, 23] have a 1 byte
   encodings, other values in the interval [-256, 255] have a 2 byte
   encodings, and the remaining values in the interval [-65536, 65535]
   have 3 byte encodings.

8.1.

11.1.  C509 Certificate Types Registry

   IANA has created a new registry titled "C509 Certificate Types" under
   the new heading "C509 Certificate".  The columns of the registry are
   Value, Description, and Reference, where Value is an integer, and the
   other columns are text strings.  For values in the interval [-24, 23]
   the registration procedure is "IETF Review" and "Expert Review".  For
   all other values the registration procedure is "Expert Review".  The
   initial contents of the registry are:

   +-------+-----------------------------------------------------------+
   | Value Value | Description                                               |
   +=======+===========================================================+
   |     0 | Natively Signed C509 Certificate following X.509 v3       |
   +-------+-----------------------------------------------------------+
   |     1 | CBOR re-encoding of X.509 v3 Certificate                  |
   +-------+-----------------------------------------------------------+

                     Figure 6: C509 Certificate Types

11.2.  C509 Attributes Registry

   IANA has created a new registry titled "C509 Attributes" under the
   new heading "CBOR Encoded X509 Certificates (C509 Certificates)".
   The columns of the registry are Value, Name, Identifiers, OID, DER,
   Comments, and Reference, where Value is an non-negative integer, and
   the other columns are text strings.  For values in the interval [0,
   23] the registration procedure is "IETF Review" and "Expert Review".
   For all other values the registration procedure is "Expert Review".
   The initial contents of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | Attribute                                                 |
   +=======+===========================================================+
   |     0 | Name:            Email Address                            |
   |       | Identifiers:     emailAddress, e-mailAddress              |
   |       | OID:             1.2.840.113549.1.9.1                     |
   |       | DER:             06 09 2A 86 48 86 F7 0D 01 09 01         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     1 | Name:            Common Name                              |
   |       | Identifiers:     commonName, cn                           |
   |       | OID:             2.5.4.3                                  |
   |       | DER:             06 03 55 04 03                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            Surname                                  |
   |       | Identifiers:     surname, sn                              |
   |       | OID:             2.5.4.4                                  |
   |       | DER:             06 03 55 04 04                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     3 | Name:            Serial Number                            |
   |       | Identifiers:     serialNumber                             |
   |       | OID:             2.5.4.5                                  |
   |       | DER:             06 03 55 04 05                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     4 | Name:            Country                                  |
   |       | Identifiers:     countryName, c                           |
   |       | OID:             2.5.4.6                                  |
   |       | DER:             06 03 55 04 06                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     5 | Name:            Locality                                 |
   |       | Identifiers:     localityName, locality, l                |
   |       | OID:             2.5.4.7                                  |
   |       | DER:             06 03 55 04 07                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     6 | Name:            State or Province                        |
   |       | Identifiers:     stateOrProvinceName, st                  |
   |       | OID:             2.5.4.8                                  |
   |       | DER:             06 03 55 04 08                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     7 | Name:            Street Address                           |
   |       | Identifiers:     streetAddress, street                    |
   |       | OID:             2.5.4.9                                  |
   |       | DER:             06 03 55 04 09                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     8 | Name:            Organization                             |
   |       | Identifiers:     organizationName, o                      |
   |       | OID:             2.5.4.10                                 |
   |       | DER:             06 03 55 04 0A                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     9 | Name:            Organizational Unit                      |
   |       | Identifiers:     organizationalUnitName, ou               |
   |       | OID:             2.5.4.11                                 |
   |       | DER:             06 03 55 04 0B                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    10 | Name:            Title                                    |
   |       | Identifiers:     title                                    |
   |       | OID:             2.5.4.12                                 |
   |       | DER:             06 03 55 04 0C                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    11 | Name:            Business Category                        |
   |       | Identifiers:     businessCategory                         |
   |       | OID:             2.5.4.15                                 |
   |       | DER:             06 03 55 04 0F                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    12 | Name:            Postal Code                              |
   |       | Identifiers:     postalCode                               |
   |       | OID:             2.5.4.17                                 |
   |       | DER:             06 03 55 04 11                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    13 | Name:            Given Name                               |
   |       | Identifiers:     givenName                                |
   |       | OID:             2.5.4.42                                 |
   |       | DER:             06 03 55 04 2A                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    14 | Name:            Initials                                 |
   |       | Identifiers:     initials                                 |
   |       | OID:             2.5.4.43                                 |
   |       | DER:             06 03 55 04 2B                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    15 | Name:            Generation Qualifier                     |
   |       | Identifiers:     generationQualifier                      |
   |       | OID:             2.5.4.44                                 |
   |       | DER:             06 03 55 04 2C                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    16 | Name:            DN Qualifier                             |
   |       | Identifiers:     dnQualifier                              |
   |       | OID:             2.5.4.46                                 |
   |       | DER:             06 03 55 04 2E                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    17 | Name:            Pseudonym                                |
   |       | Identifiers:     pseudonym                                |
   |       | OID:             2.5.4.65                                 |
   |       | DER:             06 03 55 04 41                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    18 | Name:            Organization Identifier                  |
   |       | Identifiers:     organizationIdentifier                   |
   |       | OID:             2.5.4.97                                 |
   |       | DER:             06 03 55 04 61                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    19 | Name:            Inc. Locality                            |
   |       | Identifiers:     jurisdictionOfIncorporationLocalityName  |
   |       | OID:             1.3.6.1.4.1.311.60.2.1.1                 |
   |       | DER:             06 0B 2B 06 01 04 01 82 37 3C 02 01 01   |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    20 | Name:            Inc. State or Province                   |
   |       | Identifiers:     jurisdictionOfIncorporation              |
   |       |                  StateOrProvinceName                      |
   |       | OID:             1.3.6.1.4.1.311.60.2.1.2                 |
   |       | DER:             06 0B 2B 06 01 04 01 82 37 3C 02 01 02   |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    21 | Name:            Inc. Country                             |
   |       | Identifiers:     jurisdictionOfIncorporationCountryName   |
   |       | OID:             1.3.6.1.4.1.311.60.2.1.3                 |
   |       | DER:             06 0B 2B 06 01 04 01 82 37 3C 02 01 03   |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    21 | Name:            Domain Component                         |
   |       | Identifiers:     domainComponent, dc                      |
   |       | OID:             0.9.2342.19200300.100.1.25               |
   |       | DER:             06 0A 09 92 26 89 93 F2 2C 64 01 19      |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+

                         Figure 7: C509 Attributes

11.3.  C509 Extensions Registry

   IANA has created a new registry titled "C509 Extensions Registry"
   under the new heading "CBOR Encoded X509 Certificates (C509
   Certificates)".  The columns of the registry are Value, Name,
   Identifiers, OID, DER, Comments, extensionValue, and Reference, where
   Value is an positive integer, and the other columns are text strings.
   For values in the interval [1, 23] the registration procedure is
   "IETF Review" and "Expert Review".  For all other values the
   registration procedure is "Expert Review".  The initial contents of
   the registry are:

   +-------+-----------------------------------------------------------+
   | Value | Extension                                                 |
   +=======+===========================================================+
   |     1 | Name:            Subject Key Identifier                   |
   |       | Identifiers:     subjectKeyIdentifier                     |
   |       | OID:             2.5.29.14                                |
   |       | DER:             06 03 55 1D 0E                           |
   |       | Comments:                                                 |
   |       | extensionValue:  SubjectKeyIdentifier                     |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            Key Usage                                |
   |       | Identifiers:     keyUsage                                 |
   |       | OID:             2.5.29.15                                |
   |       | DER:             06 03 55 1D 0F                           |
   |       | Comments:                                                 |
   |       | AttributeValue:  KeyUsage                                 |
   +-------+-----------------------------------------------------------+
   |     3 | Name:            Subject Alternative Name                 |
   |       | Identifiers:     subjectAltName                           |
   |       | OID:             2.5.29.17                                |
   |       | DER:             06 03 55 1D 11                           |
   |       | Comments:                                                 |
   |       | extensionValue:  SubjectAltName                           |
   +-------+-----------------------------------------------------------+
   |     4 | Name:            Basic Constraints                        |
   |       | Identifiers:     basicConstraints                         |
   |       | OID:             2.5.29.19                                |
   |       | DER:             06 03 55 1D 13                           |
   |       | Comments:                                                 |
   |       | extensionValue:  BasicConstraints                         |
   +-------+-----------------------------------------------------------+
   |     5 | Name:            CRL Distribution Points                  |
   |       | Identifiers:     cRLDistributionPoints                    |
   |       | OID:             2.5.29.31                                |
   |       | DER:             06 03 55 1D 1F                           |
   |       | Comments:                                                 |
   |       | extensionValue:  CRLDistributionPoints                    |
   +-------+-----------------------------------------------------------+
   |     6 | Name:            Certificate Policies                     |
   |       | Identifiers:     certificatePolicies                      |
   |       | OID:             2.5.29.32                                |
   |       | DER:             06 03 55 1D 20                           |
   |       | Comments:                                                 |
   |       | extensionValue:  CertificatePolicies                      |
   +-------+-----------------------------------------------------------+
   |     7 | Name:            Authority Key Identifier                 |
   |       | Identifiers:     authorityKeyIdentifier                   |
   |       | OID:             2.5.29.35                                |
   |       | DER:             06 03 55 1D 23                           |
   |       | Comments:                                                 |
   |       | extensionValue:  AuthorityKeyIdentifier                   |
   +-------+-----------------------------------------------------------+
   |     8 | Name:            Extended Key Usage                       |
   |       | Identifiers:     extKeyUsage                              |
   |       | OID:             2.5.29.37                                |
   |       | DER:             06 03 55 1D 25                           |
   |       | Comments:                                                 |
   |       | extensionValue:  ExtKeyUsageSyntax                        |
   +-------+-----------------------------------------------------------+
   |     9 | Name:            Authority Information Access             |
   |       | Identifiers:     authorityInfoAccess                      |
   |       | OID:             1.3.6.1.5.5.7.1.1                        |
   |       | DER:             06 08 2B 06 01 05 05 07 01 01            |
   |       | Comments:                                                 |
   |       | extensionValue:   AuthorityInfoAccessSyntax               |
   +-------+-----------------------------------------------------------+
   |    10 | Name:            Signed Certificate Timestamp List        |
   |       | Identifiers:                                              |
   |       | OID:             1.3.6.1.4.1.11129.2.4.2                  |
   |       | DER:             06 0A 2B 06 01 04 01 D6 79 02 04 02      |
   |       | Comments:                                                 |
   |       | extensionValue:  SignedCertificateTimestamps              |
   +-------+-----------------------------------------------------------+
   |    24 | Name:            Subject Directory Attributes             |
   |       | Identifiers:     subjectDirectoryAttributes               |
   |       | OID:             2.5.29.9                                 |
   |       | DER:             06 03 55 1D 09                           |
   |       | Comments:                                                 |
   |       | extensionValue:   SubjectDirectoryAttributes              |
   +-------+-----------------------------------------------------------+
   |    25 | Name:            Issuer Alternative Name                  |
   |       | Identifiers:     issuerAltName                            |
   |       | OID:             2.5.29.18                                |
   |       | DER:             06 03 55 1D 12                           |
   |       | Comments:                                                 |
   |       | extensionValue:  IssuerAltName                            |
   +-------+-----------------------------------------------------------+
   |    26 | Name:            Name Constraints                         |
   |       | Identifiers:     nameConstraints                          |
   |       | OID:             2.5.29.30                                |
   |       | DER:             06 03 55 1D 1E                           |
   |       | Comments:                                                 |
   |       | extensionValue:  NameConstraints                          |
   +-------+-----------------------------------------------------------+
   |    27 | Name:            Policy Mappings                          |
   |       | Identifiers:     policyMappings                           |
   |       | OID:             2.5.29.33                                |
   |       | DER:             06 03 55 1D 21                           |
   |       | Comments:                                                 |
   |       | extensionValue:  PolicyMappings                           |
   +-------+-----------------------------------------------------------+
   |    28 | Name:            Policy Constraints                       |
   |       | Identifiers:     policyConstraints                        |
   |       | OID:             2.5.29.36                                |
   |       | DER:             06 03 55 1D 24                           |
   |       | Comments:                                                 |
   |       | extensionValue:  PolicyConstraints                        |
   +-------+-----------------------------------------------------------+
   |    29 | Name:            Freshest CRL                             |
   |       | Identifiers:     freshestCRL                              |
   |       | OID:             2.5.29.46                                |
   |       | DER:             06 03 55 1D 2E                           |
   |       | Comments:                                                 |
   |       | extensionValue:  FreshestCRL                              |
   +-------+-----------------------------------------------------------+
   |    30 | Name:            Inhibit anyPolicy                        |
   |       | Identifiers:     inhibitAnyPolicy                         |
   |       | OID:             2.5.29.54                                |
   |       | DER:             06 03 55 1D 36                           |
   |       | Comments:                                                 |
   |       | extensionValue:  InhibitAnyPolicy                         |
   +-------+-----------------------------------------------------------+
   |    31 | Name:            Subject Information Access               |
   |       | Identifiers:     subjectInfoAccess                        |
   |       | OID:             1.3.6.1.5.5.7.1.11                       |
   |       | DER:             06 08 2B 06 01 05 05 07 01 0B            |
   |       | Comments:                                                 |
   |       | extensionValue:  SubjectInfoAccessSyntax                  |
   +-------+-----------------------------------------------------------+
   |    32 | Description Name:            IP Resources                             |
   +=======+===========================================================+
   |     0       | Natively Signed C509 Certificate following X.509 v3 Identifiers:     ipAddrBlocks                             |
   |       | OID:             1.3.6.1.5.5.7.1.7                        |
   |       | DER:             06 08 2B 06 01 05 05 07 01 07            |
   |       | Comments:                                                 |
   |       | extensionValue:  IPAddrBlocks                             |
   +-------+-----------------------------------------------------------+
   |     1    33 | CBOR re-encoding of X.509 v3 Certificate Name:            AS Resources                             |
   |       | Identifiers:     autonomousSysIds                         |
   |       | OID:             1.3.6.1.5.5.7.1.8                        |
   |       | DER:             06 08 2B 06 01 05 05 07 01 08            |
   |       | Comments:                                                 |
   |       | extensionValue:  ASIdentifiers                            |
   +-------+-----------------------------------------------------------+
   |    34 | Name:            IP Resources v2                          |
   |       | Identifiers:     ipAddrBlocks-v2                          |
   |       | OID:             1.3.6.1.5.5.7.1.28                       |
   |       | DER:             06 08 2B 06 01 05 05 07 01 1C            |
   |       | Comments:                                                 |
   |       | extensionValue:  IPAddrBlocks                             |
   +-------+-----------------------------------------------------------+
   |    35 | Name:            AS Resources v2                          |
   |       | Identifiers:     autonomousSysIds-v2                      |
   |       | OID:             1.3.6.1.5.5.7.1.29                       |
   |       | DER:             06 08 2B 06 01 05 05 07 01 1D            |
   |       | Comments:                                                 |
   |       | extensionValue:  ASIdentifiers                            |
   +-------+-----------------------------------------------------------+

                         Figure 4: 8: C509 Certificate Types

8.2. Extensions

11.4.  C509 Certificate Attributes Policies Registry

   IANA has created a new registry titled "C509 Certificate Attributes" Policies
   Registry" under the new heading "C509 Certificate". "CBOR Encoded X509 Certificates (C509
   Certificates)".  The columns of the registry are Value, Name,
   Identifiers, OID, DER, Comments, and Reference, where Value is an positive
   integer, and the other columns are text strings.  For values in the
   interval [1, [-24, 23] the registration procedure is "IETF Review" and
   "Expert Review".  For all other values the registration procedure is
   "Expert Review".  The initial contents of
   the registry are:

   +-------+-----------------------------------------------------------+
   | Value | Attribute                                                 |
   +=======+===========================================================+
   |     1 | Name:            Common Name                              |
   |       | OID:             2.5.4.3                                  |
   |       | DER:             06 03 55 04 03                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            Surname                                  |
   |       | OID:             2.5.4.4                                  |
   |       | DER:             06 03 55 04 04                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     3 | Name:            Serial Number                            |
   |       | OID:             2.5.4.5                                  | the registry are:

   +-------+-----------------------------------------------------------+
   | Value | DER:             06 03 55 04 05 Certificate Policy                                        |
   +=======+===========================================================+
   |     0 | Comments: Name:            Any Policy                               |
   +-------+-----------------------------------------------------------+
   |     4       | Name:            Country Identifiers:     anyPolicy                                |
   |       | OID:             2.5.4.6             2.5.29.32.0                              |
   |       | DER:             06 03 55 04 06 55 1D 20 00                        |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     5     1 | Name:            Locality                                 |
   |       | OID:             2.5.4.7                                  |
   |       | DER:             06 03 55 04 07                           |
   |       | Comments:            Domain Validation (DV)                   |
   +-------+-----------------------------------------------------------+
   |     6       | Name:            State or Province Identifiers:     domain-validated                         |
   |       | OID:             2.5.4.8             2.23.140.1.2.1                           |
   |       | DER:             06 03 55 04 08 06 67 81 0C 01 02 01                  |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     7     2 | Name:            Street Address                           |
   |       | OID:             2.5.4.9                                  |
   |       | DER:             06 03 55 04 09                           |
   |       | Comments:            Organization Validation (OV)             |
   +-------+-----------------------------------------------------------+
   |     8       | Name:            Organization Identifiers:     organization-validated                   |
   |       | OID:             2.5.4.10             2.23.140.1.2.2                           |
   |       | DER:             06 03 55 04 0A 06 67 81 0C 01 02 02                  |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     9     3 | Name:            Organizational Unit                      |
   |       | OID:             2.5.4.11                                 |
   |       | DER:             06 03 55 04 0B                           |
   |       | Comments:            Individual Validation (IV)               |
   +-------+-----------------------------------------------------------+
   |    10       | Name:            Title Identifiers:     individual-validated                     |
   |       | OID:             2.5.4.12             2.23.140.1.2.3                           |
   |       | DER:             06 03 55 04 06 67 81 0C 01 02 03                  |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    11     4 | Name:            Postal Code                              |
   |       | OID:             2.5.4.17                                 |
   |       | DER:             06 03 55 04 11                           |
   |       | Comments:            Extended Validation (EV)                 |
   +-------+-----------------------------------------------------------+
   |    12       | Name:            Given Name Identifiers:     ev-guidelines                            |
   |       | OID:             2.5.4.42             2.23.140.1.1                             |
   |       | DER:             06 03 55 04 2A 05 67 81 0C 01 01                     |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    13     7 | Name:            Initials            Resource PKI (RPKI)                      |
   |       | Identifiers:     id-cp-ipAddr-asNumber                    |
   |       | OID:             2.5.4.43             1.3.6.1.5.5.7.14.2                       |
   |       | DER:             06 03 55 04 08 2B 06 01 05 05 07 0E 02            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    14     8 | Name:            Generation Qualifier            Resource PKI (RPKI) (Alternative)        |
   |       | Identifiers:     id-cp-ipAddr-asNumber-v2                 |
   |       | OID:             2.5.4.44             1.3.6.1.5.5.7.14.3                       |
   |       | DER:             06 08 2B 06 01 05 05 07 0E 03 55 04 2C            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    15    10 | Name:            DN Qualifier                             |
   |       | OID:             2.5.4.46                                 |
   |       | DER:             06 03 55 04 2E            Remote SIM Provisioning Role             |
   |       | Comments:                  Certificate Issuer                       |
   +-------+-----------------------------------------------------------+
   |    16       | Name:            Pseudonym Identifiers:     id-rspRole-ci                            |
   |       | OID:             2.5.4.65             2.23.146.1.2.1.0                         |
   |       | DER:             06 03 55 04 41 07 67 81 12 01 02 01 00               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    17    11 | Name:            Organization Identifier            Remote SIM Provisioning Role             |
   |       |                  eUICC                                    |
   |       | Identifiers:     id-rspRole-euicc                         |
   |       | OID:             2.5.4.97             2.23.146.1.2.1.1                         |
   |       | DER:             06 03 55 04 61 07 67 81 12 01 02 01 01               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+

                   Figure 5: C509 Certificate Attributes

8.3.  C509 Certificate Extensions Registry

   IANA has created a new registry titled "C509 Certificate Extensions"
   under the new heading "C509 Certificate".  The columns of the
   registry are Value, Name, OID, DER, Comments, extensionValue, and
   Reference, where Value is an positive integer, and the other columns
   are text strings.  For values in the interval [1, 23] the
   registration procedure is "IETF Review" and "Expert Review".  For all
   other values the registration procedure is "Expert Review".  The
   initial contents of the registry are:

 +-------+-----------------------------------------------------------+
   | Value    12 | Extension Name:            Remote SIM Provisioning Role             |
 +=======+===========================================================+
   |     1       | Name:            Subject Key Identifier                  eUICC Manufacturer                       |
   |       | Identifiers:     id-rspRole-eum                           |
   |       | OID:             2.5.29.14             2.23.146.1.2.1.2                         |
   |       | DER:             06 03 55 1D 0E 07 67 81 12 01 02 01 02               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    13 | extensionValue:  bytes Name:            Remote SIM Provisioning Role             |
 +-------+-----------------------------------------------------------+
   |     2       | Name:            Key Usage                  SM-DP+ TLS                               |
   |       | Identifiers:     id-rspRole-dp-tls                        |
   |       | OID:             2.5.29.15             2.23.146.1.2.1.3                         |
   |       | DER:             06 07 67 81 12 01 02 01 03 55 1D 0F               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    14 | AttributeValue:  int Name:            Remote SIM Provisioning Role             |
 +-------+-----------------------------------------------------------+
   |     3       | Name:            Subject Alternative Name                  SM-DP+ Authentication                    |
   |       | Identifiers:     id-rspRole-dp-auth                       |
   |       | OID:             2.5.29.17             2.23.146.1.2.1.4                         |
   |       | DER:             06 03 55 1D 11 07 67 81 12 01 02 01 04               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    15 | extensionValue:  ExtValueSAN Name:            Remote SIM Provisioning Role             |
 +-------+-----------------------------------------------------------+
   |     4       | Name:            Basic Constraints                  SM-DP+ Profile Binding                   |
   |       | Identifiers:     id-rspRole-dp-pb                         |
   |       | OID:             2.5.29.19             2.23.146.1.2.1.5                         |
   |       | DER:             06 03 55 1D 13 07 67 81 12 01 02 01 05               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    16 | extensionValue:  int Name:            Remote SIM Provisioning Role             |
 +-------+------------------------------------------er-----------------+
   |     5       | Name:            CRL Distribution Points                  SM-DS TLS                                |
   |       | Identifiers:     id-rspRole-ds-tls                        |
   |       | OID:             2.5.29.31             2.23.146.1.2.1.6                         |
   |       | DER:             06 07 67 81 12 01 02 01 06               |
   |       | DER:             06 03 55 1D 1F Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    17 | Comments: Name:            Remote SIM Provisioning Role             |
   |       | extensionValue:  ExtValueCDP                  SM-DS Authentication                     |
 +-------+-----------------------------------------------------------+
   |     6       | Name:            Certificate Policies Identifiers:     id-rspRole-ds-auth                       |
   |       | OID:             2.5.29.32             2.23.146.1.2.1.7                         |
   |       | DER:             06 03 55 1D 20 07 67 81 12 01 02 01 07               |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+

                    Figure 9: C509 Certificate Policies

11.5.  C509 Policies Qualifiers Registry

   IANA has created a new registry titled "C509 Policies Qualifiers
   Registry" under the new heading "CBOR Encoded X509 Certificates (C509
   Certificates)".  The columns of the registry are Value, Name,
   Identifiers, OID, DER, Comments, and Reference, where Value is an
   integer, and the other columns are text strings.  For values in the
   interval [-24, 23] the registration procedure is "IETF Review" and
   "Expert Review".  For all other values the registration procedure is
   "Expert Review".  The initial contents of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | extensionValue:  ExtValueCP Certificate Policy                                        |
 +-------+-----------------------------------------------------------+
   +=======+===========================================================+
   |     7     1 | Name:            Authority Key Identifier            Certification Practice Statement         |
   |       | Identifiers:     id-qt-cps, cps                           |
   |       | OID:             2.5.29.35             1.3.6.1.5.5.7.2.1                        |
   |       | DER:             06 03 55 1D 23 08 2B 06 01 05 05 07 02 01            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     2 | extensionValue:  ExtValueAKI Name:            User Notice                              |
 +-------+-----------------------------------------------------------+
   |     8       | Name:            Extended Key Usage Identifiers:     id-qt-unotice, unotice                   |
   |       | OID:             2.5.29.37             1.3.6.1.5.5.7.2.2                        |
   |       | DER:             06 03 55 1D 25 08 2B 06 01 05 05 07 02 02            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+

                    Figure 10: C509 Policies Qualifiers

11.6.  C509 Information Access Registry

   IANA has created a new registry titled "C509 Information Access
   Registry" under the new heading "CBOR Encoded X509 Certificates (C509
   Certificates)".  The columns of the registry are Value, Name,
   Identifiers, OID, DER, Comments, and Reference, where Value is an
   integer, and the other columns are text strings.  For values in the
   interval [-24, 23] the registration procedure is "IETF Review" and
   "Expert Review".  For all other values the registration procedure is
   "Expert Review".  The initial contents of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | Comments: Information Access                                        |
   +=======+===========================================================+
   |     1 | extensionValue:  ExtValueEKU Name:            OCSP                                     |
 +-------+-----------------------------------------------------------+
   |     9       | Name:            Authority Information Access Identifiers:     id-ad-ocsp, id-pkix-ocsp                 |
   |       | OID:             1.3.6.1.5.5.7.1.1             1.3.6.1.5.5.7.48.1                       |
   |       | DER:             06 08 2B 06 01 05 05 07 01 30 01            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     2 | extensionValue:  ExtValueAIA Name:            CA Issuers                               |
 +-------+-----------------------------------------------------------+
   |    10       | Name:            Signed Certificate Timestamp List Identifiers:     id-ad-caIssuers, caIssuers               |
   |       | OID:             1.3.6.1.4.1.11129.2.4.2             1.3.6.1.5.5.7.48.2                       |
   |       | DER:             06 0A 08 2B 06 01 04 01 D6 79 02 04 05 05 07 30 02            |
   |       | Comments:                                                 |
 |       | extensionValue:  ExtValueSCT                             |
   +-------+-----------------------------------------------------------+
   |    24     3 | Name:            Subject Directory Attributes             |
 |       | OID:             2.5.29.9                                 |
 |       | DER:             06 03 55 1D 09                           |
 |       | Comments:                                                 |
 |       | extensionValue:  bytes            Time Stamping                            |
 +-------+-----------------------------------------------------------+
   |    25       | Name:            Issuer Alternative Name Identifiers:     id-ad-timeStamping, timeStamping         |
   |       | OID:             2.5.29.18             1.3.6.1.5.5.7.48.3                       |
   |       | DER:             06 08 2B 06 01 05 05 07 30 03 55 1D 12            |
   |       | Comments:                                                 |
 |       | extensionValue:  bytes                                    |
   +-------+-----------------------------------------------------------+
   |    26     5 | Name:            Name Constraints                         |
 |       | OID:             2.5.29.30                                |
 |       | DER:             06 03 55 1D 1E                           |
 |       | Comments:                                                 |
 |       | extensionValue:  bytes            CA Repository                            |
 +-------+-----------------------------------------------------------+
   |    27       | Name:            Policy Mappings Identifiers:     id-ad-caRepository                       |
   |       | OID:             2.5.29.33             1.3.6.1.5.5.7.48.5                       |
   |       | DER:             06 03 55 1D 21 08 2B 06 01 05 05 07 30 05            |
   |       | Comments:                                                 |
 |       | extensionValue:  bytes                                    |
   +-------+-----------------------------------------------------------+
   |    28    10 | Name:            Policy Constraints                       |
 |       | OID:             2.5.29.36                                |
 |       | DER:             06 03 55 1D 24                           |
 |       | Comments:            RPKI Manifest                            |
   |       | extensionValue:  bytes                                    |
 +-------+-----------------------------------------------------------+
 |    29 | Name:            Freshest CRL Identifiers:     id-ad-rpkiManifest                       |
   |       | OID:             2.5.29.46             1.3.6.1.5.5.7.48.10                      |
   |       | DER:             06 03 55 1D 2E 08 2B 06 01 05 05 07 30 0A            |
   |       | Comments:        RFC 6487                                 |
   +-------+-----------------------------------------------------------+
   |    11 | extensionValue:  bytes Name:            Signed Object                            |
 +-------+-----------------------------------------------------------+
   |    30       | Name:            Inhibit anyPolicy Identifiers:     id-ad-signedObject                       |
   |       | OID:             2.5.29.54             1.3.6.1.5.5.7.48.11                      |
   |       | DER:             06 03 55 1D 36 08 2B 06 01 05 05 07 30 0B            |
   |       | Comments:        RFC 6487                                 |
   +-------+-----------------------------------------------------------+
   |    13 | extensionValue:  bytes Name:            RPKI Notify                              |
 +-------+-----------------------------------------------------------+
   |    31       | Name:            Subject Information Access Identifiers:     id-ad-rpkiNotify                         |
   |       | OID:             1.3.6.1.5.5.7.1.11             1.3.6.1.5.5.7.48.13                      |
   |       | DER:             06 08 2B 06 01 05 05 07 01 0B            |
 |       | Comments: 30 0D            |
   |       | extensionValue:  bytes Comments:        RFC 8182                                 |
   +-------+-----------------------------------------------------------+

                   Figure 6: 11: C509 Certificate Extensions

8.4. Information Accesses

11.7.  C509 Certificate Certificate Policies Extended Key Usages Registry

   IANA has created a new registry titled "C509 Certificate Certificate
   Policies" Extended Key Usages
   Registry" under the new heading "C509 Certificate". "CBOR Encoded X509 Certificates (C509
   Certificates)".  The columns of the registry are Value, Name,
   Identifiers, OID, DER, Comments, and Reference, where Value is an
   integer, and the other columns are text strings.  For values in the
   interval [-24, 23] the registration procedure is "IETF Review" and
   "Expert Review".  For all other values the registration procedure is
   "Expert Review".  The initial contents of the registry are:

   +-------+-----------------------------------------------------------+

    +-------+---------------------------------------------------------+
    | Value | Certificate Policy Extended Key Usage                                      |
   +=======+===========================================================+
    +=======+=========================================================+
    |     0 | Name:            Any Extended Key Usage                 |
    |       | Identifiers:     anyExtendedKeyUsage                    |
    |       | OID:             2.5.29.37.0                            |
    |       | DER:             06 04 55 1D 25 00                      |
    |       | Comments:        RFC 5280                               |
    +-------+---------------------------------------------------------+
    |     1 | Name:            Domain Validation (DV)            TLS Server authentication              |
    |       | Identifiers:     id-kp-serverAuth                       |
    |       | OID:             2.23.140.1.2.1             1.3.6.1.5.5.7.3.1                      |
    |       | DER:             06 08 2B 06 67 81 0C 01 02 05 05 07 03 01          |
    |       | Comments:        RFC 5280                               |
   +-------+-----------------------------------------------------------+
    +-------+---------------------------------------------------------+
    |     2 | Name:            Organization Validation (OV)            TLS Client Authentication              |
    |       | Identifiers:     id-kp-clientAuth                       |
    |       | OID:             2.23.140.1.2.2             1.3.6.1.5.5.7.3.2                      |
    |       | DER:             06 08 2B 06 67 81 0C 01 02 05 05 07 03 02          |
    |       | Comments:        RFC 5280                               |
   +-------+-----------------------------------------------------------+
    +-------+---------------------------------------------------------+
    |     3 | Name:            Individual Validation (IV)            Code Signing                           |
    |       | Identifiers:     id-kp-codeSigning                      |
    |       | OID:             2.23.140.1.2.3             1.3.6.1.5.5.7.3.3                      |
    |       | DER:             06 08 2B 06 67 81 0C 01 02 05 05 07 03 03          |
    |       | Comments:        RFC 5280                               |
   +-------+-----------------------------------------------------------+
    +-------+---------------------------------------------------------+
    |     4 | Name:            Extended Validation (EV)            Email protection (S/MIME)              |
    |       | Identifiers:     id-kp-emailProtection                  |
    |       | OID:             2.23.140.1.1             1.3.6.1.5.5.7.3.4                      |
    |       | DER:             06 05 67 81 0C 01 08 2B 06 01 05 05 07 03 04          |
    |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+

              Figure 7: C509 Certificate Certificate Policies

8.5.  C509 Certificate Extended Key Usages Registry

   IANA has created a new registry titled "C509 Certificate Extended Key
   Usages" under the new heading "C509 Certificate".  The columns of the
   registry are Value, Name, OID, DER, Comments, and Reference, where
   Value is an integer, and the other columns are text strings.  For
   values in the interval [-24, 23] the registration procedure is "IETF
   Review" and "Expert Review".  For all other values the registration
   procedure is "Expert Review".  The initial contents of the registry
   are:

   +-------+-----------------------------------------------------------+
   | Value | Extended Key Usage                                        |
   +=======+===========================================================+ Comments:        RFC 5280                               |     1
    +-------+---------------------------------------------------------+
    |     8 | Name:            TLS Server authentication            Time Stamping                          |
    |       | Identifiers:     id-kp-timeStamping, timestamping       |
    |       | OID:             1.3.6.1.5.5.7.3.1             1.3.6.1.5.5.7.3.8                      |
    |       | DER:             06 08 2B 06 01 05 05 07 03 01 08          |
    |       | Comments:                                               |
   +-------+-----------------------------------------------------------+
    +-------+---------------------------------------------------------+
    |     2     9 | Name:            TLS Client Authentication            OCSP Signing                           |
    |       | Identifiers:     id-kp-OCSPSigning                      |
    |       | OID:             1.3.6.1.5.5.7.3.2             1.3.6.1.5.5.7.3.9                      |
    |       | DER:             06 08 2B 06 01 05 05 07 03 02 09          |
    |       | Comments:        RFC 5280                               |
   +-------+-----------------------------------------------------------+
    +-------+---------------------------------------------------------+
    |     3    10 | Name:            Code Signing            Kerberos PKINIT Client Auth            |
    |       | Identifiers:     id-pkinit-KPClientAuth                 |
    |       | OID:             1.3.6.1.5.5.7.3.3             1.3.6.1.5.2.3.4                        |
    |       | DER:             06 08 07 2B 06 01 05 05 07 03 02 03 04             |
    |       | Comments:        RFC 4556                               |
   +-------+-----------------------------------------------------------+
    +-------+---------------------------------------------------------+
    |     4    11 | Name:            Email protection (S/MIME)            Kerberos PKINIT KDC                    |
    |       | Identifiers:     id-pkinit-KPKdc                        |
    |       | OID:             1.3.6.1.5.5.7.3.4             1.3.6.1.5.2.3.5                        |
    |       | DER:             06 08 07 2B 06 01 05 05 07 02 03 04 05             |
    |       | Comments:        RFC 4556                               |
   +-------+-----------------------------------------------------------+
    +-------+---------------------------------------------------------+
    |     8    12 | Name:            Time Stamping            SSH Client                             |
    |       | Identifiers:     id-kp-secureShellClient                |
    |       | OID:             1.3.6.1.5.5.7.3.8             1.3.6.1.5.5.7.3.21                     |
    |       | DER:             06 08 2B 06 01 05 05 07 03 08 15          |
    |       | Comments:        RFC 6187                               |
   +-------+-----------------------------------------------------------+
    +-------+---------------------------------------------------------+
    |     9    13 | Name:            OCSP Signing            Kerberos PKINIT KDC                    |
    |       | Identifiers:     id-pkinit-KPKdc                        |
    |       | OID:             1.3.6.1.5.5.7.3.9             1.3.6.1.5.5.7.3.22                     |
    |       | DER:             06 08 2B 06 01 05 05 07 03 09 16          |
    |       | Comments:        RFC 6187                               |
   +-------+-----------------------------------------------------------+
    +-------+---------------------------------------------------------+

                    Figure 8: 12: C509 Certificate Extended Key Usages

8.6.

11.8.  C509 Certificate General Names Registry

   IANA has created a new registry titled "C509 Certificate General
   Names" Names Registry"
   under the new heading "C509 Certificate". "CBOR Encoded X509 Certificates (C509
   Certificates)".  The columns of the registry are Value, General Name,
   and Reference, where Value is an integer, and the other columns are
   text strings.  For values in the interval [-24, 23] the registration
   procedure is "IETF Review" and "Expert Review".  For all other values
   the registration procedure is "Expert Review".  The initial contents
   of the registry are:

   +-------+-----------------------------------------------------------+
   | Value | General Names                                             |
   +=======+===========================================================+
   |    -2 | Name:            otherName with SmtpUTF8Mailbox           |
   |       | Comments:        id-on-SmtpUTF8Mailbox                    |
   |       |                  (1.3.6.1.5.5.7.8.9)                      |
   |       |                  06 08 2B 06 01 05 05 07 08 09            |
   |       | Value:           text                                     |
   +-------+-----------------------------------------------------------+
   |    -1 | Name:            otherName with hardwareModuleName        |
   |       | Comments:        id-on-hardwareModuleNamee                |
   |       |                  (1.3.6.1.5.5.7.8.4)                      |
   |       |                  06 08 2B 06 01 05 05 07 08 04            |
   |       | Value:           [ ~oid, bytes ]                          |
   +-------+-----------------------------------------------------------+
   |     0 | Name:            otherName                                |
   |       | Comments:                                                 |
   |       | Value:           [ ~oid, bytes ]                          |
   +-------+-----------------------------------------------------------+
   |     1 | Name:            rfc822Name                               |
   |       | Comments:                                                 |
   |       | Value:           text                                     |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            dNSName                                  |
   |       | Comments:                                                 |
   |       | Value:           text                                     |
   +-------+-----------------------------------------------------------+
   |     4 | Name:            directoryName                            |
   |       | Comments:                                                 |
   |       | Value:           Name                                     |
   +-------+-----------------------------------------------------------+
   |     6 | Name:            uniformResourceIdentifier                |
   |       | Comments:                                                 |
   |       | Value:           text                                     |
   +-------+-----------------------------------------------------------+
   |     7 | Name:            iPAddress                                |
   |       | Comments:                                                 |
   |       | Value:           bytes                                    |
   +-------+-----------------------------------------------------------+
   |     8 | Name:            registeredID                             |
   |       | Comments:                                                 |
   |       | Value:           ~oid                                     |
   +-------+-----------------------------------------------------------+

                       Figure 9: 13: C509 Certificate General Names

8.7.

11.9.  C509 Certificate Signature Algorithms Registry

   IANA has created a new registry titled "C509 Certificate Signature Algorithms"
   under the new heading "C509 Certificate". "CBOR Encoded X509 Certificates (C509
   Certificates)".  The columns of the registry are Value, Name,
   Identifiers, OID, Parameters, DER, Comments, and Reference, where
   Value is an integer, and the other columns are text strings.  For
   values in the interval [-24, 23] the registration procedure is "IETF
   Review" and "Expert Review".  For all other values the registration
   procedure is "Expert Review".  The initial contents of the registry
   are:

   +-------+-----------------------------------------------------------+
   | Value | X.509 Signature Algorithms                                |
   +=======+===========================================================+
   |  -256 | Name:        RSASSA-PKCS1-v1_5 with SHA-1                 |
   |       | Identifiers: sha1-with-rsa-signature,                     |
   |       |              sha1WithRSAEncryption,                       |
   |       |              sha-1WithRSAEncryption                       |
   |       | OID:         1.2.840.113549.1.1.5                         |
   |       | Parameters:  NULL                                         |
   |       | DER:         30 0D 06 09 2A 86 48 86 F7 0D 01 01 05 05 00 |
   |       | Comments:    Don't use                                    |
   +-------+-----------------------------------------------------------+
   |  -255 | Name:        ECDSA with SHA-1                             |
   |       | Identifiers: ecdsa-with-SHA1                              |
   |       | OID:         1.2.840.10045.4.1                            |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 09 06 07 2A 86 48 CE 3D 04 01             |
   |       | Comments:    Don't use. Compressed signature value        |
   +-------+-----------------------------------------------------------+
   |     0 | Name:        ECDSA with SHA-256                           |
   |       | Identifiers: ecdsa-with-SHA256                            |
   |       | OID:         1.2.840.10045.4.3.2                          |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2A 86 48 CE 3D 04 03 02          |
   |       | Comments:    Compressed signature value                   |
   +-------+-----------------------------------------------------------+
   |     1 | Name:        ECDSA with SHA-384                           |
   |       | Identifiers: ecdsa-with-SHA384                            |
   |       | OID:         1.2.840.10045.4.3.3                          |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2A 86 48 CE 3D 04 03 03          |
   |       | Comments:    Compressed signature value                   |
   +-------+-----------------------------------------------------------+
   |     2 | Name:        ECDSA with SHA-512                           |
   |       | Identifiers: ecdsa-with-SHA512                            |
   |       | OID:         1.2.840.10045.4.3.4                          |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2A 86 48 CE 3D 04 03 04          |
   |       | Comments:    Compressed signature value                   |
   +-------+-----------------------------------------------------------+
   |     3 | Name:        ECDSA with SHAKE128                          |
   |       | Identifiers: id-ecdsa-with-shake128                       |
   |       | OID:         1.3.6.1.5.5.7.6.32                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 20          |
   |       | Comments:    Compressed signature value                   |
   +-------+-----------------------------------------------------------+
   |     4 | Name:        ECDSA with SHAKE256                          |
   |       | Identifiers: id-ecdsa-with-shake256                       |
   |       | OID:         1.3.6.1.5.5.7.6.33                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 21          |
   |       | Comments:    Compressed signature value                   |
   +-------+-----------------------------------------------------------+
   |    12 | Name:        Ed25519                                      |
   |       | Identifiers: id-Ed25519, id-EdDSA25519                    |
   |       | OID:         1.3.101.112                                  |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 05 06 03 2B 65 70                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    13 | Name:        Ed448                                        |
   |       | Identifiers: id-Ed448, id-EdDSA448                        |
   |       | OID:         1.3.101.113                                  |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 05 06 03 2B 65 71                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    23 | Name:        RSASSA-PKCS1-v1_5 with SHA-256               |
   |       | Identifiers: sha256WithRSAEncryption                      |
   |       | OID:         1.2.840.113549.1.1.11                        |
   |       | Parameters:  NULL                                         |
   |       | DER:         30 0B 06 09 2A 86 48 86 F7 0D 01 01 0B 05 00 |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    24 | Name:        RSASSA-PKCS1-v1_5 with SHA-384               |
   |       | Identifiers: sha384WithRSAEncryption                      |
   |       | OID:         1.2.840.113549.1.1.12                        |
   |       | Parameters:  NULL                                         |
   |       | DER:         30 0B 06 09 2A 86 48 86 F7 0D 01 01 0C 05 00 |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    25 | Name:        RSASSA-PKCS1-v1_5 with SHA-512               |
   |       | Identifiers: sha512WithRSAEncryption                      |
   |       | OID:         1.2.840.113549.1.1.13                        |
   |       | Parameters:  NULL                                         |
   |       | DER:         30 0B 06 09 2A 86 48 86 F7 0D 01 01 0D 05 00 |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    26 | Name:        RSASSA-PSS with SHA-256                      |
   |       | Identifiers: rsassa-pss, id-RSASSA-PSS                    |
   |       | OID:         1.2.840.113549.1.1.10                        |
   |       | Parameters:  SHA-256, MGF-1 with SHA-256, saltLength = 32 |
   |       | DER:         30 41 06 09 2A 86 48 86 F7 0D 01 01 0A 30 34 |
   |       |              A0 0F 30 0D 06 09 60 86 48 01 65 03 04 02 01 |
   |       |              05 00 A1 1C 30 1A 06 09 2A 86 48 86 F7 0D 01 |
   |       |              01 08 30 0D 06 09 60 86 48 01 65 03 04 02 01 |
   |       |              05 00 a2 03 02 01 20                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    27 | Name:        RSASSA-PSS with SHA-384                      |
   |       | Identifiers: rsassa-pss, id-RSASSA-PSS                    |
   |       | OID:         1.2.840.113549.1.1.10                        |
   |       | Parameters:  SHA-384, MGF-1 with SHA-384, saltLength = 48 |
   |       | DER:         30 41 06 09 2A 86 48 86 F7 0D 01 01 0A 30 34 |
   |       |              A0 0F 30 0D 06 09 60 86 48 01 65 03 04 02 02 |
   |       |              05 00 A1 1C 30 1A 06 09 2A 86 48 86 F7 0D 01 |
   |       |              01 08 30 0D 06 09 60 86 48 01 65 03 04 02 02 |
   |       |              05 00 A2 03 02 01 30                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    28 | Name:        RSASSA-PSS with SHA-512                      |
   |       | Identifiers: rsassa-pss, id-RSASSA-PSS                    |
   |       | OID:         1.2.840.113549.1.1.10                        |
   |       | Parameters:  SHA-512, MGF-1 with SHA-512, saltLength = 64 |
   |       | DER:         30 41 06 09 2A 86 48 86 F7 0D 01 01 0A 30 34 |
   |       |              A0 0F 30 0D 06 09 60 86 48 01 65 03 04 02 03 |
   |       |              05 00 A1 1C 30 1A 06 09 2A 86 48 86 F7 0D 01 |
   |       |              01 08 30 0D 06 09 60 86 48 01 65 03 04 02 03 |
   |       |              05 00 A2 03 02 01 40                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    29 | Name:        RSASSA-PSS with SHAKE128                     |
   |       | Identifiers: id-RSASSA-PSS-SHAKE128                       |
   |       | OID:         1.3.6.1.5.5.7.6.30                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 1E          |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    30 | Name:        RSASSA-PSS with SHAKE256                     |
   |       | Identifiers: id-RSASSA-PSS-SHAKE256                       |
   |       | OID:         1.3.6.1.5.5.7.6.31                           |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0A 06 08 2B 06 01 05 05 07 06 1F          |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    42 | Name:        HSS / LMS                                    |
   |       | Identifiers: id-alg-hss-lms-hashsig, id-alg-mts-hashsig   |
   |       | OID:         1.2.840.113549.1.9.16.3.17                   |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0D 06 0B 2A 86 48 86 F7 0D 01 09 10 03 11 |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    43 | Name:        XMSS                                         |
   |       | Identifiers: id_alg_xmss                                  |
   |       | OID:         0.4.0.127.0.15.1.1.13.0                      |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0B 06 09 04 00 7F 00 0F 01 01 0D 00       |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    44 | Name:        XMSS^MT                                      |
   |       | Identifiers: id_alg_xmssmt                                |
   |       | OID:         0.4.0.127.0.15.1.1.14.0                      |
   |       | Parameters:  Absent                                       |
   |       | DER:         30 0B 06 09 04 00 7F 00 0F 01 01 0E 00       |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+

                   Figure 10: 14: C509 Certificate Signature Algorithms

8.8.

11.10.  C509 Certificate Public Key Algorithms Registry

   IANA has created a new registry titled "C509 Certificate Public Key Algorithms"
   under the new heading "C509 Certificate". "CBOR Encoded X509 Certificates (C509
   Certificates)".  The columns of the registry are Value, Name,
   Identifiers, OID, Parameters, DER, Comments, and Reference, where
   Value is an integer, and the other columns are text strings.  For
   values in the interval [-24, 23] the registration procedure is "IETF
   Review" and "Expert Review".  For all other values the registration
   procedure is "Expert Review".  T The initial contents of the registry
   are:

  +-------+-----------------------------------------------------------+
  | Value | X.509 Public Key Algorithms                               |
  +=======+===========================================================+
  |     0 | Name:        RSA Name:        RSA                                          |
  |       | Identifiers: rsaEncryption                                |
  |       | OID:         1.2.840.113549.1.1.1                         |
  |       | Parameters:  NULL                                         |
  |       | DER:         30 0d 06 09 2a 86 48 86 f7 0d 01 01 01 05 00 |
  |       | Comments:    Compressed subjectPublicKey                  |
  +-------+-----------------------------------------------------------+
  |     1 | Name:        EC Public Key (Weierstrass) with secp256r1    |
  |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
  |       | OID:         1.2.840.10045.2.1                            |
  |       | Parameters:  namedCurve = secp256r1 (1.2.840.10045.3.1.7) |
  |       | DER:         30 13 06 07 2A 86 48 CE 3D 02 01 06 08 2A 86 |
  |       |              48 CE 3D 03 01 07                            |
  |       | Comments:    Point compressed subjectPublicKey            |
  |       |              Also known as P-256, ansip256r1, prime256v1  |
  +-------+-----------------------------------------------------------+
  |     2 | Name:        EC Public Key (Weierstrass) with secp384r1    |
  |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
  |       | OID:         1.2.840.10045.2.1                            |
  |       | Parameters:  namedCurve = secp384r1 (1.3.132.0.34)        |
  |       | DER:         30 10 06 07 2A 86 48 CE 3D 02 01 06 05 2B 81 |
  |       |              04 00 22                                     |
  |       | Comments:    Point compressed subjectPublicKey            |
  |       |              Also known as P-384, ansip384r1              |
  +-------+-----------------------------------------------------------+
  |     3 | Name:        EC Public Key (Weierstrass) with secp521r1    |
  |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
  |       | OID:         1.2.840.10045.2.1                            |
  |       | Parameters:  namedCurve = secp521r1 (1.3.132.0.35)        |
  |       | DER:         30 10 06 07 2A 86 48 CE 3D 02 01 06 05 2B 81 |
  |       |              04 00 23                                     |
  |       | Comments:    Point compressed subjectPublicKey            |
  |       |              Also known as P-521, ansip521r1              |
  +-------+-----------------------------------------------------------+
  |     8 | Name:        X25519 (Montgomery)                          |
  |       | Identifiers: id-X25519                                    |
  |       | OID:         1.3.101.110                                  |
  |       | Parameters:  Absent                                       |
  |       | DER:         30 05 06 03 2B 65 6E                         |
  |       | Comments:                                                 |
  +-------+-----------------------------------------------------------+
  |     9 | Name:        X448 (Montgomery)                            |
  |       | Identifiers: id-X448                                      |
  |       | OID:         1.3.101.111                                  |
  |       | Parameters:  Absent                                       |
  |       | DER:         30 05 06 03 2B 65 6F                         |
  |       | Comments:                                                 |
  +-------+-----------------------------------------------------------+
  |    10 | Name:        Ed25519 (Twisted Edwards)                    |
  |       | Identifiers: id-Ed25519, id-EdDSA25519                    |
  |       | OID:         1.3.101.112                                  |
  |       | Parameters:  Absent                                       |
  |       | DER:         30 05 06 03 2B 65 70                         |
  |       | Comments:                                                 |
  +-------+-----------------------------------------------------------+
  |    11 | Name:        Ed448 (Edwards)                              |
  |       | Identifiers: id-Ed448, id-EdDSA448                        |
  |       | OID:         1.3.101.113                                  |
  |       | Parameters:  Absent                                       |
  |       | DER:         30 05 06 03 2B 65 71                         |
  |       | Comments:                                                 |
  +-------+-----------------------------------------------------------+
  |    16 | Name:        HSS / LMS                                    |
  |       | Identifiers: id-alg-hss-lms-hashsig, id-alg-mts-hashsig   |
  |       | OID:         1.2.840.113549.1.9.16.3.17                   |
  |       | Parameters:  Absent Parameters:  Absent                                       |
  |       | DER:         30 0D 06 0B 2A 86 48 86 F7 0D 01 09 10 03 11 |
  |       | Comments:                                                 |
  +-------+-----------------------------------------------------------+
  |    17 | Name:        XMSS                                         |
  |       | Identifiers: id_alg_xmss                                  |
  |       | OID:         0.4.0.127.0.15.1.1.13.0                      |
  |       | Parameters:  Absent                                       |
  |       | DER:         30 0B 06 09 04 00 7F 00 0F 01 01 0D 00       |
  |       | Comments:                                                 |
  +-------+-----------------------------------------------------------+
  |    18 | Name:        XMSS^MT                                      |
  |       | Identifiers: id_alg_xmssmt                                |
  |       | OID:         0.4.0.127.0.15.1.1.14.0                      |
  |       | Parameters:  Absent                                       |
  |       | DER:         30 0B 06 09 04 00 7F 00 0F 01 01 0E 00       |
  |       | Comments:                                                 |
  +-------+-----------------------------------------------------------+
  |    24 | Name:        EC Public Key (Weierstrass) with              |
  |       |              brainpoolP256r1                              |
  |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
  |       | OID:         1.2.840.10045.2.1                            |
  |       | Parameters:  namedCurve = brainpoolP256r1                 |
  |       |              (1.3.36.3.3.2.8.1.1.7)                       |
  |       | DER:         30 13 06 07 2A 86 48 CE 3D 02 01 06 09 2B 24 |
  |       |              03 03 02 08 01 01 07                         |
  |       | Comments:    Point compressed subjectPublicKey            |
  +-------+-----------------------------------------------------------+
  |    25 | Name:        EC Public Key (Weierstrass) with              |
  |       |              brainpoolP384r1                              |
  |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
  |       | OID:         1.2.840.10045.2.1                            |
  |       | Parameters:  namedCurve = brainpoolP384r1                 |
  |       |              (1.3.36.3.3.2.8.1.1.11)                      |
  |       | DER:         30 0D 13 06 0B 07 2A 86 48 86 F7 0D CE 3D 02 01 06 09 10 2B 24 |
  |       |              03 11 03 02 08 01 01 0B                         |
  |       | Comments:    Point compressed subjectPublicKey            |
  +-------+-----------------------------------------------------------+
  |    17    26 | Name:        XMSS        EC Public Key (Weierstrass) with              |
  |       |              brainpoolP512r1                              |
  |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
  |       | OID:         0.4.0.127.0.15.1.1.13.0         1.2.840.10045.2.1                            |
  |       | Parameters:  Absent  namedCurve = brainpoolP512r1                 |
  |       |              (1.3.36.3.3.2.8.1.1.13)                      |
  |       | DER:         30 0B 13 06 07 2A 86 48 CE 3D 02 01 06 09 04 00 7F 00 0F 2B 24 |
  |       |              03 03 02 08 01 01 0D 00                         |
  |       | Comments:    Point compressed subjectPublicKey            |
  +-------+-----------------------------------------------------------+
  |    18    27 | Name:        XMSS^MT        EC Public Key (Weierstrass) with              |
  |       |              FRP256v1                                     |
  |       | Identifiers: ecPublicKey, id-ecPublicKey                  |
  |       | OID:         0.4.0.127.0.15.1.1.14.0         1.2.840.10045.2.1                            |
  |       | Parameters:  Absent  namedCurve = FRP256v1                        |
  |       |              (1.2.250.1.223.101.256.1)                    |
  |       | DER:         30 0B 13 06 09 04 00 7F 00 0F 07 2A 86 48 CE 3D 02 01 06 0A 2A 81 |
  |       |              7A 01 0E 81 5F 65 82 00 01                      |
  |       | Comments:    Point compressed subjectPublicKey            |
  +-------+-----------------------------------------------------------+

                   Figure 11: 15: C509 Certificate Public Key Algorithms

8.9.

11.11.  COSE Header Parameters Registry

   EDITORS NOTE: The text should be moved a section and not be in the
   IANA Section.

   This document registers the following entries in the "COSE Header
   Parameters" registry under the "CBOR Object Signing and Encryption
   (COSE)" heading.  The formatting and processing for c5b, c5c, and
   c5t, and c5u are similar to x5bag, x5chain, x5t, x5u defined in
   [I-D.ietf-cose-x509] except that the certificates are C509 instead of
   DER encoded X.509 and uses a COSE_C509 structure instead of
   COSE_X509. c5u provides an alternative way to identify an untrusted
   certificate bag/chain by reference with a URI.  The content is a
   COSE_C509 item served with the application/cbor content format.  The
   COSE_C509 structure used in c5b, c5c, and c5u is defined as:

   COSE_C509 = C509Certificate / [ 2* C509Certificate ]

   As the contents of c5bag, c5chain, c5t, and c5u are untrusted input,
   the header parameters can be in either the protected or unprotected
   header bucket.  The trust mechanism MUST process any certificates in
   the c5b, c5c, and c5u parameters as untrusted input.  The presence of
   a self-signed certificate in the parameter MUST NOT cause the update
   of the set of trust anchors without some out-of-band confirmation.

   Note that certificates can also be identified with a 'kid' header
   parameter by storing 'kid' and the associated bag or chain in a
   dictionary.

   +-----------+-------+----------------+------------------------------+
   | Name      | Label | Value Type     | Description                  |
   +===========+=======+================+==============================+
   | c5b       |  TBD1 | COSE_C509      | An unordered bag of C509     |
   |           |       |                | certificates                 |
   +-----------+-------+----------------+------------------------------+
   | c5c       |  TBD2 | COSE_C509      | An ordered chain of C509     |
   |           |       |                | certificates                 |
   +-----------+-------+----------------+------------------------------+
   | c5t       |  TBD3 | COSE_CertHash  | Hash of a C509Certificate    |
   +-----------+-------+----------------+------------------------------+
   | c5u       |  TBD4 | uri            | URI pointing to a COSE_C509  |
   |           |       |                | containing a ordered chain   |
   |           |       |                | of certificates              |
   +-----------+-------+----------------+------------------------------+

8.10.

11.12.  TLS Certificate Types Registry

   This document registers the following entry in the "TLS Certificate
   Types" registry under the "Transport Layer Security (TLS) Extensions"
   heading.  The new certificate type can be used with additional TLS
   certificate compression [RFC8879].  C509 is defined in the same way
   as as X509, but uses a different value and instead of DER-encoded
   X.509 certificate, opaque cert_data<1..2^24-1> contains a the CBOR
   sequence ~C509Certificate (an unwrapped C509Certificate).

   EDITOR'S NOTE: The TLS registrations should be discussed and approved
   by the TLS WG at a later stage.  When COSE WG has adopted work on
   C509 certificates, it could perhaps be presented in the TLS WG.  The
   TLS WG might e.g. want a separate draft in the TLS WG.

   +-------+------------------+-------------+--------------------------+
   | Value | Name             | Recommended | Comment                  |
   +=======+==================+=============+==========================+
   |  TBD5 | C509 Certificate |           Y |                          |
   +-------+------------------+-------------+--------------------------+

8.11.

11.13.  CBOR Tags Registry

   This document registers the following entries in the "CBOR Tags"
   registry under the "Concise Binary Object Representation (CBOR) Tags"
   heading.

   +------+------------------------------------------------------------+
   |  Tag | X.509 Public Key Algorithms                                |
   +======+============================================================+
   | TDB6 | Data Item: COSE_C509                                       |
   |      | Semantics: An ordered chain of C509 certificates           |
   |      | Reference: This document                                   |
   +------+------------------------------------------------------------+

9.

12.  References

9.1.

12.1.  Normative References

   [I-D.ietf-cbor-tags-oid]
              Bormann, C., "Concise Binary Object Representation (CBOR)
              Tags for Object Identifiers", draft-ietf-cbor-tags-oid-06
              (work in progress), March 2021.

   [I-D.ietf-cose-x509]
              Schaad, J., "CBOR Object Signing and Encryption (COSE):
              Header parameters for carrying and referencing X.509
              certificates", draft-ietf-cose-x509-08 (work in progress),
              December 2020.

   [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>.

   [RFC2986]  Nystrom, M. and B. Kaliski, "PKCS #10: Certification
              Request Syntax Specification Version 1.7", RFC 2986,
              DOI 10.17487/RFC2986, November 2000,
              <https://www.rfc-editor.org/info/rfc2986>.

   [RFC4108]  Housley, R., "Using Cryptographic Message Syntax (CMS) to
              Protect Firmware Packages", RFC 4108,
              DOI 10.17487/RFC4108, August 2005,
              <https://www.rfc-editor.org/info/rfc4108>.

   [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>.

   [RFC8152]  Schaad, J., "CBOR Object Signing and Encryption (COSE)",
              RFC 8152, DOI 10.17487/RFC8152, July 2017,
              <https://www.rfc-editor.org/info/rfc8152>.

   [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>.

   [RFC8610]  Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
              Definition Language (CDDL): A Notational Convention to
              Express Concise Binary Object Representation (CBOR) and
              JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
              June 2019, <https://www.rfc-editor.org/info/rfc8610>.

   [RFC8742]  Bormann, C., "Concise Binary Object Representation (CBOR)
              Sequences", RFC 8742, DOI 10.17487/RFC8742, February 2020,
              <https://www.rfc-editor.org/info/rfc8742>.

   [RFC8949]  Bormann, C. and P. Hoffman, "Concise Binary Object
              Representation (CBOR)", STD 94, RFC 8949,
              DOI 10.17487/RFC8949, December 2020,
              <https://www.rfc-editor.org/info/rfc8949>.

   [SECG]     "Elliptic Curve Cryptography, Standards for Efficient
              Cryptography Group, ver. 2", 2009,
              <https://secg.org/sec1-v2.pdf>.

9.2.

12.2.  Informative References

   [CAB-Baseline]

   [CAB-Code]
              CA/Browser Forum, ., "CA/Browser Forum, "Baseline
              Requirements for the Issuance and Management of Publicly-
              Trusted Code Signing Certificates Version 1.7.3", October 2020, 2.3"", May 2021,
              <https://cabforum.org/baseline-requirements-code-
              signing/>.

   [CAB-TLS]  CA/Browser Forum, ., "CA/Browser Forum, "Baseline
              Requirements for the Issuance and Management of Publicly-
              Trusted Certificates Version 1.7.6"", June 2021,
              <https://cabforum.org/baseline-requirements-documents/>.

   [CborMe]   Bormann, C., "CBOR Playground", May 2018,
              <http://cbor.me/>.

   [GSMA-eUICC]
              GSMA, ., "GSMA eUICC PKI Certificate Policy Version 2.1",
              February 2021, <https://www.gsma.com/esim/wp-
              content/uploads/2021/02/SGP.14-v2.1.pdf>.

   [I-D.ietf-emu-eap-tls13]
              Mattsson, J. and M. Sethi, "Using EAP-TLS with TLS 1.3",
              draft-ietf-emu-eap-tls13-15 1.3
              (EAP-TLS 1.3)", draft-ietf-emu-eap-tls13-18 (work in
              progress), May July 2021.

   [I-D.ietf-emu-eaptlscert]
              Sethi, M., Mattsson, J., and S. Turner, "Handling Large
              Certificates and Long Certificate Chains in TLS-based EAP
              Methods", draft-ietf-emu-eaptlscert-08 (work in progress),
              November 2020.

   [I-D.ietf-lake-edhoc]
              Selander, G., Mattsson, J. P., and F. Palombini,
              "Ephemeral Diffie-Hellman Over COSE (EDHOC)", draft-ietf-
              lake-edhoc-06 (work in progress), April 2021.

   [I-D.ietf-quic-transport]
              Iyengar, J. and M. Thomson, "QUIC: A UDP-Based Multiplexed
              and Secure Transport", draft-ietf-quic-transport-34 (work
              in progress), January 2021.

   [I-D.ietf-tls-ctls]
              Rescorla, E., Barnes, R., and H. Tschofenig, "Compact TLS
              1.3", draft-ietf-tls-ctls-01 (work in progress), November
              2020.

   [I-D.ietf-tls-dtls13]
              Rescorla, E., Tschofenig, H., and N. Modadugu, "The
              Datagram Transport Layer Security (DTLS) Protocol Version
              1.3", draft-ietf-tls-dtls13-43 (work in progress), April
              2021.

   [I-D.ietf-uta-tls13-iot-profile]
              Tschofenig, H. and T. Fossati, "TLS/DTLS 1.3 Profiles for
              the Internet of Things", draft-ietf-uta-tls13-iot-
              profile-01 (work in progress), February 2021.

   [IEEE-802.1AR]
              Institute of Electrical and Electronics Engineers, .,
              "IEEE Standard for Local and metropolitan area networks-
              Secure Device Identity", IEEE Standard 802.1AR-2018 ,
              August 2018,
              <https://standards.ieee.org/standard/802_1AR-2018.html>.

   [RFC6487]  Huston, G., Michaelson, G., and R. Loomans, "A Profile for
              X.509 PKIX Resource Certificates", RFC 6487,
              DOI 10.17487/RFC6487, February 2012,
              <https://www.rfc-editor.org/info/rfc6487>.

   [RFC7228]  Bormann, C., Ersue, M., and A. Keranen, "Terminology for
              Constrained-Node Networks", RFC 7228,
              DOI 10.17487/RFC7228, May 2014,
              <https://www.rfc-editor.org/info/rfc7228>.

   [RFC7925]  Tschofenig, H., Ed. and T. Fossati, "Transport Layer
              Security (TLS) / Datagram Transport Layer Security (DTLS)
              Profiles for the Internet of Things", RFC 7925,
              DOI 10.17487/RFC7925, July 2016,
              <https://www.rfc-editor.org/info/rfc7925>.

   [RFC7932]  Alakuijala, J. and Z. Szabadka, "Brotli Compressed Data
              Format", RFC 7932, DOI 10.17487/RFC7932, July 2016,
              <https://www.rfc-editor.org/info/rfc7932>.

   [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>.

   [RFC8603]  Jenkins, M. and L. Zieglar, "Commercial National Security
              Algorithm (CNSA) Suite Certificate and Certificate
              Revocation List (CRL) Profile", RFC 8603,
              DOI 10.17487/RFC8603, May 2019,
              <https://www.rfc-editor.org/info/rfc8603>.

   [RFC8879]  Ghedini, A. and V. Vasiliev, "TLS Certificate
              Compression", RFC 8879, DOI 10.17487/RFC8879, December
              2020, <https://www.rfc-editor.org/info/rfc8879>.

   [RFC9000]  Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
              Multiplexed and Secure Transport", RFC 9000,
              DOI 10.17487/RFC9000, May 2021,
              <https://www.rfc-editor.org/info/rfc9000>.

   [X.509-IoT]
              Forsby, F., Furuhed, M., Papadimitratos, P., and S. Raza,
              "Lightweight X.509 Digital Certificates for the Internet
              of Things.", Springer, Cham. Lecture Notes of the
              Institute for Computer Sciences, Social Informatics and
              Telecommunications Engineering, vol 242., July 2018,
              <https://doi.org/10.1007/978-3-319-93797-7_14>.

Appendix A.  Example C509 Certificates

A.1.  Example RFC 7925 profiled X.509 Certificate

   Example of [RFC7925] profiled X.509 certificate parsed with OpenSSL.

   Certificate:
       Data:
           Version: 3 (0x2)
           Serial Number: 128269 (0x1f50d)
           Signature Algorithm: ecdsa-with-SHA256
           Issuer: CN=RFC test CA
           Validity
               Not Before: Jan  1 00:00:00 2020 GMT
               Not After : Feb  2 00:00:00 2021 GMT
           Subject: CN=01-23-45-FF-FE-67-89-AB
           Subject Public Key Info:
               Public Key Algorithm: id-ecPublicKey
                   Public-Key: (256 bit)
                   pub:
                       04:b1:21:6a:b9:6e:5b:3b:33:40:f5:bd:f0:2e:69:
                       3f:16:21:3a:04:52:5e:d4:44:50:b1:01:9c:2d:fd:
                       38:38:ab:ac:4e:14:d8:6c:09:83:ed:5e:9e:ef:24:
                       48:c6:86:1c:c4:06:54:71:77:e6:02:60:30:d0:51:
                       f7:79:2a:c2:06
                   ASN1 OID: prime256v1
                   NIST CURVE: P-256
           X509v3 extensions:
               X509v3 Key Usage:
                   Digital Signature
       Signature Algorithm: ecdsa-with-SHA256
            30:44:02:20:44:5d:79:8c:90:e7:f5:00:dc:74:7a:65:4c:ec:
            6c:fa:6f:03:72:76:e1:4e:52:ed:07:fc:16:29:4c:84:66:0d:
            02:20:5a:33:98:5d:fb:d4:bf:dd:6d:4a:cf:38:04:c3:d4:6e:
            bf:3b:7f:a6:26:40:67:4f:c0:35:4f:a0:56:db:ae:a6

   The DER encoding of the above certificate is 314 bytes.

   30 82 01 36 30 81 DE A0 03 02 01 02 02 03 01 F5 0D 30 0A 06 08 2A 86
   48 CE 3D 04 03 02 30 16 31 14 30 12 06 03 55 04 03 0C 0B 52 46 43 20
   74 65 73 74 20 43 41 30 1E 17 0D 32 30 30 31 30 31 30 30 30 30 30 30
   5A 17 0D 32 31 30 32 30 32 30 30 30 30 30 30 5A 30 22 31 20 30 1E 06
   03 55 04 03 0C 17 30 31 2D 32 33 2D 34 35 2D 46 46 2D 46 45 2D 36 37
   2D 38 39 2D 41 42 30 59 30 13 06 07 2A 86 48 CE 3D 02 01 06 08 2A 86
   48 CE 3D 03 01 07 03 42 00 04 B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E
   69 3F 16 21 3A 04 52 5E D4 44 50 B1 01 9C 2D FD 38 38 AB AC 4E 14 D8
   6C 09 83 ED 5E 9E EF 24 48 C6 86 1C C4 06 54 71 77 E6 02 60 30 D0 51
   F7 79 2A C2 06 A3 0F 30 0D 30 0B 06 03 55 1D 0F 04 04 03 02 07 80 30
   0A 06 08 2A 86 48 CE 3D 04 03 02 03 47 00 30 44 02 20 44 5D 79 8C 90
   E7 F5 00 DC 74 7A 65 4C EC 6C FA 6F 03 72 76 E1 4E 52 ED 07 FC 16 29
   4C 84 66 0D 02 20 5A 33 98 5D FB D4 BF DD 6D 4A CF 38 04 C3 D4 6E BF
   3B 7F A6 26 40 67 4F C0 35 4F A0 56 DB AE A6

A.1.1.  Example C509 Certificate Encoding

   The CBOR encoding (~C509Certificate) of the same X.509 certificate is
   shown below in CBOR diagnostic format.

   /This defines a CBOR Sequence (RFC 8742):/

     1,
     h'01f50d',
     "RFC test CA",
     1577836800,
     1612224000,
     h'0123456789AB',
     1,
     h'02B1216AB96E5B3B3340F5BDF02E693F16213A04525ED44450
       B1019C2DFD3838AB',
     1,
     0,
     h'445D798C90E7F500DC747A654CEC6CFA6F037276E14E52ED07
       FC16294C84660D5A33985DFBD4BFDD6D4ACF3804C3D46EBF3B
       7FA62640674FC0354FA056DBAEA6
       7FA62640674FC0354FA056DBAEA6'

   The size of the CBOR encoding (CBOR sequence) is 138 bytes.

   01
   43 01 F5 0D
   6B 52 46 43 20 74 65 73 74 20 43 41
   1A 5E 0B E1 00
   1A 60 18 96 00
   46 01 23 45 67 89 AB
   01
   58 21 02 B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E 69 3F 16 21 3A 04 52
   5E D4 44 50 B1 01 9C 2D FD 38 38 AB
   01
   00
   58 40 44 5D 79 8C 90 E7 F5 00 DC 74 7A 65 4C EC 6C FA 6F 03 72 76 E1
   4E 52 ED 07 FC 16 29 4C 84 66 0D 5A 33 98 5D FB D4 BF DD 6D 4A CF 38
   04 C3 D4 6E BF 3B 7F A6 26 40 67 4F C0 35 4F A0 56 DB AE A6

A.1.2.  Example: Natively Signed C509 Certificate

   The corresponding natively signed C509 certificate in CBOR diagnostic
   format is identical, except for c509CertificateType and
   signatureValue.

   /This defines a CBOR Sequence (RFC 8742):/

     0,
     h'01f50d',
     "RFC test CA",
     1577836800,
     1612224000,
     h'0123456789AB',
     1,
     h'02B1216AB96E5B3B3340F5BDF02E693F16213A04525ED44450
       B1019C2DFD3838AB',
     1,
     6,
     0,
     h'B27A0B781455F71B68290F6C2EC9A897F18FDE9B6C59575953
       BC67268AB0E4DDE99D273E04E4715383AB2257C6AAA35284E5
       ED18BDB91247E9F2C433136480B9'

   The size of the CBOR encoding (CBOR sequence) is 138 bytes.

   00
   43 01 F5 0D
   6B 52 46 43 20 74 65 73 74 20 43 41
   1A 5E 0B E1 00
   1A 60 18 96 00
   46 01 23 45 67 89 AB
   01
   58 21 02 B1 21 6A B9 6E 5B 3B 33 40 F5 BD F0 2E 69 3F 16 21 3A 04 52
   5E D4 44 50 B1 01 9C 2D FD 38 38 AB
   01
   00
   58 40 B2 7A 0B 78 14 55 F7 1B 68 29 0F 6C 2E C9 A8 97 F1 8F DE 9B 6C
   59 57 59 53 BC 67 26 8A B0 E4 DD E9 9D 27 3E 04 E4 71 53 83 AB 22 57
   C6 AA A3 52 84 E5 ED 18 BD B9 12 47 E9 F2 C4 33 13 64 80 B9

A.1.3.  Example: Additonal Keys for the Example Certificates

   Below are the issuer key pair and the subject private key belonging
   to the above example certificates.  The private keys are encoded as
   in COSE [RFC8152].  These issuer key pair can be used to sign or
   verify the example certificates and the subject private key allows
   the example certificates to be used in test vectors for other
   protocols like EDHOC.

   issuerPublicKeyAlgorithm :
   1 (EC Public Key (Weierstrass) with secp256r1)

   issuerPublicKey :
   h'02AE4CDB01F614DEFC7121285FDC7F5C6D1D42C95647F061BA0080DF678867845E'

   issuerPrivateKey :
   h'DC66B3415456D649429B53223DF7532B942D6B0E0842C30BCA4C0ACF91547BB2'

   subjectPrivateKey :
   h'D718111F3F9BD91B92FF6877F386BDBFCEA7154268FD7F2FB56EE17D99EA16D4'

A.2.  Example IEEE 802.1AR profiled X.509 Certificate

   EDITOR'S NOTE: To do

A.3.  Example CAB Baseline ECDSA HTTPS X.509 Certificate

   The www.ietf.org HTTPS server replies with a certificate message with
   2 certificates.  The DER encoding of the first certificate is 1209
   bytes.

   30 82 04 b5 30 82 04 5a a0 03 02 01 02 02 10 04 7f a1 e3 19 28 ee 40
   3b a0 b8 3a 39 56 73 fc 30 0a 06 08 2a 86 48 ce 3d 04 03 02 30 4a 31
   0b 30 09 06 03 55 04 06 13 02 55 53 31 19 30 17 06 03 55 04 0a 13 10
   43 6c 6f 75 64 66 6c 61 72 65 2c 20 49 6e 63 2e 31 20 30 1e 06 03 55
   04 03 13 17 43 6c 6f 75 64 66 6c 61 72 65 20 49 6e 63 20 45 43 43 20
   43 41 2d 33 30 1e 17 0d 32 30 30 37 32 39 30 30 30 30 30 30 5a 17 0d
   32 31 30 37 32 39 31 32 30 30 30 30 5a 30 6d 31 0b 30 09 06 03 55 04
   06 13 02 55 53 31 0b 30 09 06 03 55 04 08 13 02 43 41 31 16 30 14 06
   03 55 04 07 13 0d 53 61 6e 20 46 72 61 6e 63 69 73 63 6f 31 19 30 17
   06 03 55 04 0a 13 10 43 6c 6f 75 64 66 6c 61 72 65 2c 20 49 6e 63 2e
   31 1e 30 1c 06 03 55 04 03 13 15 73 6e 69 2e 63 6c 6f 75 64 66 6c 61
   72 65 73 73 6c 2e 63 6f 6d 30 59 30 13 06 07 2a 86 48 ce 3d 02 01 06
   08 2a 86 48 ce 3d 03 01 07 03 42 00 04 96 3e cd d8 4d cd 1b 93 a1 cf
   43 2d 1a 72 17 d6 c6 3b de 33 55 a0 2f 8c fb 5a d8 99 4c d4 4e 20 5f
   15 f6 e3 d2 3b 38 2b a6 49 9b b1 7f 34 1f a5 92 fa 21 86 1f 16 d3 12
   06 63 24 05 fd 70 42 bd a3 82 02 fd 30 82 02 f9 30 1f 06 03 55 1d 23
   04 18 30 16 80 14 a5 ce 37 ea eb b0 75 0e 94 67 88 b4 45 fa d9 24 10
   87 96 1f 30 1d 06 03 55 1d 0e 04 16 04 14 cc 0b 50 e7 d8 37 db f2 43
   f3 85 3d 48 60 f5 3b 39 be 9b 2a 30 2e 06 03 55 1d 11 04 27 30 25 82
   15 73 6e 69 2e 63 6c 6f 75 64 66 6c 61 72 65 73 73 6c 2e 63 6f 6d 82
   0c 77 77 77 2e 69 65 74 66 2e 6f 72 67 30 0e 06 03 55 1d 0f 01 01 ff
   04 04 03 02 07 80 30 1d 06 03 55 1d 25 04 16 30 14 06 08 2b 06 01 05
   05 07 03 01 06 08 2b 06 01 05 05 07 03 02 30 7b 06 03 55 1d 1f 04 74
   30 72 30 37 a0 35 a0 33 86 31 68 74 74 70 3a 2f 2f 63 72 6c 33 2e 64
   69 67 69 63 65 72 74 2e 63 6f 6d 2f 43 6c 6f 75 64 66 6c 61 72 65 49
   6e 63 45 43 43 43 41 2d 33 2e 63 72 6c 30 37 a0 35 a0 33 86 31 68 74
   74 70 3a 2f 2f 63 72 6c 34 2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 2f
   43 6c 6f 75 64 66 6c 61 72 65 49 6e 63 45 43 43 43 41 2d 33 2e 63 72
   6c 30 4c 06 03 55 1d 20 04 45 30 43 30 37 06 09 60 86 48 01 86 fd 6c
   01 01 30 2a 30 28 06 08 2b 06 01 05 05 07 02 01 16 1c 68 74 74 70 73
   3a 2f 2f 77 77 77 2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 2f 43 50 53
   30 08 06 06 67 81 0c 01 02 02 30 76 06 08 2b 06 01 05 05 07 01 01 04
   6a 30 68 30 24 06 08 2b 06 01 05 05 07 30 01 86 18 68 74 74 70 3a 2f
   2f 6f 63 73 70 2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 30 40 06 08 2b
   06 01 05 05 07 30 02 86 34 68 74 74 70 3a 2f 2f 63 61 63 65 72 74 73
   2e 64 69 67 69 63 65 72 74 2e 63 6f 6d 2f 43 6c 6f 75 64 66 6c 61 72
   65 49 6e 63 45 43 43 43 41 2d 33 2e 63 72 74 30 0c 06 03 55 1d 13 01
   01 ff 04 02 30 00 30 82 01 05 06 0a 2b 06 01 04 01 d6 79 02 04 02 04
   81 f6 04 81 f3 00 f1 00 76 00 f6 5c 94 2f d1 77 30 22 14 54 18 08 30
   94 56 8e e3 4d 13 19 33 bf df 0c 2f 20 0b cc 4e f1 64 e3 00 00 01 73
   9c 83 5f 8e 00 00 04 03 00 47 30 45 02 21 00 f8 d1 b4 a9 3d 2f 0d 4c
   41 76 df b4 88 bc c7 3b 86 44 3d 7d e0 0e 6a c8 17 4d 89 48 a8 84 36
   68 02 20 29 ff 5a 34 06 8a 24 0c 69 50 27 88 e8 ee 25 ab 7e d2 cb cf
   68 6e ce 7b 5f 96 b4 31 a9 07 02 fa 00 77 00 5c dc 43 92 fe e6 ab 45
   44 b1 5e 9a d4 56 e6 10 37 fb d5 fa 47 dc a1 73 94 b2 5e e6 f6 c7 0e
   ca 00 00 01 73 9c 83 5f be 00 00 04 03 00 48 30 46 02 21 00 e8 91 c1
   97 bf b0 e3 d3 0c b6 ce e6 0d 94 c3 c7 5f d1 17 53 36 93 11 08 d8 98
   12 d4 d2 9d 81 d0 02 21 00 a1 59 d1 6c 46 47 d1 48 37 57 fc d6 ce 4e
   75 ec 7b 5e f6 57 ef e0 28 f8 e5 cc 47 92 68 2d ac 43 30 0a 06 08 2a
   86 48 ce 3d 04 03 02 03 49 00 30 46 02 21 00 bd 63 cf 4f 7e 5c fe 6c
   29 38 5e a7 1c fb fc 1e 3f 7b 1c d0 72 51 a2 21 f7 77 69 c0 f4 71 df
   ea 02 21 00 b5 c0 6c c4 58 54 fa 30 b2 82 88 b1 d3 bb 9a 66 61 ed 50
   31 72 5b 1a 82 02 e0 da 5b 59 f9 54 02

A.3.1.  Example C509 Certificate Encoding

   The CBOR encoding (~C509Certificate) of the first X.509 certificate
   is shown below in CBOR diagnostic format.

/This defines a CBOR Sequence (RFC 8742):/

1,
h'047FA1E31928EE403BA0B83A395673FC',
[
 -4, "US",
 -8, "Cloudflare, Inc.",
 -1, "Cloudflare Inc ECC CA-3"
],
1595980800,
1627560000,
[
 -4, "US",
 -6, "CA",
 -5, "San Francisco",
 -8, "Cloudflare, Inc.",
 -1, "sni.cloudflaressl.com"
],
1,
h'03963ECDD84DCD1B93A1CF432D1A7217D6C63BDE3355A02F8CFB5AD8994CD44E20',
[
 7, h'A5CE37EAEBB0750E946788B445FAD9241087961F',
 1, h'CC0B50E7D837DBF243F3853D4860F53B39BE9B2A',
 3, [2, "sni.cloudflaressl.com", 2, "www.ietf.org"],
-2, 1,
 8, [1, 2],
 5, ["http://crl3.digicert.com/CloudflareIncECCCA-3.crl",
     "http://crl4.digicert.com/CloudflareIncECCCA-3.crl"],
 6, [h'6086480186FD6C0101', "https://www.digicert.com/CPS", [1, "https://www.digicert.com/CPS"],  2],
 9, [1, "http://ocsp.digicert.com",
     2, "http://cacerts.digicert.com/CloudflareIncECCCA-3.crt"],
-4, -2,
10, [
    h'F65C942FD1773022145418083094568EE34D131933BFDF0C2F200BCC4EF164E3',
    77922190,
    0,
    h'F8D1B4A93D2F0D4C4176DFB488BCC73B86443D7DE00E6AC8174D8948A8843668
    29FF5A34068A240C69502788E8EE25AB7ED2CBCF686ECE7B5F96B431A90702FA',
    h'5CDC4392FEE6AB4544B15E9AD456E61037FBD5FA47DCA17394B25EE6F6C70ECA',
    77922238,
    0,
    h'E891C197BFB0E3D30CB6CEE60D94C3C75FD1175336931108D89812D4D29D81D0
    A159D16C4647D1483757FCD6CE4E75EC7B5EF657EFE028F8E5CC4792682DAC43'
    ]
],
0,
h'BD63CF4F7E5CFE6C29385EA71CFBFC1E3F7B1CD07251A221F77769C0F471DFEA
  B5C06CC45854FA30B28288B1D3BB9A6661ED5031725B1A8202E0DA5B59F95402'
   The size of the CBOR encoding (CBOR sequence) is 781 783 bytes.

A.4.  Example CAB Baseline RSA HTTPS X.509 Certificate

   The tools.ietf.org HTTPS server replies with a certificate message
   with 4 certificates.  The DER encoding of the first certificate is
   1647 bytes.

   30 82 06 6b 30 82 05 53 a0 03 02 01 02 02 09 00 a6 a5 5c 87 0e 39 b4
   0e 30 0d 06 09 2a 86 48 86 f7 0d 01 01 0b 05 00 30 81 c6 31 0b 30 09
   06 03 55 04 06 13 02 55 53 31 10 30 0e 06 03 55 04 08 13 07 41 72 69
   7a 6f 6e 61 31 13 30 11 06 03 55 04 07 13 0a 53 63 6f 74 74 73 64 61
   6c 65 31 25 30 23 06 03 55 04 0a 13 1c 53 74 61 72 66 69 65 6c 64 20
   54 65 63 68 6e 6f 6c 6f 67 69 65 73 2c 20 49 6e 63 2e 31 33 30 31 06
   03 55 04 0b 13 2a 68 74 74 70 3a 2f 2f 63 65 72 74 73 2e 73 74 61 72
   66 69 65 6c 64 74 65 63 68 2e 63 6f 6d 2f 72 65 70 6f 73 69 74 6f 72
   79 2f 31 34 30 32 06 03 55 04 03 13 2b 53 74 61 72 66 69 65 6c 64 20
   53 65 63 75 72 65 20 43 65 72 74 69 66 69 63 61 74 65 20 41 75 74 68
   6f 72 69 74 79 20 2d 20 47 32 30 1e 17 0d 32 30 31 30 30 31 31 39 33
   38 33 36 5a 17 0d 32 31 31 31 30 32 31 39 33 38 33 36 5a 30 3e 31 21
   30 1f 06 03 55 04 0b 13 18 44 6f 6d 61 69 6e 20 43 6f 6e 74 72 6f 6c
   20 56 61 6c 69 64 61 74 65 64 31 19 30 17 06 03 55 04 03 0c 10 2a 2e
   74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67 30 82 01 22 30 0d 06 09 2a
   86 48 86 f7 0d 01 01 01 05 00 03 82 01 0f 00 30 82 01 0a 02 82 01 01
   00 b1 e1 37 e8 eb 82 d6 89 fa db f5 c2 4b 77 f0 2c 4a de 72 6e 3e 13
   60 d1 a8 66 1e c4 ad 3d 32 60 e5 f0 99 b5 f4 7a 7a 48 55 21 ee 0e 39
   12 f9 ce 0d ca f5 69 61 c7 04 ed 6e 0f 1d 3b 1e 50 88 79 3a 0e 31 41
   16 f1 b1 02 64 68 a5 cd f5 4a 0a ca 99 96 35 08 c3 7e 27 5d d0 a9 cf
   f3 e7 28 af 37 d8 b6 7b dd f3 7e ae 6e 97 7f f7 ca 69 4e cc d0 06 df
   5d 27 9b 3b 12 e7 e6 fe 08 6b 52 7b 82 11 7c 72 b3 46 eb c1 e8 78 b8
   0f cb e1 eb bd 06 44 58 dc 83 50 b2 a0 62 5b dc 81 b8 36 e3 9e 7c 79
   b2 a9 53 8a e0 0b c9 4a 2a 13 39 31 13 bd 2c cf a8 70 cf 8c 8d 3d 01
   a3 88 ae 12 00 36 1d 1e 24 2b dd 79 d8 53 01 26 ed 28 4f c9 86 94 83
   4e c8 e1 14 2e 85 b3 af d4 6e dd 69 46 af 41 25 0e 7a ad 8b f2 92 ca
   79 d9 7b 32 4f f7 77 e8 f9 b4 4f 23 5c d4 5c 03 ae d8 ab 3a ca 13 5f
   5d 5d 5d a1 02 03 01 00 01 a3 82 02 e1 30 82 02 dd 30 0c 06 03 55 1d
   13 01 01 ff 04 02 30 00 30 1d 06 03 55 1d 25 04 16 30 14 06 08 2b 06
   01 05 05 07 03 01 06 08 2b 06 01 05 05 07 03 02 30 0e 06 03 55 1d 0f
   01 01 ff 04 04 03 02 05 a0 30 3d 06 03 55 1d 1f 04 36 30 34 30 32 a0
   30 a0 2e 86 2c 68 74 74 70 3a 2f 2f 63 72 6c 2e 73 74 61 72 66 69 65
   6c 64 74 65 63 68 2e 63 6f 6d 2f 73 66 69 67 32 73 31 2d 32 34 32 2e
   63 72 6c 30 63 06 03 55 1d 20 04 5c 30 5a 30 4e 06 0b 60 86 48 01 86
   fd 6e 01 07 17 01 30 3f 30 3d 06 08 2b 06 01 05 05 07 02 01 16 31 68
   74 74 70 3a 2f 2f 63 65 72 74 69 66 69 63 61 74 65 73 2e 73 74 61 72
   66 69 65 6c 64 74 65 63 68 2e 63 6f 6d 2f 72 65 70 6f 73 69 74 6f 72
   79 2f 30 08 06 06 67 81 0c 01 02 01 30 81 82 06 08 2b 06 01 05 05 07
   01 01 04 76 30 74 30 2a 06 08 2b 06 01 05 05 07 30 01 86 1e 68 74 74
   70 3a 2f 2f 6f 63 73 70 2e 73 74 61 72 66 69 65 6c 64 74 65 63 68 2e
   63 6f 6d 2f 30 46 06 08 2b 06 01 05 05 07 30 02 86 3a 68 74 74 70 3a
   2f 2f 63 65 72 74 69 66 69 63 61 74 65 73 2e 73 74 61 72 66 69 65 6c
   64 74 65 63 68 2e 63 6f 6d 2f 72 65 70 6f 73 69 74 6f 72 79 2f 73 66
   69 67 32 2e 63 72 74 30 1f 06 03 55 1d 23 04 18 30 16 80 14 25 45 81
   68 50 26 38 3d 3b 2d 2c be cd 6a d9 b6 3d b3 66 63 30 2b 06 03 55 1d
   11 04 24 30 22 82 10 2a 2e 74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67
   82 0e 74 6f 6f 6c 73 2e 69 65 74 66 2e 6f 72 67 30 1d 06 03 55 1d 0e
   04 16 04 14 ad 8a b4 1c 07 51 d7 92 89 07 b0 b7 84 62 2f 36 55 7a 5f
   4d 30 82 01 06 06 0a 2b 06 01 04 01 d6 79 02 04 02 04 81 f7 04 81 f4
   00 f2 00 77 00 f6 5c 94 2f d1 77 30 22 14 54 18 08 30 94 56 8e e3 4d
   13 19 33 bf df 0c 2f 20 0b cc 4e f1 64 e3 00 00 01 74 e5 ac 71 13 00
   00 04 03 00 48 30 46 02 21 00 8c f5 48 52 ce 56 35 43 39 11 cf 10 cd
   b9 1f 52 b3 36 39 22 3a d1 38 a4 1d ec a6 fe de 1f e9 0f 02 21 00 bc
   a2 25 43 66 c1 9a 26 91 c4 7a 00 b5 b6 53 ab bd 44 c2 f8 ba ae f4 d2
   da f2 52 7c e6 45 49 95 00 77 00 5c dc 43 92 fe e6 ab 45 44 b1 5e 9a
   d4 56 e6 10 37 fb d5 fa 47 dc a1 73 94 b2 5e e6 f6 c7 0e ca 00 00 01
   74 e5 ac 72 3c 00 00 04 03 00 48 30 46 02 21 00 a5 e0 90 6e 63 e9 1d
   4f dd ef ff 03 52 b9 1e 50 89 60 07 56 4b 44 8a 38 28 f5 96 dc 6b 28
   72 6d 02 21 00 fc 91 ea ed 02 16 88 66 05 4e e1 8a 2e 53 46 c4 cc 51
   fe b3 fa 10 a9 1d 2e db f9 91 25 f8 6c e6 30 0d 06 09 2a 86 48 86 f7
   0d 01 01 0b 05 00 03 82 01 01 00 14 04 3f a0 be d2 ee 3f a8 6e 3a 1f
   78 8e a0 4c 35 53 0f 11 06 1f ff 60 a1 6d 0b 83 e9 d9 2a db b3 3f 9d
   b3 d7 e0 59 4c 19 a8 e4 19 a5 0c a7 70 72 77 63 d5 fe 64 51 0a d2 7a
   d6 50 a5 8a 92 38 ec cb 2f 0f 5a c0 64 58 4d 5c 06 b9 73 63 68 27 8b
   89 34 dc 79 c7 1d 3a fd 34 5f 83 14 41 58 49 80 68 29 80 39 8a 86 72
   69 cc 79 37 ce e3 97 f7 dc f3 95 88 ed 81 03 29 00 d2 a2 c7 ba ab d6
   3a 8e ca 09 0b d9 fb 39 26 4b ff 03 d8 8e 2d 3f 6b 21 ca 8a 7d d8 5f
   fb 94 ba 83 de 9c fc 15 8d 61 fa 67 2d b0 c7 db 3d 25 0a 41 4a 85 d3
   7f 49 46 37 3c f4 b1 75 d0 52 f3 dd c7 66 f1 4b fd aa 00 ed bf e4 7e
   ed 01 ec 7b e4 f6 46 fc 31 fd 72 fe 03 d2 f2 65 af 4d 7e e2 81 9b 7a
   fd 30 3c f5 52 f4 05 34 a0 8a 3e 19 41 58 c8 a8 e0 51 71 84 09 15 ae
   ec a5 77 75 fa 18 f7 d5 77 d5 31 cc c7 2d

A.4.1.  Example C509 Certificate Encoding

   The CBOR encoding (~C509Certificate) of the first X.509 certificate
   is shown below in CBOR diagnostic format.

/This defines a CBOR Sequence (RFC 8742):/

1,
h'A6A55C870E39B40E',
[
 -4, "US",
 -6, "Arizona",
 -5, "Scottsdale",
 -8, "Starfield Technologies, Inc.",
 -9, "http://certs.starfieldtech.com/repository/",
 -1, "Starfield Secure Certificate Authority - G2"
],
1601581116,
1635881916,
[
  -9, "Domain Control Validated",
   1, "*.tools.ietf.org"
],
0,
h'B1E137E8EB82D689FADBF5C24B77F02C4ADE726E3E1360D1A8661EC4AD3D3260
  E5F099B5F47A7A485521EE0E3912F9CE0DCAF56961C704ED6E0F1D3B1E508879
  3A0E314116F1B1026468A5CDF54A0ACA99963508C37E275DD0A9CFF3E728AF37
  D8B67BDDF37EAE6E977FF7CA694ECCD006DF5D279B3B12E7E6FE086B527B8211
  7C72B346EBC1E878B80FCBE1EBBD064458DC8350B2A0625BDC81B836E39E7C79
  B2A9538AE00BC94A2A13393113BD2CCFA870CF8C8D3D01A388AE1200361D1E24
  2BDD79D8530126ED284FC98694834EC8E1142E85B3AFD46EDD6946AF41250E7A
  AD8BF292CA79D97B324FF777E8F9B44F235CD45C03AED8AB3ACA135F5D5D5DA1',
[
-4, -2,
 8, [ 1, 2 ],
 -2, 5,
 5, "http://crl.starfieldtech.com/sfig2s1-242.crl", ["http://crl.starfieldtech.com/sfig2s1-242.crl"],
 6, [ h'6086480186fd6e01071701',
       "http://certificates.starfieldtech.com/repository/",
      [1, "http://certificates.starfieldtech.com/repository/"], 1 ],
 9, [ 1, "http://ocsp.starfieldtech.com/",
      2, "http://certificates.starfieldtech.com/repository/sfig2.crt" ],
 7, h'254581685026383D3B2D2CBECD6AD9B63DB36663',
 3, [ 2, "*.tools.ietf.org", 2, "tools.ietf.org" ],
 1, h'AD8AB41C0751D7928907B0B784622F36557A5F4D',
10, [
    h'F65C942FD1773022145418083094568EE34D131933BFDF0C2F200BCC4EF164E3',
    1715,
    0,
    h'8CF54852CE5635433911CF10CDB91F52B33639223AD138A41DECA6FEDE1FE90F
      BCA2254366C19A2691C47A00B5B653ABBD44C2F8BAAEF4D2DAF2527CE6454995',
    h'5CDC4392FEE6AB4544B15E9AD456E61037FBD5FA47DCA17394B25EE6F6C70ECA',
    2012,
    0,
    h'A5E0906E63E91D4FDDEFFF0352B91E50896007564B448A3828F596DC6B28726D
      FC91EAED02168866054EE18A2E5346C4CC51FEB3FA10A91D2EDBF99125F86CE6'
    ]
],
23,
h'14043FA0BED2EE3FA86E3A1F788EA04C35530F11061FFF60A16D0B83E9D92ADB
  B33F9DB3D7E0594C19A8E419A50CA770727763D5FE64510AD27AD650A58A9238
  ECCB2F0F5AC064584D5C06B9736368278B8934DC79C71D3AFD345F8314415849
  80682980398A867269CC7937CEE397F7DCF39588ED81032900D2A2C7BAABD63A
  8ECA090BD9FB39264BFF03D88E2D3F6B21CA8A7DD85FFB94BA83DE9CFC158D61
  FA672DB0C7DB3D250A414A85D37F4946373CF4B175D052F3DDC766F14BFDAA00
  EDBFE47EED01EC7BE4F646FC31FD72FE03D2F265AF4D7EE2819B7AFD303CF552
  F40534A08A3E194158C8A8E05171840915AEECA57775FA18F7D577D531CCC72D'

   The size of the CBOR encoding (CBOR sequence) is 1242 1245 bytes.

Acknowledgments

   The authors want to thank Henk Birkholz, Carsten Bormann, Russ
   Housley, Olle Johansson, Benjamin Kaduk, Ilari Liusvaara, Laurence
   Lundblade, Francesca Palombinini, Thomas Peterson, Michael
   Richardson, Maik Reichert, Stefan Santesson, Jim Schaad, Fraser
   Tweedale, and Rene Struik for reviewing and commenting on
   intermediate versions of the draft. draft and helping with GitHub.

Authors' Addresses

   John Preuss Mattsson
   Ericsson AB

   Email: john.mattsson@ericsson.com

   Goeran Selander
   Ericsson AB

   Email: goran.selander@ericsson.com

   Shahid Raza
   RISE AB

   Email: shahid.raza@ri.se

   Joel Hoeglund
   RISE AB

   Email: joel.hoglund@ri.se

   Goeran Selander
   Ericsson AB

   Email: goran.selander@ericsson.com

   John Preuss Mattsson
   Ericsson AB

   Email: john.mattsson@ericsson.com

   Martin Furuhed
   Nexus Group

   Email: martin.furuhed@nexusgroup.com