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Versions: (draft-raza-ace-cbor-certificates) 00 01 02 03 04 05 06 07 08

Network Working Group                                            S. Raza
Internet-Draft                                               J. Hoeglund
Intended status: Standards Track                                 RISE AB
Expires: July 23, 2021                                       G. Selander
                                                             J. Mattsson
                                                             Ericsson AB
                                                              M. Furuhed
                                                             Nexus Group
                                                        January 19, 2021


        CBOR Encoding of X.509 Certificates (CBOR Certificates)
               draft-mattsson-cose-cbor-cert-compress-06

Abstract

   This document specifies a CBOR encoding of X.509 certificates.  The
   resulting certificates are called CBOR Certificates.  The CBOR
   encoding supports a large subset of RFC 5280 and significantly
   reduces the size of certificates compatible with e.g.  RFC 7925, IEEE
   802.1AR (DevID), CNSA, and CA/Browser Forum Baseline Requirements.
   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 encoding can also be used to
   encode "natively signed" CBOR certificates, which does not require
   re-encoding for the signature to be verified.  The document also
   specifies COSE headers as well as a TLS certificate type for CBOR
   certificates.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on July 23, 2021.






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Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Notational Conventions  . . . . . . . . . . . . . . . . . . .   4
   3.  CBOR Encoding . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.1.  Message Fields  . . . . . . . . . . . . . . . . . . . . .   5
     3.2.  Encoding of subjectPublicKey and issuerSingatureValue . .   8
     3.3.  Encoding of Extensions  . . . . . . . . . . . . . . . . .   9
   4.  Compliance Requirements for Constrained IoT . . . . . . . . .  11
   5.  Legacy Considerations . . . . . . . . . . . . . . . . . . . .  11
   6.  Expected Certificate Sizes  . . . . . . . . . . . . . . . . .  12
   7.  Natively Signed CBOR Certificates . . . . . . . . . . . . . .  12
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
     9.1.  CBOR Certificate Types Registry . . . . . . . . . . . . .  14
     9.2.  CBOR Certificate Attributes Registry  . . . . . . . . . .  14
     9.3.  CBOR Certificate Extensions Registry  . . . . . . . . . .  16
     9.4.  CBOR Extended Key Usages Registry . . . . . . . . . . . .  19
     9.5.  CBOR Certificate General Names Registry . . . . . . . . .  20
     9.6.  CBOR Certificate Signature Algorithms Registry  . . . . .  21
     9.7.  CBOR Certificate Public Key Algorithms Registry . . . . .  24
     9.8.  COSE Header Parameters Registry . . . . . . . . . . . . .  26
     9.9.  TLS Certificate Types Registry  . . . . . . . . . . . . .  27
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  27
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  27
     10.2.  Informative References . . . . . . . . . . . . . . . . .  28
   Appendix A.  Example CBOR Certificates  . . . . . . . . . . . . .  31
     A.1.  Example RFC 7925 profiled X.509 Certificate . . . . . . .  31
     A.2.  Example IEEE 802.1AR profiled X.509 Certificate . . . . .  34
     A.3.  Example CAB Baseline ECDSA HTTPS X.509 Certificate  . . .  34
     A.4.  Example CAB Baseline RSA HTTPS X.509 Certificate  . . . .  37
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  40
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  40



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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 QUIC [I-D.ietf-quic-transport] where the latency
   increases significantly unless the server only send less than three
   times as many bytes as received prior to validating the client
   address.  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] 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].

   CAB Baseline Requirements [CAB-Baseline], 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], 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



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   [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].  The encoding support all
   [RFC7925] and IEEE 802.1AR [IEEE-802.1AR] and CAB Baseline
   [CAB-Baseline] profiled X.509 certificates.  Two variants are defined
   using the same CBOR encoding and differing only in what is being
   signed:

   o  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.

   o  Natively signed CBOR certificates, which further optimizes the
      performance in constrained environments but is not backwards
      compatible with [RFC5280], see Section 7.

   This document specifies COSE headers for use of the CBOR certificates
   with COSE, see Section 9.8.  The document also specifies a TLS
   certificate type for use of the CBOR certificates with TLS and QUIC
   (with or without additional TLS certificate compression), see
   Section 9.9.

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].

3.  CBOR Encoding

   This section specifies the content and encoding for CBOR
   certificates, with the overall objective to produce a very compact
   representation supporting large parts of [RFC5280], and everything in
   [RFC7925], [IEEE-802.1AR], and CAB Baseline [CAB-Baseline].  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 compressions algorithms, see Figure 2.

   The CBOR 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



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   signed CBOR certificate, in which case the signature is calculated
   directly on the CBOR encoded data (see Section 7).  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 CBOR Certificates, see Figure 1.

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

   o  version.  The 'version' field is encoded in the
      'cborCertificateType' CBOR int.  The field 'cborCertificateType'
      also indicates the type of the CBOR certificate.  Currently, the
      type can be a natively signed CBOR certificate following X.509 v3
      (cborCertificateType = 0) or a CBOR re-encoded X.509 v3 DER
      certificate (cborCertificateType = 1), see Section 9.1.

   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 each RelativeDistinguishedName
      only contains a single attribute and the sequence is then ecoded
      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 4) encodes the attribute type and the sign is used to
      represent the character string type; positive for Utf8String,
      negative for PrintableString.  In natively signed CBOR
      certificates all text strings are UTF-8 encoded and all attributes
      SHALL have a positive sign.  Text strings SHALL still adhere to
      any X.509 restrictions, i.e. serialNumber SHALL only contain the



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      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 '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. 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 9.7) 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 9.3) 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, 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.



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      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 9.6) 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 CBOR
      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
   CBORCertificate and TBSCertificate, which are encoded as CBOR
   Sequences [RFC8742].  The member names therefore only have
   documentary value.




























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; The elements of the following array are to be used in a CBOR Sequence:
CBORCertificate = [
   TBSCertificate,
   issuerSignatureValue : any,
]

TBSCertificate = (
   cborCertificateType: 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 / [ algorithm: ~oid, ? parameters: bytes ]

Extensions = [ * Extension ] / int

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

                    Figure 1: CDDL for CBORCertificate.

3.2.  Encoding of subjectPublicKey and issuerSingatureValue

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 :



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   ~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 Weirstrass 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

   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 a CBOR OID tag.  If 'extensionID'
   is encoded an int (see Section 9.3),the sign is used to encode if the
   extension is critical and the 'critical' field is omitted.  Critical
   extensions are encoded with a positive sign and non-critical
   extensions are encoded with a negative sign.

   The 'extnValue' OCTET STREAM value field is encoded as the CBOR byte
   string 'extensionValue' except for the extensions specified below.
   The 'extensionValue' for the extensions mandated to be supported by
   [RFC7925], [IEEE-802.1AR], and [CAB-Baseline] are encoded as follows:

   o  keyUsage.  The 'KeyUsage' BIT STRING is interpreted as an unsigned
      integer n in network byte order and encoded as a CBOR int.

   o  subjectAltName. extensionValue is encoded as an array of (int,
      any) pairs where each pair encodes a general name (see
      Section 9.5).  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].



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

   o  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.

   o  extKeyUsage. extensionValue is encoded as an array of CBOR ints
      (see Section 9.4) 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, the array is
      omitted.

      ExtValueEKU = [ + int / ~oid ] / int

   o  subjectKeyIdentifier. extensionValue is the value of the
      'keyIdentifier' field encoded as a CBOR byte string.

   o  authorityKeyIdentifier. extensionValue is encoded as an array
      where the value of the 'keyIdentifier' is encoded as a CBOR byte
      string, 'GeneralNames' is encoded like in subjectAltName, and
      'AuthorityCertSerialNumber' is encoded as ~biguint exactly like
      certificateSerialNumber.  Omitted values are encoded as CBOR null.

   ExtValueAKI = [ keyIdentifier: bytes / null, certIssuer: GeneralNames / null, certSerialNumber: CertificateSerialNumber / null ] / bytes

   o  cRLDistributionPoints.  If the cRLDistributionPoints is a sequence
      of DistributionPointName, it is encoded like subjectAltName, with
      the difference that if cRLDistributionPoints contains exactly one
      uniformResourceIdentifier, the array and the int are omitted and
      extensionValue is the uniformResourceIdentifier encoded as a CBOR
      text string.

   o  authorityInfoAccess.  If authorityInfoAccess consist of only
      uniformResourceIdentifiers it is encoded as an array of uris.

      ExtValueAIA = [ + ( ocsp : 1 // caIssuers : 2 , uri : text ) ]

3.3.1.  Example Encoding of Extensions

   The examples below use values from Section 9.3, Section 9.4, and
   Section 9.5:

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





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   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 3 followed by the CBOR
      array [ 3, 6 ].

   o  A non-critical subjectAltName containing only the dNSName
      example.com is encoded as the CBOR int 4 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 [ -1, -1, 2, 17, 3, [ 3, 6 ], 4, "example.com" ].

4.  Compliance Requirements for Constrained IoT

   For general purpose applications, the normative requirements of
   [RFC5280] applies.  This section describes the mandatory to implement
   algorithms and OIDs for constrained IoT application; the values of
   the OIDs including certificate fields and extensions, time format,
   attributes in distinguished names, etc.

   TODO: Write this section

5.  Legacy Considerations

   CBOR certificates can be deployed with legacy X.509 certificates and
   CA infrastructure.  In order to verify the signature, the CBOR
   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 CBOR 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 CBOR 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 CBOR
   certificate and does not perform the conversion to X.509.  This
   option is viable when client authentication can be asserted by other
   means.



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   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.  Expected Certificate Sizes

   The CBOR encoding of the sample certificate given in Appendix A
   results in the numbers shown in Figure 2.  After [RFC7925] 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 will be small, mainly
   corresponding to making the ASN.1 encoding more compact.  For Brtoli
   [RFC7932], the brotli command line tool 1.09 was used with the
   default best compression level.

   +------------------+--------------+------------+--------------------+
   |                  |   RFC 7925   |   Brotli   |  CBOR Certificate  |
   +------------------+---------------------------+--------------------+
   | Certificate Size |     314      |     303    |         138        |
   +------------------+--------------+------------+--------------------+

             Figure 2: Comparing Sizes of Certificates (bytes)

7.  Natively Signed CBOR Certificates

   The difference between CBOR encoded X.509 certificate and natively
   signed CBOR certificate is that the signature is calculated over the
   CBOR encoding of the CBOR sequence TBSCertficate rather than the DER
   encoded ASN.1 data.  This removes entirely the need for ASN.1 DER and
   base64 encodings which reduces the processing in the authenticating
   devices, and avoids known complexities and security issues with these
   encodings.

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

   CBOR encoded X.509 certificates provides an intermediate step between
   [RFC7925] or [IEEE-802.1AR] profiled X.509 certificates and natively
   signed CBOR certificates: An implementation of CBOR encoded X.509
   certificates contains both the CBOR encoding of the X.509 certificate
   and the signature operations sufficient for natively signed CBOR
   certificates.





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   The natively signed approach based on DER encoded X.509 certificates
   described in this document has also other benefits.  For example, a
   CA can use existing ASN.1 machinery to create a DER encoded
   certificate, the DER encoded certificate can then be transformed to
   CBOR before signing.

8.  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 CBOR 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 requires unencrypted certificates and
   is not recommended.

9.  IANA Considerations

   This document creates several new registries under the new heading
   "CBOR 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 remaning values in the interval [-65536, 65535]
   have 3 byte encodings.






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9.1.  CBOR Certificate Types Registry

   IANA has created a new registry titled "CBOR Certificate Types" under
   the new heading "CBOR 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 | Description                                               |
   +=======+===========================================================+
   |     0 | Natively Signed CBOR Certificate following X.509 v3       |
   +-------+-----------------------------------------------------------+
   |     1 | CBOR re-encoding of X.509 v3 Certificate                  |
   +-------+-----------------------------------------------------------+

                     Figure 3: CBOR Certificate Types

9.2.  CBOR Certificate Attributes Registry

   IANA has created a new registry titled "CBOR Certificate Attributes"
   under the new heading "CBOR 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.  Only
   non-negative values can be registered.  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                                                 |
   +=======+===========================================================+
   |     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                                  |
   |       | DER:             06 03 55 04 05                           |
   |       | Comments:                                                 |



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   +-------+-----------------------------------------------------------+
   |     4 | Name:            Country                                  |
   |       | OID:             2.5.4.6                                  |
   |       | DER:             06 03 55 04 06                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     5 | Name:            Locality                                 |
   |       | OID:             2.5.4.7                                  |
   |       | DER:             06 03 55 04 07                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     6 | Name:            State or Province                        |
   |       | OID:             2.5.4.8                                  |
   |       | DER:             06 03 55 04 08                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     7 | Name:            Street Address                           |
   |       | OID:             2.5.4.9                                  |
   |       | DER:             06 03 55 04 09                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     8 | Name:            Organization                             |
   |       | OID:             2.5.4.10                                 |
   |       | DER:             06 03 55 04 0A                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     9 | Name:            Organizational Unit                      |
   |       | OID:             2.5.4.11                                 |
   |       | DER:             06 03 55 04 0B                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    10 | Name:            Title                                    |
   |       | OID:             2.5.4.12                                 |
   |       | DER:             06 03 55 04 0C                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    11 | Name:            Postal Code                              |
   |       | OID:             2.5.4.17                                 |
   |       | DER:             06 03 55 04 11                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    12 | Name:            Given Name                               |
   |       | OID:             2.5.4.42                                 |
   |       | DER:             06 03 55 04 2A                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    13 | Name:            Initials                                 |
   |       | OID:             2.5.4.43                                 |



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   |       | DER:             06 03 55 04 2B                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    14 | Name:            Generation Qualifier                     |
   |       | OID:             2.5.4.44                                 |
   |       | DER:             06 03 55 04 2C                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    15 | Name:            DN Qualifier                             |
   |       | OID:             2.5.4.46                                 |
   |       | DER:             06 03 55 04 2E                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    16 | Name:            Pseudonym                                |
   |       | OID:             2.5.4.65                                 |
   |       | DER:             06 03 55 04 41                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    17 | Name:            Organization Identifier                  |
   |       | OID:             2.5.4.97                                 |
   |       | DER:             06 03 55 04 61                           |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+

                   Figure 4: CBOR Certificate Attributes

9.3.  CBOR Certificate Extensions Registry

   IANA has created a new registry titled "CBOR Certificate Extensions"
   under the new heading "CBOR Certificate".  The columns of the
   registry are Value, Name, OID, DER, Comments, extensionValue, and
   Reference, where Value is an integer, and the other columns are text
   strings.  Only non-negative values can be registered.  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 | Extension                                                |
   +=======+===========================================================+
   |     0 | Name:            Subject Key Identifier                   |
   |       | OID:             2.5.29.14                                |
   |       | DER:             06 03 55 1D 0E                           |
   |       | Comments:                                                 |
   |       | extensionValue:  bytes                                    |
   +-------+-----------------------------------------------------------+
   |     1 | Name:            Key Usage                                |
   |       | OID:             2.5.29.15                                |



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   |       | DER:             06 03 55 1D 0F                           |
   |       | Comments:                                                 |
   |       | AttributeValue:  int                                      |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            Subject Alternative Name                 |
   |       | OID:             2.5.29.17                                |
   |       | DER:             06 03 55 1D 11                           |
   |       | Comments:                                                 |
   |       | extensionValue:  [ + ( int, any ) ] / text                |
   +-------+-----------------------------------------------------------+
   |     3 | Name:            Basic Constraints                        |
   |       | OID:             2.5.29.19                                |
   |       | DER:             06 03 55 1D 13                           |
   |       | Comments:                                                 |
   |       | extensionValue:  int                                      |
   +-------+-----------------------------------------------------------+
   |     4 | Name:            CRL Distribution Points                  |
   |       | OID:             2.5.29.31                                |
   |       | DER:             06 03 55 1D 1F                           |
   |       | Comments:                                                 |
   |       | extensionValue:  [ + ( int, any ) ] / text                |
   +-------+-----------------------------------------------------------+
   |     5 | Name:            Certificate Policies                     |
   |       | OID:             2.5.29.32                                |
   |       | DER:             06 03 55 1D 20                           |
   |       | Comments:                                                 |
   |       | extensionValue:  [ + ( oid, ? text ) ]                    |
   +-------+-----------------------------------------------------------+
   |     6 | Name:            Authority Key Identifier                 |
   |       | OID:             2.5.29.35                                |
   |       | DER:             06 03 55 1D 23                           |
   |       | Comments:                                                 |
   |       | extensionValue:  bytes                                    |
   +-------+-----------------------------------------------------------+
   |     7 | Name:            Extended Key Usage                       |
   |       | OID:             2.5.29.37                                |
   |       | DER:             06 03 55 1D 25                           |
   |       | Comments:                                                 |
   |       | extensionValue:  int                                      |
   +-------+-----------------------------------------------------------+
   |     8 | Name:            Authority Information Access             |
   |       | OID:             1.3.6.1.5.5.7.1.1                        |
   |       | DER:             06 08 2B 06 01 05 05 07 01 01            |
   |       | Comments:                                                 |
   |       | extensionValue:  [ + ( 1 / 2 , text ) ]                   |
   +-------+-----------------------------------------------------------+
   |     9 | Name:            Signed Certificate Timestamp List        |
   |       | OID:             1.3.6.1.4.1.11129.2.4.2                  |



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   |       | DER:             06 0A 2B 06 01 04 01 D6 79 02 04 02      |
   |       | Comments:                                                 |
   |       | extensionValue:  [ bytes, ~biguint,                       |
   |       |                    AlgorithmIdentifier, bytes]            |
   +-------+-----------------------------------------------------------+
   |    24 | Name:            Subject Directory Attributes             |
   |       | OID:             2.5.29.9                                 |
   |       | DER:             06 03 55 1D 09                           |
   |       | Comments:                                                 |
   |       | extensionValue:  bytes                                    |
   +-------+-----------------------------------------------------------+
   |    25 | Name:            Issuer Alternative Name                  |
   |       | OID:             2.5.29.18                                |
   |       | DER:             06 03 55 1D 12                           |
   |       | Comments:                                                 |
   |       | extensionValue:  bytes                                    |
   +-------+-----------------------------------------------------------+
   |    26 | Name:            Name Constraints                         |
   |       | OID:             2.5.29.30                                |
   |       | DER:             06 03 55 1D 1E                           |
   |       | Comments:                                                 |
   |       | extensionValue:  bytes                                    |
   +-------+-----------------------------------------------------------+
   |    27 | Name:            Policy Mappings                          |
   |       | OID:             2.5.29.33                                |
   |       | DER:             06 03 55 1D 21                           |
   |       | Comments:                                                 |
   |       | extensionValue:  bytes                                    |
   +-------+-----------------------------------------------------------+
   |    28 | Name:            Policy Constraints                       |
   |       | OID:             2.5.29.36                                |
   |       | DER:             06 03 55 1D 24                           |
   |       | Comments:                                                 |
   |       | extensionValue:  bytes                                    |
   +-------+-----------------------------------------------------------+
   |    29 | Name:            Freshest CRL                             |
   |       | OID:             2.5.29.46                                |
   |       | DER:             06 03 55 1D 2E                           |
   |       | Comments:                                                 |
   |       | extensionValue:  bytes                                    |
   +-------+-----------------------------------------------------------+
   |    30 | Name:            Inhibit anyPolicy                        |
   |       | OID:             2.5.29.54                                |
   |       | DER:             06 03 55 1D 36                           |
   |       | Comments:                                                 |
   |       | extensionValue:  bytes                                    |
   +-------+-----------------------------------------------------------+
   |    31 | Name:            Subject Information Access               |



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   |       | OID:             1.3.6.1.5.5.7.1.11                       |
   |       | DER:             06 08 2B 06 01 05 05 07 01 0B            |
   |       | Comments:                                                 |
   |       | extensionValue:  bytes                                    |
   +-------+-----------------------------------------------------------+

                   Figure 5: CBOR Certificate Extensions

9.4.  CBOR Extended Key Usages Registry

   IANA has created a new registry titled "CBOR Certificate Extended Key
   Usages" under the new heading "CBOR 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:

































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   +-------+-----------------------------------------------------------+
   | Value | Extended Key Usage                                        |
   +=======+===========================================================+
   |     1 | Name:            TLS Server authentication                |
   |       | OID:             1.3.6.1.5.5.7.3.1                        |
   |       | DER:             06 08 2B 06 01 05 05 07 03 01            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     2 | Name:            TLS Client Authentication                |
   |       | OID:             1.3.6.1.5.5.7.3.2                        |
   |       | DER:             06 08 2B 06 01 05 05 07 03 02            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     3 | Name:            Code Signing                             |
   |       | OID:             1.3.6.1.5.5.7.3.3                        |
   |       | DER:             06 08 2B 06 01 05 05 07 03 03            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     4 | Name:            Email protection (S/MIME)                |
   |       | OID:             1.3.6.1.5.5.7.3.4                        |
   |       | DER:             06 08 2B 06 01 05 05 07 03 04            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     8 | Name:            Time Stamping                            |
   |       | OID:             1.3.6.1.5.5.7.3.8                        |
   |       | DER:             06 08 2B 06 01 05 05 07 03 08            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |     9 | Name:            OCSP Signing                             |
   |       | OID:             1.3.6.1.5.5.7.3.9                        |
   |       | DER:             06 08 2B 06 01 05 05 07 03 09            |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+

              Figure 6: CBOR Certificate Extended Key Usages

9.5.  CBOR Certificate General Names Registry

   IANA has created a new registry titled "CBOR Certificate General
   Names" under the new heading "CBOR Certificate".  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:






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   +-------+-----------------------------------------------------------+
   | Value | General Names                                             |
   +=======+===========================================================+
   |    -1 | Name:            otherName with hardwareModuleName        |
   |       | Comments:                                                 |
   |       | 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 7: CBOR Certificate General Names

9.6.  CBOR Certificate Signature Algorithms Registry

   IANA has created a new registry titled "CBOR Certificate Signature
   Algorithms" under the new heading "CBOR Certificate".  The columns of
   the registry are Value, Name, 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:



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   +-------+-----------------------------------------------------------+
   | Value | X.509 Signature Algorithms                                |
   +=======+===========================================================+
   |  -256 | Name:        RSASSA-PKCS1-v1_5 with SHA-1                 |
   |       | 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                             |
   |       | 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                           |
   |       | 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                           |
   |       | 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                           |
   |       | 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                          |
   |       | 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                          |
   |       | 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                                      |
   |       | OID:         1.3.101.112                                  |
   |       | Parameters:  Absent                                       |



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   |       | DER:         30 05 06 03 2B 65 70                         |
   |       | Comments:                                                 |
   +-------+-----------------------------------------------------------+
   |    13 | Name:        Ed448                                        |
   |       | 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               |
   |       | 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               |
   |       | 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               |
   |       | 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                      |
   |       | 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                      |
   |       | 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                      |



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   |       | 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                     |
   |       | 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                     |
   |       | 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                                    |
   |       | 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                                         |
   |       | 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                                      |
   |       | 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 8: CBOR Certificate Signature Algorithms

9.7.  CBOR Certificate Public Key Algorithms Registry

   IANA has created a new registry titled "CBOR Certificate Public Key
   Algorithms" under the new heading "CBOR Certificate".  The columns of
   the registry are Value, Name, OID, Parameters, DER, Comments, and
   Reference, where Value is an integer, and the other columns are text



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   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                                          |
  |       | 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    |
  |       | 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            |
  +-------+-----------------------------------------------------------+
  |     2 | Name:        EC Public Key (Weierstrass) with secp384r1    |
  |       | 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            |
  +-------+-----------------------------------------------------------+
  |     3 | Name:        EC Public Key (Weierstrass) with secp521r1    |
  |       | 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            |
  +-------+-----------------------------------------------------------+
  |     8 | Name:        X25519 (Montgomery)                          |
  |       | OID:         1.3.101.110                                  |
  |       | Parameters:  Absent                                       |
  |       | DER:         30 05 06 03 2B 65 6E                         |
  |       | Comments:                                                 |
  +-------+-----------------------------------------------------------+
  |     9 | Name:        X448 (Montgomery)                            |
  |       | OID:         1.3.101.111                                  |
  |       | Parameters:  Absent                                       |
  |       | DER:         30 05 06 03 2B 65 6F                         |
  |       | Comments:                                                 |
  +-------+-----------------------------------------------------------+
  |    10 | Name:        Ed25519 (Twisted Edwards)                    |



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  |       | OID:         1.3.101.112                                  |
  |       | Parameters:  Absent                                       |
  |       | DER:         30 05 06 03 2B 65 70                         |
  |       | Comments:                                                 |
  +-------+-----------------------------------------------------------+
  |    11 | Name:        Ed448 (Edwards)                              |
  |       | OID:         1.3.101.113                                  |
  |       | Parameters:  Absent                                       |
  |       | DER:         30 05 06 03 2B 65 71                         |
  |       | Comments:                                                 |
  +-------+-----------------------------------------------------------+
  |    16 | Name:        HSS / LMS                                    |
  |       | 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:                                                 |
  +-------+-----------------------------------------------------------+
  |    17 | Name:        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                                      |
  |       | 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 9: CBOR Certificate Public Key Algorithms

9.8.  COSE Header Parameters Registry

   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 are the same as the
   corresponding x5bag, x5chain, x5t, and x5u defined in
   [I-D.ietf-cose-x509] except that the certificates are CBOR encoded
   instead of DER encoded.  Note that certificates can also be
   identified with a 'kid' header parameter by storing 'kid' and the
   associated bag or chain in a dictionary.









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   +-----------+-------+----------------+------------------------------+
   | Name      | Label | Value Type     | Description                  |
   +===========+=======+================+==============================+
   | c5bag     |  TBD1 | COSE_X509      | An unordered bag of CBOR     |
   |           |       |                | certificates                 |
   +-----------+-------+----------------+------------------------------+
   | c5chain   |  TBD2 | COSE_X509      | An ordered chain of CBOR     |
   |           |       |                | certificates                 |
   +-----------+-------+----------------+------------------------------+
   | c5t       |  TBD3 | COSE_CertHash  | Hash of a CBOR certificate   |
   +-----------+-------+----------------+------------------------------+
   | c5u       |  TBD4 | uri            | URI pointing to a CBOR       |
   |           |       |                | certificate                  |
   +-----------+-------+----------------+------------------------------+

9.9.  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 addtional TLS
   certificate compression [RFC8879].

   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
   CBOR 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 | CBOR Certificate |           Y |                          |
   +-------+------------------+-------------+--------------------------+

10.  References

10.1.  Normative References

   [I-D.ietf-cbor-tags-oid]
              Bormann, C. and S. Leonard, "Concise Binary Object
              Representation (CBOR) Tags for Object Identifiers", draft-
              ietf-cbor-tags-oid-03 (work in progress), November 2020.

   [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.




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   [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>.

   [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>.

10.2.  Informative References







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

   [I-D.ietf-emu-eap-tls13]
              Mattsson, J. and M. Sethi, "Using EAP-TLS with TLS 1.3",
              draft-ietf-emu-eap-tls13-13 (work in progress), November
              2020.

   [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., and F. Palombini, "Ephemeral
              Diffie-Hellman Over COSE (EDHOC)", draft-ietf-lake-
              edhoc-03 (work in progress), December 2020.

   [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-dtls13-39 (work in progress),
              November 2020.

   [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-00 (work in progress), June 2020.









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   [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>.

   [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>.

   [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>.








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Appendix A.  Example CBOR 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.













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   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 CBOR Certificate Encoding

   The CBOR encoding 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


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












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   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 CBOR Certificate

   The corresponding natively signed CBOR certificate in CBOR diagnostic
   format is identical, except for cborCertificateType 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,
     h'B27A0B781455F71B68290F6C2EC9A897F18FDE9B6C59575953
       BC67268AB0E4DDE99D273E04E4715383AB2257C6AAA35284E5
       ED18BDB91247E9F2C433136480B9'


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











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   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



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   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



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   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 CBOR Certificate Encoding

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

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

1,
h'047FA1E31928EE403BA0B83A395673FC',
[
 -4, "IE",
 -8, "Baltimore",
 -9, "CyberTrust",
 -1, "Baltimore CyberTrust Root"
],
1595980800,
1627560000,
[
 -4, "US",
 -6, "CA",
 -5, "San Francisco",
 -8, "Cloudflare, Inc.",
 -1, "sni.cloudflaressl.com"
],
1,
h'03963ECDD84DCD1B93A1CF432D1A7217D6C63BDE3355A02F8CFB5AD8994CD44E20',
[
  6, h'A5CE37EAEBB0750E946788B445FAD9241087961F',
  0, h'CC0B50E7D837DBF243F3853D4860F53B39BE9B2A',
  2, [2, "sni.cloudflaressl.com", 2, "www.ietf.org"],
 -1, 1,
  7, [1, 2],
  4, ["http://crl3.digicert.com/CloudflareIncECCCA-3.crl", "http://crl4.digicert.com/CloudflareIncECCCA-3.crl"],
  5, [h'6086480186FD6C0101', "https://www.digicert.com/CPS", 2],
  8, [1, "http://ocsp.digicert.com", 2, "http://cacerts.digicert.com/CloudflareIncECCCA-3.crt"],
 -3, -2,
  9, ...
],
0,
h'BD63CF4F7E5CFE6C29385EA71CFBFC1E3F7B1CD07251A221F77769C0F471DFEAB5C06CC45854FA30B28288B1D3BB9A6661ED5031725B1A8202E0DA5B59F95402'







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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



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   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 CBOR Certificate Encoding

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
















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/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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
[
 -3, -2,
  7, [ 1, 2 ],
 -1, 5,
  4, "http://crl.starfieldtech.com/sfig2s1-242.crl",
  5, [ h'6086480186fd6e01071701', "http://certificates.starfieldtech.com/repository/", 1 ],
  8, [ 1, "http://ocsp.starfieldtech.com/", 2, "http://certificates.starfieldtech.com/repository/sfig2.crt" ],
  6, h'254581685026383D3B2D2CBECD6AD9B63DB36663',
  2, [ 2, "*.tools.ietf.org", 2, "tools.ietf.org" ],
  0, h'AD8AB41C0751D7928907B0B784622F36557A5F4D',
  9, [
       h'F65C942FD1773022145418083094568EE34D131933BFDF0C2F200BCC4EF164E3',
       1715,
       1,
       h'8CF54852CE5635433911CF10CDB91F52B33639223AD138A41DECA6FEDE1FE90FBCA2254366C19A2691C47A00B5B653ABBD44C2F8BAAEF4D2DAF2527CE6454995',
       h'5CDC4392FEE6AB4544B15E9AD456E61037FBD5FA47DCA17394B25EE6F6C70ECA',
       2012,
       1,
       h'A5E0906E63E91D4FDDEFFF0352B91E50896007564B448A3828F596DC6B28726DFC91EAED02168866054EE18A2E5346C4CC51FEB3FA10A91D2EDBF99125F86CE6'
     ]
],
23,
h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

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






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Internet-DrafCBOR Encoding of X.509 Certificates (CBOR Cert January 2021


Acknowledgments

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

Authors' Addresses

   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













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