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Selective Disclosure for JWTs (SD-JWT)
draft-ietf-oauth-selective-disclosure-jwt-06

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This is an older version of an Internet-Draft whose latest revision state is "Active".
Authors Daniel Fett , Kristina Yasuda , Brian Campbell
Last updated 2023-10-23 (Latest revision 2023-06-30)
Replaces draft-fett-oauth-selective-disclosure-jwt
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draft-ietf-oauth-selective-disclosure-jwt-06
Web Authorization Protocol                                       D. Fett
Internet-Draft                                                  Authlete
Intended status: Standards Track                               K. Yasuda
Expires: 25 April 2024                                         Microsoft
                                                             B. Campbell
                                                           Ping Identity
                                                         23 October 2023

                 Selective Disclosure for JWTs (SD-JWT)
              draft-ietf-oauth-selective-disclosure-jwt-06

Abstract

   This specification defines a mechanism for selective disclosure of
   individual elements of a JSON object used as the payload of a JSON
   Web Signature (JWS) structure.  It encompasses various applications,
   including but not limited to the selective disclosure of JSON Web
   Token (JWT) claims.

Discussion Venues

   This note is to be removed before publishing as an RFC.

   Discussion of this document takes place on the Web Authorization
   Protocol Working Group mailing list (oauth@ietf.org), which is
   archived at https://mailarchive.ietf.org/arch/browse/oauth/.

   Source for this draft and an issue tracker can be found at
   https://github.com/oauth-wg/oauth-selective-disclosure-jwt.

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 25 April 2024.

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Copyright Notice

   Copyright (c) 2023 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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Feature Summary . . . . . . . . . . . . . . . . . . . . .   5
     1.2.  Conventions and Terminology . . . . . . . . . . . . . . .   6
   2.  Terms and Definitions . . . . . . . . . . . . . . . . . . . .   6
   3.  Flow Diagram  . . . . . . . . . . . . . . . . . . . . . . . .   7
   4.  Concepts  . . . . . . . . . . . . . . . . . . . . . . . . . .   7
     4.1.  SD-JWT and Disclosures  . . . . . . . . . . . . . . . . .   8
     4.2.  Disclosing to a Verifier  . . . . . . . . . . . . . . . .   8
     4.3.  Optional Key Binding  . . . . . . . . . . . . . . . . . .   8
     4.4.  Verification  . . . . . . . . . . . . . . . . . . . . . .   9
   5.  SD-JWT Data Formats . . . . . . . . . . . . . . . . . . . . .   9
     5.1.  Issuer-signed JWT Payload . . . . . . . . . . . . . . . .  10
       5.1.1.  Hash Function Claim . . . . . . . . . . . . . . . . .  11
       5.1.2.  Holder Public Key Claim . . . . . . . . . . . . . . .  11
     5.2.  Disclosures . . . . . . . . . . . . . . . . . . . . . . .  11
       5.2.1.  Disclosures for Object Properties . . . . . . . . . .  12
       5.2.2.  Disclosures for Array Elements  . . . . . . . . . . .  13
       5.2.3.  Hashing Disclosures . . . . . . . . . . . . . . . . .  14
       5.2.4.  Embedding Disclosure Digests in SD-JWTs . . . . . . .  14
       5.2.5.  Decoy Digests . . . . . . . . . . . . . . . . . . . .  16
     5.3.  Key Binding JWT . . . . . . . . . . . . . . . . . . . . .  16
       5.3.1.  Integrity Protection of the Presentation  . . . . . .  17
       5.3.2.  Validating the Key Binding JWT  . . . . . . . . . . .  17
       5.3.3.  Alternatives to a Key Binding JWT . . . . . . . . . .  18
   6.  Example 1: SD-JWT . . . . . . . . . . . . . . . . . . . . . .  18
     6.1.  Issuance  . . . . . . . . . . . . . . . . . . . . . . . .  18
     6.2.  Presentation  . . . . . . . . . . . . . . . . . . . . . .  23
   7.  Considerations on Nested Data in SD-JWTs  . . . . . . . . . .  24
     7.1.  Example: Flat SD-JWT  . . . . . . . . . . . . . . . . . .  25
     7.2.  Example: Structured SD-JWT  . . . . . . . . . . . . . . .  26
     7.3.  Example: SD-JWT with Recursive Disclosures  . . . . . . .  28
   8.  Verification and Processing . . . . . . . . . . . . . . . . .  30

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     8.1.  Verification of the SD-JWT  . . . . . . . . . . . . . . .  30
     8.2.  Processing by the Holder  . . . . . . . . . . . . . . . .  32
     8.3.  Verification by the Verifier  . . . . . . . . . . . . . .  32
   9.  JWS JSON Serialization  . . . . . . . . . . . . . . . . . . .  34
   10. Enveloping SD-JWTs  . . . . . . . . . . . . . . . . . . . . .  36
   11. Security Considerations . . . . . . . . . . . . . . . . . . .  37
     11.1.  Mandatory Signing of the Issuer-signed JWT . . . . . . .  38
     11.2.  Manipulation of Disclosures  . . . . . . . . . . . . . .  38
     11.3.  Entropy of the salt  . . . . . . . . . . . . . . . . . .  39
     11.4.  Minimum length of the salt . . . . . . . . . . . . . . .  39
     11.5.  Choice of a Hash Algorithm . . . . . . . . . . . . . . .  39
     11.6.  Key Binding  . . . . . . . . . . . . . . . . . . . . . .  40
     11.7.  Blinding Claim Names . . . . . . . . . . . . . . . . . .  41
     11.8.  Selectively-Disclosable Validity Claims  . . . . . . . .  41
     11.9.  Issuer Signature Key Distribution and Rotation . . . . .  41
     11.10. Forwarding Credentials . . . . . . . . . . . . . . . . .  41
     11.11. Integrity of Presentation  . . . . . . . . . . . . . . .  42
     11.12. Explicit Typing  . . . . . . . . . . . . . . . . . . . .  42
   12. Privacy Considerations  . . . . . . . . . . . . . . . . . . .  42
     12.1.  Storage of Signed User Data  . . . . . . . . . . . . . .  42
     12.2.  Confidentiality during Transport . . . . . . . . . . . .  43
     12.3.  Decoy Digests  . . . . . . . . . . . . . . . . . . . . .  44
     12.4.  Unlinkability  . . . . . . . . . . . . . . . . . . . . .  44
     12.5.  Issuer Identifier  . . . . . . . . . . . . . . . . . . .  45
   13. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  45
   14. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  45
     14.1.  JSON Web Token Claims Registration . . . . . . . . . . .  45
     14.2.  Media Type Registration  . . . . . . . . . . . . . . . .  46
     14.3.  Structured Syntax Suffix Registration  . . . . . . . . .  49
   15. Normative References  . . . . . . . . . . . . . . . . . . . .  50
   16. Informative References  . . . . . . . . . . . . . . . . . . .  50
   Appendix A.  Additional Examples  . . . . . . . . . . . . . . . .  52
     A.1.  Example 2: Handling Structured Claims . . . . . . . . . .  53
     A.2.  Example 3 - Complex Structured SD-JWT . . . . . . . . . .  57
     A.3.  Example 4a - SD-JWT-based Verifiable Credentials (SD-JWT
           VC) . . . . . . . . . . . . . . . . . . . . . . . . . . .  65
     A.4.  Example 4b - W3C Verifiable Credentials Data Model
           v2.0  . . . . . . . . . . . . . . . . . . . . . . . . . .  72
     A.5.  Elliptic Curve Key Used in the Examples . . . . . . . . .  81
   Appendix B.  Disclosure Format Considerations . . . . . . . . . .  82
   Appendix C.  Document History . . . . . . . . . . . . . . . . . .  84
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  89

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1.  Introduction

   This document specifies conventions for creating JSON Web Signature
   (JWS) [RFC7515] structures with JSON [RFC8259] objects as the payload
   while supporting selective disclosure of individual elements of that
   JSON.  Because JSON Web Token (JWT) [RFC7519] is a very prevalent
   application of JWS with a JSON payload, the selective disclosure of
   JWT claims receives primary treatment herein.  However, that does not
   preclude the mechanism's applicability to other or more general
   applications of JWS with JSON payloads.

   The JSON-based representation of claims in a signed JWT is secured
   against modification using JWS digital signatures.  A consumer of a
   signed JWT that has checked the signature can safely assume that the
   contents of the token have not been modified.  However, anyone
   receiving an unencrypted JWT can read all the claims.  Likewise,
   anyone with the decryption key receiving encrypted JWT can also read
   all the claims.

   One of the common use cases of a signed JWT is representing a user's
   identity.  As long as the signed JWT is one-time use, it typically
   only contains those claims the user has consented to disclose to a
   specific Verifier.  However, there is an increasing number of use
   cases where a signed JWT is created once and then used a number of
   times by the user (the "Holder" of the JWT).  In such use cases, the
   signed JWT needs to contain the superset of all claims the user of
   the signed JWT might want to disclose to Verifiers at some point.
   The ability to selectively disclose a subset of these claims
   depending on the Verifier becomes crucial to ensure minimum
   disclosure and prevent Verifiers from obtaining claims irrelevant for
   the transaction at hand.  SD-JWTs defined in this document enable
   such selective disclosure of JWT claims.

   One example of a multi-use JWT is a verifiable credential, an Issuer-
   signed credential that contains the claims about a subject, and whose
   authenticity can be cryptographically verified.

   Similar to the JWT specification on which it builds, this document is
   a product of the Web Authorization Protocol (oauth) working group.
   However, while both JWT and SD-JWT have potential OAuth 2.0
   applications, their utility and application is certainly not
   constrained to OAuth 2.0.  JWT was developed as a general-purpose
   token format and has seen widespread usage in a variety of
   applications.  SD-JWT is a selective disclosure mechanism for JWT and
   is similarly intended to be general-purpose specification.

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   While JWTs with claims describing natural persons are a common use
   case, the mechanisms defined in this document can be used for other
   use cases as well.

   In an SD-JWT, claims can be hidden, but cryptographically protected
   against undetected modification.  "Claims" here refers to both object
   properties (key-value pairs) as well as array elements.  When issuing
   the SD-JWT to the Holder, the Issuer includes the cleartext
   counterparts of all hidden claims, the so-called Disclosures, outside
   the signed part of the SD-JWT.

   The Holder decides which claims to disclose to a particular Verifier
   and includes the respective Disclosures in the SD-JWT to that
   Verifier.  The Verifier has to verify that all disclosed claim values
   were part of the original Issuer-signed JWT.  The Verifier will not,
   however, learn any claim values not disclosed in the Disclosures.

   This document also specifies an optional mechanism for Key Binding,
   which is the concept of binding an SD-JWT to a Holder's public key
   and requiring that the Holder prove possession of the corresponding
   private key when presenting the SD-JWT.  The strength of the binding
   is conditional upon the trust in the protection of the private key of
   the key pair an SD-JWT is bound to.

   SD-JWT can be used with any JSON-based representation of claims,
   including JSON-LD.

   This specification aims to be easy to implement and to leverage
   established and widely used data formats and cryptographic algorithms
   wherever possible.

1.1.  Feature Summary

   *  This specification defines

      -  a format for the payload of an Issuer-signed JWT containing
         selectively disclosable claims that include object properties
         (key-value pairs), array elements, and nested data structures
         built from these,

      -  a format for data associated with the JWT that enables
         selectively disclosing those claims,

      -  facilities for binding the JWT to a key and associated data to
         prove possession thereof, and

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      -  a format, extending the JWS Compact Serialization, for the
         combined transport of the JWT and associated data that is
         suitable for both issuance and presentation.

   *  An alternate format utilizing the JWS JSON Serialization is also
      specified.

   *  This specification enables combining selectively disclosable
      claims with clear-text claims that are always disclosed.

   *  For selectively disclosable claims that are object properties,
      both the key and value are always blinded.

1.2.  Conventions and Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in BCP
   14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   *base64url* denotes the URL-safe base64 encoding without padding
   defined in Section 2 of [RFC7515].

2.  Terms and Definitions

   Selective disclosure:  Process of a Holder disclosing to a Verifier a
      subset of claims contained in a claim set issued by an Issuer.

   Selectively Disclosable JWT (SD-JWT):  A composite structure,
      consisting of an Issuer-signed JWT (JWS, [RFC7515]), Disclosures,
      and optionally a Key Binding JWT that supports selective
      disclosure as defined in this document.  It can contain both
      regular claims and digests of selectively-disclosable claims.

   Disclosure:  A combination of a salt, a cleartext claim name (present
      when the claim is a key-value pair and absent when the claim is an
      array element), and a cleartext claim value, all of which are used
      to calculate a digest for the respective claim.

   Key Binding:  Ability of the Holder to prove legitimate possession of
      an SD-JWT by proving control over the same private key during the
      issuance and presentation.  An SD-JWT with Key Binding contains a
      public key, or a reference to a public key, that matches to the
      private key controlled by the Holder.

   Key Binding JWT:  A JWT for proving Key Binding as defined in
      Section 5.3.

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   Issuer:  An entity that creates SD-JWTs.

   Holder:  An entity that received SD-JWTs from the Issuer and has
      control over them.

   Verifier:  An entity that requests, checks, and extracts the claims
      from an SD-JWT with its respective Disclosures.

3.  Flow Diagram

              +------------+
              |            |
              |   Issuer   |
              |            |
              +------------+
                    |
               Issues SD-JWT
         including all Disclosures
                    |
                    v
              +------------+
              |            |
              |   Holder   |
              |            |
              +------------+
                    |
              Presents SD-JWT
       including selected Disclosures
                    |
                    v
              +-------------+
              |             |+
              |  Verifiers  ||+
              |             |||
              +-------------+||
               +-------------+|
                +-------------+

              Figure 1: SD-JWT Issuance and Presentation Flow

4.  Concepts

   This section describes SD-JWTs with their respective Disclosures and
   Key Binding at a conceptual level, abstracting from the data formats
   described in Section 5.

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4.1.  SD-JWT and Disclosures

   An SD-JWT, at its core, is a digitally signed JSON document
   containing digests over the selectively disclosable claims with the
   Disclosures outside the document.  Disclosures can be omitted without
   breaking the signature, and modifying them can be detected.
   Selectively disclosable claims can be individual object properties
   (key-value pairs) or array elements.

   Each digest value ensures the integrity of, and maps to, the
   respective Disclosure.  Digest values are calculated using a hash
   function over the Disclosures, each of which contains a
   cryptographically secure random salt, the claim name (only when the
   claim is an object property), and the claim value.  The Disclosures
   are sent to the Holder as part of the SD-JWT in the format defined in
   Section 5.

   An SD-JWT MAY also contain clear-text claims that are always
   disclosed to the Verifier.

4.2.  Disclosing to a Verifier

   To disclose to a Verifier a subset of the SD-JWT claim values, a
   Holder sends only the Disclosures of those selectively released
   claims to the Verifier as part of the SD-JWT.

4.3.  Optional Key Binding

   Key Binding is an optional feature.  When Key Binding is required by
   the use-case, the SD-JWT MUST contain information about the key
   material controlled by the Holder.

   Note: How the public key is included in SD-JWT is out of scope of
   this document.  It can be passed by value or by reference.

   For presenting an SD-JWT to a Verifier that enforces Key Binding, the
   Holder creates a signed document, the Key Binding JWT as defined in
   Section 5.3, using its private key.  This document contains a nonce
   to ensure the freshness of the signature, an audience value to
   indicate the intended audience for the document, and a hash that
   ensures the integrity of the data sent from the Holder to the
   Verifier.  Details of the format of Key Binding JWTs are described in
   Section 5.3.

   Note that there may be other ways to send a Key Binding JWT to the
   Verifier or for the Holder to prove possession of the key material
   included in an SD-JWT.  In these cases, inclusion of the Key Binding
   JWT in the SD-JWT is not required.

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4.4.  Verification

   At a high level, the Verifier

   *  receives the SD-JWT from the Holder and verifies its signature
      using the Issuer's public key,

   *  verifies the Key Binding JWT, if Key Binding is required by the
      Verifier's policy, using the public key included in the SD-JWT,

   *  calculates the digests over the Holder-Selected Disclosures and
      verifies that each digest is contained in the SD-JWT.

   The detailed algorithm is described in Section 8.3.

5.  SD-JWT Data Formats

   An SD-JWT is composed of the following:

   *  an Issuer-signed JWT,

   *  zero or more Disclosures, and

   *  optionally a Key Binding JWT.

   The individual parts will be explained in the following subsections.

   The serialized format for the SD-JWT is the concatenation of each
   part delineated with a single tilde ('~') character as follows:

<Issuer-signed JWT>~<Disclosure 1>~<Disclosure 2>~...~<Disclosure N>~<optional KB-JWT>

   The order of the tilde separated values MUST be the Issuer-signed
   JWT, followed by any number of Disclosures, and lastly the optional
   Key Binding JWT.  In the case that there is no Key Binding JWT, the
   last element MUST be an empty string and the last separating tilde
   character MUST NOT be omitted.

   The Disclosures are linked to the Issuer-signed JWT through the
   digest values included therein.

   When issuing to a Holder, the Issuer includes all the relevant
   Disclosures in the SD-JWT.

   When presenting to a Verifier, the Holder sends only the selected set
   of the Disclosures in the SD-JWT.

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   The Holder MAY send any subset of the Disclosures to the Verifier,
   i.e., none, some, or all Disclosures.  For data that the Holder does
   not want to reveal to the Verifier, the Holder MUST NOT send
   Disclosures or reveal the salt values in any other way.

   A Holder MUST NOT send a Disclosure that was not included in the SD-
   JWT or send a Disclosure more than once.

5.1.  Issuer-signed JWT Payload

   An SD-JWT has a JWT component that MUST be signed using the Issuer's
   private key.  It MUST use a JWS asymmetric digital signature
   algorithm.  It MUST NOT use none or an identifier for a symmetric
   algorithm (MAC).

   The payload of an SD-JWT is a JSON object according to the following
   rules:

   1.  The payload MAY contain the _sd_alg key described in
       Section 5.1.1.

   2.  The payload MAY contain one or more digests of Disclosures to
       enable selective disclosure of the respective claims, created and
       formatted as described in Section 5.2.

   3.  The payload MAY contain one or more decoy digests to obscure the
       actual number of claims in the SD-JWT, created and formatted as
       described in Section 5.2.5.

   4.  The payload MAY contain one or more non-selectively disclosable
       claims.

   5.  The payload MAY contain the Holder's public key(s) or
       reference(s) thereto, as explained in Section 5.1.2.

   6.  The payload MAY contain further claims such as iss, iat, etc. as
       defined or required by the application using SD-JWTs.

   7.  The payload MUST NOT contain the reserved claims _sd or ...
       except for the purpose of transporting digests as described
       below.

   The same digest value MUST NOT appear more than once in the SD-JWT.

   Applications of SD-JWT SHOULD be explicitly typed using the typ
   header parameter.  See Section 11.12 for more details.

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   It is the Issuer who decides which claims are selectively disclosable
   and which are not.  End-User claims MAY be included as plaintext as
   well, e.g., if hiding the particular claims from the Verifier is not
   required in the intended use case.  See Section 11.8 for
   considerations on making validity-controlling claims such as exp
   selectively disclosable.

   Claims that are not selectively disclosable are included in the SD-
   JWT in plaintext just as they would be in any other JSON structure.

5.1.1.  Hash Function Claim

   The claim _sd_alg indicates the hash algorithm used by the Issuer to
   generate the digests as described in Section 5.2.  When used, this
   claim MUST appear at the top level of the SD-JWT payload.  It MUST
   NOT be used in any object nested within the payload.  If the _sd_alg
   claim is not present at the top level, a default value of sha-256
   MUST be used.

   The hash algorithm identifier MUST be a hash algorithm value from the
   "Hash Name String" column in the IANA "Named Information Hash
   Algorithm" registry [IANA.Hash.Algorithms] or a value defined in
   another specification and/or profile of this specification.

   To promote interoperability, implementations MUST support the sha-256
   hash algorithm.

   See Section 11 for requirements regarding entropy of the salt,
   minimum length of the salt, and choice of a hash algorithm.

5.1.2.  Holder Public Key Claim

   If the Issuer wants to enable Key Binding, it includes a public key
   associated with the Holder, or a reference thereto.

   It is out of the scope of this document to describe how the Holder
   key pair is established.  For example, the Holder MAY create a key
   pair and provide a public key to the Issuer, the Issuer MAY create
   the key pair for the Holder, or Holder and Issuer MAY use pre-
   established key material.

   Note: The examples in this document use the cnf claim defined in
   [RFC7800] to include the raw public key by value in SD-JWT.

5.2.  Disclosures

   Disclosures are created differently depending on whether a claim is
   an object property (key-value pair) or an array element.

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   *  For a claim that is an object property, the Issuer creates a
      Disclosure as described in Section 5.2.1.

   *  For a claim that is an array element, the Issuer creates a
      Disclosure as described in Section 5.2.2.

5.2.1.  Disclosures for Object Properties

   For each claim that is an object property and that is to be made
   selectively disclosable, the Issuer MUST create a Disclosure as
   follows:

   *  Create an array of three elements in this order:

      1.  A salt value.  MUST be a string.  See Section 11.3 and
          Section 11.4 for security considerations.  It is RECOMMENDED
          to base64url-encode minimum 128 bits of cryptographically
          secure random data, producing a string.  The salt value MUST
          be unique for each claim that is to be selectively disclosed.
          The Issuer MUST NOT disclose the salt value to any party other
          than the Holder.

      2.  The claim name, or key, as it would be used in a regular JWT
          payload.  The value MUST be a string.  The value MUST NOT be
          _sd, ..., or a claim name existing in the object as a non-
          selectively disclosable claim.

      3.  The claim value, as it would be used in a regular JWT payload.
          The value MAY be of any type that is allowed in JSON,
          including numbers, strings, booleans, arrays, and objects.

   *  JSON-encode the array, producing an UTF-8 string.

   *  base64url-encode the byte representation of the UTF-8 string,
      producing a US-ASCII [RFC0020] string.  This string is the
      Disclosure.

   The order is decided based on the readability considerations: salts
   would have a constant length within the SD-JWT, claim names would be
   around the same length all the time, and claim values would vary in
   size, potentially being large objects.

   The following example illustrates the steps described above.

   The array is created as follows:

   ["_26bc4LT-ac6q2KI6cBW5es", "family_name", "Möbius"]

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   The resulting Disclosure would be: WyJfMjZiYzRMVC1hYzZxMktJNmNCVzVlcy
   IsICJmYW1pbHlfbmFtZSIsICJNw7ZiaXVzIl0

   Note that variations in whitespace, encoding of Unicode characters,
   ordering of object properties, etc., are allowed in the JSON
   representation and no canonicalization needs be performed before
   base64url-encoding.  For example, the following strings are all valid
   and encode the same claim value "Möbius":

   *  A different way to encode the unicode umlaut:
      WyJfMjZiYzRMVC1hYzZxMktJNmNCVzVlcyIsICJmYW1pbHlfbmFtZSIsICJNX
      HUwMGY2Yml1cyJd

   *  No white space:
      WyJfMjZiYzRMVC1hYzZxMktJNmNCVzVlcyIsImZhbWlseV9uYW1lIiwiTcO2Y
      ml1cyJd

   *  Newline characters between elements:
      WwoiXzI2YmM0TFQtYWM2cTJLSTZjQlc1ZXMiLAoiZmFtaWx5X25hbWUiLAoiT
      cO2Yml1cyIKXQ

   See Appendix B for some further considerations on the Disclosure
   format approach.

5.2.2.  Disclosures for Array Elements

   For each claim that is an array element and that is to be made
   selectively disclosable, the Issuer MUST create a Disclosure as
   follows:

   *  The array MUST contain two elements in this order:

      1.  The salt value as described in Section 5.2.1.

      2.  The array element that is to be hidden.  This value MAY be of
          any type that is allowed in JSON, including numbers, strings,
          booleans, arrays, and objects.

   The Disclosure string is created by JSON-encoding this array and
   base64url-encoding the byte representation of the resulting string as
   described in Section 5.2.1.  The same considerations regarding
   variations in the result of the JSON encoding apply.

   For example, a Disclosure for the second element of the nationalities
   array in the following claim set:

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   {
     "nationalities": ["DE", "FR"]
   }

   could be created by first creating the following array:

   ["lklxF5jMYlGTPUovMNIvCA", "FR"]

   The resulting Disclosure would be:
   WyJsa2x4RjVqTVlsR1RQVW92TU5JdkNBIiwgIkZSIl0

5.2.3.  Hashing Disclosures

   For embedding the Disclosures in the SD-JWT, the Disclosures are
   hashed using the hash algorithm specified in the _sd_alg claim
   described in Section 5.1.1.  The resulting digest is then included in
   the SD-JWT payload instead of the original claim value, as described
   next.

   The digest MUST be taken over the US-ASCII bytes of the base64url-
   encoded Disclosure.  This follows the convention in JWS [RFC7515] and
   JWE [RFC7516].  The bytes of the digest MUST then be base64url-
   encoded.

   It is important to note that:

   *  The input to the hash function MUST be the base64url-encoded
      Disclosure, not the bytes encoded by the base64url string.

   *  The bytes of the output of the hash function MUST be base64url-
      encoded, and are not the bytes making up the (often used) hex
      representation of the bytes of the digest.

   For example, the SHA-256 digest of the Disclosure
   WyI2cU1RdlJMNWhhaiIsICJmYW1pbHlfbmFtZSIsICJNw7ZiaXVzIl0 would be
   uutlBuYeMDyjLLTpf6Jxi7yNkEF35jdyWMn9U7b_RYY.

   The SHA-256 digest of the Disclosure
   WyJsa2x4RjVqTVlsR1RQVW92TU5JdkNBIiwgIkZSIl0 would be
   w0I8EKcdCtUPkGCNUrfwVp2xEgNjtoIDlOxc9-PlOhs.

5.2.4.  Embedding Disclosure Digests in SD-JWTs

   For selectively disclosable claims, the digests of the Disclosures
   are embedded into the Issuer-signed JWT instead of the claims
   themselves.  The precise way of embedding depends on whether a claim
   is an object property (key-value pair) or an array element.

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   *  For a claim that is an object property, the Issuer embeds a
      Disclosure digest as described in Section 5.2.4.1.

   *  For a claim that is an array element, the Issuer creates a
      Disclosure digest as described in Section 5.2.4.2.

5.2.4.1.  Object Properties

   Digests of Disclosures for object properties are added to an array
   under the new key _sd in the object.  The _sd key MUST refer to an
   array of strings, each string being a digest of a Disclosure or a
   decoy digest as described in Section 5.2.5.

   The array MAY be empty in case the Issuer decided not to selectively
   disclose any of the claims at that level.  However, it is RECOMMENDED
   to omit the _sd key in this case to save space.

   The Issuer MUST hide the original order of the claims in the array.
   To ensure this, it is RECOMMENDED to shuffle the array of hashes,
   e.g., by sorting it alphanumerically or randomly, after potentially
   adding decoy digests as described in Section 5.2.5.  The precise
   method does not matter as long as it does not depend on the original
   order of elements.

   For example, using the digest of the object property Disclosure
   created above, the Issuer could create the following SD-JWT payload
   to make family_name selectively disclosable:

   {
     "given_name": "Alice",
     "_sd": ["uutlBuYeMDyjLLTpf6Jxi7yNkEF35jdyWMn9U7b_RYY"]
   }

5.2.4.2.  Array Elements

   Digests of Disclosures for array elements are added to the array in
   the same position as the original claim value in the array.  For each
   digest, an object of the form {"...": "<digest>"} is added to the
   array.  The key MUST always be the string ... (three dots).  The
   value MUST be the digest of the Disclosure created as described in
   Section 5.2.3.  There MUST NOT be any other keys in the object.

   For example, using the digest of the array element Disclosure created
   above, the Issuer could create the following SD-JWT payload to make
   the second element of the nationalities array selectively
   disclosable:

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   {
     "nationalities":
       ["DE", {"...": "w0I8EKcdCtUPkGCNUrfwVp2xEgNjtoIDlOxc9-PlOhs"}]
   }

   As described in Section 8.3, Verifiers ignore all selectively
   disclosable array elements for which they did not receive a
   Disclosure.  In the example above, the verification process would
   output an array with only one element unless a matching Disclosure
   for the second element is received.

5.2.5.  Decoy Digests

   An Issuer MAY add additional digests to the SD-JWT payload that are
   not associated with any claim.  The purpose of such "decoy" digests
   is to make it more difficult for an attacker to see the original
   number of claims contained in the SD-JWT.  Decoy digests MAY be added
   both to the _sd array for objects as well as in arrays.

   It is RECOMMENDED to create the decoy digests by hashing over a
   cryptographically secure random number.  The bytes of the digest MUST
   then be base64url-encoded as above.  The same digest function as for
   the Disclosures MUST be used.

   For decoy digests, no Disclosure is sent to the Holder, i.e., the
   Holder will see digests that do not correspond to any Disclosure.
   See Section 12.3 for additional privacy considerations.

   To ensure readability and replicability, the examples in this
   specification do not contain decoy digests unless explicitly stated.
   For an example with decoy digests, see Appendix A.1.

5.3.  Key Binding JWT

   This section defines the contents of the optional Key Binding JWT,
   which the Holder MAY include in the SD-JWT to prove the Key Binding
   to the Verifier.

   The JWT MUST contain the following elements:

   *  in the JOSE header,

      -  typ: REQUIRED.  MUST be kb+jwt, which explicitly types the Key
         Binding JWT as recommended in Section 3.11 of [RFC8725].

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      -  alg: REQUIRED.  A digital signature algorithm identifier such
         as per IANA "JSON Web Signature and Encryption Algorithms"
         registry.  MUST NOT be none or an identifier for a symmetric
         algorithm (MAC).

   *  in the JWT payload,

      -  iat: REQUIRED.  The value of this claim MUST be the time at
         which the Key Binding JWT was issued using the syntax defined
         in [RFC7519].

      -  aud: REQUIRED.  The intended receiver of the Key Binding JWT.
         How the value is represented is up to the protocol used and out
         of scope of this specification.

      -  nonce: REQUIRED.  Ensures the freshness of the signature.  The
         value type of this claim MUST be a string.  How this value is
         obtained is up to the protocol used and out of scope of this
         specification.

      -  _sd_hash: REQUIRED.  The base64url-encoded hash digest over the
         Issuer-signed JWT and the selected Disclosures as defined
         below.

5.3.1.  Integrity Protection of the Presentation

   The hash digest in _sd_hash ensures the integrity of the
   Presentation.  It MUST be taken over the US-ASCII bytes preceding the
   KB-JWT in the Presentation, i.e., the Issuer-signed JWT, a tilde
   character, and zero or more Disclosures selected for presentation to
   the Verifier, each followed by a tilde character:

   <Issuer-signed JWT>~<Disclosure 1>~<Disclosure 2>~...~<Disclosure N>~

   The bytes of the digest MUST then be base64url-encoded.

   The same hash algorithm as for the Disclosures MUST be used (defined
   by the _sd_alg element in the Issuer-signed JWT or the default value,
   as defined in Section 5.1.1).

5.3.2.  Validating the Key Binding JWT

   To validate the signature on the Key Binding JWT, the Verifier MUST
   use the key material in the SD-JWT.  If it is not clear from the SD-
   JWT, the Key Binding JWT MUST specify which key material the Verifier
   needs to use to validate the Key Binding JWT signature using JOSE
   header parameters such as kid and x5c.

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   Whether to require Key Binding is up to the Verifier's policy, based
   on the set of trust requirements such as trust frameworks it belongs
   to.  See Section 11.6 for security considerations.

5.3.3.  Alternatives to a Key Binding JWT

   Other ways of proving Key Binding MAY be used when supported by the
   Verifier, e.g., when the presented SD-JWT without a Key Binding JWT
   is itself embedded in a signed JWT.  See Section 10 for details.

6.  Example 1: SD-JWT

   In this example, a simple SD-JWT is demonstrated.  This example is
   split into issuance and presentation.

   Note: Throughout the examples in this document, line breaks had to be
   added to JSON strings and base64-encoded strings to adhere to the 72
   character limit for lines in RFCs and for readability.  JSON does not
   allow line breaks within strings.

6.1.  Issuance

   The Issuer is using the following input claim set:

   {
     "sub": "user_42",
     "given_name": "John",
     "family_name": "Doe",
     "email": "johndoe@example.com",
     "phone_number": "+1-202-555-0101",
     "phone_number_verified": true,
     "address": {
       "street_address": "123 Main St",
       "locality": "Anytown",
       "region": "Anystate",
       "country": "US"
     },
     "birthdate": "1940-01-01",
     "updated_at": 1570000000,
     "nationalities": [
       "US",
       "DE"
     ]
   }

   The Issuer in this case made the following decisions:

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   *  The nationalities array is always visible, but its contents are
      selectively disclosable.

   *  The sub element and essential verification data (iss, iat, cnf,
      etc.) are always visible.

   *  All other End-User claims are selectively disclosable.

   *  For address, the Issuer is using a flat structure, i.e., all of
      the claims in the address claim can only be disclosed in full.
      Other options are discussed in Section 7.

   The following payload is used for the SD-JWT:

   {
     "_sd": [
       "CrQe7S5kqBAHt-nMYXgc6bdt2SH5aTY1sU_M-PgkjPI",
       "JzYjH4svliH0R3PyEMfeZu6Jt69u5qehZo7F7EPYlSE",
       "PorFbpKuVu6xymJagvkFsFXAbRoc2JGlAUA2BA4o7cI",
       "TGf4oLbgwd5JQaHyKVQZU9UdGE0w5rtDsrZzfUaomLo",
       "XQ_3kPKt1XyX7KANkqVR6yZ2Va5NrPIvPYbyMvRKBMM",
       "XzFrzwscM6Gn6CJDc6vVK8BkMnfG8vOSKfpPIZdAfdE",
       "gbOsI4Edq2x2Kw-w5wPEzakob9hV1cRD0ATN3oQL9JM",
       "jsu9yVulwQQlhFlM_3JlzMaSFzglhQG0DpfayQwLUK4"
     ],
     "iss": "https://issuer.example.com",
     "iat": 1683000000,
     "exp": 1883000000,
     "sub": "user_42",
     "nationalities": [
       {
         "...": "pFndjkZ_VCzmyTa6UjlZo3dh-ko8aIKQc9DlGzhaVYo"
       },
       {
         "...": "7Cf6JkPudry3lcbwHgeZ8khAv1U1OSlerP0VkBJrWZ0"
       }
     ],
     "_sd_alg": "sha-256",
     "cnf": {
       "jwk": {
         "kty": "EC",
         "crv": "P-256",
         "x": "TCAER19Zvu3OHF4j4W4vfSVoHIP1ILilDls7vCeGemc",
         "y": "ZxjiWWbZMQGHVWKVQ4hbSIirsVfuecCE6t4jT9F2HZQ"
       }
     }
   }

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   The following Disclosures are created by the Issuer:

   *Claim given_name*:

   *  SHA-256 Hash: jsu9yVulwQQlhFlM_3JlzMaSFzglhQG0DpfayQwLUK4

   *  Disclosure:
      WyIyR0xDNDJzS1F2ZUNmR2ZyeU5STjl3IiwgImdpdmVuX25hbWUiLCAiSm9o
      biJd

   *  Contents: ["2GLC42sKQveCfGfryNRN9w", "given_name", "John"]

   *Claim family_name*:

   *  SHA-256 Hash: TGf4oLbgwd5JQaHyKVQZU9UdGE0w5rtDsrZzfUaomLo

   *  Disclosure:
      WyJlbHVWNU9nM2dTTklJOEVZbnN4QV9BIiwgImZhbWlseV9uYW1lIiwgIkRv
      ZSJd

   *  Contents: ["eluV5Og3gSNII8EYnsxA_A", "family_name", "Doe"]

   *Claim email*:

   *  SHA-256 Hash: JzYjH4svliH0R3PyEMfeZu6Jt69u5qehZo7F7EPYlSE

   *  Disclosure:
      WyI2SWo3dE0tYTVpVlBHYm9TNXRtdlZBIiwgImVtYWlsIiwgImpvaG5kb2VA
      ZXhhbXBsZS5jb20iXQ

   *  Contents: ["6Ij7tM-a5iVPGboS5tmvVA", "email",
      "johndoe@example.com"]

   *Claim phone_number*:

   *  SHA-256 Hash: PorFbpKuVu6xymJagvkFsFXAbRoc2JGlAUA2BA4o7cI

   *  Disclosure:
      WyJlSThaV205UW5LUHBOUGVOZW5IZGhRIiwgInBob25lX251bWJlciIsICIr
      MS0yMDItNTU1LTAxMDEiXQ

   *  Contents: ["eI8ZWm9QnKPpNPeNenHdhQ", "phone_number",
      "+1-202-555-0101"]

   *Claim phone_number_verified*:

   *  SHA-256 Hash: XQ_3kPKt1XyX7KANkqVR6yZ2Va5NrPIvPYbyMvRKBMM

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   *  Disclosure:
      WyJRZ19PNjR6cUF4ZTQxMmExMDhpcm9BIiwgInBob25lX251bWJlcl92ZXJp
      ZmllZCIsIHRydWVd

   *  Contents: ["Qg_O64zqAxe412a108iroA", "phone_number_verified",
      true]

   *Claim address*:

   *  SHA-256 Hash: XzFrzwscM6Gn6CJDc6vVK8BkMnfG8vOSKfpPIZdAfdE

   *  Disclosure:
      WyJBSngtMDk1VlBycFR0TjRRTU9xUk9BIiwgImFkZHJlc3MiLCB7InN0cmVl
      dF9hZGRyZXNzIjogIjEyMyBNYWluIFN0IiwgImxvY2FsaXR5IjogIkFueXRv
      d24iLCAicmVnaW9uIjogIkFueXN0YXRlIiwgImNvdW50cnkiOiAiVVMifV0

   *  Contents: ["AJx-095VPrpTtN4QMOqROA", "address", {"street_address":
      "123 Main St", "locality": "Anytown", "region": "Anystate",
      "country": "US"}]

   *Claim birthdate*:

   *  SHA-256 Hash: gbOsI4Edq2x2Kw-w5wPEzakob9hV1cRD0ATN3oQL9JM

   *  Disclosure:
      WyJQYzMzSk0yTGNoY1VfbEhnZ3ZfdWZRIiwgImJpcnRoZGF0ZSIsICIxOTQw
      LTAxLTAxIl0

   *  Contents: ["Pc33JM2LchcU_lHggv_ufQ", "birthdate", "1940-01-01"]

   *Claim updated_at*:

   *  SHA-256 Hash: CrQe7S5kqBAHt-nMYXgc6bdt2SH5aTY1sU_M-PgkjPI

   *  Disclosure:
      WyJHMDJOU3JRZmpGWFE3SW8wOXN5YWpBIiwgInVwZGF0ZWRfYXQiLCAxNTcw
      MDAwMDAwXQ

   *  Contents: ["G02NSrQfjFXQ7Io09syajA", "updated_at", 1570000000]

   *Array Entry*:

   *  SHA-256 Hash: pFndjkZ_VCzmyTa6UjlZo3dh-ko8aIKQc9DlGzhaVYo

   *  Disclosure:
      WyJsa2x4RjVqTVlsR1RQVW92TU5JdkNBIiwgIlVTIl0

   *  Contents: ["lklxF5jMYlGTPUovMNIvCA", "US"]

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   *Array Entry*:

   *  SHA-256 Hash: 7Cf6JkPudry3lcbwHgeZ8khAv1U1OSlerP0VkBJrWZ0

   *  Disclosure:
      WyJuUHVvUW5rUkZxM0JJZUFtN0FuWEZBIiwgIkRFIl0

   *  Contents: ["nPuoQnkRFq3BIeAm7AnXFA", "DE"]

   The payload is then signed by the Issuer to create a JWT like the
   following:

   eyJhbGciOiAiRVMyNTYifQ.eyJfc2QiOiBbIkNyUWU3UzVrcUJBSHQtbk1ZWGdjNmJkd
   DJTSDVhVFkxc1VfTS1QZ2tqUEkiLCAiSnpZakg0c3ZsaUgwUjNQeUVNZmVadTZKdDY5d
   TVxZWhabzdGN0VQWWxTRSIsICJQb3JGYnBLdVZ1Nnh5bUphZ3ZrRnNGWEFiUm9jMkpHb
   EFVQTJCQTRvN2NJIiwgIlRHZjRvTGJnd2Q1SlFhSHlLVlFaVTlVZEdFMHc1cnREc3Jae
   mZVYW9tTG8iLCAiWFFfM2tQS3QxWHlYN0tBTmtxVlI2eVoyVmE1TnJQSXZQWWJ5TXZSS
   0JNTSIsICJYekZyendzY002R242Q0pEYzZ2Vks4QmtNbmZHOHZPU0tmcFBJWmRBZmRFI
   iwgImdiT3NJNEVkcTJ4Mkt3LXc1d1BFemFrb2I5aFYxY1JEMEFUTjNvUUw5Sk0iLCAia
   nN1OXlWdWx3UVFsaEZsTV8zSmx6TWFTRnpnbGhRRzBEcGZheVF3TFVLNCJdLCAiaXNzI
   jogImh0dHBzOi8vaXNzdWVyLmV4YW1wbGUuY29tIiwgImlhdCI6IDE2ODMwMDAwMDAsI
   CJleHAiOiAxODgzMDAwMDAwLCAic3ViIjogInVzZXJfNDIiLCAibmF0aW9uYWxpdGllc
   yI6IFt7Ii4uLiI6ICJwRm5kamtaX1ZDem15VGE2VWpsWm8zZGgta284YUlLUWM5RGxHe
   mhhVllvIn0sIHsiLi4uIjogIjdDZjZKa1B1ZHJ5M2xjYndIZ2VaOGtoQXYxVTFPU2xlc
   lAwVmtCSnJXWjAifV0sICJfc2RfYWxnIjogInNoYS0yNTYiLCAiY25mIjogeyJqd2siO
   iB7Imt0eSI6ICJFQyIsICJjcnYiOiAiUC0yNTYiLCAieCI6ICJUQ0FFUjE5WnZ1M09IR
   jRqNFc0dmZTVm9ISVAxSUxpbERsczd2Q2VHZW1jIiwgInkiOiAiWnhqaVdXYlpNUUdIV
   ldLVlE0aGJTSWlyc1ZmdWVjQ0U2dDRqVDlGMkhaUSJ9fX0.OeQrinudSFTXNysz2NuNQ
   rwWJv-P9gQ-Ce3wWEYZkxngeA4GKfPfApdNzBa40dH1urt8tXhW2WQl-I00v8teuw

   The issued SD-JWT might look as follows:

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   eyJhbGciOiAiRVMyNTYifQ.eyJfc2QiOiBbIkNyUWU3UzVrcUJBSHQtbk1ZWGdjNmJkd
   DJTSDVhVFkxc1VfTS1QZ2tqUEkiLCAiSnpZakg0c3ZsaUgwUjNQeUVNZmVadTZKdDY5d
   TVxZWhabzdGN0VQWWxTRSIsICJQb3JGYnBLdVZ1Nnh5bUphZ3ZrRnNGWEFiUm9jMkpHb
   EFVQTJCQTRvN2NJIiwgIlRHZjRvTGJnd2Q1SlFhSHlLVlFaVTlVZEdFMHc1cnREc3Jae
   mZVYW9tTG8iLCAiWFFfM2tQS3QxWHlYN0tBTmtxVlI2eVoyVmE1TnJQSXZQWWJ5TXZSS
   0JNTSIsICJYekZyendzY002R242Q0pEYzZ2Vks4QmtNbmZHOHZPU0tmcFBJWmRBZmRFI
   iwgImdiT3NJNEVkcTJ4Mkt3LXc1d1BFemFrb2I5aFYxY1JEMEFUTjNvUUw5Sk0iLCAia
   nN1OXlWdWx3UVFsaEZsTV8zSmx6TWFTRnpnbGhRRzBEcGZheVF3TFVLNCJdLCAiaXNzI
   jogImh0dHBzOi8vaXNzdWVyLmV4YW1wbGUuY29tIiwgImlhdCI6IDE2ODMwMDAwMDAsI
   CJleHAiOiAxODgzMDAwMDAwLCAic3ViIjogInVzZXJfNDIiLCAibmF0aW9uYWxpdGllc
   yI6IFt7Ii4uLiI6ICJwRm5kamtaX1ZDem15VGE2VWpsWm8zZGgta284YUlLUWM5RGxHe
   mhhVllvIn0sIHsiLi4uIjogIjdDZjZKa1B1ZHJ5M2xjYndIZ2VaOGtoQXYxVTFPU2xlc
   lAwVmtCSnJXWjAifV0sICJfc2RfYWxnIjogInNoYS0yNTYiLCAiY25mIjogeyJqd2siO
   iB7Imt0eSI6ICJFQyIsICJjcnYiOiAiUC0yNTYiLCAieCI6ICJUQ0FFUjE5WnZ1M09IR
   jRqNFc0dmZTVm9ISVAxSUxpbERsczd2Q2VHZW1jIiwgInkiOiAiWnhqaVdXYlpNUUdIV
   ldLVlE0aGJTSWlyc1ZmdWVjQ0U2dDRqVDlGMkhaUSJ9fX0.OeQrinudSFTXNysz2NuNQ
   rwWJv-P9gQ-Ce3wWEYZkxngeA4GKfPfApdNzBa40dH1urt8tXhW2WQl-I00v8teuw~Wy
   IyR0xDNDJzS1F2ZUNmR2ZyeU5STjl3IiwgImdpdmVuX25hbWUiLCAiSm9obiJd~WyJlb
   HVWNU9nM2dTTklJOEVZbnN4QV9BIiwgImZhbWlseV9uYW1lIiwgIkRvZSJd~WyI2SWo3
   dE0tYTVpVlBHYm9TNXRtdlZBIiwgImVtYWlsIiwgImpvaG5kb2VAZXhhbXBsZS5jb20i
   XQ~WyJlSThaV205UW5LUHBOUGVOZW5IZGhRIiwgInBob25lX251bWJlciIsICIrMS0yM
   DItNTU1LTAxMDEiXQ~WyJRZ19PNjR6cUF4ZTQxMmExMDhpcm9BIiwgInBob25lX251bW
   Jlcl92ZXJpZmllZCIsIHRydWVd~WyJBSngtMDk1VlBycFR0TjRRTU9xUk9BIiwgImFkZ
   HJlc3MiLCB7InN0cmVldF9hZGRyZXNzIjogIjEyMyBNYWluIFN0IiwgImxvY2FsaXR5I
   jogIkFueXRvd24iLCAicmVnaW9uIjogIkFueXN0YXRlIiwgImNvdW50cnkiOiAiVVMif
   V0~WyJQYzMzSk0yTGNoY1VfbEhnZ3ZfdWZRIiwgImJpcnRoZGF0ZSIsICIxOTQwLTAxL
   TAxIl0~WyJHMDJOU3JRZmpGWFE3SW8wOXN5YWpBIiwgInVwZGF0ZWRfYXQiLCAxNTcwM
   DAwMDAwXQ~WyJsa2x4RjVqTVlsR1RQVW92TU5JdkNBIiwgIlVTIl0~WyJuUHVvUW5rUk
   ZxM0JJZUFtN0FuWEZBIiwgIkRFIl0~

6.2.  Presentation

   The following non-normative example shows an associated SD-JWT
   Presentation as it would be sent from the Holder to the Verifier.
   Note that it consists of six ~-separated parts, with the Issuer-
   signed JWT as shown above in the beginning, four Disclosures (for the
   claims given_name, family_name, address, and nationalities) in the
   middle, and the Key Binding JWT as the last element.

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   eyJhbGciOiAiRVMyNTYifQ.eyJfc2QiOiBbIkNyUWU3UzVrcUJBSHQtbk1ZWGdjNmJkd
   DJTSDVhVFkxc1VfTS1QZ2tqUEkiLCAiSnpZakg0c3ZsaUgwUjNQeUVNZmVadTZKdDY5d
   TVxZWhabzdGN0VQWWxTRSIsICJQb3JGYnBLdVZ1Nnh5bUphZ3ZrRnNGWEFiUm9jMkpHb
   EFVQTJCQTRvN2NJIiwgIlRHZjRvTGJnd2Q1SlFhSHlLVlFaVTlVZEdFMHc1cnREc3Jae
   mZVYW9tTG8iLCAiWFFfM2tQS3QxWHlYN0tBTmtxVlI2eVoyVmE1TnJQSXZQWWJ5TXZSS
   0JNTSIsICJYekZyendzY002R242Q0pEYzZ2Vks4QmtNbmZHOHZPU0tmcFBJWmRBZmRFI
   iwgImdiT3NJNEVkcTJ4Mkt3LXc1d1BFemFrb2I5aFYxY1JEMEFUTjNvUUw5Sk0iLCAia
   nN1OXlWdWx3UVFsaEZsTV8zSmx6TWFTRnpnbGhRRzBEcGZheVF3TFVLNCJdLCAiaXNzI
   jogImh0dHBzOi8vaXNzdWVyLmV4YW1wbGUuY29tIiwgImlhdCI6IDE2ODMwMDAwMDAsI
   CJleHAiOiAxODgzMDAwMDAwLCAic3ViIjogInVzZXJfNDIiLCAibmF0aW9uYWxpdGllc
   yI6IFt7Ii4uLiI6ICJwRm5kamtaX1ZDem15VGE2VWpsWm8zZGgta284YUlLUWM5RGxHe
   mhhVllvIn0sIHsiLi4uIjogIjdDZjZKa1B1ZHJ5M2xjYndIZ2VaOGtoQXYxVTFPU2xlc
   lAwVmtCSnJXWjAifV0sICJfc2RfYWxnIjogInNoYS0yNTYiLCAiY25mIjogeyJqd2siO
   iB7Imt0eSI6ICJFQyIsICJjcnYiOiAiUC0yNTYiLCAieCI6ICJUQ0FFUjE5WnZ1M09IR
   jRqNFc0dmZTVm9ISVAxSUxpbERsczd2Q2VHZW1jIiwgInkiOiAiWnhqaVdXYlpNUUdIV
   ldLVlE0aGJTSWlyc1ZmdWVjQ0U2dDRqVDlGMkhaUSJ9fX0.OeQrinudSFTXNysz2NuNQ
   rwWJv-P9gQ-Ce3wWEYZkxngeA4GKfPfApdNzBa40dH1urt8tXhW2WQl-I00v8teuw~Wy
   JlbHVWNU9nM2dTTklJOEVZbnN4QV9BIiwgImZhbWlseV9uYW1lIiwgIkRvZSJd~WyJBS
   ngtMDk1VlBycFR0TjRRTU9xUk9BIiwgImFkZHJlc3MiLCB7InN0cmVldF9hZGRyZXNzI
   jogIjEyMyBNYWluIFN0IiwgImxvY2FsaXR5IjogIkFueXRvd24iLCAicmVnaW9uIjogI
   kFueXN0YXRlIiwgImNvdW50cnkiOiAiVVMifV0~WyIyR0xDNDJzS1F2ZUNmR2ZyeU5ST
   jl3IiwgImdpdmVuX25hbWUiLCAiSm9obiJd~WyJsa2x4RjVqTVlsR1RQVW92TU5JdkNB
   IiwgIlVTIl0~eyJhbGciOiAiRVMyNTYiLCAidHlwIjogImtiK2p3dCJ9.eyJub25jZSI
   6ICIxMjM0NTY3ODkwIiwgImF1ZCI6ICJodHRwczovL3ZlcmlmaWVyLmV4YW1wbGUub3J
   nIiwgImlhdCI6IDE2OTgwNzc3OTAsICJfc2RfaGFzaCI6ICIzNHQ4dkNDX2NfdlZMbk9
   hZEJ0d2g0ZEZ2QkVyU2w5ektPcXdtNmloVF9VIn0.ZlotfwqF9NUTRAShrd8jGSJEB6e
   3Z3EKm-AD5udfzggxfK-lQM4TCKbHK81eV088YTKl-UfM7WSyQpx5wpNpZw

   The following Key Binding JWT payload was created and signed for this
   presentation by the Holder:

   {
     "nonce": "1234567890",
     "aud": "https://verifier.example.org",
     "iat": 1698077790,
     "_sd_hash": "34t8vCC_c_vVLnOadBtwh4dFvBErSl9zKOqwm6ihT_U"
   }

7.  Considerations on Nested Data in SD-JWTs

   Being JSON, an object in an SD-JWT payload MAY contain key-value
   pairs where the value is another object or objects MAY be elements in
   arrays.  In SD-JWT, the Issuer decides for each claim individually,
   on each level of the JSON, whether the claim should be selectively
   disclosable or not.  This choice can be made on each level
   independent from whether keys higher in the hierarchy are selectively
   disclosable.

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   From this it follows that the _sd key containing digests MAY appear
   multiple times in an SD-JWT, and likewise, there MAY be multiple
   arrays within the hierarchy with each having selectively disclosable
   elements.  Digests of selectively disclosable claims MAY even appear
   within other Disclosures.

   The following examples illustrate some of the options an Issuer has.
   It is up to the Issuer to decide which structure to use, depending
   on, for example, the expected use cases for the SD-JWT, requirements
   for privacy, size considerations, or ecosystem requirements.  For
   more examples with nested structures, see Appendix A.1 and
   Appendix A.2.

   The following input claim set is used as an example throughout this
   section:

   {
     "sub": "6c5c0a49-b589-431d-bae7-219122a9ec2c",
     "address": {
       "street_address": "Schulstr. 12",
       "locality": "Schulpforta",
       "region": "Sachsen-Anhalt",
       "country": "DE"
     }
   }

   Important: The following examples of the structures are non-normative
   and are not intended to represent all possible options.  They are
   also not meant to define or restrict how address can be represented
   in an SD-JWT.

7.1.  Example: Flat SD-JWT

   The Issuer can decide to treat the address claim as a block that can
   either be disclosed completely or not at all.  The following example
   shows that in this case, the entire address claim is treated as an
   object in the Disclosure.

   {
     "_sd": [
       "fOBUSQvo46yQO-wRwXBcGqvnbKIueISEL961_Sjd4do"
     ],
     "iss": "https://issuer.example.com",
     "iat": 1683000000,
     "exp": 1883000000,
     "sub": "6c5c0a49-b589-431d-bae7-219122a9ec2c",
     "_sd_alg": "sha-256"
   }

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   The Issuer would create the following Disclosure:

   *Claim address*:

   *  SHA-256 Hash: fOBUSQvo46yQO-wRwXBcGqvnbKIueISEL961_Sjd4do

   *  Disclosure:
      WyIyR0xDNDJzS1F2ZUNmR2ZyeU5STjl3IiwgImFkZHJlc3MiLCB7InN0cmVl
      dF9hZGRyZXNzIjogIlNjaHVsc3RyLiAxMiIsICJsb2NhbGl0eSI6ICJTY2h1
      bHBmb3J0YSIsICJyZWdpb24iOiAiU2FjaHNlbi1BbmhhbHQiLCAiY291bnRy
      eSI6ICJERSJ9XQ

   *  Contents: ["2GLC42sKQveCfGfryNRN9w", "address", {"street_address":
      "Schulstr. 12", "locality": "Schulpforta", "region":
      "Sachsen-Anhalt", "country": "DE"}]

7.2.  Example: Structured SD-JWT

   The Issuer may instead decide to make the address claim contents
   selectively disclosable individually:

   {
     "iss": "https://issuer.example.com",
     "iat": 1683000000,
     "exp": 1883000000,
     "sub": "6c5c0a49-b589-431d-bae7-219122a9ec2c",
     "address": {
       "_sd": [
         "6vh9bq-zS4GKM_7GpggVbYzzu6oOGXrmNVGPHP75Ud0",
         "9gjVuXtdFROCgRrtNcGUXmF65rdezi_6Er_j76kmYyM",
         "KURDPh4ZC19-3tiz-Df39V8eidy1oV3a3H1Da2N0g88",
         "WN9r9dCBJ8HTCsS2jKASxTjEyW5m5x65_Z_2ro2jfXM"
       ]
     },
     "_sd_alg": "sha-256"
   }

   In this case, the Issuer would use the following data in the
   Disclosures for the address sub-claims:

   *Claim street_address*:

   *  SHA-256 Hash: 9gjVuXtdFROCgRrtNcGUXmF65rdezi_6Er_j76kmYyM

   *  Disclosure:
      WyIyR0xDNDJzS1F2ZUNmR2ZyeU5STjl3IiwgInN0cmVldF9hZGRyZXNzIiwg
      IlNjaHVsc3RyLiAxMiJd

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   *  Contents: ["2GLC42sKQveCfGfryNRN9w", "street_address", "Schulstr.
      12"]

   *Claim locality*:

   *  SHA-256 Hash: 6vh9bq-zS4GKM_7GpggVbYzzu6oOGXrmNVGPHP75Ud0

   *  Disclosure:
      WyJlbHVWNU9nM2dTTklJOEVZbnN4QV9BIiwgImxvY2FsaXR5IiwgIlNjaHVs
      cGZvcnRhIl0

   *  Contents: ["eluV5Og3gSNII8EYnsxA_A", "locality", "Schulpforta"]

   *Claim region*:

   *  SHA-256 Hash: KURDPh4ZC19-3tiz-Df39V8eidy1oV3a3H1Da2N0g88

   *  Disclosure:
      WyI2SWo3dE0tYTVpVlBHYm9TNXRtdlZBIiwgInJlZ2lvbiIsICJTYWNoc2Vu
      LUFuaGFsdCJd

   *  Contents: ["6Ij7tM-a5iVPGboS5tmvVA", "region", "Sachsen-Anhalt"]

   *Claim country*:

   *  SHA-256 Hash: WN9r9dCBJ8HTCsS2jKASxTjEyW5m5x65_Z_2ro2jfXM

   *  Disclosure:
      WyJlSThaV205UW5LUHBOUGVOZW5IZGhRIiwgImNvdW50cnkiLCAiREUiXQ

   *  Contents: ["eI8ZWm9QnKPpNPeNenHdhQ", "country", "DE"]

   The Issuer may also make one sub-claim of address non-selectively
   disclosable and hide only the other sub-claims:

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   {
     "iss": "https://issuer.example.com",
     "iat": 1683000000,
     "exp": 1883000000,
     "sub": "6c5c0a49-b589-431d-bae7-219122a9ec2c",
     "address": {
       "_sd": [
         "6vh9bq-zS4GKM_7GpggVbYzzu6oOGXrmNVGPHP75Ud0",
         "9gjVuXtdFROCgRrtNcGUXmF65rdezi_6Er_j76kmYyM",
         "KURDPh4ZC19-3tiz-Df39V8eidy1oV3a3H1Da2N0g88"
       ],
       "country": "DE"
     },
     "_sd_alg": "sha-256"
   }

   In this case there would be no Disclosure for country since it is
   provided in the clear.

7.3.  Example: SD-JWT with Recursive Disclosures

   The Issuer may also decide to make the address claim contents
   selectively disclosable recursively, i.e., the address claim is made
   selectively disclosable as well as its sub-claims:

   {
     "_sd": [
       "HvrKX6fPV0v9K_yCVFBiLFHsMaxcD_114Em6VT8x1lg"
     ],
     "iss": "https://issuer.example.com",
     "iat": 1683000000,
     "exp": 1883000000,
     "sub": "6c5c0a49-b589-431d-bae7-219122a9ec2c",
     "_sd_alg": "sha-256"
   }

   The Issuer creates Disclosures first for the sub-claims and then
   includes their digests in the Disclosure for the address claim:

   *Claim street_address*:

   *  SHA-256 Hash: 9gjVuXtdFROCgRrtNcGUXmF65rdezi_6Er_j76kmYyM

   *  Disclosure:
      WyIyR0xDNDJzS1F2ZUNmR2ZyeU5STjl3IiwgInN0cmVldF9hZGRyZXNzIiwg
      IlNjaHVsc3RyLiAxMiJd

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   *  Contents: ["2GLC42sKQveCfGfryNRN9w", "street_address", "Schulstr.
      12"]

   *Claim locality*:

   *  SHA-256 Hash: 6vh9bq-zS4GKM_7GpggVbYzzu6oOGXrmNVGPHP75Ud0

   *  Disclosure:
      WyJlbHVWNU9nM2dTTklJOEVZbnN4QV9BIiwgImxvY2FsaXR5IiwgIlNjaHVs
      cGZvcnRhIl0

   *  Contents: ["eluV5Og3gSNII8EYnsxA_A", "locality", "Schulpforta"]

   *Claim region*:

   *  SHA-256 Hash: KURDPh4ZC19-3tiz-Df39V8eidy1oV3a3H1Da2N0g88

   *  Disclosure:
      WyI2SWo3dE0tYTVpVlBHYm9TNXRtdlZBIiwgInJlZ2lvbiIsICJTYWNoc2Vu
      LUFuaGFsdCJd

   *  Contents: ["6Ij7tM-a5iVPGboS5tmvVA", "region", "Sachsen-Anhalt"]

   *Claim country*:

   *  SHA-256 Hash: WN9r9dCBJ8HTCsS2jKASxTjEyW5m5x65_Z_2ro2jfXM

   *  Disclosure:
      WyJlSThaV205UW5LUHBOUGVOZW5IZGhRIiwgImNvdW50cnkiLCAiREUiXQ

   *  Contents: ["eI8ZWm9QnKPpNPeNenHdhQ", "country", "DE"]

   *Claim address*:

   *  SHA-256 Hash: HvrKX6fPV0v9K_yCVFBiLFHsMaxcD_114Em6VT8x1lg

   *  Disclosure:
      WyJRZ19PNjR6cUF4ZTQxMmExMDhpcm9BIiwgImFkZHJlc3MiLCB7Il9zZCI6
      IFsiNnZoOWJxLXpTNEdLTV83R3BnZ1ZiWXp6dTZvT0dYcm1OVkdQSFA3NVVk
      MCIsICI5Z2pWdVh0ZEZST0NnUnJ0TmNHVVhtRjY1cmRlemlfNkVyX2o3Nmtt
      WXlNIiwgIktVUkRQaDRaQzE5LTN0aXotRGYzOVY4ZWlkeTFvVjNhM0gxRGEy
      TjBnODgiLCAiV045cjlkQ0JKOEhUQ3NTMmpLQVN4VGpFeVc1bTV4NjVfWl8y
      cm8yamZYTSJdfV0

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   *  Contents: ["Qg_O64zqAxe412a108iroA", "address", {"_sd":
      ["6vh9bq-zS4GKM_7GpggVbYzzu6oOGXrmNVGPHP75Ud0",
      "9gjVuXtdFROCgRrtNcGUXmF65rdezi_6Er_j76kmYyM",
      "KURDPh4ZC19-3tiz-Df39V8eidy1oV3a3H1Da2N0g88",
      "WN9r9dCBJ8HTCsS2jKASxTjEyW5m5x65_Z_2ro2jfXM"]}]

8.  Verification and Processing

8.1.  Verification of the SD-JWT

   Upon receiving an SD-JWT, a Holder or a Verifier MUST ensure that

   *  the Issuer-signed JWT is valid, i.e., it is signed by the Issuer
      and the signature is valid, and

   *  all Disclosures are correct, i.e., their digests are referenced in
      the Issuer-signed JWT.

   The Holder or the Verifier MUST perform the following (or equivalent)
   steps when receiving an SD-JWT:

   1.  Separate the SD-JWT into the Issuer-signed JWT, the Disclosures
       (if any), and the Key Binding JWT (if present).

   2.  Validate the Issuer-signed JWT:

       1.  Ensure that a signing algorithm was used that was deemed
           secure for the application.  Refer to [RFC8725], Sections 3.1
           and 3.2 for details.  The none algorithm MUST NOT be
           accepted.

       2.  Validate the signature over the Issuer-signed JWT.

       3.  Validate the Issuer and that the signing key belongs to this
           Issuer.

       4.  Check that the _sd_alg claim value is understood and the hash
           algorithm is deemed secure.

   3.  Process the Disclosures and embedded digests in the Issuer-signed
       JWT as follows:

       1.  For each Disclosure provided:

           1.  Calculate the digest over the base64url-encoded string as
               described in Section 5.2.3.

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       2.  (*) Identify all embedded digests in the Issuer-signed JWT as
           follows:

           1.  Find all objects having an _sd key that refers to an
               array of strings.

           2.  Find all array elements that are objects with one key,
               that key being ... and referring to a string.

       3.  (**) For each embedded digest found in the previous step:

           1.  Compare the value with the digests calculated previously
               and find the matching Disclosure.  If no such Disclosure
               can be found, the digest MUST be ignored.

           2.  If the digest was found in an object's _sd key:

               1.  If the respective Disclosure is not a JSON-encoded
                   array of three elements (salt, claim name, claim
                   value), the SD-JWT MUST be rejected.

               2.  If the claim name is _sd or ..., the SD-JWT MUST be
                   rejected.

               3.  If the claim name already exists at the level of the
                   _sd key, the SD-JWT MUST be rejected.

               4.  Insert, at the level of the _sd key, a new claim
                   using the claim name and claim value from the
                   Disclosure.

               5.  Recursively process the value using the steps
                   described in (*) and (**).

           3.  If the digest was found in an array element:

               1.  If the respective Disclosure is not a JSON-encoded
                   array of two elements (salt, value), the SD-JWT MUST
                   be rejected.

               2.  Replace the array element with the value from the
                   Disclosure.

               3.  Recursively process the value using the steps
                   described in (*) and (**).

       4.  If any digests were found more than once in the previous
           step, the SD-JWT MUST be rejected.

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       5.  Remove all array elements for which the digest was not found
           in the previous step.

       6.  Remove all _sd keys and their contents from the Issuer-signed
           JWT payload.

       7.  Remove the claim _sd_alg from the SD-JWT payload.

   4.  Check that the SD-JWT is valid using claims such as nbf, iat, and
       exp in the processed payload.  If a required validity-controlling
       claim is missing (see Section 11.8), the SD-JWT MUST be rejected.

   If any step fails, the SD-JWT is not valid and processing MUST be
   aborted.

   It is up to the Holder how to maintain the mapping between the
   Disclosures and the plaintext claim values to be able to display them
   to the End-User when needed.

8.2.  Processing by the Holder

   If a Key Binding JWT is received by a Holder, the SD-JWT SHOULD be
   rejected.

   For presentation to a Verifier, the Holder MUST perform the following
   (or equivalent) steps:

   1.  Decide which Disclosures to release to the Verifier, obtaining
       proper End-User consent if necessary.

   2.  If Key Binding is required, create a Key Binding JWT.

   3.  Assemble the SD-JWT for Presentation, including the Issuer-signed
       JWT, the selected Disclosures and, if applicable, the Key Binding
       JWT.

   4.  Send the Presentation to the Verifier.

8.3.  Verification by the Verifier

   Upon receiving a Presentation, in addition to the checks outlined in
   Section 8.1, Verifiers MUST ensure that

   *  if Key Binding is required, the Key Binding JWT is signed by the
      Holder and valid.

   To this end, Verifiers MUST follow the following steps (or
   equivalent):

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   1.  Determine if Key Binding is to be checked according to the
       Verifier's policy for the use case at hand.  This decision MUST
       NOT be based on whether a Key Binding JWT is provided by the
       Holder or not.  Refer to Section 11.6 for details.

   2.  Process the SD-JWT as defined in Section 8.1.

   3.  If Key Binding is required:

       1.  If Key Binding is provided by means not defined in this
           specification, verify the Key Binding according to the method
           used.

       2.  Otherwise, verify the Key Binding JWT as follows:

           1.  If a Key Binding JWT is not provided, the Verifier MUST
               reject the Presentation.

           2.  Determine the public key for the Holder from the SD-JWT.

           3.  Ensure that a signing algorithm was used that was deemed
               secure for the application.  Refer to [RFC8725], Sections
               3.1 and 3.2 for details.  The none algorithm MUST NOT be
               accepted.

           4.  Validate the signature over the Key Binding JWT.

           5.  Check that the typ of the Key Binding JWT is kb+jwt.

           6.  Check that the creation time of the Key Binding JWT, as
               determined by the iat claim, is within an acceptable
               window.

           7.  Determine that the Key Binding JWT is bound to the
               current transaction and was created for this Verifier
               (replay protection) by validating nonce and aud claims.

           8.  Calculate the digest over the Issuer-signed JWT and
               Disclosures as defined in Section 5.3.1 and verify that
               it matches the value of the _sd_hash claim in the Key
               Binding JWT.

           9.  Check that the Key Binding JWT is valid in all other
               respects, per [RFC7519] and [RFC8725].

   If any step fails, the Presentation is not valid and processing MUST
   be aborted.

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   Otherwise, the processed SD-JWT payload can be passed to the
   application to be used for the intended purpose.

9.  JWS JSON Serialization

   This section describes an optional alternate format for SD-JWT using
   the JWS JSON Serialization from [RFC7515].

   For both the General and Flattened JSON Serialization, the SD-JWT is
   represented as a JSON object according to Section 7.2 of [RFC7515].
   The disclosures (both for issuance and presentation) SHOULD be
   included in the serialized JWS using the member name disclosures at
   the top-level of the JSON object (the same level as the payload
   member).  The value of the disclosures member is an array of strings
   where each element is an individual Disclosure as described in
   Section 5.2.  The Issuer includes a Disclosure for each selectively
   disclosable claim of the SD-JWT payload, whereas the Holder includes
   only the Disclosures selected for the given presentation.

   Alternative methods for conveying the disclosures MAY be used (such
   as including them in a disclosures member of an outer JSON structure
   also containing the JSON Serialized SD-JWT) as dictated by a specific
   application or transport protocol.  However, the details of such
   approaches fall outside the scope of this specification.

   Verification of the JWS JSON serialized SD-JWT follows the same rules
   defined in Section 4.4, except that the SD-JWT does not need to be
   split into component parts, the disclosures can be found in the
   respective member of the JSON object (or elsewhere), and Key Binding
   (if applicable) will be provided by means not specifically defined in
   this specification.

   Using a payload similar to that from Example 1 (#example-1), the
   following is a non-normative example of a JWS JSON serialized SD-JWT
   from an Issuer with all the respective Disclosures.

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   {
     "payload": "eyJfc2QiOiBbIjRIQm42YUlZM1d0dUdHV1R4LXFVajZjZGs2V0JwWn
       lnbHRkRmF2UGE3TFkiLCAiOHNtMVFDZjAyMXBObkhBQ0k1c1A0bTRLWmd5Tk9PQV
       ljVGo5SE5hQzF3WSIsICJTRE43OU5McEFuSFBta3JkZVlkRWE4OVhaZHNrME04RE
       tZU1FPVTJaeFFjIiwgIlh6RnJ6d3NjTTZHbjZDSkRjNnZWSzhCa01uZkc4dk9TS2
       ZwUElaZEFmZEUiLCAiZ2JPc0k0RWRxMngyS3ctdzV3UEV6YWtvYjloVjFjUkQwQV
       ROM29RTDlKTSIsICJqTUNYVnotLTliOHgzN1ljb0RmWFFpbnp3MXdaY2NjZkZSQk
       NGR3FkRzJvIiwgIm9LSTFHZDJmd041V3d2amxGa29oaWRHdmltLTMxT3VsUjNxMG
       hyRE8wNzgiXSwgImlzcyI6ICJodHRwczovL2lzc3Vlci5leGFtcGxlLmNvbSIsIC
       JpYXQiOiAxNjgzMDAwMDAwLCAiZXhwIjogMTg4MzAwMDAwMCwgIl9zZF9hbGciOi
       Aic2hhLTI1NiJ9",
     "protected": "eyJhbGciOiAiRVMyNTYifQ",
     "signature": "9tz3nIr4COwA4VjSkRwk6v1Dt62Q4-zwdidjlCHogtdAYLdtMtbe
       we6b009hobPl3DeG4n-ZNESaS-WMiFWGgA",
     "disclosures": [
       "WyIyR0xDNDJzS1F2ZUNmR2ZyeU5STjl3IiwgInN1YiIsICJqb2huX2RvZV80MiJ
         d",
       "WyJlbHVWNU9nM2dTTklJOEVZbnN4QV9BIiwgImdpdmVuX25hbWUiLCAiSm9obiJ
         d",
       "WyI2SWo3dE0tYTVpVlBHYm9TNXRtdlZBIiwgImZhbWlseV9uYW1lIiwgIkRvZSJ
         d",
       "WyJlSThaV205UW5LUHBOUGVOZW5IZGhRIiwgImVtYWlsIiwgImpvaG5kb2VAZXh
         hbXBsZS5jb20iXQ",
       "WyJRZ19PNjR6cUF4ZTQxMmExMDhpcm9BIiwgInBob25lX251bWJlciIsICIrMS0
         yMDItNTU1LTAxMDEiXQ",
       "WyJBSngtMDk1VlBycFR0TjRRTU9xUk9BIiwgImFkZHJlc3MiLCB7InN0cmVldF9
         hZGRyZXNzIjogIjEyMyBNYWluIFN0IiwgImxvY2FsaXR5IjogIkFueXRvd24iL
         CAicmVnaW9uIjogIkFueXN0YXRlIiwgImNvdW50cnkiOiAiVVMifV0",
       "WyJQYzMzSk0yTGNoY1VfbEhnZ3ZfdWZRIiwgImJpcnRoZGF0ZSIsICIxOTQwLTA
         xLTAxIl0"
     ]
   }

   Below is a non-normative example of a presentation of the JWS JSON
   serialized SD-JWT, where the Holder has selected to disclose
   given_name, family_name, and address.

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   {
     "payload": "eyJfc2QiOiBbIjRIQm42YUlZM1d0dUdHV1R4LXFVajZjZGs2V0JwWn
       lnbHRkRmF2UGE3TFkiLCAiOHNtMVFDZjAyMXBObkhBQ0k1c1A0bTRLWmd5Tk9PQV
       ljVGo5SE5hQzF3WSIsICJTRE43OU5McEFuSFBta3JkZVlkRWE4OVhaZHNrME04RE
       tZU1FPVTJaeFFjIiwgIlh6RnJ6d3NjTTZHbjZDSkRjNnZWSzhCa01uZkc4dk9TS2
       ZwUElaZEFmZEUiLCAiZ2JPc0k0RWRxMngyS3ctdzV3UEV6YWtvYjloVjFjUkQwQV
       ROM29RTDlKTSIsICJqTUNYVnotLTliOHgzN1ljb0RmWFFpbnp3MXdaY2NjZkZSQk
       NGR3FkRzJvIiwgIm9LSTFHZDJmd041V3d2amxGa29oaWRHdmltLTMxT3VsUjNxMG
       hyRE8wNzgiXSwgImlzcyI6ICJodHRwczovL2lzc3Vlci5leGFtcGxlLmNvbSIsIC
       JpYXQiOiAxNjgzMDAwMDAwLCAiZXhwIjogMTg4MzAwMDAwMCwgIl9zZF9hbGciOi
       Aic2hhLTI1NiJ9",
     "protected": "eyJhbGciOiAiRVMyNTYifQ",
     "signature": "9tz3nIr4COwA4VjSkRwk6v1Dt62Q4-zwdidjlCHogtdAYLdtMtbe
       we6b009hobPl3DeG4n-ZNESaS-WMiFWGgA",
     "disclosures": [
       "WyI2SWo3dE0tYTVpVlBHYm9TNXRtdlZBIiwgImZhbWlseV9uYW1lIiwgIkRvZSJ
         d",
       "WyJBSngtMDk1VlBycFR0TjRRTU9xUk9BIiwgImFkZHJlc3MiLCB7InN0cmVldF9
         hZGRyZXNzIjogIjEyMyBNYWluIFN0IiwgImxvY2FsaXR5IjogIkFueXRvd24iL
         CAicmVnaW9uIjogIkFueXN0YXRlIiwgImNvdW50cnkiOiAiVVMifV0",
       "WyJlbHVWNU9nM2dTTklJOEVZbnN4QV9BIiwgImdpdmVuX25hbWUiLCAiSm9obiJ
         d"
     ]
   }

10.  Enveloping SD-JWTs

   In some applications or transport protocols, it is desirable to
   encapsulate an SD-JWT into an outer JWT container.  For example, an
   implementation may enclose multiple credentials and presentations,
   independent of their format, in a JWT to enable application-layer
   encryption during transport.

   For such use cases, a compact serialized SD-JWT SHOULD be included as
   a single string value and a JSON serialized SD-JWT SHOULD be included
   as a JSON object value.  Key Binding MAY be achieved by signing the
   envelope JWT instead of including a separate Key Binding JWT.

   The following non-normative example payload shows a compact
   serialized SD-JWT Presentation enveloped in a JWT.  The SD-JWT is
   shown as the value of an _sd_jwt claim where eyJhbGci...emhlaUJhZzBZ
   is the Issuer-signed JWT and eyJhb...dYALCGg is a Disclosure.  The
   SD-JWT does not contain a Key Binding JWT as the outer container can
   be signed instead.

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   {
     "aud": "https://verifier.example.org",
     "iat": 1580000000,
     "nonce": "iRnRdKuu1AtLM4ltc16by2XF0accSeutUescRw6BWC14",
     "_sd_jwt": "eyJhbGci...emhlaUJhZzBZ~eyJhb...dYALCGg~"
   }

   This next non-normative example payload shows a JSON serialized SD-
   JWT enveloped in a JWT.  The JSON serialized SD-JWT appears as the
   value of an _js_sd_jwt claim and the disclosures are included
   separately as a top-level claim.  Key Binding is achieved by the
   signature on the enclosing JWT.

   {
     "aud": "https://verifier.example.org",
     "iat": 2813308004,
     "nonce": "8z8z9X3jUtbthem84swFAzp4aqlHf-sCqQ6eM_qmpUQ",
     "_js_sd_jwt": {
       "protected": "eyJhbGciOiAiRVMyNTYifQ",
       "payload": "eyJfc2QiOiBbIjRIQm42YUlZM1d0dUdHV1R4LX...1NiJ9",
       "signature": "y_b8KFVc2GZ1n-...PKsjU3Q",
     }
     "disclosures": [
       "WyI2SWo3dE0tYTVpVlBHYm9TNXRtdlZBIiwgImZhbWlseV9uYW1...vZSJd",
       "WyJBSngtMDk1VlBycFR0TjRRTU9xUk9BIiwgImFkZHJlc3MiLC...iVVMifV0",
       "WyJlbHVWNU9nM2dTTklJO...V9BIiwgImdpdmVuX25hbWUiLCAiSm9obiJd"
    ]
   }

   Other specifications or profiles of this specification may define
   alternative formats for transporting an SD-JWT that envelope multiple
   such SD-JWTs into one object and provide Key Binding and integrity
   protection of the presentation using means other than the Key Binding
   JWT.

11.  Security Considerations

   Security considerations in this section help achieve the following
   properties:

   *Selective Disclosure:* An adversary in the role of the Verifier
   cannot obtain information from an SD-JWT about any claim name or
   claim value that was not explicitly disclosed by the Holder unless
   that information can be derived from other disclosed claims or
   sources other than the presented SD-JWT.

   *Integrity:* A malicious Holder cannot modify names or values of
   selectively disclosable claims without detection by the Verifier.

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   Additionally, as described in Section 11.6, the application of Key
   Binding can ensure that the presenter of an SD-JWT credential is the
   legitimate Holder of the credential.

11.1.  Mandatory Signing of the Issuer-signed JWT

   The Issuer-signed JWT MUST be signed by the Issuer to protect
   integrity of the issued claims.  An attacker can modify or add claims
   if this JWT is not signed (e.g., change the "email" attribute to take
   over the victim's account or add an attribute indicating a fake
   academic qualification).

   The Verifier MUST always check the signature of the Issuer-signed JWT
   to ensure that it has not been tampered with since the issuance.  The
   Issuer-signed JWT MUST be rejected if the signature cannot be
   verified.

   The security of the Issuer-signed JWT depends on the security of the
   signature algorithm.  Any of the JWS asymmetric digital signature
   algorithms registered in [IANA.JWS.Algorithms] can be used, including
   post-quantum algorithms, when they are ready.

11.2.  Manipulation of Disclosures

   Holders can manipulate the Disclosures by changing the values of the
   claims before sending them to the Verifier.  The Verifier MUST check
   the Disclosures to ensure that the values of the claims are correct,
   i.e., the digests of the Disclosures are actually present in the
   signed SD-JWT.

   A naive Verifier that extracts all claim values from the Disclosures
   (without checking the hashes) and inserts them into the SD-JWT
   payload is vulnerable to this attack.  However, in a structured SD-
   JWT, without comparing the digests of the Disclosures, such an
   implementation could not determine the correct place in a nested
   object where a claim needs to be inserted.  Therefore, the naive
   implementation would not only be insecure, but also incorrect.

   The steps described in Section 8.3 ensure that the Verifier checks
   the Disclosures correctly.

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11.3.  Entropy of the salt

   The security model that conceals the plaintext claims relies on the
   fact that salts not revealed to an attacker cannot be learned or
   guessed by the attacker, even if other salts have been revealed.  It
   is vitally important to adhere to this principle.  As such, each salt
   MUST be created in such a manner that it is cryptographically random,
   long enough, and has high entropy that it is not practical for the
   attacker to guess.  A new salt MUST be chosen for each claim
   independently from other salts.

11.4.  Minimum length of the salt

   The RECOMMENDED minimum length of the randomly-generated portion of
   the salt is 128 bits.

   The Issuer MUST ensure that a new salt value is chosen for each
   claim, including when the same claim name occurs at different places
   in the structure of the SD-JWT.  This can be seen in Example 3 in the
   Appendix, where multiple claims with the name type appear, but each
   of them has a different salt.

11.5.  Choice of a Hash Algorithm

   For the security of this scheme, the hash algorithm is required to be
   preimage resistant and second-preimage resistant, i.e., it is
   infeasible to calculate the salt and claim value that result in a
   particular digest, and, for any salt and claim value pair, it is
   infeasible to find a different salt and claim value pair that result
   in the same digest, respectively.

   Hash algorithms that do not meet the aforementioned requirements MUST
   NOT be used.  Inclusion in the "Named Information Hash Algorithm"
   registry [IANA.Hash.Algorithms] alone does not indicate a hash
   algorithm's suitability for use in SD-JWT (it contains several
   heavily truncated digests, such as sha-256-32 and sha-256-64, which
   are unfit for security applications).

   Furthermore, the hash algorithms MD2, MD4, MD5, and SHA-1 revealed
   fundamental weaknesses and they MUST NOT be used.

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11.6.  Key Binding

   Key Binding aims to ensure that the presenter of an SD-JWT credential
   is actually the legitimate Holder of the credential.  An SD-JWT with
   Key Binding contains a public key, or a reference to a public key,
   that corresponds to a private key possessed by the Holder.  The
   Verifier requires that the Holder prove possession of that private
   key when presenting the SD-JWT credential.

   Without Key Binding, a Verifier only gets the proof that the
   credential was issued by a particular Issuer, but the credential
   itself can be replayed by anyone who gets access to it.  This means
   that, for example, after a credential was leaked to an attacker, the
   attacker can present the credential to any verifier that does not
   require a binding.  But also a malicious Verifier to which the Holder
   presented the credential can present the credential to another
   Verifier if that other Verifier does not require Key Binding.

   Verifiers MUST decide whether Key Binding is required for a
   particular use case before verifying a credential.  This decision can
   be informed by various factors including, but not limited to the
   following: business requirements, the use case, the type of binding
   between a Holder and its credential that is required for a use case,
   the sensitivity of the use case, the expected properties of a
   credential, the type and contents of other credentials expected to be
   presented at the same time, etc.

   It is important that a Verifier does not make its security policy
   decisions based on data that can be influenced by an attacker or that
   can be misinterpreted.  For this reason, when deciding whether Key
   Binding is required or not, Verifiers MUST NOT take into account

   *  whether a Key Binding JWT is present or not, as an attacker can
      remove the Key Binding JWT from any Presentation and present it to
      the Verifier, or

   *  whether Key Binding data is present in the SD-JWT or not, as the
      Issuer might have added the key to the SD-JWT in a format/claim
      that is not recognized by the Verifier.

   If a Verifier has decided that Key Binding is required for a
   particular use case and the Key Binding is not present, does not
   fulfill the requirements (e.g., on the signing algorithm), or no
   recognized Key Binding data is present in the SD-JWT, the Verifier
   will reject the presentation, as described in Section 8.3.

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11.7.  Blinding Claim Names

   SD-JWT ensures that names of claims that are selectively disclosable
   are always blinded.  This prevents an attacker from learning the
   names of the disclosable claims.  However, the names of the claims
   that are not disclosable are not blinded.  This includes the keys of
   objects that themselves are not blinded, but contain disclosable
   claims.  This limitation needs to be taken into account by Issuers
   when creating the structure of the SD-JWT.

11.8.  Selectively-Disclosable Validity Claims

   Claims controlling the validity of the SD-JWT, such as nbf, iat, and
   exp, are usually included in plaintext in the SD-JWT payload, but MAY
   be selectively disclosable instead.  In this case, however, it is up
   to the Holder to release the claims to the Verifier.  A malicious
   Holder may try to hide, for example, an expiration time (exp) in
   order to get a Verifier that "fails open" to accept an expired SD-
   JWT.

   Verifiers therefore MUST ensure that all claims they deem necessary
   for checking the validity of the SD-JWT are present (or disclosed,
   respectively) before checking the validity and accepting the SD-JWT.
   This is implemented in the last step of the verification defined in
   Section 8.1.

   The precise set of required validity claims will typically be defined
   by ecosystem rules or the credential format and MAY include claims
   other than nbf, iat, and exp.

11.9.  Issuer Signature Key Distribution and Rotation

   This specification does not define how signature verification keys of
   Issuers are distributed to Verifiers.  However, it is RECOMMENDED
   that Issuers publish their keys in a way that allows for efficient
   and secure key rotation and revocation, for example, by publishing
   keys at a predefined location using the JSON Web Key Set (JWKS)
   format [RFC7517].  Verifiers need to ensure that they are not using
   expired or revoked keys for signature verification using reasonable
   and appropriate means for the given key-distribution method.

11.10.  Forwarding Credentials

   When Key Binding is not enforced, any entity in possession of an SD-
   JWT Presentation can forward the contents to third parties.  When
   doing so, that entity may remove Disclosures such that the receiver
   learns only a subset of the claims contained in the original SD-JWT.

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   For example, a device manufacturer might produce an SD-JWT containing
   information about upstream and downstream supply chain contributors.
   Each supply chain party can verify only the claims that were
   selectively disclosed to them by an upstream party, and they can
   choose to further reduce the disclosed claims when presenting to a
   downstream party.

   In some scenarios this behavior could be desirable, but if it is not,
   Issuers need to support and Verifiers need to enforce Key Binding.

11.11.  Integrity of Presentation

   In a Presentation, the Issuer-signed JWT is integrity-protected by
   the Issuer's signature, and the Disclosures are integrity-protected
   by the digests included in the Issuer-signed JWT.  If used, the KB-
   JWT, besides proving Key Binding, protects the integrity of the set
   of Disclosures the Holder disclosed.

11.12.  Explicit Typing

   Section 3.11 of [RFC8725] describes the use of explicit typing to
   prevent confusion attacks in which one kind of JWT is mistaken for
   another.  SD-JWTs are also potentially vulnerable to such confusion
   attacks, so it is RECOMMENDED to specify an explicit type by
   including the typ header parameter when the SD-JWT is issued, and for
   Verifiers to check this value.

   When explicit typing is employed for an SD-JWT, it is RECOMMENDED
   that a media type name of the format "application/example+sd-jwt" be
   used, where "example" is replaced by the identifier for the specific
   kind of SD-JWT.  The definition of typ in Section 4.1.9 of [RFC7515]
   recommends that the "application/" prefix be omitted, so "example+sd-
   jwt" would be the value of the typ header parameter.

12.  Privacy Considerations

   The privacy principles of [ISO.29100] should be adhered to.

12.1.  Storage of Signed User Data

   Wherever End-User data is stored, it represents a potential target
   for an attacker.  This target can be of particularly high value when
   the data is signed by a trusted authority like an official national
   identity service.  For example, in OpenID Connect, signed ID Tokens
   can be stored by Relying Parties.  In the case of SD-JWT, Holders
   have to store SD-JWTs, and Issuers and Verifiers may decide to do so
   as well.

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   Not surprisingly, a leak of such data risks revealing private data of
   End-Users to third parties.  Signed End-User data, the authenticity
   of which can be easily verified by third parties, further exacerbates
   the risk.  As discussed in Section 11.6, leaked SD-JWTs may also
   allow attackers to impersonate Holders unless Key Binding is enforced
   and the attacker does not have access to the Holder's cryptographic
   keys.  Altogether, leaked SD-JWT credentials may have a high monetary
   value on black markets.

   Due to these risks, systems implementing SD-JWT SHOULD be designed to
   minimize the amount of data that is stored.  All involved parties
   SHOULD store SD-JWTs containing privacy-sensitive data only for as
   long as needed, including in log files.

   After Issuance, Issuers SHOULD NOT store the Issuer-signed JWT or the
   respective Disclosures if they contain privacy-sensitive data.

   Holders SHOULD store SD-JWTs only in encrypted form, and, wherever
   possible, use hardware-backed encryption in particular for the
   private Key Binding key.  Decentralized storage of data, e.g., on
   End-User devices, SHOULD be preferred for End-User credentials over
   centralized storage.  Expired SD-JWTs SHOULD be deleted as soon as
   possible.

   After Verification, Verifiers SHOULD NOT store the Issuer-signed JWT
   or the respective Disclosures if they contain privacy-sensitive data.
   It may be sufficient to store the result of the verification and any
   End-User data that is needed for the application.

   If reliable and secure key rotation and revocation is ensured
   according to Section 11.9, Issuers may opt to publish expired or
   revoked private signing keys (after a grace period that ensures that
   the keys are not cached any longer at any Verifier).  This reduces
   the value of any leaked credentials as the signatures on them can no
   longer be trusted to originate from the Issuer.

12.2.  Confidentiality during Transport

   If the SD-JWT is transmitted over an insecure channel during issuance
   or presentation, an adversary may be able to intercept and read the
   End-User's personal data or correlate the information with previous
   uses of the same SD-JWT.

   Usually, transport protocols for issuance and presentation of
   credentials are designed to protect the confidentiality of the
   transmitted data, for example, by requiring the use of TLS.

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   This specification therefore considers the confidentiality of the
   data to be provided by the transport protocol and does not specify
   any encryption mechanism.

   Implementers MUST ensure that the transport protocol provides
   confidentiality if the privacy of End-User data or correlation
   attacks by passive observers are a concern.

   To encrypt the SD-JWT when transmitted over an insecure channel,
   implementers MAY use JSON Web Encryption (JWE) [RFC7516] by nesting
   the SD-JWT as the plaintext payload of a JWE.  Especially, when an
   SD-JWT is transmitted via a URL and information may be stored/cached
   in the browser or end up in web server logs, the SD-JWT SHOULD be
   encrypted using JWE.

12.3.  Decoy Digests

   The use of decoy digests is RECOMMENDED when the number of claims (or
   the existence of particular claims) can be a side-channel disclosing
   information about otherwise undisclosed claims.  In particular, if a
   claim in an SD-JWT is present only if a certain condition is met
   (e.g., a membership number is only contained if the End-User is a
   member of a group), the Issuer SHOULD add decoy digests when the
   condition is not met.

   Decoy digests increase the size of the SD-JWT.  The number of decoy
   digests (or whether to use them at all) is a trade-off between the
   size of the SD-JWT and the privacy of the End-User's data.

12.4.  Unlinkability

   Colluding Issuer/Verifier or Verifier/Verifier pairs could link
   issuance/presentation or two presentation sessions to the same user
   on the basis of unique values encoded in the SD-JWT (Issuer
   signature, salts, digests, etc.).

   To prevent these types of linkability, various methods, including but
   not limited to the following ones can be used:

   *  Use advanced cryptographic schemes, outside the scope of this
      specification.

   *  Issue a batch of SD-JWTs to the Holder to enable the Holder to use
      a unique SD-JWT per Verifier.  This only helps with Verifier/
      Verifier unlinkability.

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12.5.  Issuer Identifier

   An Issuer issuing only one type of SD-JWT might have privacy
   implications, because if the Holder has an SD-JWT issued by that
   Issuer, its type and claim names can be determined.

   For example, if the National Cancer Institute only issued SD-JWTs
   with cancer registry information, it is possible to deduce that the
   Holder owning its SD-JWT is a cancer patient.

   Moreover, the issuer identifier alone may reveal information about
   the user.

   For example, when a military organization or a drug rehabilitation
   center issues a vaccine credential, verifiers can deduce that the
   holder is a military member or may have a substance use disorder.

   To mitigate this issue, a group of issuers may elect to use a common
   Issuer identifier.  A group signature scheme outside the scope of
   this specification may also be used, instead of an individual
   signature.

13.  Acknowledgements

   We would like to thank Alen Horvat, Anders Rundgren, Arjan Geluk,
   Christian Bormann, Christian Paquin, David Bakker, David Waite,
   Fabian Hauck, Filip Skokan, Giuseppe De Marco, John Mattsson, Justin
   Richer, Kushal Das, Matthew Miller, Mike Jones, Mike Prorock, Nat
   Sakimura, Oliver Terbu, Orie Steele, Paul Bastian, Pieter Kasselman,
   Ryosuke Abe, Shawn Butterfield, Simon Schulz, Tobias Looker, Takahiko
   Kawasaki, Torsten Lodderstedt, Vittorio Bertocci, and Yaron Sheffer
   for their contributions (some of which substantial) to this draft and
   to the initial set of implementations.

   The work on this draft was started at OAuth Security Workshop 2022 in
   Trondheim, Norway.

14.  IANA Considerations

14.1.  JSON Web Token Claims Registration

   This specification requests registration of the following Claims in
   the IANA "JSON Web Token Claims" registry [IANA.JWT] established by
   [RFC7519].

   *  Claim Name: _sd

   *  Claim Description: Digests of Disclosures for object properties

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   *  Change Controller: IETF

   *  Specification Document(s): [[ Section 5.2.4.1 of this
      specification ]]

   *  Claim Name: ...

   *  Claim Description: Digest of the Disclosure for an array element

   *  Change Controller: IETF

   *  Specification Document(s): [[ Section 5.2.4.2 of this
      specification ]]

   *  Claim Name: _sd_alg

   *  Claim Description: Hash algorithm used to generate disclosure
      digests and digest over presentation

   *  Change Controller: IETF

   *  Specification Document(s): [[ Section 5.1.1 of this specification
      ]]

   *  Claim Name: _sd_hash

   *  Claim Description: Digest of the Issuer-signed JWT and Disclosures
      in a Presentation

   *  Change Controller: IETF

   *  Specification Document(s): [[ Section 5.3 of this specification ]]

14.2.  Media Type Registration

   This section requests registration of the following media types
   [RFC2046] in the "Media Types" registry [IANA.MediaTypes] in the
   manner described in [RFC6838].

   To indicate that the content is an SD-JWT:

   *  Type name: application

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   *  Subtype name: sd-jwt

   *  Required parameters: n/a

   *  Optional parameters: n/a

   *  Encoding considerations: binary; application/sd-jwt values are a
      series of base64url-encoded values (some of which may be the empty
      string) separated by period ('.') or tilde ('~') characters.

   *  Security considerations: See the Security Considerations section
      of [[ this specification ]], [RFC7519], and [RFC8725].

   *  Interoperability considerations: n/a

   *  Published specification: [[ this specification ]]

   *  Applications that use this media type: TBD

   *  Fragment identifier considerations: n/a

   *  Additional information:

      -  Magic number(s): n/a

      -  File extension(s): n/a

      -  Macintosh file type code(s): n/a

   *  Person & email address to contact for further information: Daniel
      Fett, mail@danielfett.de

   *  Intended usage: COMMON

   *  Restrictions on usage: none

   *  Author: Daniel Fett, mail@danielfett.de

   *  Change Controller: IETF

   *  Provisional registration?  No

   To indicate that the content is a JWS JSON serialized SD-JWT:

   *  Type name: application

   *  Subtype name: sd-jwt+json

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   *  Required parameters: n/a

   *  Optional parameters: n/a

   *  Encoding considerations: binary; application/sd-jwt+json values
      are represented as a JSON Object; UTF-8 encoding SHOULD be
      employed for the JSON object.

   *  Security considerations: See the Security Considerations section
      of [[ this specification ]], and [RFC7515].

   *  Interoperability considerations: n/a

   *  Published specification: [[ this specification ]]

   *  Applications that use this media type: TBD

   *  Fragment identifier considerations: n/a

   *  Additional information:

      -  Magic number(s): n/a

      -  File extension(s): n/a

      -  Macintosh file type code(s): n/a

   *  Person & email address to contact for further information: Daniel
      Fett, mail@danielfett.de

   *  Intended usage: COMMON

   *  Restrictions on usage: none

   *  Author: Daniel Fett, mail@danielfett.de

   *  Change Controller: IETF

   *  Provisional registration?  No

   To indicate that the content is a Key Binding JWT:

   *  Type name: application

   *  Subtype name: kb+jwt

   *  Required parameters: n/a

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   *  Optional parameters: n/a

   *  Encoding considerations: binary; A Key Binding JWT is a JWT; JWT
      values are encoded as a series of base64url-encoded values (some
      of which may be the empty string) separated by period ('.')
      characters.

   *  Security considerations: See the Security Considerations section
      of [[ this specification ]], [RFC7519], and [RFC8725].

   *  Interoperability considerations: n/a

   *  Published specification: [[ this specification ]]

   *  Applications that use this media type: TBD

   *  Fragment identifier considerations: n/a

   *  Additional information:

      -  Magic number(s): n/a

      -  File extension(s): n/a

      -  Macintosh file type code(s): n/a

   *  Person & email address to contact for further information: Daniel
      Fett, mail@danielfett.de

   *  Intended usage: COMMON

   *  Restrictions on usage: none

   *  Author: Daniel Fett, mail@danielfett.de

   *  Change Controller: IETF

   *  Provisional registration?  No

14.3.  Structured Syntax Suffix Registration

   This section requests registration of the "+sd-jwt" structured syntax
   suffix in the "Structured Syntax Suffix" registry
   [IANA.StructuredSuffix] in the manner described in [RFC6838], which
   can be used to indicate that the media type is encoded as an SD-JWT.

   *  Name: SD-JWT

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   *  +suffix: +sd-jwt

   *  References: [[ this specification ]]

   *  Encoding considerations: binary; SD-JWT values are a series of
      base64url-encoded values (some of which may be the empty string)
      separated by period ('.') or tilde ('~') characters.

   *  Interoperability considerations: n/a

   *  Fragment identifier considerations: n/a

   *  Security considerations: See the Security Considerations section
      of [[ this specification ]], [RFC7519], and [RFC8725].

   *  Contact: Daniel Fett, mail@danielfett.de

   *  Author/Change controller: IESG

15.  Normative References

   [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>.

   [RFC7516]  Jones, M. and J. Hildebrand, "JSON Web Encryption (JWE)",
              RFC 7516, DOI 10.17487/RFC7516, May 2015,
              <https://www.rfc-editor.org/info/rfc7516>.

   [RFC7519]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web Token
              (JWT)", RFC 7519, DOI 10.17487/RFC7519, May 2015,
              <https://www.rfc-editor.org/info/rfc7519>.

   [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>.

   [RFC8259]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", STD 90, RFC 8259,
              DOI 10.17487/RFC8259, December 2017,
              <https://www.rfc-editor.org/info/rfc8259>.

16.  Informative References

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   [EUDIW.ARF]
              Commission, E., "The European Digital Identity Wallet
              Architecture and Reference Framework", <https://digital-
              strategy.ec.europa.eu/en/library/european-digital-
              identity-wallet-architecture-and-reference-framework>.

   [I-D.terbu-sd-jwt-vc]
              Terbu, O. and D. Fett, "SD-JWT-based Verifiable
              Credentials with JSON payloads (SD-JWT VC)", Work in
              Progress, Internet-Draft, draft-terbu-sd-jwt-vc-02, 26 May
              2023, <https://datatracker.ietf.org/doc/html/draft-terbu-
              sd-jwt-vc-02>.

   [IANA.Hash.Algorithms]
              IANA, "Named Information Hash Algorithm",
              <https://www.iana.org/assignments/named-information/named-
              information.xhtml>.

   [IANA.JWS.Algorithms]
              IANA, "JSON Web Signature and Encryption Algorithms",
              <https://www.iana.org/assignments/jose/jose.xhtml#web-
              signature-encryption-algorithms>.

   [IANA.JWT] IANA, "JSON Web Token Claims",
              <https://www.iana.org/assignments/jwt>.

   [IANA.MediaTypes]
              IANA, "Media Types", <https://www.iana.org/assignments/
              media-types/media-types.xhtml>.

   [IANA.StructuredSuffix]
              IANA, "Structured Syntax Suffixs",
              <https://www.iana.org/assignments/media-type-structured-
              suffix/media-type-structured-suffix.xhtml>.

   [ISO.29100]
              ISO, "ISO/IEC 29100:2011 Information technology — Security
              techniques — Privacy framework",
              <https://standards.iso.org/ittf/
              PubliclyAvailableStandards/index.html>.

   [OIDC.IDA] Lodderstedt, T., Fett, D., Haine, M., Pulido, A., Lehmann,
              K., and K. Koiwai, "OpenID Connect for Identity Assurance
              1.0", <https://openid.net/specs/openid-connect-4-identity-
              assurance-1_0-13.html>.

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   [RFC0020]  Cerf, V., "ASCII format for network interchange", STD 80,
              RFC 20, DOI 10.17487/RFC0020, October 1969,
              <https://www.rfc-editor.org/info/rfc20>.

   [RFC2046]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
              Extensions (MIME) Part Two: Media Types", RFC 2046,
              DOI 10.17487/RFC2046, November 1996,
              <https://www.rfc-editor.org/info/rfc2046>.

   [RFC6838]  Freed, N., Klensin, J., and T. Hansen, "Media Type
              Specifications and Registration Procedures", BCP 13,
              RFC 6838, DOI 10.17487/RFC6838, January 2013,
              <https://www.rfc-editor.org/info/rfc6838>.

   [RFC7515]  Jones, M., Bradley, J., and N. Sakimura, "JSON Web
              Signature (JWS)", RFC 7515, DOI 10.17487/RFC7515, May
              2015, <https://www.rfc-editor.org/info/rfc7515>.

   [RFC7517]  Jones, M., "JSON Web Key (JWK)", RFC 7517,
              DOI 10.17487/RFC7517, May 2015,
              <https://www.rfc-editor.org/info/rfc7517>.

   [RFC7800]  Jones, M., Bradley, J., and H. Tschofenig, "Proof-of-
              Possession Key Semantics for JSON Web Tokens (JWTs)",
              RFC 7800, DOI 10.17487/RFC7800, April 2016,
              <https://www.rfc-editor.org/info/rfc7800>.

   [RFC8725]  Sheffer, Y., Hardt, D., and M. Jones, "JSON Web Token Best
              Current Practices", BCP 225, RFC 8725,
              DOI 10.17487/RFC8725, February 2020,
              <https://www.rfc-editor.org/info/rfc8725>.

   [RFC8785]  Rundgren, A., Jordan, B., and S. Erdtman, "JSON
              Canonicalization Scheme (JCS)", RFC 8785,
              DOI 10.17487/RFC8785, June 2020,
              <https://www.rfc-editor.org/info/rfc8785>.

   [VC_DATA_v2.0]
              Sporny, M., Steele, O., Jones, M. B., Cohen, G., and O.
              Terbu, "Verifiable Credentials Data Model 2.0", 7 March
              2023, <https://www.w3.org/TR/vc-data-model-2.0/>.

Appendix A.  Additional Examples

   All of the following examples are non-normative.

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A.1.  Example 2: Handling Structured Claims

   In this example, in contrast to Example 1 (#example-1), the Issuer
   decided to create a structured object for the address claim, allowing
   to separately disclose individual members of the claim.

   The Issuer is using the following input claim set:

   {
     "sub": "6c5c0a49-b589-431d-bae7-219122a9ec2c",
     "given_name": "太郎",
     "family_name": "山田",
     "email": "\"unusual email address\"@example.jp",
     "phone_number": "+81-80-1234-5678",
     "address": {
       "street_address": "東京都港区芝公園4丁目2−8",
       "locality": "東京都",
       "region": "港区",
       "country": "JP"
     },
     "birthdate": "1940-01-01"
   }

   The Issuer also decided to add decoy digests to prevent the Verifier
   from deducing the true number of claims.

   The following payload is used for the SD-JWT:

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   {
     "_sd": [
       "C9inp6YoRaEXR427zYJP7Qrk1WH_8bdwOA_YUrUnGQU",
       "Kuet1yAa0HIQvYnOVd59hcViO9Ug6J2kSfqYRBeowvE",
       "MMldOFFzB2d0umlmpTIaGerhWdU_PpYfLvKhh_f_9aY",
       "X6ZAYOII2vPN40V7xExZwVwz7yRmLNcVwt5DL8RLv4g",
       "Y34zmIo0QLLOtdMpXGwjBgLvr17yEhhYT0FGofR-aIE",
       "fyGp0WTwwPv2JDQln1lSiaeobZsMWA10bQ5989-9DTs",
       "ommFAicVT8LGHCB0uywx7fYuo3MHYKO15cz-RZEYM5Q",
       "s0BKYsLWxQQeU8tVlltM7MKsIRTrEIa1PkJmqxBBf5U"
     ],
     "iss": "https://issuer.example.com",
     "iat": 1683000000,
     "exp": 1883000000,
     "address": {
       "_sd": [
         "6aUhzYhZ7SJ1kVmagQAO3u2ETN2CC1aHheZpKnaF0_E",
         "AzLlFobkJ2xiaupREPyoJz-9-NSldB6Cgjr7fUyoHzg",
         "PzzcVu0qbMuBGSjulfewzkesD9zutOExn5EWNwkrQ-k",
         "b2Dkw0jcIF9rGg8_PF8ZcvncW7zwZj5ryBWvXfrpzek",
         "cPYJHIZ8Vu-f9CCyVub2UfgEk8jvvXezwK1p_JneeXQ",
         "glT3hrSU7fSWgwF5UDZmWwBTw32gnUldIhi8hGVCaV4",
         "rvJd6iq6T5ejmsBMoGwuNXh9qAAFATAci40oidEeVsA",
         "uNHoWYhXsZhVJCNE2Dqy-zqt7t69gJKy5QaFv7GrMX4"
       ]
     },
     "_sd_alg": "sha-256"
   }

   The following Disclosures are created:

   *Claim sub*:

   *  SHA-256 Hash: X6ZAYOII2vPN40V7xExZwVwz7yRmLNcVwt5DL8RLv4g

   *  Disclosure:
      WyIyR0xDNDJzS1F2ZUNmR2ZyeU5STjl3IiwgInN1YiIsICI2YzVjMGE0OS1i
      NTg5LTQzMWQtYmFlNy0yMTkxMjJhOWVjMmMiXQ

   *  Contents: ["2GLC42sKQveCfGfryNRN9w", "sub",
      "6c5c0a49-b589-431d-bae7-219122a9ec2c"]

   *Claim given_name*:

   *  SHA-256 Hash: ommFAicVT8LGHCB0uywx7fYuo3MHYKO15cz-RZEYM5Q

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   *  Disclosure:
      WyJlbHVWNU9nM2dTTklJOEVZbnN4QV9BIiwgImdpdmVuX25hbWUiLCAiXHU1
      OTJhXHU5MGNlIl0

   *  Contents: ["eluV5Og3gSNII8EYnsxA_A", "given_name", "\u592a\u90ce"]

   *Claim family_name*:

   *  SHA-256 Hash: C9inp6YoRaEXR427zYJP7Qrk1WH_8bdwOA_YUrUnGQU

   *  Disclosure:
      WyI2SWo3dE0tYTVpVlBHYm9TNXRtdlZBIiwgImZhbWlseV9uYW1lIiwgIlx1
      NWM3MVx1NzUzMCJd

   *  Contents: ["6Ij7tM-a5iVPGboS5tmvVA", "family_name",
      "\u5c71\u7530"]

   *Claim email*:

   *  SHA-256 Hash: Kuet1yAa0HIQvYnOVd59hcViO9Ug6J2kSfqYRBeowvE

   *  Disclosure:
      WyJlSThaV205UW5LUHBOUGVOZW5IZGhRIiwgImVtYWlsIiwgIlwidW51c3Vh
      bCBlbWFpbCBhZGRyZXNzXCJAZXhhbXBsZS5qcCJd

   *  Contents: ["eI8ZWm9QnKPpNPeNenHdhQ", "email", "\"unusual email
      address\"@example.jp"]

   *Claim phone_number*:

   *  SHA-256 Hash: s0BKYsLWxQQeU8tVlltM7MKsIRTrEIa1PkJmqxBBf5U

   *  Disclosure:
      WyJRZ19PNjR6cUF4ZTQxMmExMDhpcm9BIiwgInBob25lX251bWJlciIsICIr
      ODEtODAtMTIzNC01Njc4Il0

   *  Contents: ["Qg_O64zqAxe412a108iroA", "phone_number",
      "+81-80-1234-5678"]

   *Claim street_address*:

   *  SHA-256 Hash: 6aUhzYhZ7SJ1kVmagQAO3u2ETN2CC1aHheZpKnaF0_E

   *  Disclosure:
      WyJBSngtMDk1VlBycFR0TjRRTU9xUk9BIiwgInN0cmVldF9hZGRyZXNzIiwg
      Ilx1Njc3MVx1NGVhY1x1OTBmZFx1NmUyZlx1NTMzYVx1ODI5ZFx1NTE2Y1x1
      NTcxMlx1ZmYxNFx1NGUwMVx1NzZlZVx1ZmYxMlx1MjIxMlx1ZmYxOCJd

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   *  Contents: ["AJx-095VPrpTtN4QMOqROA", "street_address",
      "\u6771\u4eac\u
      90fd\u6e2f\u533a\u829d\u516c\u5712\uff14\u4e01\u76ee\uff12\u
      2212\uff18"]

   *Claim locality*:

   *  SHA-256 Hash: rvJd6iq6T5ejmsBMoGwuNXh9qAAFATAci40oidEeVsA

   *  Disclosure:
      WyJQYzMzSk0yTGNoY1VfbEhnZ3ZfdWZRIiwgImxvY2FsaXR5IiwgIlx1Njc3
      MVx1NGVhY1x1OTBmZCJd

   *  Contents: ["Pc33JM2LchcU_lHggv_ufQ", "locality",
      "\u6771\u4eac\u90fd"]

   *Claim region*:

   *  SHA-256 Hash: PzzcVu0qbMuBGSjulfewzkesD9zutOExn5EWNwkrQ-k

   *  Disclosure:
      WyJHMDJOU3JRZmpGWFE3SW8wOXN5YWpBIiwgInJlZ2lvbiIsICJcdTZlMmZc
      dTUzM2EiXQ

   *  Contents: ["G02NSrQfjFXQ7Io09syajA", "region", "\u6e2f\u533a"]

   *Claim country*:

   *  SHA-256 Hash: uNHoWYhXsZhVJCNE2Dqy-zqt7t69gJKy5QaFv7GrMX4

   *  Disclosure:
      WyJsa2x4RjVqTVlsR1RQVW92TU5JdkNBIiwgImNvdW50cnkiLCAiSlAiXQ

   *  Contents: ["lklxF5jMYlGTPUovMNIvCA", "country", "JP"]

   *Claim birthdate*:

   *  SHA-256 Hash: MMldOFFzB2d0umlmpTIaGerhWdU_PpYfLvKhh_f_9aY

   *  Disclosure:
      WyJ5eXRWYmRBUEdjZ2wyckk0QzlHU29nIiwgImJpcnRoZGF0ZSIsICIxOTQw
      LTAxLTAxIl0

   *  Contents: ["yytVbdAPGcgl2rI4C9GSog", "birthdate", "1940-01-01"]

   The following decoy digests are added:

   *  AzLlFobkJ2xiaupREPyoJz-9-NSldB6Cgjr7fUyoHzg

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   *  cPYJHIZ8Vu-f9CCyVub2UfgEk8jvvXezwK1p_JneeXQ

   *  glT3hrSU7fSWgwF5UDZmWwBTw32gnUldIhi8hGVCaV4

   *  b2Dkw0jcIF9rGg8_PF8ZcvncW7zwZj5ryBWvXfrpzek

   *  fyGp0WTwwPv2JDQln1lSiaeobZsMWA10bQ5989-9DTs

   *  Y34zmIo0QLLOtdMpXGwjBgLvr17yEhhYT0FGofR-aIE

   The following is how a presentation of the SD-JWT that discloses only
   region and country of the address property and without a Key Binding
   JWT could look like:

   eyJhbGciOiAiRVMyNTYifQ.eyJfc2QiOiBbIkM5aW5wNllvUmFFWFI0Mjd6WUpQN1Fya
   zFXSF84YmR3T0FfWVVyVW5HUVUiLCAiS3VldDF5QWEwSElRdlluT1ZkNTloY1ZpTzlVZ
   zZKMmtTZnFZUkJlb3d2RSIsICJNTWxkT0ZGekIyZDB1bWxtcFRJYUdlcmhXZFVfUHBZZ
   kx2S2hoX2ZfOWFZIiwgIlg2WkFZT0lJMnZQTjQwVjd4RXhad1Z3ejd5Um1MTmNWd3Q1R
   Ew4Ukx2NGciLCAiWTM0em1JbzBRTExPdGRNcFhHd2pCZ0x2cjE3eUVoaFlUMEZHb2ZSL
   WFJRSIsICJmeUdwMFdUd3dQdjJKRFFsbjFsU2lhZW9iWnNNV0ExMGJRNTk4OS05RFRzI
   iwgIm9tbUZBaWNWVDhMR0hDQjB1eXd4N2ZZdW8zTUhZS08xNWN6LVJaRVlNNVEiLCAic
   zBCS1lzTFd4UVFlVTh0VmxsdE03TUtzSVJUckVJYTFQa0ptcXhCQmY1VSJdLCAiaXNzI
   jogImh0dHBzOi8vaXNzdWVyLmV4YW1wbGUuY29tIiwgImlhdCI6IDE2ODMwMDAwMDAsI
   CJleHAiOiAxODgzMDAwMDAwLCAiYWRkcmVzcyI6IHsiX3NkIjogWyI2YVVoelloWjdTS
   jFrVm1hZ1FBTzN1MkVUTjJDQzFhSGhlWnBLbmFGMF9FIiwgIkF6TGxGb2JrSjJ4aWF1c
   FJFUHlvSnotOS1OU2xkQjZDZ2pyN2ZVeW9IemciLCAiUHp6Y1Z1MHFiTXVCR1NqdWxmZ
   Xd6a2VzRDl6dXRPRXhuNUVXTndrclEtayIsICJiMkRrdzBqY0lGOXJHZzhfUEY4WmN2b
   mNXN3p3Wmo1cnlCV3ZYZnJwemVrIiwgImNQWUpISVo4VnUtZjlDQ3lWdWIyVWZnRWs4a
   nZ2WGV6d0sxcF9KbmVlWFEiLCAiZ2xUM2hyU1U3ZlNXZ3dGNVVEWm1Xd0JUdzMyZ25Vb
   GRJaGk4aEdWQ2FWNCIsICJydkpkNmlxNlQ1ZWptc0JNb0d3dU5YaDlxQUFGQVRBY2k0M
   G9pZEVlVnNBIiwgInVOSG9XWWhYc1poVkpDTkUyRHF5LXpxdDd0NjlnSkt5NVFhRnY3R
   3JNWDQiXX0sICJfc2RfYWxnIjogInNoYS0yNTYifQ.IjE4EfnYu1RZ1uz6yqtFh5Lppq
   36VC4VeSr-hLDFpZ9zqBNmMrT5JHLLXTuMJqKQp3NIzDsLaft4GK5bYyfqhg~WyJHMDJ
   OU3JRZmpGWFE3SW8wOXN5YWpBIiwgInJlZ2lvbiIsICJcdTZlMmZcdTUzM2EiXQ~WyJs
   a2x4RjVqTVlsR1RQVW92TU5JdkNBIiwgImNvdW50cnkiLCAiSlAiXQ~

A.2.  Example 3 - Complex Structured SD-JWT

   In this example, an SD-JWT with a complex object is represented.  The
   data structures defined in OIDC4IDA [OIDC.IDA] are used.

   The Issuer is using the following input claim set:

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   {
     "verified_claims": {
       "verification": {
         "trust_framework": "de_aml",
         "time": "2012-04-23T18:25Z",
         "verification_process": "f24c6f-6d3f-4ec5-973e-b0d8506f3bc7",
         "evidence": [
           {
             "type": "document",
             "method": "pipp",
             "time": "2012-04-22T11:30Z",
             "document": {
               "type": "idcard",
               "issuer": {
                 "name": "Stadt Augsburg",
                 "country": "DE"
               },
               "number": "53554554",
               "date_of_issuance": "2010-03-23",
               "date_of_expiry": "2020-03-22"
             }
           }
         ]
       },
       "claims": {
         "given_name": "Max",
         "family_name": "Müller",
         "nationalities": [
           "DE"
         ],
         "birthdate": "1956-01-28",
         "place_of_birth": {
           "country": "IS",
           "locality": "Þykkvabæjarklaustur"
         },
         "address": {
           "locality": "Maxstadt",
           "postal_code": "12344",
           "country": "DE",
           "street_address": "Weidenstraße 22"
         }
       }
     },
     "birth_middle_name": "Timotheus",
     "salutation": "Dr.",
     "msisdn": "49123456789"
   }

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   The following payload is used for the SD-JWT:

   {
     "_sd": [
       "-aSznId9mWM8ocuQolCllsxVggq1-vHW4OtnhUtVmWw",
       "IKbrYNn3vA7WEFrysvbdBJjDDU_EvQIr0W18vTRpUSg",
       "otkxuT14nBiwzNJ3MPaOitOl9pVnXOaEHal_xkyNfKI"
     ],
     "iss": "https://issuer.example.com",
     "iat": 1683000000,
     "exp": 1883000000,
     "verified_claims": {
       "verification": {
         "_sd": [
           "7h4UE9qScvDKodXVCuoKfKBJpVBfXMF_TmAGVaZe3Sc",
           "vTwe3raHIFYgFA3xaUD2aMxFz5oDo8iBu05qKlOg9Lw"
         ],
         "trust_framework": "de_aml",
         "evidence": [
           {
             "...": "tYJ0TDucyZZCRMbROG4qRO5vkPSFRxFhUELc18CSl3k"
           }
         ]
       },
       "claims": {
         "_sd": [
           "RiOiCn6_w5ZHaadkQMrcQJf0Jte5RwurRs54231DTlo",
           "S_498bbpKzB6Eanftss0xc7cOaoneRr3pKr7NdRmsMo",
           "WNA-UNK7F_zhsAb9syWO6IIQ1uHlTmOU8r8CvJ0cIMk",
           "Wxh_sV3iRH9bgrTBJi-aYHNCLt-vjhX1sd-igOf_9lk",
           "_O-wJiH3enSB4ROHntToQT8JmLtz-mhO2f1c89XoerQ",
           "hvDXhwmGcJQsBCA2OtjuLAcwAMpDsaU0nkovcKOqWNE"
         ]
       }
     },
     "_sd_alg": "sha-256"
   }

   The following Disclosures are created by the Issuer:

   *Claim time*:

   *  SHA-256 Hash: vTwe3raHIFYgFA3xaUD2aMxFz5oDo8iBu05qKlOg9Lw

   *  Disclosure:
      WyIyR0xDNDJzS1F2ZUNmR2ZyeU5STjl3IiwgInRpbWUiLCAiMjAxMi0wNC0y
      M1QxODoyNVoiXQ

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   *  Contents: ["2GLC42sKQveCfGfryNRN9w", "time", "2012-04-23T18:25Z"]

   *Claim verification_process*:

   *  SHA-256 Hash: 7h4UE9qScvDKodXVCuoKfKBJpVBfXMF_TmAGVaZe3Sc

   *  Disclosure:
      WyJlbHVWNU9nM2dTTklJOEVZbnN4QV9BIiwgInZlcmlmaWNhdGlvbl9wcm9j
      ZXNzIiwgImYyNGM2Zi02ZDNmLTRlYzUtOTczZS1iMGQ4NTA2ZjNiYzciXQ

   *  Contents: ["eluV5Og3gSNII8EYnsxA_A", "verification_process",
      "f24c6f-6d3f-4ec5-973e-b0d8506f3bc7"]

   *Claim type*:

   *  SHA-256 Hash: G5EnhOAOoU9X_6QMNvzFXjpEA_Rc-AEtm1bG_wcaKIk

   *  Disclosure:
      WyI2SWo3dE0tYTVpVlBHYm9TNXRtdlZBIiwgInR5cGUiLCAiZG9jdW1lbnQi
      XQ

   *  Contents: ["6Ij7tM-a5iVPGboS5tmvVA", "type", "document"]

   *Claim method*:

   *  SHA-256 Hash: WpxQ4HSoEtcTmCCKOeDslB_emucYLz2oO8oHNr1bEVQ

   *  Disclosure:
      WyJlSThaV205UW5LUHBOUGVOZW5IZGhRIiwgIm1ldGhvZCIsICJwaXBwIl0

   *  Contents: ["eI8ZWm9QnKPpNPeNenHdhQ", "method", "pipp"]

   *Claim time*:

   *  SHA-256 Hash: 9wpjVPWuD7PK0nsQDL8B06lmdgV3LVybhHydQpTNyLI

   *  Disclosure:
      WyJRZ19PNjR6cUF4ZTQxMmExMDhpcm9BIiwgInRpbWUiLCAiMjAxMi0wNC0y
      MlQxMTozMFoiXQ

   *  Contents: ["Qg_O64zqAxe412a108iroA", "time", "2012-04-22T11:30Z"]

   *Claim document*:

   *  SHA-256 Hash: IhwFrWUB63RcZq9yvgZ0XPc7Gowh3O2kqXeBIswg1B4

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   *  Disclosure:
      WyJBSngtMDk1VlBycFR0TjRRTU9xUk9BIiwgImRvY3VtZW50IiwgeyJ0eXBl
      IjogImlkY2FyZCIsICJpc3N1ZXIiOiB7Im5hbWUiOiAiU3RhZHQgQXVnc2J1
      cmciLCAiY291bnRyeSI6ICJERSJ9LCAibnVtYmVyIjogIjUzNTU0NTU0Iiwg
      ImRhdGVfb2ZfaXNzdWFuY2UiOiAiMjAxMC0wMy0yMyIsICJkYXRlX29mX2V4
      cGlyeSI6ICIyMDIwLTAzLTIyIn1d

   *  Contents: ["AJx-095VPrpTtN4QMOqROA", "document", {"type":
      "idcard",
      "issuer": {"name": "Stadt Augsburg", "country": "DE"},
      "number": "53554554", "date_of_issuance": "2010-03-23",
      "date_of_expiry": "2020-03-22"}]

   *Array Entry*:

   *  SHA-256 Hash: tYJ0TDucyZZCRMbROG4qRO5vkPSFRxFhUELc18CSl3k

   *  Disclosure:
      WyJQYzMzSk0yTGNoY1VfbEhnZ3ZfdWZRIiwgeyJfc2QiOiBbIjl3cGpWUFd1
      RDdQSzBuc1FETDhCMDZsbWRnVjNMVnliaEh5ZFFwVE55TEkiLCAiRzVFbmhP
      QU9vVTlYXzZRTU52ekZYanBFQV9SYy1BRXRtMWJHX3djYUtJayIsICJJaHdG
      cldVQjYzUmNacTl5dmdaMFhQYzdHb3doM08ya3FYZUJJc3dnMUI0IiwgIldw
      eFE0SFNvRXRjVG1DQ0tPZURzbEJfZW11Y1lMejJvTzhvSE5yMWJFVlEiXX1d

   *  Contents: ["Pc33JM2LchcU_lHggv_ufQ", {"_sd":
      ["9wpjVPWuD7PK0nsQDL8B06lmdgV3LVybhHydQpTNyLI",
      "G5EnhOAOoU9X_6QMNvzFXjpEA_Rc-AEtm1bG_wcaKIk",
      "IhwFrWUB63RcZq9yvgZ0XPc7Gowh3O2kqXeBIswg1B4",
      "WpxQ4HSoEtcTmCCKOeDslB_emucYLz2oO8oHNr1bEVQ"]}]

   *Claim given_name*:

   *  SHA-256 Hash: S_498bbpKzB6Eanftss0xc7cOaoneRr3pKr7NdRmsMo

   *  Disclosure:
      WyJHMDJOU3JRZmpGWFE3SW8wOXN5YWpBIiwgImdpdmVuX25hbWUiLCAiTWF4
      Il0

   *  Contents: ["G02NSrQfjFXQ7Io09syajA", "given_name", "Max"]

   *Claim family_name*:

   *  SHA-256 Hash: Wxh_sV3iRH9bgrTBJi-aYHNCLt-vjhX1sd-igOf_9lk

   *  Disclosure:
      WyJsa2x4RjVqTVlsR1RQVW92TU5JdkNBIiwgImZhbWlseV9uYW1lIiwgIk1c
      dTAwZmNsbGVyIl0

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   *  Contents: ["lklxF5jMYlGTPUovMNIvCA", "family_name", "M\u00fcller"]

   *Claim nationalities*:

   *  SHA-256 Hash: hvDXhwmGcJQsBCA2OtjuLAcwAMpDsaU0nkovcKOqWNE

   *  Disclosure:
      WyJuUHVvUW5rUkZxM0JJZUFtN0FuWEZBIiwgIm5hdGlvbmFsaXRpZXMiLCBb
      IkRFIl1d

   *  Contents: ["nPuoQnkRFq3BIeAm7AnXFA", "nationalities", ["DE"]]

   *Claim birthdate*:

   *  SHA-256 Hash: WNA-UNK7F_zhsAb9syWO6IIQ1uHlTmOU8r8CvJ0cIMk

   *  Disclosure:
      WyI1YlBzMUlxdVpOYTBoa2FGenp6Wk53IiwgImJpcnRoZGF0ZSIsICIxOTU2
      LTAxLTI4Il0

   *  Contents: ["5bPs1IquZNa0hkaFzzzZNw", "birthdate", "1956-01-28"]

   *Claim place_of_birth*:

   *  SHA-256 Hash: RiOiCn6_w5ZHaadkQMrcQJf0Jte5RwurRs54231DTlo

   *  Disclosure:
      WyI1YTJXMF9OcmxFWnpmcW1rXzdQcS13IiwgInBsYWNlX29mX2JpcnRoIiwg
      eyJjb3VudHJ5IjogIklTIiwgImxvY2FsaXR5IjogIlx1MDBkZXlra3ZhYlx1
      MDBlNmphcmtsYXVzdHVyIn1d

   *  Contents: ["5a2W0_NrlEZzfqmk_7Pq-w", "place_of_birth", {"country":
      "IS", "locality": "\u00deykkvab\u00e6jarklaustur"}]

   *Claim address*:

   *  SHA-256 Hash: _O-wJiH3enSB4ROHntToQT8JmLtz-mhO2f1c89XoerQ

   *  Disclosure:
      WyJ5MXNWVTV3ZGZKYWhWZGd3UGdTN1JRIiwgImFkZHJlc3MiLCB7ImxvY2Fs
      aXR5IjogIk1heHN0YWR0IiwgInBvc3RhbF9jb2RlIjogIjEyMzQ0IiwgImNv
      dW50cnkiOiAiREUiLCAic3RyZWV0X2FkZHJlc3MiOiAiV2VpZGVuc3RyYVx1
      MDBkZmUgMjIifV0

   *  Contents: ["y1sVU5wdfJahVdgwPgS7RQ", "address", {"locality":
      "Maxstadt", "postal_code": "12344", "country": "DE",
      "street_address": "Weidenstra\u00dfe 22"}]

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   *Claim birth_middle_name*:

   *  SHA-256 Hash: otkxuT14nBiwzNJ3MPaOitOl9pVnXOaEHal_xkyNfKI

   *  Disclosure:
      WyJIYlE0WDhzclZXM1FEeG5JSmRxeU9BIiwgImJpcnRoX21pZGRsZV9uYW1l
      IiwgIlRpbW90aGV1cyJd

   *  Contents: ["HbQ4X8srVW3QDxnIJdqyOA", "birth_middle_name",
      "Timotheus"]

   *Claim salutation*:

   *  SHA-256 Hash: -aSznId9mWM8ocuQolCllsxVggq1-vHW4OtnhUtVmWw

   *  Disclosure:
      WyJDOUdTb3VqdmlKcXVFZ1lmb2pDYjFBIiwgInNhbHV0YXRpb24iLCAiRHIu
      Il0

   *  Contents: ["C9GSoujviJquEgYfojCb1A", "salutation", "Dr."]

   *Claim msisdn*:

   *  SHA-256 Hash: IKbrYNn3vA7WEFrysvbdBJjDDU_EvQIr0W18vTRpUSg

   *  Disclosure:
      WyJreDVrRjE3Vi14MEptd1V4OXZndnR3IiwgIm1zaXNkbiIsICI0OTEyMzQ1
      Njc4OSJd

   *  Contents: ["kx5kF17V-x0JmwUx9vgvtw", "msisdn", "49123456789"]

   The following is how a presentation of the SD-JWT without a Key
   Binding JWT could look like:

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   eyJhbGciOiAiRVMyNTYifQ.eyJfc2QiOiBbIi1hU3puSWQ5bVdNOG9jdVFvbENsbHN4V
   mdncTEtdkhXNE90bmhVdFZtV3ciLCAiSUticllObjN2QTdXRUZyeXN2YmRCSmpERFVfR
   XZRSXIwVzE4dlRScFVTZyIsICJvdGt4dVQxNG5CaXd6TkozTVBhT2l0T2w5cFZuWE9hR
   UhhbF94a3lOZktJIl0sICJpc3MiOiAiaHR0cHM6Ly9pc3N1ZXIuZXhhbXBsZS5jb20iL
   CAiaWF0IjogMTY4MzAwMDAwMCwgImV4cCI6IDE4ODMwMDAwMDAsICJ2ZXJpZmllZF9jb
   GFpbXMiOiB7InZlcmlmaWNhdGlvbiI6IHsiX3NkIjogWyI3aDRVRTlxU2N2REtvZFhWQ
   3VvS2ZLQkpwVkJmWE1GX1RtQUdWYVplM1NjIiwgInZUd2UzcmFISUZZZ0ZBM3hhVUQyY
   U14Rno1b0RvOGlCdTA1cUtsT2c5THciXSwgInRydXN0X2ZyYW1ld29yayI6ICJkZV9hb
   WwiLCAiZXZpZGVuY2UiOiBbeyIuLi4iOiAidFlKMFREdWN5WlpDUk1iUk9HNHFSTzV2a
   1BTRlJ4RmhVRUxjMThDU2wzayJ9XX0sICJjbGFpbXMiOiB7Il9zZCI6IFsiUmlPaUNuN
   l93NVpIYWFka1FNcmNRSmYwSnRlNVJ3dXJSczU0MjMxRFRsbyIsICJTXzQ5OGJicEt6Q
   jZFYW5mdHNzMHhjN2NPYW9uZVJyM3BLcjdOZFJtc01vIiwgIldOQS1VTks3Rl96aHNBY
   jlzeVdPNklJUTF1SGxUbU9VOHI4Q3ZKMGNJTWsiLCAiV3hoX3NWM2lSSDliZ3JUQkppL
   WFZSE5DTHQtdmpoWDFzZC1pZ09mXzlsayIsICJfTy13SmlIM2VuU0I0Uk9IbnRUb1FUO
   EptTHR6LW1oTzJmMWM4OVhvZXJRIiwgImh2RFhod21HY0pRc0JDQTJPdGp1TEFjd0FNc
   ERzYVUwbmtvdmNLT3FXTkUiXX19LCAiX3NkX2FsZyI6ICJzaGEtMjU2In0.kbfpTas9_
   -dLMgyeUxIXuBGLtCZUO2bG9JA7v73ebzpX1LA5MBtQsyZZut-Bm3_TW8sTqLCDPUN4Z
   C5pKCyQig~WyIyR0xDNDJzS1F2ZUNmR2ZyeU5STjl3IiwgInRpbWUiLCAiMjAxMi0wNC
   0yM1QxODoyNVoiXQ~WyJQYzMzSk0yTGNoY1VfbEhnZ3ZfdWZRIiwgeyJfc2QiOiBbIjl
   3cGpWUFd1RDdQSzBuc1FETDhCMDZsbWRnVjNMVnliaEh5ZFFwVE55TEkiLCAiRzVFbmh
   PQU9vVTlYXzZRTU52ekZYanBFQV9SYy1BRXRtMWJHX3djYUtJayIsICJJaHdGcldVQjY
   zUmNacTl5dmdaMFhQYzdHb3doM08ya3FYZUJJc3dnMUI0IiwgIldweFE0SFNvRXRjVG1
   DQ0tPZURzbEJfZW11Y1lMejJvTzhvSE5yMWJFVlEiXX1d~WyJlSThaV205UW5LUHBOUG
   VOZW5IZGhRIiwgIm1ldGhvZCIsICJwaXBwIl0~WyJHMDJOU3JRZmpGWFE3SW8wOXN5YW
   pBIiwgImdpdmVuX25hbWUiLCAiTWF4Il0~WyJsa2x4RjVqTVlsR1RQVW92TU5JdkNBIi
   wgImZhbWlseV9uYW1lIiwgIk1cdTAwZmNsbGVyIl0~WyJ5MXNWVTV3ZGZKYWhWZGd3UG
   dTN1JRIiwgImFkZHJlc3MiLCB7ImxvY2FsaXR5IjogIk1heHN0YWR0IiwgInBvc3RhbF
   9jb2RlIjogIjEyMzQ0IiwgImNvdW50cnkiOiAiREUiLCAic3RyZWV0X2FkZHJlc3MiOi
   AiV2VpZGVuc3RyYVx1MDBkZmUgMjIifV0~

   After the validation, the Verifier will have the following data for
   further processing:

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   {
     "iss": "https://issuer.example.com",
     "iat": 1683000000,
     "exp": 1883000000,
     "verified_claims": {
       "verification": {
         "trust_framework": "de_aml",
         "evidence": [
           {
             "method": "pipp"
           }
         ],
         "time": "2012-04-23T18:25Z"
       },
       "claims": {
         "given_name": "Max",
         "family_name": "Müller",
         "address": {
           "locality": "Maxstadt",
           "postal_code": "12344",
           "country": "DE",
           "street_address": "Weidenstraße 22"
         }
       }
     }
   }

A.3.  Example 4a - SD-JWT-based Verifiable Credentials (SD-JWT VC)

   In this example, the artifacts defined in this specification are used
   to represent SD-JWT-based Verifiable Credentials (SD-JWT VC) as
   defined in [I-D.terbu-sd-jwt-vc].  Person Identification Data (PID)
   defined in [EUDIW.ARF] is used.

   Key Binding is applied using the Holder's public key passed in a cnf
   claim in the SD-JWT.

   The Issuer is using the following input claim set:

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   {
     "iss": "https://pid-provider.memberstate.example.eu",
     "iat": 1541493724,
     "type": "PersonIdentificationData",
     "first_name": "Erika",
     "family_name": "Mustermann",
     "nationalities": [
       "DE"
     ],
     "birth_family_name": "Schmidt",
     "birthdate": "1973-01-01",
     "address": {
       "postal_code": "12345",
       "locality": "Irgendwo",
       "street_address": "Sonnenstrasse 23",
       "country_code": "DE"
     },
     "is_over_18": true,
     "is_over_21": true,
     "is_over_65": false
   }

   The following is the issued SD-JWT:

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   eyJhbGciOiAiRVMyNTYifQ.eyJfc2QiOiBbIjBuOXl6RlNXdktfQlVIaWFNaG0xMmdoc
   kN0VmFockdKNl8ta1pQLXlTcTQiLCAiQ2gtREJjTDNrYjRWYkhJd3Rrbm5aZE5VSHRoR
   XE5TVpqb0ZkZzZpZGlobyIsICJEVzdnRlZaU3V5cjQyWVNZeDhwOHJWS0VrdEp6SjN1R
   kltZW5tSkJJbWRzIiwgIkkwMGZjRlVvRFhDdWNwNXl5MnVqcVBzc0RWR2FXTmlVbGlOe
   l9hd0QwZ2MiLCAiWDlNYVBhRldtUVlwZkhFZHl0UmRhY2xuWW9FcnU4RXp0QkVVUXVXT
   2U0NCIsICJkOHFrZlBkb2UyUFlFOTNkNU1fZ0JMMWdabHBGUktDYzBkMWxhb2RfX3MwI
   iwgImxJM0wwaHNlQ1JXbVVQZzgyVkNVTl9hMTdzTUxfNjRRZ0E0SkZUWURGREUiLCAic
   HVNcEdMb0FHUmJjc0FnNTBVWjBoaFFMS0NMNnF6eFNLNDMwNGtCbjNfSSIsICJ6VTQ1M
   mxrR2JFS2g4WnVIXzhLeDNDVXZuMUY0eTFnWkxxbERUZ1hfOFBrIl0sICJpc3MiOiAia
   HR0cHM6Ly9waWQtcHJvdmlkZXIubWVtYmVyc3RhdGUuZXhhbXBsZS5ldSIsICJpYXQiO
   iAxNTQxNDkzNzI0LCAiZXhwIjogMTg4MzAwMDAwMCwgInR5cGUiOiAiUGVyc29uSWRlb
   nRpZmljYXRpb25EYXRhIiwgIl9zZF9hbGciOiAic2hhLTI1NiIsICJjbmYiOiB7Imp3a
   yI6IHsia3R5IjogIkVDIiwgImNydiI6ICJQLTI1NiIsICJ4IjogIlRDQUVSMTladnUzT
   0hGNGo0VzR2ZlNWb0hJUDFJTGlsRGxzN3ZDZUdlbWMiLCAieSI6ICJaeGppV1diWk1RR
   0hWV0tWUTRoYlNJaXJzVmZ1ZWNDRTZ0NGpUOUYySFpRIn19fQ.9hyAKjlth_-BLWKYWk
   zg-oshIAKIauwC-y8w-a2bWyPGnZ8SE9ijvDEPEdddIi2EFJlt76fK-vN2QcMLCrNR7Q
   ~WyIyR0xDNDJzS1F2ZUNmR2ZyeU5STjl3IiwgImZpcnN0X25hbWUiLCAiRXJpa2EiXQ~
   WyJlbHVWNU9nM2dTTklJOEVZbnN4QV9BIiwgImZhbWlseV9uYW1lIiwgIk11c3Rlcm1h
   bm4iXQ~WyI2SWo3dE0tYTVpVlBHYm9TNXRtdlZBIiwgIkRFIl0~WyJlSThaV205UW5LU
   HBOUGVOZW5IZGhRIiwgIm5hdGlvbmFsaXRpZXMiLCBbeyIuLi4iOiAiSnVMMzJRWER6a
   XpsLUw2Q0xyZnhmanBac1gzTzZ2c2ZwQ1ZkMWprd0pZZyJ9XV0~WyJRZ19PNjR6cUF4Z
   TQxMmExMDhpcm9BIiwgImJpcnRoX2ZhbWlseV9uYW1lIiwgIlNjaG1pZHQiXQ~WyJBSn
   gtMDk1VlBycFR0TjRRTU9xUk9BIiwgImJpcnRoZGF0ZSIsICIxOTczLTAxLTAxIl0~Wy
   JQYzMzSk0yTGNoY1VfbEhnZ3ZfdWZRIiwgImFkZHJlc3MiLCB7InBvc3RhbF9jb2RlIj
   ogIjEyMzQ1IiwgImxvY2FsaXR5IjogIklyZ2VuZHdvIiwgInN0cmVldF9hZGRyZXNzIj
   ogIlNvbm5lbnN0cmFzc2UgMjMiLCAiY291bnRyeV9jb2RlIjogIkRFIn1d~WyJHMDJOU
   3JRZmpGWFE3SW8wOXN5YWpBIiwgImlzX292ZXJfMTgiLCB0cnVlXQ~WyJsa2x4RjVqTV
   lsR1RQVW92TU5JdkNBIiwgImlzX292ZXJfMjEiLCB0cnVlXQ~WyJuUHVvUW5rUkZxM0J
   JZUFtN0FuWEZBIiwgImlzX292ZXJfNjUiLCBmYWxzZV0~

   The following payload is used for the SD-JWT:

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   {
     "_sd": [
       "0n9yzFSWvK_BUHiaMhm12ghrCtVahrGJ6_-kZP-ySq4",
       "Ch-DBcL3kb4VbHIwtknnZdNUHthEq9MZjoFdg6idiho",
       "DW7gFVZSuyr42YSYx8p8rVKEktJzJ3uFImenmJBImds",
       "I00fcFUoDXCucp5yy2ujqPssDVGaWNiUliNz_awD0gc",
       "X9MaPaFWmQYpfHEdytRdaclnYoEru8EztBEUQuWOe44",
       "d8qkfPdoe2PYE93d5M_gBL1gZlpFRKCc0d1laod__s0",
       "lI3L0hseCRWmUPg82VCUN_a17sML_64QgA4JFTYDFDE",
       "puMpGLoAGRbcsAg50UZ0hhQLKCL6qzxSK4304kBn3_I",
       "zU452lkGbEKh8ZuH_8Kx3CUvn1F4y1gZLqlDTgX_8Pk"
     ],
     "iss": "https://pid-provider.memberstate.example.eu",
     "iat": 1541493724,
     "exp": 1883000000,
     "type": "PersonIdentificationData",
     "_sd_alg": "sha-256",
     "cnf": {
       "jwk": {
         "kty": "EC",
         "crv": "P-256",
         "x": "TCAER19Zvu3OHF4j4W4vfSVoHIP1ILilDls7vCeGemc",
         "y": "ZxjiWWbZMQGHVWKVQ4hbSIirsVfuecCE6t4jT9F2HZQ"
       }
     }
   }

   The following Disclosures are created by the Issuer:

   *Claim first_name*:

   *  SHA-256 Hash: Ch-DBcL3kb4VbHIwtknnZdNUHthEq9MZjoFdg6idiho

   *  Disclosure:
      WyIyR0xDNDJzS1F2ZUNmR2ZyeU5STjl3IiwgImZpcnN0X25hbWUiLCAiRXJp
      a2EiXQ

   *  Contents: ["2GLC42sKQveCfGfryNRN9w", "first_name", "Erika"]

   *Claim family_name*:

   *  SHA-256 Hash: I00fcFUoDXCucp5yy2ujqPssDVGaWNiUliNz_awD0gc

   *  Disclosure:
      WyJlbHVWNU9nM2dTTklJOEVZbnN4QV9BIiwgImZhbWlseV9uYW1lIiwgIk11
      c3Rlcm1hbm4iXQ

   *  Contents: ["eluV5Og3gSNII8EYnsxA_A", "family_name", "Mustermann"]

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   *Array Entry*:

   *  SHA-256 Hash: JuL32QXDzizl-L6CLrfxfjpZsX3O6vsfpCVd1jkwJYg

   *  Disclosure:
      WyI2SWo3dE0tYTVpVlBHYm9TNXRtdlZBIiwgIkRFIl0

   *  Contents: ["6Ij7tM-a5iVPGboS5tmvVA", "DE"]

   *Claim nationalities*:

   *  SHA-256 Hash: zU452lkGbEKh8ZuH_8Kx3CUvn1F4y1gZLqlDTgX_8Pk

   *  Disclosure:
      WyJlSThaV205UW5LUHBOUGVOZW5IZGhRIiwgIm5hdGlvbmFsaXRpZXMiLCBb
      eyIuLi4iOiAiSnVMMzJRWER6aXpsLUw2Q0xyZnhmanBac1gzTzZ2c2ZwQ1Zk
      MWprd0pZZyJ9XV0

   *  Contents: ["eI8ZWm9QnKPpNPeNenHdhQ", "nationalities", [{"...":
      "JuL32QXDzizl-L6CLrfxfjpZsX3O6vsfpCVd1jkwJYg"}]]

   *Claim birth_family_name*:

   *  SHA-256 Hash: X9MaPaFWmQYpfHEdytRdaclnYoEru8EztBEUQuWOe44

   *  Disclosure:
      WyJRZ19PNjR6cUF4ZTQxMmExMDhpcm9BIiwgImJpcnRoX2ZhbWlseV9uYW1l
      IiwgIlNjaG1pZHQiXQ

   *  Contents: ["Qg_O64zqAxe412a108iroA", "birth_family_name",
      "Schmidt"]

   *Claim birthdate*:

   *  SHA-256 Hash: 0n9yzFSWvK_BUHiaMhm12ghrCtVahrGJ6_-kZP-ySq4

   *  Disclosure:
      WyJBSngtMDk1VlBycFR0TjRRTU9xUk9BIiwgImJpcnRoZGF0ZSIsICIxOTcz
      LTAxLTAxIl0

   *  Contents: ["AJx-095VPrpTtN4QMOqROA", "birthdate", "1973-01-01"]

   *Claim address*:

   *  SHA-256 Hash: d8qkfPdoe2PYE93d5M_gBL1gZlpFRKCc0d1laod__s0

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   *  Disclosure:
      WyJQYzMzSk0yTGNoY1VfbEhnZ3ZfdWZRIiwgImFkZHJlc3MiLCB7InBvc3Rh
      bF9jb2RlIjogIjEyMzQ1IiwgImxvY2FsaXR5IjogIklyZ2VuZHdvIiwgInN0
      cmVldF9hZGRyZXNzIjogIlNvbm5lbnN0cmFzc2UgMjMiLCAiY291bnRyeV9j
      b2RlIjogIkRFIn1d

   *  Contents: ["Pc33JM2LchcU_lHggv_ufQ", "address", {"postal_code":
      "12345", "locality": "Irgendwo", "street_address":
      "Sonnenstrasse 23", "country_code": "DE"}]

   *Claim is_over_18*:

   *  SHA-256 Hash: puMpGLoAGRbcsAg50UZ0hhQLKCL6qzxSK4304kBn3_I

   *  Disclosure:
      WyJHMDJOU3JRZmpGWFE3SW8wOXN5YWpBIiwgImlzX292ZXJfMTgiLCB0cnVl
      XQ

   *  Contents: ["G02NSrQfjFXQ7Io09syajA", "is_over_18", true]

   *Claim is_over_21*:

   *  SHA-256 Hash: lI3L0hseCRWmUPg82VCUN_a17sML_64QgA4JFTYDFDE

   *  Disclosure:
      WyJsa2x4RjVqTVlsR1RQVW92TU5JdkNBIiwgImlzX292ZXJfMjEiLCB0cnVl
      XQ

   *  Contents: ["lklxF5jMYlGTPUovMNIvCA", "is_over_21", true]

   *Claim is_over_65*:

   *  SHA-256 Hash: DW7gFVZSuyr42YSYx8p8rVKEktJzJ3uFImenmJBImds

   *  Disclosure:
      WyJuUHVvUW5rUkZxM0JJZUFtN0FuWEZBIiwgImlzX292ZXJfNjUiLCBmYWxz
      ZV0

   *  Contents: ["nPuoQnkRFq3BIeAm7AnXFA", "is_over_65", false]

   The following is how a presentation of the SD-JWT with a Key Binding
   JWT that discloses only nationality and the fact that the person is
   over 18 years old could look like:

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   eyJhbGciOiAiRVMyNTYifQ.eyJfc2QiOiBbIjBuOXl6RlNXdktfQlVIaWFNaG0xMmdoc
   kN0VmFockdKNl8ta1pQLXlTcTQiLCAiQ2gtREJjTDNrYjRWYkhJd3Rrbm5aZE5VSHRoR
   XE5TVpqb0ZkZzZpZGlobyIsICJEVzdnRlZaU3V5cjQyWVNZeDhwOHJWS0VrdEp6SjN1R
   kltZW5tSkJJbWRzIiwgIkkwMGZjRlVvRFhDdWNwNXl5MnVqcVBzc0RWR2FXTmlVbGlOe
   l9hd0QwZ2MiLCAiWDlNYVBhRldtUVlwZkhFZHl0UmRhY2xuWW9FcnU4RXp0QkVVUXVXT
   2U0NCIsICJkOHFrZlBkb2UyUFlFOTNkNU1fZ0JMMWdabHBGUktDYzBkMWxhb2RfX3MwI
   iwgImxJM0wwaHNlQ1JXbVVQZzgyVkNVTl9hMTdzTUxfNjRRZ0E0SkZUWURGREUiLCAic
   HVNcEdMb0FHUmJjc0FnNTBVWjBoaFFMS0NMNnF6eFNLNDMwNGtCbjNfSSIsICJ6VTQ1M
   mxrR2JFS2g4WnVIXzhLeDNDVXZuMUY0eTFnWkxxbERUZ1hfOFBrIl0sICJpc3MiOiAia
   HR0cHM6Ly9waWQtcHJvdmlkZXIubWVtYmVyc3RhdGUuZXhhbXBsZS5ldSIsICJpYXQiO
   iAxNTQxNDkzNzI0LCAiZXhwIjogMTg4MzAwMDAwMCwgInR5cGUiOiAiUGVyc29uSWRlb
   nRpZmljYXRpb25EYXRhIiwgIl9zZF9hbGciOiAic2hhLTI1NiIsICJjbmYiOiB7Imp3a
   yI6IHsia3R5IjogIkVDIiwgImNydiI6ICJQLTI1NiIsICJ4IjogIlRDQUVSMTladnUzT
   0hGNGo0VzR2ZlNWb0hJUDFJTGlsRGxzN3ZDZUdlbWMiLCAieSI6ICJaeGppV1diWk1RR
   0hWV0tWUTRoYlNJaXJzVmZ1ZWNDRTZ0NGpUOUYySFpRIn19fQ.9hyAKjlth_-BLWKYWk
   zg-oshIAKIauwC-y8w-a2bWyPGnZ8SE9ijvDEPEdddIi2EFJlt76fK-vN2QcMLCrNR7Q
   ~WyJHMDJOU3JRZmpGWFE3SW8wOXN5YWpBIiwgImlzX292ZXJfMTgiLCB0cnVlXQ~WyJl
   SThaV205UW5LUHBOUGVOZW5IZGhRIiwgIm5hdGlvbmFsaXRpZXMiLCBbeyIuLi4iOiAi
   SnVMMzJRWER6aXpsLUw2Q0xyZnhmanBac1gzTzZ2c2ZwQ1ZkMWprd0pZZyJ9XV0~WyI2
   SWo3dE0tYTVpVlBHYm9TNXRtdlZBIiwgIkRFIl0~eyJhbGciOiAiRVMyNTYiLCAidHlw
   IjogImtiK2p3dCJ9.eyJub25jZSI6ICIxMjM0NTY3ODkwIiwgImF1ZCI6ICJodHRwczo
   vL3ZlcmlmaWVyLmV4YW1wbGUub3JnIiwgImlhdCI6IDE2OTgwNzc3OTAsICJfc2RfaGF
   zaCI6ICJXTlNjU2w2MVpucnhtTS13LVlRYnBIM21uVGhDVy1HUHd1bk5Vd1RWaDU0In0
   .W5jjtJfj3ejo33gQdp7iNNeSvEQsxv2x9tzNN_uIw9UtaAPTRC0gB4VJDe8H7T55Khh
   qf67eGPrpbuOzjkU8PQ

   The following is the payload of a corresponding Key Binding JWT:

   {
     "nonce": "1234567890",
     "aud": "https://verifier.example.org",
     "iat": 1698077790,
     "_sd_hash": "WNScSl61ZnrxmM-w-YQbpH3mnThCW-GPwunNUwTVh54"
   }

   After the validation, the Verifier will have the following data for
   further processing:

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   {
     "iss": "https://pid-provider.memberstate.example.eu",
     "iat": 1541493724,
     "exp": 1883000000,
     "type": "PersonIdentificationData",
     "cnf": {
       "jwk": {
         "kty": "EC",
         "crv": "P-256",
         "x": "TCAER19Zvu3OHF4j4W4vfSVoHIP1ILilDls7vCeGemc",
         "y": "ZxjiWWbZMQGHVWKVQ4hbSIirsVfuecCE6t4jT9F2HZQ"
       }
     },
     "is_over_18": true,
     "nationalities": [
       "DE"
     ]
   }

A.4.  Example 4b - W3C Verifiable Credentials Data Model v2.0

   In this example, the artifacts defined in this specification are used
   to represent a payload that is represented as a W3C Verifiable
   Credentials Data Model v2.0 [VC_DATA_v2.0].

   Key Binding is applied using the Holder's public key passed in a cnf
   claim in the SD-JWT.

   The Issuer is using the following input claim set:

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   {
     "@context": [
       "https://www.w3.org/2018/credentials/v1",
       "https://w3id.org/vaccination/v1"
     ],
     "type": [
       "VerifiableCredential",
       "VaccinationCertificate"
     ],
     "issuer": "https://example.com/issuer",
     "issuanceDate": "2023-02-09T11:01:59Z",
     "expirationDate": "2028-02-08T11:01:59Z",
     "name": "COVID-19 Vaccination Certificate",
     "description": "COVID-19 Vaccination Certificate",
     "credentialSubject": {
       "vaccine": {
         "type": "Vaccine",
         "atcCode": "J07BX03",
         "medicinalProductName": "COVID-19 Vaccine Moderna",
         "marketingAuthorizationHolder": "Moderna Biotech"
       },
       "nextVaccinationDate": "2021-08-16T13:40:12Z",
       "countryOfVaccination": "GE",
       "dateOfVaccination": "2021-06-23T13:40:12Z",
       "order": "3/3",
       "recipient": {
         "type": "VaccineRecipient",
         "gender": "Female",
         "birthDate": "1961-08-17",
         "givenName": "Marion",
         "familyName": "Mustermann"
       },
       "type": "VaccinationEvent",
       "administeringCentre": "Praxis Sommergarten",
       "batchNumber": "1626382736",
       "healthProfessional": "883110000015376"
     }
   }

   The following is the issued SD-JWT:

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   eyJhbGciOiAiRVMyNTYifQ.eyJAY29udGV4dCI6IFsiaHR0cHM6Ly93d3cudzMub3JnL
   zIwMTgvY3JlZGVudGlhbHMvdjEiLCAiaHR0cHM6Ly93M2lkLm9yZy92YWNjaW5hdGlvb
   i92MSJdLCAidHlwZSI6IFsiVmVyaWZpYWJsZUNyZWRlbnRpYWwiLCAiVmFjY2luYXRpb
   25DZXJ0aWZpY2F0ZSJdLCAiaXNzdWVyIjogImh0dHBzOi8vZXhhbXBsZS5jb20vaXNzd
   WVyIiwgImlzc3VhbmNlRGF0ZSI6ICIyMDIzLTAyLTA5VDExOjAxOjU5WiIsICJleHBpc
   mF0aW9uRGF0ZSI6ICIyMDI4LTAyLTA4VDExOjAxOjU5WiIsICJuYW1lIjogIkNPVklEL
   TE5IFZhY2NpbmF0aW9uIENlcnRpZmljYXRlIiwgImRlc2NyaXB0aW9uIjogIkNPVklEL
   TE5IFZhY2NpbmF0aW9uIENlcnRpZmljYXRlIiwgImNyZWRlbnRpYWxTdWJqZWN0Ijoge
   yJfc2QiOiBbIjFWX0stOGxEUThpRlhCRlhiWlk5ZWhxUjRIYWJXQ2k1VDB5Ykl6WlBld
   3ciLCAiSnpqTGd0UDI5ZFAtQjN0ZDEyUDY3NGdGbUsyenk4MUhNdEJnZjZDSk5XZyIsI
   CJSMmZHYmZBMDdaX1lsa3FtTlp5bWExeHl5eDFYc3RJaVM2QjFZYmwySlo0IiwgIlRDb
   XpybDdLMmdldl9kdTdwY01JeXpSTEhwLVllZy1GbF9jeHRyVXZQeGciLCAiVjdrSkJMS
   zc4VG1WRE9tcmZKN1p1VVBIdUtfMmNjN3laUmE0cVYxdHh3TSIsICJiMGVVc3ZHUC1PR
   ERkRm9ZNE5semxYYzN0RHNsV0p0Q0pGNzVOdzhPal9nIiwgInpKS19lU01YandNOGRYb
   U1aTG5JOEZHTTA4ekozX3ViR2VFTUotNVRCeTAiXSwgInZhY2NpbmUiOiB7Il9zZCI6I
   FsiMWNGNWhMd2toTU5JYXFmV0pyWEk3Tk1XZWRMLTlmNlkyUEE1MnlQalNaSSIsICJIa
   Xk2V1d1ZUxENWJuMTYyOTh0UHY3R1hobWxkTURPVG5CaS1DWmJwaE5vIiwgIkxiMDI3c
   TY5MWpYWGwtakM3M3ZpOGViT2o5c214M0MtX29nN2dBNFRCUUUiXSwgInR5cGUiOiAiV
   mFjY2luZSJ9LCAicmVjaXBpZW50IjogeyJfc2QiOiBbIjFsU1FCTlkyNHEwVGg2T0d6d
   GhxLTctNGw2Y0FheHJZWE9HWnBlV19sbkEiLCAiM256THE4MU0yb04wNndkdjFzaEh2T
   0VKVnhaNUtMbWREa0hFREpBQldFSSIsICJQbjFzV2kwNkc0TEpybm4tX1JUMFJiTV9IV
   GR4blBKUXVYMmZ6V3ZfSk9VIiwgImxGOXV6ZHN3N0hwbEdMYzcxNFRyNFdPN01HSnphN
   3R0N1FGbGVDWDRJdHciXSwgInR5cGUiOiAiVmFjY2luZVJlY2lwaWVudCJ9LCAidHlwZ
   SI6ICJWYWNjaW5hdGlvbkV2ZW50In0sICJfc2RfYWxnIjogInNoYS0yNTYiLCAiY25mI
   jogeyJqd2siOiB7Imt0eSI6ICJFQyIsICJjcnYiOiAiUC0yNTYiLCAieCI6ICJUQ0FFU
   jE5WnZ1M09IRjRqNFc0dmZTVm9ISVAxSUxpbERsczd2Q2VHZW1jIiwgInkiOiAiWnhqa
   VdXYlpNUUdIVldLVlE0aGJTSWlyc1ZmdWVjQ0U2dDRqVDlGMkhaUSJ9fX0.l7byWDsTt
   DOjFbWS4lko-3mkeeZwzUYw6ZicrJurES_gzs6EK_svPiVwj5g6evb_nmLWpK2_cXQ_J
   0cjH0XnGw~WyIyR0xDNDJzS1F2ZUNmR2ZyeU5STjl3IiwgImF0Y0NvZGUiLCAiSjA3Ql
   gwMyJd~WyJlbHVWNU9nM2dTTklJOEVZbnN4QV9BIiwgIm1lZGljaW5hbFByb2R1Y3ROY
   W1lIiwgIkNPVklELTE5IFZhY2NpbmUgTW9kZXJuYSJd~WyI2SWo3dE0tYTVpVlBHYm9T
   NXRtdlZBIiwgIm1hcmtldGluZ0F1dGhvcml6YXRpb25Ib2xkZXIiLCAiTW9kZXJuYSBC
   aW90ZWNoIl0~WyJlSThaV205UW5LUHBOUGVOZW5IZGhRIiwgIm5leHRWYWNjaW5hdGlv
   bkRhdGUiLCAiMjAyMS0wOC0xNlQxMzo0MDoxMloiXQ~WyJRZ19PNjR6cUF4ZTQxMmExM
   Dhpcm9BIiwgImNvdW50cnlPZlZhY2NpbmF0aW9uIiwgIkdFIl0~WyJBSngtMDk1VlByc
   FR0TjRRTU9xUk9BIiwgImRhdGVPZlZhY2NpbmF0aW9uIiwgIjIwMjEtMDYtMjNUMTM6N
   DA6MTJaIl0~WyJQYzMzSk0yTGNoY1VfbEhnZ3ZfdWZRIiwgIm9yZGVyIiwgIjMvMyJd~
   WyJHMDJOU3JRZmpGWFE3SW8wOXN5YWpBIiwgImdlbmRlciIsICJGZW1hbGUiXQ~WyJsa
   2x4RjVqTVlsR1RQVW92TU5JdkNBIiwgImJpcnRoRGF0ZSIsICIxOTYxLTA4LTE3Il0~W
   yJuUHVvUW5rUkZxM0JJZUFtN0FuWEZBIiwgImdpdmVuTmFtZSIsICJNYXJpb24iXQ~Wy
   I1YlBzMUlxdVpOYTBoa2FGenp6Wk53IiwgImZhbWlseU5hbWUiLCAiTXVzdGVybWFubi
   Jd~WyI1YTJXMF9OcmxFWnpmcW1rXzdQcS13IiwgImFkbWluaXN0ZXJpbmdDZW50cmUiL
   CAiUHJheGlzIFNvbW1lcmdhcnRlbiJd~WyJ5MXNWVTV3ZGZKYWhWZGd3UGdTN1JRIiwg
   ImJhdGNoTnVtYmVyIiwgIjE2MjYzODI3MzYiXQ~WyJIYlE0WDhzclZXM1FEeG5JSmRxe
   U9BIiwgImhlYWx0aFByb2Zlc3Npb25hbCIsICI4ODMxMTAwMDAwMTUzNzYiXQ~

   The following payload is used for the SD-JWT:

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   {
     "@context": [
       "https://www.w3.org/2018/credentials/v1",
       "https://w3id.org/vaccination/v1"
     ],
     "type": [
       "VerifiableCredential",
       "VaccinationCertificate"
     ],
     "issuer": "https://example.com/issuer",
     "issuanceDate": "2023-02-09T11:01:59Z",
     "expirationDate": "2028-02-08T11:01:59Z",
     "name": "COVID-19 Vaccination Certificate",
     "description": "COVID-19 Vaccination Certificate",
     "credentialSubject": {
       "_sd": [
         "1V_K-8lDQ8iFXBFXbZY9ehqR4HabWCi5T0ybIzZPeww",
         "JzjLgtP29dP-B3td12P674gFmK2zy81HMtBgf6CJNWg",
         "R2fGbfA07Z_YlkqmNZyma1xyyx1XstIiS6B1Ybl2JZ4",
         "TCmzrl7K2gev_du7pcMIyzRLHp-Yeg-Fl_cxtrUvPxg",
         "V7kJBLK78TmVDOmrfJ7ZuUPHuK_2cc7yZRa4qV1txwM",
         "b0eUsvGP-ODDdFoY4NlzlXc3tDslWJtCJF75Nw8Oj_g",
         "zJK_eSMXjwM8dXmMZLnI8FGM08zJ3_ubGeEMJ-5TBy0"
       ],
       "vaccine": {
         "_sd": [
           "1cF5hLwkhMNIaqfWJrXI7NMWedL-9f6Y2PA52yPjSZI",
           "Hiy6WWueLD5bn16298tPv7GXhmldMDOTnBi-CZbphNo",
           "Lb027q691jXXl-jC73vi8ebOj9smx3C-_og7gA4TBQE"
         ],
         "type": "Vaccine"
       },
       "recipient": {
         "_sd": [
           "1lSQBNY24q0Th6OGzthq-7-4l6cAaxrYXOGZpeW_lnA",
           "3nzLq81M2oN06wdv1shHvOEJVxZ5KLmdDkHEDJABWEI",
           "Pn1sWi06G4LJrnn-_RT0RbM_HTdxnPJQuX2fzWv_JOU",
           "lF9uzdsw7HplGLc714Tr4WO7MGJza7tt7QFleCX4Itw"
         ],
         "type": "VaccineRecipient"
       },
       "type": "VaccinationEvent"
     },
     "_sd_alg": "sha-256",
     "cnf": {
       "jwk": {
         "kty": "EC",
         "crv": "P-256",

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         "x": "TCAER19Zvu3OHF4j4W4vfSVoHIP1ILilDls7vCeGemc",
         "y": "ZxjiWWbZMQGHVWKVQ4hbSIirsVfuecCE6t4jT9F2HZQ"
       }
     }
   }

   The following Disclosures are created by the Issuer:

   *Claim atcCode*:

   *  SHA-256 Hash: 1cF5hLwkhMNIaqfWJrXI7NMWedL-9f6Y2PA52yPjSZI

   *  Disclosure:
      WyIyR0xDNDJzS1F2ZUNmR2ZyeU5STjl3IiwgImF0Y0NvZGUiLCAiSjA3Qlgw
      MyJd

   *  Contents: ["2GLC42sKQveCfGfryNRN9w", "atcCode", "J07BX03"]

   *Claim medicinalProductName*:

   *  SHA-256 Hash: Hiy6WWueLD5bn16298tPv7GXhmldMDOTnBi-CZbphNo

   *  Disclosure:
      WyJlbHVWNU9nM2dTTklJOEVZbnN4QV9BIiwgIm1lZGljaW5hbFByb2R1Y3RO
      YW1lIiwgIkNPVklELTE5IFZhY2NpbmUgTW9kZXJuYSJd

   *  Contents: ["eluV5Og3gSNII8EYnsxA_A", "medicinalProductName",
      "COVID-19
      Vaccine Moderna"]

   *Claim marketingAuthorizationHolder*:

   *  SHA-256 Hash: Lb027q691jXXl-jC73vi8ebOj9smx3C-_og7gA4TBQE

   *  Disclosure:
      WyI2SWo3dE0tYTVpVlBHYm9TNXRtdlZBIiwgIm1hcmtldGluZ0F1dGhvcml6
      YXRpb25Ib2xkZXIiLCAiTW9kZXJuYSBCaW90ZWNoIl0

   *  Contents: ["6Ij7tM-a5iVPGboS5tmvVA",
      "marketingAuthorizationHolder",
      "Moderna Biotech"]

   *Claim nextVaccinationDate*:

   *  SHA-256 Hash: R2fGbfA07Z_YlkqmNZyma1xyyx1XstIiS6B1Ybl2JZ4

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   *  Disclosure:
      WyJlSThaV205UW5LUHBOUGVOZW5IZGhRIiwgIm5leHRWYWNjaW5hdGlvbkRh
      dGUiLCAiMjAyMS0wOC0xNlQxMzo0MDoxMloiXQ

   *  Contents: ["eI8ZWm9QnKPpNPeNenHdhQ", "nextVaccinationDate",
      "2021-08-16T13:40:12Z"]

   *Claim countryOfVaccination*:

   *  SHA-256 Hash: JzjLgtP29dP-B3td12P674gFmK2zy81HMtBgf6CJNWg

   *  Disclosure:
      WyJRZ19PNjR6cUF4ZTQxMmExMDhpcm9BIiwgImNvdW50cnlPZlZhY2NpbmF0
      aW9uIiwgIkdFIl0

   *  Contents: ["Qg_O64zqAxe412a108iroA", "countryOfVaccination", "GE"]

   *Claim dateOfVaccination*:

   *  SHA-256 Hash: zJK_eSMXjwM8dXmMZLnI8FGM08zJ3_ubGeEMJ-5TBy0

   *  Disclosure:
      WyJBSngtMDk1VlBycFR0TjRRTU9xUk9BIiwgImRhdGVPZlZhY2NpbmF0aW9u
      IiwgIjIwMjEtMDYtMjNUMTM6NDA6MTJaIl0

   *  Contents: ["AJx-095VPrpTtN4QMOqROA", "dateOfVaccination",
      "2021-06-23T13:40:12Z"]

   *Claim order*:

   *  SHA-256 Hash: b0eUsvGP-ODDdFoY4NlzlXc3tDslWJtCJF75Nw8Oj_g

   *  Disclosure:
      WyJQYzMzSk0yTGNoY1VfbEhnZ3ZfdWZRIiwgIm9yZGVyIiwgIjMvMyJd

   *  Contents: ["Pc33JM2LchcU_lHggv_ufQ", "order", "3/3"]

   *Claim gender*:

   *  SHA-256 Hash: 3nzLq81M2oN06wdv1shHvOEJVxZ5KLmdDkHEDJABWEI

   *  Disclosure:
      WyJHMDJOU3JRZmpGWFE3SW8wOXN5YWpBIiwgImdlbmRlciIsICJGZW1hbGUi
      XQ

   *  Contents: ["G02NSrQfjFXQ7Io09syajA", "gender", "Female"]

   *Claim birthDate*:

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   *  SHA-256 Hash: Pn1sWi06G4LJrnn-_RT0RbM_HTdxnPJQuX2fzWv_JOU

   *  Disclosure:
      WyJsa2x4RjVqTVlsR1RQVW92TU5JdkNBIiwgImJpcnRoRGF0ZSIsICIxOTYx
      LTA4LTE3Il0

   *  Contents: ["lklxF5jMYlGTPUovMNIvCA", "birthDate", "1961-08-17"]

   *Claim givenName*:

   *  SHA-256 Hash: lF9uzdsw7HplGLc714Tr4WO7MGJza7tt7QFleCX4Itw

   *  Disclosure:
      WyJuUHVvUW5rUkZxM0JJZUFtN0FuWEZBIiwgImdpdmVuTmFtZSIsICJNYXJp
      b24iXQ

   *  Contents: ["nPuoQnkRFq3BIeAm7AnXFA", "givenName", "Marion"]

   *Claim familyName*:

   *  SHA-256 Hash: 1lSQBNY24q0Th6OGzthq-7-4l6cAaxrYXOGZpeW_lnA

   *  Disclosure:
      WyI1YlBzMUlxdVpOYTBoa2FGenp6Wk53IiwgImZhbWlseU5hbWUiLCAiTXVz
      dGVybWFubiJd

   *  Contents: ["5bPs1IquZNa0hkaFzzzZNw", "familyName", "Mustermann"]

   *Claim administeringCentre*:

   *  SHA-256 Hash: TCmzrl7K2gev_du7pcMIyzRLHp-Yeg-Fl_cxtrUvPxg

   *  Disclosure:
      WyI1YTJXMF9OcmxFWnpmcW1rXzdQcS13IiwgImFkbWluaXN0ZXJpbmdDZW50
      cmUiLCAiUHJheGlzIFNvbW1lcmdhcnRlbiJd

   *  Contents: ["5a2W0_NrlEZzfqmk_7Pq-w", "administeringCentre",
      "Praxis
      Sommergarten"]

   *Claim batchNumber*:

   *  SHA-256 Hash: V7kJBLK78TmVDOmrfJ7ZuUPHuK_2cc7yZRa4qV1txwM

   *  Disclosure:
      WyJ5MXNWVTV3ZGZKYWhWZGd3UGdTN1JRIiwgImJhdGNoTnVtYmVyIiwgIjE2
      MjYzODI3MzYiXQ

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   *  Contents: ["y1sVU5wdfJahVdgwPgS7RQ", "batchNumber", "1626382736"]

   *Claim healthProfessional*:

   *  SHA-256 Hash: 1V_K-8lDQ8iFXBFXbZY9ehqR4HabWCi5T0ybIzZPeww

   *  Disclosure:
      WyJIYlE0WDhzclZXM1FEeG5JSmRxeU9BIiwgImhlYWx0aFByb2Zlc3Npb25h
      bCIsICI4ODMxMTAwMDAwMTUzNzYiXQ

   *  Contents: ["HbQ4X8srVW3QDxnIJdqyOA", "healthProfessional",
      "883110000015376"]

   The following is how a presentation of the SD-JWT with Key Binding
   JWT that discloses only type, medicinalProductName, atcCode of the
   vaccine, type of the recipient, type, order and dateOfVaccination
   could look like:

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   eyJhbGciOiAiRVMyNTYifQ.eyJAY29udGV4dCI6IFsiaHR0cHM6Ly93d3cudzMub3JnL
   zIwMTgvY3JlZGVudGlhbHMvdjEiLCAiaHR0cHM6Ly93M2lkLm9yZy92YWNjaW5hdGlvb
   i92MSJdLCAidHlwZSI6IFsiVmVyaWZpYWJsZUNyZWRlbnRpYWwiLCAiVmFjY2luYXRpb
   25DZXJ0aWZpY2F0ZSJdLCAiaXNzdWVyIjogImh0dHBzOi8vZXhhbXBsZS5jb20vaXNzd
   WVyIiwgImlzc3VhbmNlRGF0ZSI6ICIyMDIzLTAyLTA5VDExOjAxOjU5WiIsICJleHBpc
   mF0aW9uRGF0ZSI6ICIyMDI4LTAyLTA4VDExOjAxOjU5WiIsICJuYW1lIjogIkNPVklEL
   TE5IFZhY2NpbmF0aW9uIENlcnRpZmljYXRlIiwgImRlc2NyaXB0aW9uIjogIkNPVklEL
   TE5IFZhY2NpbmF0aW9uIENlcnRpZmljYXRlIiwgImNyZWRlbnRpYWxTdWJqZWN0Ijoge
   yJfc2QiOiBbIjFWX0stOGxEUThpRlhCRlhiWlk5ZWhxUjRIYWJXQ2k1VDB5Ykl6WlBld
   3ciLCAiSnpqTGd0UDI5ZFAtQjN0ZDEyUDY3NGdGbUsyenk4MUhNdEJnZjZDSk5XZyIsI
   CJSMmZHYmZBMDdaX1lsa3FtTlp5bWExeHl5eDFYc3RJaVM2QjFZYmwySlo0IiwgIlRDb
   XpybDdLMmdldl9kdTdwY01JeXpSTEhwLVllZy1GbF9jeHRyVXZQeGciLCAiVjdrSkJMS
   zc4VG1WRE9tcmZKN1p1VVBIdUtfMmNjN3laUmE0cVYxdHh3TSIsICJiMGVVc3ZHUC1PR
   ERkRm9ZNE5semxYYzN0RHNsV0p0Q0pGNzVOdzhPal9nIiwgInpKS19lU01YandNOGRYb
   U1aTG5JOEZHTTA4ekozX3ViR2VFTUotNVRCeTAiXSwgInZhY2NpbmUiOiB7Il9zZCI6I
   FsiMWNGNWhMd2toTU5JYXFmV0pyWEk3Tk1XZWRMLTlmNlkyUEE1MnlQalNaSSIsICJIa
   Xk2V1d1ZUxENWJuMTYyOTh0UHY3R1hobWxkTURPVG5CaS1DWmJwaE5vIiwgIkxiMDI3c
   TY5MWpYWGwtakM3M3ZpOGViT2o5c214M0MtX29nN2dBNFRCUUUiXSwgInR5cGUiOiAiV
   mFjY2luZSJ9LCAicmVjaXBpZW50IjogeyJfc2QiOiBbIjFsU1FCTlkyNHEwVGg2T0d6d
   GhxLTctNGw2Y0FheHJZWE9HWnBlV19sbkEiLCAiM256THE4MU0yb04wNndkdjFzaEh2T
   0VKVnhaNUtMbWREa0hFREpBQldFSSIsICJQbjFzV2kwNkc0TEpybm4tX1JUMFJiTV9IV
   GR4blBKUXVYMmZ6V3ZfSk9VIiwgImxGOXV6ZHN3N0hwbEdMYzcxNFRyNFdPN01HSnphN
   3R0N1FGbGVDWDRJdHciXSwgInR5cGUiOiAiVmFjY2luZVJlY2lwaWVudCJ9LCAidHlwZ
   SI6ICJWYWNjaW5hdGlvbkV2ZW50In0sICJfc2RfYWxnIjogInNoYS0yNTYiLCAiY25mI
   jogeyJqd2siOiB7Imt0eSI6ICJFQyIsICJjcnYiOiAiUC0yNTYiLCAieCI6ICJUQ0FFU
   jE5WnZ1M09IRjRqNFc0dmZTVm9ISVAxSUxpbERsczd2Q2VHZW1jIiwgInkiOiAiWnhqa
   VdXYlpNUUdIVldLVlE0aGJTSWlyc1ZmdWVjQ0U2dDRqVDlGMkhaUSJ9fX0.l7byWDsTt
   DOjFbWS4lko-3mkeeZwzUYw6ZicrJurES_gzs6EK_svPiVwj5g6evb_nmLWpK2_cXQ_J
   0cjH0XnGw~WyJQYzMzSk0yTGNoY1VfbEhnZ3ZfdWZRIiwgIm9yZGVyIiwgIjMvMyJd~W
   yJBSngtMDk1VlBycFR0TjRRTU9xUk9BIiwgImRhdGVPZlZhY2NpbmF0aW9uIiwgIjIwM
   jEtMDYtMjNUMTM6NDA6MTJaIl0~WyIyR0xDNDJzS1F2ZUNmR2ZyeU5STjl3IiwgImF0Y
   0NvZGUiLCAiSjA3QlgwMyJd~WyJlbHVWNU9nM2dTTklJOEVZbnN4QV9BIiwgIm1lZGlj
   aW5hbFByb2R1Y3ROYW1lIiwgIkNPVklELTE5IFZhY2NpbmUgTW9kZXJuYSJd~eyJhbGc
   iOiAiRVMyNTYiLCAidHlwIjogImtiK2p3dCJ9.eyJub25jZSI6ICIxMjM0NTY3ODkwIi
   wgImF1ZCI6ICJodHRwczovL3ZlcmlmaWVyLmV4YW1wbGUub3JnIiwgImlhdCI6IDE2OT
   gwNzc3OTAsICJfc2RfaGFzaCI6ICJ1MXpzTkxGUXhlVkVGcFRmT1Z1NFRjSTNaYjdDX1
   UzYTFFNGVzQVlRLXpZIn0.LLaMyLVXmAC5YVj29d8T-QbyJaxORbMCuWtxnw8VLZHjz9
   kyyMMTFaOfGb3CZmytVWfwXIYXevyBfsR4Ir5EQA

   After the validation, the Verifier will have the following data for
   further processing:

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   {
     "@context": [
       "https://www.w3.org/2018/credentials/v1",
       "https://w3id.org/vaccination/v1"
     ],
     "type": [
       "VerifiableCredential",
       "VaccinationCertificate"
     ],
     "issuer": "https://example.com/issuer",
     "issuanceDate": "2023-02-09T11:01:59Z",
     "expirationDate": "2028-02-08T11:01:59Z",
     "name": "COVID-19 Vaccination Certificate",
     "description": "COVID-19 Vaccination Certificate",
     "credentialSubject": {
       "vaccine": {
         "type": "Vaccine",
         "atcCode": "J07BX03",
         "medicinalProductName": "COVID-19 Vaccine Moderna"
       },
       "recipient": {
         "type": "VaccineRecipient"
       },
       "type": "VaccinationEvent",
       "order": "3/3",
       "dateOfVaccination": "2021-06-23T13:40:12Z"
     },
     "cnf": {
       "jwk": {
         "kty": "EC",
         "crv": "P-256",
         "x": "TCAER19Zvu3OHF4j4W4vfSVoHIP1ILilDls7vCeGemc",
         "y": "ZxjiWWbZMQGHVWKVQ4hbSIirsVfuecCE6t4jT9F2HZQ"
       }
     }
   }

A.5.  Elliptic Curve Key Used in the Examples

   The following Elliptic Curve public key, represented in JWK format,
   can be used to validate the Issuer signatures in the above examples:

   {
     "kty": "EC",
     "crv": "P-256",
     "x": "b28d4MwZMjw8-00CG4xfnn9SLMVMM19SlqZpVb_uNtQ",
     "y": "Xv5zWwuoaTgdS6hV43yI6gBwTnjukmFQQnJ_kCxzqk8"
   }

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   The public key used to validate a Key Binding JWT can be found in the
   examples as the content of the cnf claim.

Appendix B.  Disclosure Format Considerations

   As described in Section 5.2, the Disclosure structure is JSON
   containing salt and the cleartext content of a claim, which is
   base64url encoded.  The encoded value is the input used to calculate
   a digest for the respective claim.  The inclusion of digest value in
   the signed JWT ensures the integrity of the claim value.  Using
   encoded content as the input to the integrity mechanism is
   conceptually similar to the approach in JWS and particularly useful
   when the content, like JSON, can have differences but be semantically
   equivalent.  Some further discussion of the considerations around
   this design decision follows.

   When receiving an SD-JWT, a Verifier must be able to re-compute
   digests of the disclosed claim values and, given the same input
   values, obtain the same digest values as signed by the Issuer.

   Usually, JSON-based formats transport claim values as simple
   properties of a JSON object such as this:

   ...
     "family_name": "Möbius",
     "address": {
       "street_address": "Schulstr. 12",
       "locality": "Schulpforta"
     }
   ...

   However, a problem arises when computation over the data need to be
   performed and verified, like signing or computing digests.  Common
   signature schemes require the same byte string as input to the
   signature verification as was used for creating the signature.  In
   the digest approach outlined above, the same problem exists: for the
   Issuer and the Verifier to arrive at the same digest, the same byte
   string must be hashed.

   JSON, however, does not prescribe a unique encoding for data, but
   allows for variations in the encoded string.  The data above, for
   example, can be encoded as

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   ...
   "family_name": "M\u00f6bius",
   "address": {
     "street_address": "Schulstr. 12",
     "locality": "Schulpforta"
   }
   ...

   or as

  ...
  "family_name": "Möbius",
  "address": {"locality":"Schulpforta", "street_address":"Schulstr. 12"}
  ...

   The two representations of the value in family_name are very
   different on the byte-level, but yield equivalent objects.  Same for
   the representations of address, varying in white space and order of
   elements in the object.

   The variations in white space, ordering of object properties, and
   encoding of Unicode characters are all allowed by the JSON
   specification, including further variations, e.g., concerning
   floating-point numbers, as described in [RFC8785].  Variations can be
   introduced whenever JSON data is serialized or deserialized and
   unless dealt with, will lead to different digests and the inability
   to verify signatures.

   There are generally two approaches to deal with this problem:

   1.  Canonicalization: The data is transferred in JSON format,
       potentially introducing variations in its representation, but is
       transformed into a canonical form before computing a digest.
       Both the Issuer and the Verifier must use the same
       canonicalization algorithm to arrive at the same byte string for
       computing a digest.

   2.  Source string hardening: Instead of transferring data in a format
       that may introduce variations, a representation of the data is
       serialized.  This representation is then used as the hashing
       input at the Verifier, but also transferred to the Verifier and
       used for the same digest calculation there.  This means that the
       Verifier can easily compute and check the digest of the byte
       string before finally deserializing and accessing the data.

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   Mixed approaches are conceivable, i.e., transferring both the
   original JSON data plus a string suitable for computing a digest, but
   such approaches can easily lead to undetected inconsistencies
   resulting in time-of-check-time-of-use type security vulnerabilities.

   In this specification, the source string hardening approach is used,
   as it allows for simple and reliable interoperability without the
   requirement for a canonicalization library.  To harden the source
   string, any serialization format that supports the necessary data
   types could be used in theory, like protobuf, msgpack, or pickle.  In
   this specification, JSON is used and plaintext values of each
   Disclosure are encoded using base64url-encoding for transport.  This
   approach means that SD-JWTs can be implemented purely based on widely
   available JWT, JSON, and Base64 encoding and decoding libraries.

   A Verifier can then easily check the digest over the source string
   before extracting the original JSON data.  Variations in the encoding
   of the source string are implicitly tolerated by the Verifier, as the
   digest is computed over a predefined byte string and not over a JSON
   object.

   It is important to note that the Disclosures are neither intended nor
   suitable for direct consumption by an application that needs to
   access the disclosed claim values after the verification by the
   Verifier.  The Disclosures are only intended to be used by a Verifier
   to check the digests over the source strings and to extract the
   original JSON data.  The original JSON data is then used by the
   application.  See Section 8.3 for details.

Appendix C.  Document History

   [[ To be removed from the final specification ]]

   -06

   *  Added hash of Issuer-signed part and Disclosures in KB-JWT

   *  Fix minor issues in some examples

   *  Added IANA media type registration request for the JSON
      Serialization

   *  More precise wording around storing artifacts with sensitive data

   *  The claim name _sd or ... must not be used in a disclosure.

   *  Added JWT claims registration requests to IANA

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   *  Ensure claims that control validity are checked after decoding
      payload

   *  Restructure sections around data formats and Example 1

   *  Update JSON Serialization to remove the kb_jwt member and allow
      for the disclosures to be conveyed elsewhere

   *  Expand the Enveloping SD-JWTs section to also discuss enveloping
      JSON serialized SD-JWTs

   -05

   *  Consolidate processing rules for Holder and Verifier

   *  Add support for selective disclosure of array elements.

   *  Consolidate SD-JWT terminology and format

   *  Use the term Key Binding rather than Holder Binding

   *  Defined the structure of the Key Binding JWT

   *  Added a JWS JSON Serialization

   *  Added initial IANA media type and structured suffix registration
      requests

   *  Added recommendation for explicit typing of SD-JWTs

   *  Added considerations around forwarding credentials

   *  Removed Example 2b and merged the demo of decoy digests into
      Example 2a

   *  Improved example for allowed variations in Disclosures

   *  Added some text to the Abstract and Introduction to be more
      inclusive of JWS with JSON

   *  Added some security considerations text about the scope of the Key
      Binding JWT

   *  Aligned examples structure and used the term input claim set

   *  Replaced the general SD-JWT VC example with one based on Person
      Identification Data (PID) from the European Digital Identity
      Wallet Architecture and Reference Framework

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   *  Added/clarified some privacy considerations in Confidentiality
      during Transport

   *  No longer recommending a claim name for enveloped SD-JWTs

   *  Mention prospective future PQ algs for JWS

   *  Include the public key in the draft, which can be used to verify
      the issuer signature examples

   *  Clarify that _sd_alg can only be at the top level of the SD-JWT
      payload

   *  Externalized the SD-JWT library that generates examples

   *  Attempt to improve description of security properties

   -04

   *  Improve description of processing of disclosures

   -03

   *  Clarify that other specifications may define enveloping multiple
      Combined Formats for Presentation

   *  Add an example of W3C vc-data-model that uses a JSON-LD object as
      the claims set

   *  Clarify requirements for the combined formats for issuance and
      presentation

   *  Added overview of the Security Considerations section

   *  Enhanced examples in the Privacy Considerations section

   *  Allow for recursive disclosures

   *  Discussion on holder binding and privacy of stored credentials

   *  Add some context about SD-JWT being general-purpose despite being
      a product of the OAuth WG

   *  More explicitly say that SD-JWTs have to be signed asymmetrically
      (no MAC and no none)

   *  Make sha-256 the default hash algorithm, if the hash alg claim is
      omitted

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   *  Use ES256 instead of RS256 in examples

   *  Rename and move the c14n challenges section to an appendix

   *  A bit more in security considerations for Choice of a Hash
      Algorithm (1st & 2nd preimage resistant and not majorly truncated)

   *  Remove the notational figures from the Concepts section

   *  Change salt to always be a string (rather than any JSON type)

   *  Fix the Document History (which had a premature list for -03)

   -02

   *  Disclosures are now delivered not as a JWT but as separate
      base64url-encoded JSON objects.

   *  In the SD-JWT, digests are collected under a _sd claim per level.

   *  Terms "II-Disclosures" and "HS-Disclosures" are replaced with
      "Disclosures".

   *  Holder Binding is now separate from delivering the Disclosures and
      implemented, if required, with a separate JWT.

   *  Examples updated and modified to properly explain the specifics of
      the new SD-JWT format.

   *  Examples are now pulled in from the examples directory, not
      inlined.

   *  Updated and automated the W3C VC example.

   *  Added examples with multibyte characters to show that the
      specification and demo code work well with UTF-8.

   *  reverted back to hash alg from digest derivation alg (renamed to
      _sd_alg)

   *  reformatted

   -01

   *  introduced blinded claim names

   *  explained why JSON-encoding of values is needed

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   *  explained merging algorithm ("processing model")

   *  generalized hash alg to digest derivation alg which also enables
      HMAC to calculate digests

   *  _sd_hash_alg renamed to sd_digest_derivation_alg

   *  Salt/Value Container (SVC) renamed to Issuer-Issued Disclosures
      (II-Disclosures)

   *  SD-JWT-Release (SD-JWT-R) renamed to Holder-Selected Disclosures
      (HS-Disclosures)

   *  sd_disclosure in II-Disclosures renamed to sd_ii_disclosures

   *  sd_disclosure in HS-Disclosures renamed to sd_hs_disclosures

   *  clarified relationship between sd_hs_disclosure and SD-JWT

   *  clarified combined formats for issuance and presentation

   *  clarified security requirements for blinded claim names

   *  improved description of Holder Binding security considerations -
      especially around the usage of "alg=none".

   *  updated examples

   *  text clarifications

   *  fixed cnf structure in examples

   *  added feature summary

   -00

   *  Upload as draft-ietf-oauth-selective-disclosure-jwt-00

   [[ pre Working Group Adoption: ]]

   -02

   *  Added acknowledgements

   *  Improved Security Considerations

   *  Stressed entropy requirements for salts

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   *  Python reference implementation clean-up and refactoring

   *  hash_alg renamed to _sd_hash_alg

   -01

   *  Editorial fixes

   *  Added hash_alg claim

   *  Renamed _sd to sd_digests and sd_release

   *  Added descriptions on Holder Binding - more work to do

   *  Clarify that signing the SD-JWT is mandatory

   -00

   *  Renamed to SD-JWT (focus on JWT instead of JWS since signature is
      optional)

   *  Make Holder Binding optional

   *  Rename proof to release, since when there is no signature, the
      term "proof" can be misleading

   *  Improved the structure of the description

   *  Described verification steps

   *  All examples generated from python demo implementation

   *  Examples for structured objects

Authors' Addresses

   Daniel Fett
   Authlete
   Email: mail@danielfett.de
   URI:   https://danielfett.de/

   Kristina Yasuda
   Microsoft
   Email: Kristina.Yasuda@microsoft.com

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   Brian Campbell
   Ping Identity
   Email: bcampbell@pingidentity.com

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