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Versions: 00 01

DPRIVE WG                                                       T. Reddy
Internet-Draft                                                    McAfee
Intended status: Standards Track                                 D. Wing
Expires: April 27, 2020                                           Citrix
                                                           M. Richardson
                                                Sandelman Software Works
                                                        October 25, 2019


             DNS server privacy policy with assertion token
              draft-reddy-dprive-dprive-privacy-policy-01

Abstract

   Users want to control how their DNS queries are handled by DNS
   servers so they can configure their system to use DNS servers that
   comply with their privacy expectations.

   This document defines a mechanism for a DNS server to communicate its
   privacy policy to a DNS client.  This communication is
   cryptographically signed to attest to its authenticity.  By
   evaluating the DNS privacy policy and the signatory, the DNS client
   can choose a DNS server that best supports its desired privacy
   policies.  The privacy assertion token is particularly useful for
   DNS-over-TLS and DNS-over-HTTPS servers, both public resolvers and
   those discovered on the local network.

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 April 27, 2020.








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Copyright Notice

   Copyright (c) 2019 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Use Cases Overview  . . . . . . . . . . . . . . . . . . . . .   4
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  Privacy assertion token (PAT) overview  . . . . . . . . . . .   5
   5.  PAT Header  . . . . . . . . . . . . . . . . . . . . . . . . .   6
     5.1.  "typ" (Type) Header Parameter . . . . . . . . . . . . . .   6
     5.2.  "alg" (Algorithm) Header Parameter  . . . . . . . . . . .   6
     5.3.  "x5u" (X.509 URL) Header Parameter  . . . . . . . . . . .   7
     5.4.  Example PAT header  . . . . . . . . . . . . . . . . . . .   7
   6.  PAT Payload . . . . . . . . . . . . . . . . . . . . . . . . .   7
     6.1.  JWT defined claims  . . . . . . . . . . . . . . . . . . .   8
       6.1.1.  "iat" - Issued At claim . . . . . . . . . . . . . . .   8
       6.1.2.  "exp" - Expiration Time claim . . . . . . . . . . . .   8
     6.2.  PAT specific claims . . . . . . . . . . . . . . . . . . .   8
       6.2.1.  DNS server Identity Claims  . . . . . . . . . . . . .   8
       6.2.2.  "privinfo" (Privacy Information) Claim  . . . . . . .   9
       6.2.3.  Example . . . . . . . . . . . . . . . . . . . . . . .  11
   7.  PAT Signature . . . . . . . . . . . . . . . . . . . . . . . .  12
   8.  Extending PAT . . . . . . . . . . . . . . . . . . . . . . . .  13
   9.  Deterministic JSON Serialization  . . . . . . . . . . . . . .  13
     9.1.  Example PAT deterministic JSON form . . . . . . . . . . .  14
   10. Privacy Considerations  . . . . . . . . . . . . . . . . . . .  14
   11. Security Considerations . . . . . . . . . . . . . . . . . . .  15
   12. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
     12.1.  Media Type Registration  . . . . . . . . . . . . . . . .  16
       12.1.1.  Media Type Registry Contents Additions Requested . .  16
     12.2.  JSON Web Token Claims Registration . . . . . . . . . . .  17
       12.2.1.  Registry Contents Additions Requested  . . . . . . .  17
     12.3.  DNS Resolver Information Registration  . . . . . . . . .  17
   13. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  17
   14. References  . . . . . . . . . . . . . . . . . . . . . . . . .  17



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     14.1.  Normative References . . . . . . . . . . . . . . . . . .  17
     14.2.  Informative References . . . . . . . . . . . . . . . . .  19
   Appendix A.  Example ES256 based PAT JWS Serialization and
                Signature  . . . . . . . . . . . . . . . . . . . . .  20
     A.1.  X.509 Private Key in PKCS#8 format for ES256 Example**  .  22
     A.2.  X.509 Public Key for ES256 Example**  . . . . . . . . . .  22
   Appendix B.  Complete JWS JSON Serialization Representation with
                multiple Signatures  . . . . . . . . . . . . . . . .  22
     B.1.  X.509 Private Key in PKCS#8 format for E384 Example** . .  24
     B.2.  X.509 Public Key for ES384 Example**  . . . . . . . . . .  24
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  24

1.  Introduction

   [RFC7626] discusses DNS privacy considerations in both "on the wire"
   (Section 2.4 of [RFC7626]) and "in the server" (Section 2.5 of
   [RFC7626] contexts.  In recent years there has also been an increase
   in the availability of "public resolvers"
   [I-D.ietf-dnsop-terminology-bis] which DNS clients may be pre-
   configured to use instead of the default network resolver because
   they offer a specific feature (e.g., good reachability, encrypted
   transport, strong privacy policy, filtering (or lack of), etc.).
   While a human can read the privacy policy of a DNS server operator,
   this information is not machine-parsable to allow automatic DNS
   server selection by the DNS client software.  For DNS servers
   operated on the local network, the DNS client can be securely
   bootstrapped to discover and authenticate DNS-over-TLS and DNS-over-
   HTTPS servers provided by a local network using the technique
   proposed in [I-D.reddy-dprive-bootstrap-dns-server].  By creating a
   machine-parsable DNS server privacy policy, the DNS client can
   automatically allow using a DNS server on the local network that
   complies with the DNS client's privacy policy.

   This document defines a method for creating and validating a token
   that cryptographically verifies the privacy policy information of a
   DNS server, such as a DNS-over-TLS or DNS-over-HTTPS server.

   The cryptographically signed privacy statement allows a DNS client to
   connect to multiple DNS servers and select the DNS server that
   adheres to the privacy preserving data policy requirements of the
   client.  For example, a browser with pre-configured DNS-over-HTTPS
   server can discover the DNS-over-HTTPS server provided the local
   network, connects to both the DNS servers, gets the privacy policy
   information from each of the DNS servers, validates the signatures
   and uses a server that meets the privacy preserving data policy
   requirements of the client.  If both servers meet the privacy
   preserving data policy requirements of the client, it can select to
   use the local DNS server.  In addition, the cryptographically signed



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   privacy statement allows a DNS-over-TLS or DNS-over-HTTPS client to
   securely determine whether the local DNS server performs DNS-based
   content filtering, and if the local server meets the privacy
   preserving data policy requirements of the client, the client can
   continue to use the local DNS-over-TLS server to resolve DNS queries
   and does not have to switch to the pre-configured public resolver.

2.  Use Cases Overview

   The mechanism for a DNS server to communicate its cryptographically
   signed privacy policy to a DNS client solves the following problems
   in various deployments:

   o  Typically Enterprise networks do not assume that all devices in
      their network are managed by the IT team or Mobile Device
      Management (MDM) devices, especially in the quite common BYOD
      ("Bring Your Own Device") scenario.  The mechanism specified in
      this document can be used by BYOD devices to determine if the DNS
      server on the local network complies with the client's privacy
      policy.

   o  The user must select specific well known networks (e.g.,
      organization for which a user works or a user works temporarily
      within another corporation) to learn the privacy policy
      information of the local DNS server, and user can choose to use
      the discovered DNS-over-TLS or DNS-over-HTTPS server.  If that
      discovered DNS-over-TLS or DNS-over-HTTPS server does not meet the
      privacy requirements of the user, user can be warned and the
      client can take appropriate action.  For example, use the network
      only to access internal-only DNS names or fallback to a privacy-
      enabling public DNS server.

   o  The privacy policy information signals the presence of DNS-based
      content filtering in the attached network.  If the network is well
      known and the local DNS server meets the privacy requirements of
      the user, the client can continue to use encrypted connection with
      the local DNS-over-TLS or DNS-over-HTTPS server.  If the error
      code returned by the DNS server indicates access to the domain is
      blocked because of internal security policy
      [I-D.ietf-dnsop-extended-error], the client can securely identify
      access to the domain is censored by the network.

   o  The privacy policy conveys a URL that points to the human readable
      privacy policy information of the DNS server for the user to
      review and can make an informed decision whether the DNS server is
      trustworthy to honor the privacy of the user.  The client
      automatically learns updates to the privacy policy of the DNS
      server, and whenever the privacy policy of the DNS server changes,



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      the client can notify the user to re-visit the URL to re-review
      the privacy policy information of the DNS server.

   If the device joins a public WiFi without any security credential
   verification, such networks are typically not known to the user, and
   the device cannot be securely bootstrapped with the network's DNS-
   over-HTTPS or DNS-over-TLS server.  Such networks can be
   misconfigured or malicious.  Further, the client cannot know if the
   discovered DNS-over-HTTPS or DNS-over-TLS server is hosted by the
   network operator or by an attacker.  This specification does not
   cater to such networks.

3.  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.

   (D)TLS is used for statements that apply to both Transport Layer
   Security [RFC8446] and Datagram Transport Layer Security [RFC6347].
   Specific terms are used for any statement that applies to either
   protocol alone.

   This document uses the terms defined in [RFC8499].

4.  Privacy assertion token (PAT) overview

   JSON Web Token (JWT) [RFC7519] and JSON Web Signature (JWS) [RFC7515]
   and related specifications define a standard token format that can be
   used as a way of encapsulating claimed or asserted information with
   an associated digital signature using X.509 based certificates.  JWT
   provides a set of claims in JSON format that can conveniently
   accommodate asserted privacy policy information of the DNS-over-TLS
   or DNS-over-HTTPS server.  Additionally, JWS provides a path for
   updating methods and cryptographic algorithms used for the associated
   digital signatures.

   JWS defines the use of JSON data structures in a specified canonical
   format for signing data corresponding to JOSE header, JWS Payload,
   and JWS Signature.  JWT defines a set of claims that are represented
   by specified JSON objects which can be extended with custom keys for
   specific applications.  The next sections define the header and
   claims that MUST be minimally used with JWT and JWS for privacy
   assertion token.





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   The privacy assertion token (PAT) specifically uses this token format
   and defines claims that convey the privacy policy information of DNS-
   over-TLS or DNS-over-HTTPS server.  The signer of a PAT object may or
   may not correspond to the DNS server's domain.  The PAT object can be
   validated by the DNS client, and if the DNS server meets the privacy
   preserving data policy requirements of the client and/or end user, it
   can switch to the privacy-enabling DNS server discovered in the
   located network.  The creation of the PAT object is performed by an
   entity that is authoritative to assert the DNS server privacy policy
   information.  This authority is represented by the certificate
   credentials and the signature, and PAT object is created and the
   client can retrieve the PAT object using the method discussed in
   [I-D.ietf-dnsop-resolver-information].

   For example, the PAT object could be created by the domain hosting
   the DNS-over-TLS or DNS-over-HTTPS server, or by a third party who
   performed privacy and security audit of the DNS-over-TLS or DNS-over-
   HTTPS server.  The DNS client needs to have the capability to verify
   the PAT token and the digital signature.  The PAT associated
   certificate is used to validate the authority of the originating
   signer, generally via a certificate chain to the trust anchor for the
   DNS client.

5.  PAT Header

   The JWS token header is a JOSE header, [RFC7515] Section 4, that
   defines the type and encryption algorithm used in the token.

   PAT header should include, at a minimum, the header parameters
   defined in the next three subsections.

5.1.  "typ" (Type) Header Parameter

   The "typ" (Type) Header Parameter is defined in JWS [RFC7515]
   Section 4.1.9 to declare the media type of the complete JWS.

   For PAT Token the "typ" header MUST be the string "pat".  This
   represents that the encoded token is a JWT of type pat.

5.2.  "alg" (Algorithm) Header Parameter

   The "alg" (Algorithm) Header Parameter is defined in JWS [RFC7515]
   Section 4.1.1.  This definition includes the ability to specify the
   use of a cryptographic algorithm for the signature part of the JWS.
   It also refers to a list of defined "alg" values as part of a
   registry established by JSON Web Algorithms (JWA) [RFC7518]
   Section 3.1.




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   For the creation and verification of PAT tokens and their digital
   signatures, implementations MUST support ES256 as defined in JWA
   [RFC7518] Section 3.4.  Implementations MAY support other algorithms
   registered in the JSON Web Signature and Encryption Algorithms
   registry created by [RFC7518].  The contents of that registry may be
   updated in the future depending on cryptographic strength
   requirements guided by current security best practice.  The
   mandatory-to-support algorithm for PAT tokens may likewise be updated
   in future updates to this document.

   Implementations of PAT digital signatures using ES256 as defined
   above SHOULD use deterministic ECDSA if/when supported for the
   reasons stated in [RFC6979].

5.3.  "x5u" (X.509 URL) Header Parameter

   As defined in JWS [RFC7515] Section 4.1.5., the "x5u" header
   parameter defines a URI [RFC3986] referring to the resource for the
   X.509 public key certificate or certificate chain [RFC5280]
   corresponding to the key used to digitally sign the JWS.  Generally,
   as defined in JWS [RFC7515] section 4.1.5, this would correspond to
   an HTTPS or DNSSEC resource using integrity protection.

5.4.  Example PAT header

   An example of the header, would be the following, including the
   specified pat type, ES256 algorithm, and a URI referencing the
   network location of the certificate needed to validate the PAT
   signature.

   {
     "typ":"pat",
     "alg":"ES256",
     "x5u":"https://cert.example.com/pat.cer"
   }

6.  PAT Payload

   The token claims consists of the privacy policy information of the
   DNS server which needs to be verified at the DNS client.  These
   claims follow the definition of a JWT claim [RFC7519] Section 4 and
   are encoded as defined by the JWS Payload [RFC7515] Section 3.

   PAT defines the use of a standard JWT defined claim as well as custom
   claims corresponding to the DNS-over-TLS or DNS-over-HTTPS servers.

   Any claim names MUST use the US-ASCII character set.  Any claim
   values can contain characters that are outside the US-ASCII range,



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   however MUST follow the default JSON serialization defined in
   [RFC7519] Section 7.

6.1.  JWT defined claims

6.1.1.  "iat" - Issued At claim

   The JSON claim MUST include the "iat" [RFC7519] Section 4.1.6 defined
   claim Issued At.  As defined the "iat" should be set to the date and
   time of issuance of the JWT.  The time value should be of the format
   defined in [RFC7519] Section 2 NumericDate.

6.1.2.  "exp" - Expiration Time claim

   The JSON claim MUST include the "exp" [RFC7519] Section 4.1.4 defined
   claim Expiration Time.  As defined the "exp" should be set to specify
   the expiration time on or after which the JWT is not accepted for
   processing.  The PAT object should generally expire after a
   reasonable duration.  A short expiration time for the PAT object
   periodically reaffirms the privacy policy information of the DNS
   server to the client and ensures the client does not use outdated
   privacy policy information.  If the client knows the PAT object has
   expired, it makes another request to get the new PAT object from the
   DNS server.

6.2.  PAT specific claims

6.2.1.  DNS server Identity Claims

   The DNS server identity is represented by a claim that is required
   for PAT, the "server" claim.  The "server" MUST contain claim values
   that are identity claim JSON objects where the child claim name
   represents an identity type and the claim value is the identity
   string, both defined in subsequent subsections.  Currently, these
   identities can be represented as either authentication domain name
   (ADN) (defined in [RFC8310]) or Uniform Resource Indicators (URI).

6.2.1.1.  "adn" - authentication domain name identity

   If the DNS server identity is a ADN, the claim name representing the
   identity MUST be "adn".  The claim value for the "adn" claim is the
   ADN.

6.2.1.2.  "uri" - URI identity

   If the DNS server identity is of the form URI, as defined in
   [RFC3986], the claim name representing the identity MUST be "uri" and
   the claim value is the URI form of the DNS server identity.  As a



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   reminder, if DNS-over-HTTPS protocol is supported by the DNS server,
   the DNS client uses the https URI scheme (Section 3 of [RFC8484]).

6.2.2.  "privinfo" (Privacy Information) Claim

   The "privinfo" claim MUST be formatted as a JSON object.  The
   "privinfo" claim contains the privacy policy information of the DNS
   server, it includes the following attributes:

   ipaddresspii:  If the client IP address is Personally Identifiable
      Information (PII) data or non PII-data.  If client IP address is
      PII, the parameter value is set to 'true'.  This is a mandatory
      attribute.

   logging:  If the transaction data (e.g., DNS messages) is logged and
      the duration that data is stored.  A value of negative one (-1)
      indicates indefinite duration of logging transaction data.  A
      value of zero (0) indicates no logging.  Logging duration is
      represented in hours.  If any of the attributes 'useridentity',
      'notifyuser' and 'analytics' are not set to the value zero,
      'logging' attribute MUST NOT be set to the value zero.  This is a
      mandatory attribute.

   useridentity:  If the user identity that sent the DNS query is logged
      and the duration that data is retained.  User identity includes
      things such as username, IP address, MAC address, user DNS query
      patterns or any other personally identifiable data.  The server
      should also discard or minimize correlation data (Section 5.2.4 of
      [I-D.ietf-dprive-bcp-op]) that can be used to identify the end
      user.  A value of negative one (-1) indicates indefinite duration
      of logging user identity.  A value of zero (0) indicates no
      logging.  Logging duration is represented in hours.  This is a
      mandatory attribute.

   filtering:  If the DNS server changes some of the answers that it
      returns based on policy criteria, such as to prevent access to
      malware sites or objectionable content.  This optional attribute
      has the following structure:

      malwareblocking:  The DNS server offers malware blocking service.
         If access to domains is blocked on threat data, the parameter
         value is set to 'true'.

      policyblocking:  If access to domains is blocked on a blacklist or
         objectionable content, the parameter value is set to 'true'.

   notifyuser:  If the transaction data is logged to notify the user
      access to certain domains is blocked, the period for which the



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      transaction data is stored.  A value of negative one (-1)
      indicates indefinite duration of logging transaction data to
      notify the user.  A value of zero (0) indicates no logging.
      Logging duration is represented in hours.  This is an optional
      attribute.

   analytics:  If the transaction data is logged for analytics (e.g., To
      detect malicious domains), the period for which the transaction
      data is stored.  A value of negative one (-1) indicates indefinite
      duration of logging transaction data for analytics.  A value of
      zero (0) indicates no logging.  Logging duration is represented in
      hours.  This is an optional attribute.

   sharedata:  If the transaction data is shared with partners or not,
      and if the transaction data is shared with partners, the names of
      the partners.  If anonymized data or client identifiable data is
      shared with partners.  The term "anonymization" is defined in
      Section 5.2.2 of [I-D.ietf-dprive-bcp-op].  This mandatory
      attribute has the following structure:

      sharepartners:  If transaction data is shared with partners, the
         parameter value is set to 'true'.

      partners:  List of partner names.  If 'sharepartners' value is set
         to false, 'partners' MUST NOT be present in the 'sharedata'
         structure.

      anonymizeddata:  If anonymized transaction data is shared with
         partners, the parameter value is set to 'true'.  If
         'sharepartners' value is set to false, 'anonymizeddata' MUST
         NOT be present in the 'sharedata' structure.

   transferdata:  If the transaction data is shared or sold to third
      parties.  If the parameter value is set to 'true', means share or
      sell data to third parties.  This is a mandatory attribute.

   qnameminimization:  If the DNS server implements QNAME minimisation
      [RFC7816] to improve DNS privacy.  If the parameter value is set
      to 'true', QNAME minimisation is supported by the DNS server.
      This is a mandatory attribute.

   privacyurl:  A URL that points to the privacy policy information of
      the DNS server.  This is a mandatory attribute.

   auditurl:  A URL that points to the security assessment report of the
      DNS server by a third party auditor.  This is an optional
      attribute.




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   upstreamservers:  The local DNS server can be configured as a
      Forwarding DNS server [RFC8499] relying on the upstream resolver
      (e.g., at an ISP) to perform recursive DNS lookups.  The client
      needs to discover the privacy policy information of both the
      forwarder and recursive resolvers.  This optional attribute has
      the following structure:

      securechannel:  If DNS-over-TLS or DNS-over-HTTPS is used to
         encrypt the DNS messages exchanged between the local DNS server
         and recursive resolver, the parameter value is set to 'true'.

      upstreamserverspat:  The PAT object of the upstream DNS server.
         If a local DNS server is configured as a Forwarding DNS server,
         its PAT MUST include the PAT object of the upstream resolver it
         is using.  If the upstream DNS resolver does not communicate
         its privacy policy, the attribute value must be set to empty
         string.  The client can combine the local and upstream
         resolver's privacy policies, always combining for the worse
         privacy values.  For example, if the local server does not log
         queries but the upstream resolver does log queries, the
         combined PAT policy would indicate queries are logged and the
         client can evaluate if its privacy preserving data policy
         requirements are met.  The Forwarding DNS server is typically
         configured with both primary and secondary resolvers as a
         backup mechanism to handle primary server failure.  If the
         local DNS server is configured to use primary and secondary
         resolvers, 'upstreamserverspat' MUST include two entries in the
         array.  If the local DNS server is acting as a forwarder, it
         RECOMMENDED that the DNS client requests the privacy policy
         information of the server every time the connection is re-
         established with the server.  It allows the client to detect
         change in the local DNS server configuration to use an
         alternate resolver.

6.2.3.  Example

   The below Figure shows an example of privacy policy information.














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   {
     "server":{
         "adn":["example.com"]
     },
     "iat":1443208345,
     "exp":1443640345,
     "privinfo": {
        "ipaddresspii":true,
        "logging": 24,
        "useridentity": 24,
        "sharedata": {
            "sharepartners": false
        },
        "transferdata":false,
        "privacyurl": "https://example.com/commitment-to-privacy/"
     }
   }

7.  PAT Signature

   The signature of the PAT is created as specified by JWS [RFC7515]
   Section 5.1 Steps 1 through 6.  PAT MUST use the JWS Protected
   Header.  For the JWS Payload and the JWS Protected Header, the
   lexicographic ordering and white space rules described in Section 5
   and Section 6, and JSON serialization rules in Section 9 of this
   document MUST be followed.

   The PAT is cryptographically signed by the domain hosting the DNS
   server and optionally by a third party who performed privacy and
   security audit of the DNS server.  The privacy policy information
   will be attested using "Organization Validation" (OV) or "Extended
   Validation" (EV) certificates to avoid bad actors taking advantage of
   this mechanism to advertise DNS-over-TLS and DNS-over-HTTPS servers
   for illegitimate and fraudulent purposes meant to trick DNS clients
   into believing that they are using a legitimate DNS-over-TLS or DNS-
   over-HTTPS server hosted to provide privacy for DNS transactions.
   Alternatively, the DNS client will have to be configured to trust the
   leaf of the signer of the PAT object.  That is, trust of the signer
   MUST NOT be determined by validating the signer via the OS or browser
   trust chain because that would allow any arbitrary entity to operate
   a DNS server and assert any sort of privacy policy.

   Appendix A of this document has a detailed example of how to follow
   the steps to create the JWS Signature.

   JWS [RFC7515] Section 5.1 Step 7 JWS JSON serialization is supported
   for PAT to enable multiple signatures to be applied to the PAT
   object.  For example, the PAT object can be cryptographically signed



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   by the domain hosting the DNS server and by a third party who
   performed privacy and security audit of the DNS server.

   Appendix B of this document has a example of complete JWS JSON
   serialization representation with multiple signatures.

   JWS [RFC7515] Section 5.1 Step 8 describes the method to create the
   final JWS Compact Serialization form of the PAT Token.

8.  Extending PAT

   PAT includes the minimum set of claims needed to securely assert the
   privacy policy information of the DNS server.  JWT supports a
   straight forward way to add additional asserted or signed information
   by simply adding new claims.  PAT can be extended beyond the defined
   base set of claims to represent other DNS server information
   requiring assertion or validation.  Specifying new claims follows the
   baseline JWT procedures ([RFC7519] Section 10.1).  Understanding new
   claims on the DNS client is optional.  The creator of a PAT object
   cannot assume that the DNS client will understand the new claims.

9.  Deterministic JSON Serialization

   JSON objects can include spaces and line breaks, and key value pairs
   can occur in any order.  It is therefore a non-deterministic string
   format.  In order to make the digital signature verification work
   deterministically, the JSON representation of the JWS Protected
   Header object and JWS Payload object MUST be computed as follows.

   The JSON object MUST follow the following rules.  These rules are
   based on the thumbprint of a JSON Web Key (JWK) as defined in
   Section 3 Step 1 of [RFC7638].

   1.  The JSON object MUST contain no whitespace or line breaks before
       or after any syntactic elements.

   2.  JSON objects MUST have the keys ordered lexicographically by the
       Unicode [UNICODE] code points of the member names.

   3.  JSON value literals MUST be lowercase.

   4.  JSON numbers are to be encoded as integers unless the field is
       defined to be encoded otherwise.

   5.  Encoding rules MUST be applied recursively to member values and
       array values.





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9.1.  Example PAT deterministic JSON form

   This section demonstrates the deterministic JSON serialization for
   the example PAT Payload shown in Section 6.2.3.

   The initial JSON object is shown here:

   {
     "server":{
         "adn":["example.com"]
     },
     "iat":1443208345,
     "exp":1443640345,
     "privinfo": {
        "ipaddresspii":true,
        "logging": 24,
        "useridentity": 24,
        "sharedata": {
            "sharepartners": false
        },
        "transferdata":false,
        "privacyurl": "https://example.com/commitment-to-privacy/"
     }
   }

   The parent members of the JSON object are as follows, in
   lexicographic order: "exp", "iat", "privinfo", "server".

   The final constructed deterministic JSON serialization
   representation, with whitespace and line breaks removed, (with line
   breaks used for display purposes only) is:

 {"exp":1443640345,"iat":1443208345,"privinfo":{"ipaddresspii":true,
 "logging":24,"privacyurl":"https://example.com/commitment-to-privacy/",
 "sharedata":{"sharepartners":false},"transferdata":false,
 "useridentity":24},"server":{"adn":["example.com"]}}

10.  Privacy Considerations

   Users are expected to indicate to their system in some way that they
   trust certain PAT signers (e.g., if working for Example, Inc., the
   user's system is configured to trust example.com signing the PAT).
   Separately, the user is expected to indicate to their system their
   PAT privacy requirements (e.g., logging, etc.).  By doing so, the DNS
   client can automatically discover local DNS-over-TLS or DNS-over-
   HTTPS server, validate the PAT signature and check if the PAT
   complies with user's privacy needs, prior to using that DNS-over-TLS
   or DNS-over-HTTPS server for DNS queries.  The client MAY also



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   retrieve the human-readable privacy statement from the 'privacyurl'
   attribute to assist with that decision (e.g., display the privacy
   statement when it changes, show differences in previously-retrieved
   version, etc.).  With the steps above, user consent is obtained prior
   to using a locally-discovered DNS-over-TLS or DNS-over-HTTPS server
   for DNS queries.

   An average user may not be able to indicate the privacy preserving
   data policy requirements to the system.  For such users, the DNS
   client should auto check if the PAT complies with typical users
   privacy needs.  For example, the client by default does not select
   the local DNS-over-TLS or DNS-over-HTTPS server if it shares non-
   anonymized DNS transaction data with partners or if it logs the DNS
   transaction data for a very long duration.

11.  Security Considerations

   The use of PAT object based on the validation of the digital
   signature and the associated certificate requires consideration of
   the authentication and authority or reputation of the signer to
   attest the privacy policy information of the DNS server being
   asserted.  Bad actors can host DNS-over-TLS and DNS-over-HTTPS
   servers, and claim the servers offer privacy but exactly do the
   opposite to invade the privacy of the user.  Bad actor can get a
   domain name, host DNS-over-TLS and DNS-over-HTTPS servers, and get
   the DNS server certificate signed by a CA.  The privacy policy
   information will have to be attested using OV/EV certificates or a
   PAT object signer trusted by the DNS client to prevent the attack.

   If the PAT object is asserted by a third party, it can do a "time of
   check" but the DNS server is susceptible of "time of use" attack.
   For example, changes to privacy policy of the DNS server like sharing
   identifiable transaction data with partners can cause a disagreement
   between the PAT object and the DNS server operation.  In other words,
   the DNS server might have complied with the privacy policy when it
   was audited (by the 3rd party) but could now be in non-compliance
   with its privacy policy, hence the PAT object needs to be also
   asserted by the domain hosting the DNS server.  In addition, the PAT
   object needs to have a short expiration time (e.g., 7 days) to ensure
   the DNS server's domain re-asserts the privacy policy information and
   limits the damage from change in privacy policy and mis-issuance.

12.  IANA Considerations








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12.1.  Media Type Registration

12.1.1.  Media Type Registry Contents Additions Requested

   This section registers the "application/pat" media type [RFC2046] in
   the "Media Types" registry in the manner described in [RFC6838],
   which can be used to indicate that the content is a PAT defined JWT.

   o  Type name: application

   o  Subtype name: pat

   o  Required parameters: n/a

   o  Optional parameters: n/a

   o  Encoding considerations: 8bit; application/pat values are encoded
      as a series of base64url-encoded values (some of which may be the
      empty string) separated by period ('.') characters..

   o  Security considerations: See the Security Considerations
      Section of [RFC7515].

   o  Interoperability considerations: n/a

   o  Published specification: [RFCThis]

   o  Applications that use this media type: DNS

   o  Fragment identifier considerations: n/a

   o  Additional information:

      Magic number(s): n/a File extension(s): n/a Macintosh file type
      code(s): n/a

   o  Person & email address to contact for further information:
      Tirumaleswar Reddy, kondtir@gmail.com

   o  Intended usage: COMMON

   o  Restrictions on usage: none

   o  Author: Tirumaleswar Reddy, kondtir@gmail.com

   o  Change Controller: IESG

   o  Provisional registration?  No



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12.2.  JSON Web Token Claims Registration

12.2.1.  Registry Contents Additions Requested

   o  Claim Name: "server"

   o  Claim Description: DNS server identity

   o  Change Controller: IESG

   o  Specification Document(s): Section 6.2.1 of [TODO this document]

   o  Claim Name: "privinfo"

   o  Claim Description: Privacy policy information of DNS server.

   o  Change Controller: IESG

   o  Specification Document(s): Section 6.2.2 of [TODO this document]

12.3.  DNS Resolver Information Registration

   IANA will add the names ipaddresspii, logging, useridentity,
   filtering, notifyuser, analytics, sharedata, transferdata,
   qnameminimization, privacyurl, auditurl and upstreamserverpat to the
   DNS Resolver Information registry defined in Section 5.2 of
   [I-D.ietf-dnsop-resolver-information].

13.  Acknowledgments

   This specification leverages some of the work that has been done in
   [RFC8225].  Thanks to Ted Lemon, Paul Wouters and Shashank Jain for
   the discussion and comments.

14.  References

14.1.  Normative References

   [I-D.ietf-dnsop-resolver-information]
              Sood, P., Arends, R., and P. Hoffman, "DNS Resolver
              Information Self-publication", draft-ietf-dnsop-resolver-
              information-00 (work in progress), August 2019.

   [I-D.ietf-dnsop-terminology-bis]
              Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
              Terminology", draft-ietf-dnsop-terminology-bis-14 (work in
              progress), September 2018.




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

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <https://www.rfc-editor.org/info/rfc3986>.

   [RFC5280]  Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
              Housley, R., and W. Polk, "Internet X.509 Public Key
              Infrastructure Certificate and Certificate Revocation List
              (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008,
              <https://www.rfc-editor.org/info/rfc5280>.

   [RFC6347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
              January 2012, <https://www.rfc-editor.org/info/rfc6347>.

   [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>.

   [RFC6979]  Pornin, T., "Deterministic Usage of the Digital Signature
              Algorithm (DSA) and Elliptic Curve Digital Signature
              Algorithm (ECDSA)", RFC 6979, DOI 10.17487/RFC6979, August
              2013, <https://www.rfc-editor.org/info/rfc6979>.

   [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>.

   [RFC7518]  Jones, M., "JSON Web Algorithms (JWA)", RFC 7518,
              DOI 10.17487/RFC7518, May 2015,
              <https://www.rfc-editor.org/info/rfc7518>.

   [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>.





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   [RFC7638]  Jones, M. and N. Sakimura, "JSON Web Key (JWK)
              Thumbprint", RFC 7638, DOI 10.17487/RFC7638, September
              2015, <https://www.rfc-editor.org/info/rfc7638>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

   [RFC8484]  Hoffman, P. and P. McManus, "DNS Queries over HTTPS
              (DoH)", RFC 8484, DOI 10.17487/RFC8484, October 2018,
              <https://www.rfc-editor.org/info/rfc8484>.

   [RFC8499]  Hoffman, P., Sullivan, A., and K. Fujiwara, "DNS
              Terminology", BCP 219, RFC 8499, DOI 10.17487/RFC8499,
              January 2019, <https://www.rfc-editor.org/info/rfc8499>.

   [UNICODE]  The Unicode Consortium, "The Unicode Standard", June 2016,
              <http://www.unicode.org/versions/latest/>.

14.2.  Informative References

   [I-D.ietf-dnsop-extended-error]
              Kumari, W., Hunt, E., Arends, R., Hardaker, W., and D.
              Lawrence, "Extended DNS Errors", draft-ietf-dnsop-
              extended-error-12 (work in progress), October 2019.

   [I-D.ietf-dprive-bcp-op]
              Dickinson, S., Overeinder, B., Rijswijk-Deij, R., and A.
              Mankin, "Recommendations for DNS Privacy Service
              Operators", draft-ietf-dprive-bcp-op-04 (work in
              progress), October 2019.

   [I-D.reddy-dprive-bootstrap-dns-server]
              K, R., Wing, D., Richardson, M., and M. Boucadair, "A
              Bootstrapping Procedure to Discover and Authenticate DNS-
              over-(D)TLS and DNS-over-HTTPS Servers", draft-reddy-
              dprive-bootstrap-dns-server-05 (work in progress), October
              2019.

   [RFC7626]  Bortzmeyer, S., "DNS Privacy Considerations", RFC 7626,
              DOI 10.17487/RFC7626, August 2015,
              <https://www.rfc-editor.org/info/rfc7626>.





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   [RFC7816]  Bortzmeyer, S., "DNS Query Name Minimisation to Improve
              Privacy", RFC 7816, DOI 10.17487/RFC7816, March 2016,
              <https://www.rfc-editor.org/info/rfc7816>.

   [RFC8225]  Wendt, C. and J. Peterson, "PASSporT: Personal Assertion
              Token", RFC 8225, DOI 10.17487/RFC8225, February 2018,
              <https://www.rfc-editor.org/info/rfc8225>.

   [RFC8310]  Dickinson, S., Gillmor, D., and T. Reddy, "Usage Profiles
              for DNS over TLS and DNS over DTLS", RFC 8310,
              DOI 10.17487/RFC8310, March 2018,
              <https://www.rfc-editor.org/info/rfc8310>.

Appendix A.  Example ES256 based PAT JWS Serialization and Signature

   For PAT, there will always be a JWS with the following members:

   o  "protected", with the value BASE64URL(UTF8(JWS Protected Header))

   o  "payload", with the value BASE64URL (JWS Payload)

   o  "signature", with the value BASE64URL(JWS Signature)

   This example will follow the steps in JWS [RFC7515] Section 5.1,
   steps 1-6 and 8 and incorporates the additional serialization steps
   required for PAT.

   Step 1 for JWS references the JWS Payload, an example PAT Payload is
   as follows:

   {
     "server":{
         "adn":["example.com"]
     },
     "iat":1443208345,
     "exp":1443640345,
     "privinfo": {
        "ipaddresspii":true,
        "logging": 24,
        "useridentity": 24,
        "sharedata": {
            "sharepartners": false
        },
        "transferdata":false,
        "privacyurl": "https://example.com/commitment-to-privacy/"
     }
   }




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   This would be serialized to the form (with line break used for
   display purposes only):

 {"exp":1443640345,"iat":1443208345,"privinfo":{"ipaddresspii":true,
 "logging":24,"privacyurl":"https://example.com/commitment-to-privacy/",
 "sharedata":{"sharepartners":false},"transferdata":false,
 "useridentity":24},"server":{"adn":["example.com"]}}

   Step 2 Computes the BASE64URL(JWS Payload) producing this value (with
   line break used for display purposes only):

   eyJleHAiOjE0NDM2NDAzNDUsImlhdCI6MTQ0MzIwODM0NSwicHJpdmluZm8iOnsi
   aXBhZGRyZXNzcGlpIjp0cnVlLCJsb2dnaW5nIjoyNCwicHJpdmFjeXVybCI6Imh0
   dHBzOi8vZXhhbXBsZS5jb20vY29tbWl0bWVudC10by1wcml2YWN5LyIsInNoYXJl
   ZGF0YSI6eyJzaGFyZXBhcnRuZXJzIjpmYWxzZX0sInRyYW5zZmVyZGF0YSI6ZmFs
   c2UsInVzZXJpZGVudGl0eSI6MjR9LCJzZXJ2ZXIiOnsiYWRuIjpbImV4YW1wbGUu
   Y29tIl19fQ


   For Step 3, an example PAT Protected Header comprising the JOSE
   Header is as follows:

   {
     "alg":"ES256",
     "typ":"pat",
     "x5u":"https://cert.example.com/pat.cer"
   }

   This would be serialized to the form (with line break used for
   display purposes only):

   {"alg":"ES256","typ":"pat","x5u":"https://cert.example.com
   /pat.cer"}

   Step 4 Performs the BASE64URL(UTF8(JWS Protected Header)) operation
   and encoding produces this value (with line break used for display
   purposes only):

   eyJhbGciOiJFUzI1NiIsInR5cCI6InBhdCIsIng1dSI6Imh0dHBzOi8vY2VydC5l
   eGFtcGxlLmNvbS9wYXQuY2VyIn0


   Step 5 and Step 6 performs the computation of the digital signature
   of the PAT Signing Input ASCII(BASE64URL(UTF8(JWS Protected
   Header)) || '.' || BASE64URL(JWS Payload)) using ES256 as the
   algorithm and the BASE64URL(JWS Signature).





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   LEyaZpkJWVeJiQXdh6stCUo5VnLO56p9nTNsG8xhqpQMoJWc4j46Ze_43wPG-vHb
   Xq7BaVIfdb_Lw3BcKr92Cw


   Step 8 describes how to create the final PAT token, concatenating the
   values in the order Header.Payload.Signature with period ('.')
   characters.  For the above example values this would produce the
   following (with line breaks between period used for readability
   purposes only):

   eyJhbGciOiJFUzI1NiIsInR5cCI6InBhdCIsIng1dSI6Imh0dHBzOi8vY2VydC5l
   eGFtcGxlLmNvbS9wYXQuY2VyIn0
   .
   eyJleHAiOjE0NDM2NDAzNDUsImlhdCI6MTQ0MzIwODM0NSwicHJpdmluZm8iOnsi
   aXBhZGRyZXNzcGlpIjp0cnVlLCJsb2dnaW5nIjoyNCwicHJpdmFjeXVybCI6Imh0
   dHBzOi8vZXhhbXBsZS5jb20vY29tbWl0bWVudC10by1wcml2YWN5LyIsInNoYXJl
   ZGF0YSI6eyJzaGFyZXBhcnRuZXJzIjpmYWxzZX0sInRyYW5zZmVyZGF0YSI6ZmFs
   c2UsInVzZXJpZGVudGl0eSI6MjR9LCJzZXJ2ZXIiOnsiYWRuIjpbImV4YW1wbGUu
   Y29tIl19fQ
   .
   1ysb-n4O3YeN7HwPtzMP3SCEz28I80c78Lke4D_DRiwT8_-zi0p8IwmNU9778lOy
   Ub9WZehA89G4VMx8DDpm0Q


A.1.  X.509 Private Key in PKCS#8 format for ES256 Example**

   -----BEGIN PRIVATE KEY-----
   MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgevZzL1gdAFr88hb2
   OF/2NxApJCzGCEDdfSp6VQO30hyhRANCAAQRWz+jn65BtOMvdyHKcvjBeBSDZH2r
   1RTwjmYSi9R/zpBnuQ4EiMnCqfMPWiZqB4QdbAd0E7oH50VpuZ1P087G
   -----END PRIVATE KEY-----

A.2.  X.509 Public Key for ES256 Example**

   -----BEGIN PUBLIC KEY-----
   MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEEVs/o5+uQbTjL3chynL4wXgUg2R9
   q9UU8I5mEovUf86QZ7kOBIjJwqnzD1omageEHWwHdBO6B+dFabmdT9POxg==
   -----END PUBLIC KEY-----

Appendix B.  Complete JWS JSON Serialization Representation with
             multiple Signatures

   The JWS payload used in this example as follows.








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   {
     "server":{
         "adn":["example.com"]
     },
     "iat":1443208345,
     "exp":1443640345,
     "privinfo": {
        "ipaddresspii":true,
        "logging": 24,
        "useridentity": 24,
        "sharedata": {
            "sharepartners": false
        },
        "transferdata":false,
        "privacyurl": "https://example.com/commitment-to-privacy/",
        "auditurl":   "https://audit-example.com/privacyaudit"
     }
   }

   This would be serialized to the form (with line break used for
   display purposes only):

  {"auditurl":"https://audit-example.com/privacyaudit","exp":1443640345,
  "iat":1443208345,"privinfo":{"ipaddresspii":true,"logging":24,
  "privacyurl":"https://example.com/commitment-to-privacy/",
  "sharedata":{"sharepartners":false},"transferdata":false,
  "useridentity":24},"server":{"adn":["example.com"]}}

   The JWS protected Header value used for the first signature is same
   as that used in the example in Appendix A.  The X.509 private key
   used for generating the first signature is same as that used in the
   example in Appendix A.1.

   The JWS Protected Header value used for the second signature is:

   {
     "alg":"ES384",
     "typ":"pat",
     "x5u":"https://cert.audit-example.com/pat.cer"
   }

   The complete JWS JSON Serialization for these values is as follows
   (with line breaks within values for display purposes only):








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{
  "payload":
       "eyJhdWRpdHVybCI6Imh0dHBzOi8vYXVkaXQtZXhhbXBsZS5jb20vcHJpdmFjeWF
       1ZGl0IiwiZXhwIjoxNDQzNjQwMzQ1LCJpYXQiOjE0NDMyMDgzNDUsInByaXZpbmZ
       vIjp7ImlwYWRkcmVzc3BpaSI6dHJ1ZSwibG9nZ2luZyI6MjQsInByaXZhY3l1cmw
       iOiJodHRwczovL2V4YW1wbGUuY29tL2NvbW1pdG1lbnQtdG8tcHJpdmFjeS8iLCJ
       zaGFyZWRhdGEiOnsic2hhcmVwYXJ0bmVycyI6ZmFsc2V9LCJ0cmFuc2ZlcmRhdGE
       iOmZhbHNlLCJ1c2VyaWRlbnRpdHkiOjI0fSwic2VydmVyIjp7ImFkbiI6WyJleGF
       tcGxlLmNvbSJdfX0",
  "signatures":[
       {"protected":"eyJhbGciOiJFUzI1NiIsInR5cCI6InBhdCIsIng1dSI6Imh0dHB
        zOi8vY2VydC5leGFtcGxlLmNvbS9wYXQuY2VyIn0",
        "signature":
         "VeX23b4UNTRE358iXJGBnSnMXkIfrEYeZwA8aVKA1In-Nz5lpGVFXIjArnUY7T
          D9vMR01jUzTy4qVbtA0smbUA"},
       {"protected":"eyJhbGciOiJFUzM4NCIsInR5cCI6InBhdCIsIng1dSI6Imh0dHB
          zOi8vY2VydC5hdWRpdC1leGFtcGxlLmNvbS9wYXQuY2VyIn0",
        "signature":
         "PKLgW0O3YZAv5ZlIMbQqOgCegAT_TUo6fshOuuGrPqBSYRgIb2ApfvCENzdp-f
          rKQEVUTWj2odSzMaEKBkjIv49GdEEvAxIy6C5uNzugfsGZswu7gyY8-9mZ_OFV
         -nWF"}]
}

B.1.  X.509 Private Key in PKCS#8 format for E384 Example**

   -----BEGIN PRIVATE KEY-----
   MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQgevZzL1gdAFr88hb2
   OF/2NxApJCzGCEDdfSp6VQO30hyhRANCAAQRWz+jn65BtOMvdyHKcvjBeBSDZH2r
   1RTwjmYSi9R/zpBnuQ4EiMnCqfMPWiZqB4QdbAd0E7oH50VpuZ1P087G
   -----END PRIVATE KEY-----

B.2.  X.509 Public Key for ES384 Example**

   -----BEGIN PUBLIC KEY-----
   MFkwEwYHKoZIzj0CAQYIKoZIzj0DAQcDQgAEEVs/o5+uQbTjL3chynL4wXgUg2R9
   q9UU8I5mEovUf86QZ7kOBIjJwqnzD1omageEHWwHdBO6B+dFabmdT9POxg==
   -----END PUBLIC KEY-----

Authors' Addresses

   Tirumaleswar Reddy
   McAfee, Inc.
   Embassy Golf Link Business Park
   Bangalore, Karnataka  560071
   India

   Email: kondtir@gmail.com




Reddy, et al.            Expires April 27, 2020                [Page 24]


Internet-Draft     Asserted DNS server privacy policy       October 2019


   Dan Wing
   Citrix Systems, Inc.
   USA

   Email: dwing-ietf@fuggles.com


   Michael C. Richardson
   Sandelman Software Works
   USA

   Email: mcr+ietf@sandelman.ca







































Reddy, et al.            Expires April 27, 2020                [Page 25]


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