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Versions: 00 01

Network Working Group                                         V. Bertola
Internet-Draft                                              Open-Xchange
Intended status: Informational                                   M. Sanz
Expires: April 30, 2018                                         DENIC eG
                                                        October 27, 2017


 An Architecture for a Public Identity Infrastructure Based on DNS and
                             OpenID Connect
             draft-bertola-dns-openid-pidi-architecture-00

Abstract

   The following document describes an architecture for an open, global,
   federated Public Identity Infrastructure (PIDI), based on the Domain
   Name System (DNS) and on the OpenID Connect framework built over the
   OAuth protocol.

Status of This Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   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 30, 2018.

Copyright Notice

   Copyright (c) 2017 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




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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

1.  Introduction

   How to deal with online identities is one of the great unsolved
   problems of today's Internet: each Internet user has to authenticate
   for hundreds of different online services, all of which require some
   personal information that he or she has to provide and maintain
   separately; and this leads to severe usability and security issues.

   This document describes an architecture for a Public Identity
   Infrastructure (PIDI), an identity management framework, building on
   existing protocols and on new extensions, that can provide the three
   basic functions of online identity management - authentication,
   authorization, and management of personal information - and do so in
   an open, global and federated manner, creating a single interoperable
   personal identity space that can be shared by the entire Internet,
   while at the same time preventing any centralized control of all
   online identities and empowering users rather than identity
   providers.

2.  Requirements Notation and Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

   Throughout this document, values are quoted to indicate that they are
   to be taken literally.  When using these values in protocol messages,
   the quotes MUST NOT be used as part of the value.

3.  Key features

   In the PIDI architecture described in this document, people and other
   entities identify themselves in their online activities by using a
   DNS-style label, located inside an existing and valid domain name, as
   an identifier.  Such identifier allows users to log into any Internet
   service using a single account associated to their identifier.

   Identifiers are jointly managed by two complementary entities, acting
   together as the identity provider; users are able to choose the
   managers of their identifier among any number of compatible
   providers, or to host one themselves.

   Users can employ their identifier to log into any website or online
   service supporting this architecture, even without prior
   registration; on first access to that specific service, the service



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   can request access to the user's personal information as entered by
   him or her into the personal profile.

   If the user consents to this access, the requested information will
   be made available to the service, which can thus automatically
   present the appropriate messages and legal information and then
   create a local account or profile for the user, associated to the
   identifier.  Thus, "registering" for an online service is not
   necessary any more; users just self-identify themselves whenever
   necessary.

   As the architecture is federated, like email and other public
   Internet standards, multiple interoperable providers of identifiers
   can exist, including personal providers self-hosted by their users;
   all of them are intrinsically supported by any online service
   implementing the standard, though services, like in the email
   environment, may implement local policies that blacklist certain
   providers or identifiers, or treat them differently.  Users can pick
   any provider and, if they control the domain name to which the
   identifier belongs, can move their identifier to a different provider
   whenever they want, simply by changing a record in the domain name's
   zone.

   By performing authentication in a single place, users are freed from
   the need to remember, update and protect huge numbers of passwords.
   Any password change, any security update and any additional
   authentication mechanism, such as two-factor authentication, can be
   implemented once and immediately apply to all the logins of the user,
   thus making it easier to upkeep security.  The system can work with
   any type of authentication mechanism, even without passwords.

   The focus of this architecture is to authorize and authenticate users
   in the online space only, i.e. to ensure that the user of a given
   identifier is always the same that initially acquired that identifier
   at registration; the architecture does not address the issue of how
   to actually verify his or her true identity in the real world.
   Accordingly, there is no requirement for an actual real-life
   authentication of the users, and their identity and personal
   information are entirely self-declared; users may also have multiple
   identities (e.g. a personal one, a business one etc.), as an
   additional protection to their privacy.

   At the same time, nothing prevents specific implementations or
   specific identity providers to support third-party validation of the
   user's personal information, thus also providing proof of the user's
   real world identity, which may also be required by specific services
   to accept the identifier.  However, interaction with online-offline
   authentication systems and providers, such as governmental e-ID



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   documents or certification authorities, is outside of the scope of
   this document, except for what may be necessary to transfer and store
   inside this architecture the additional information related to this
   interaction.

4.  Technical design and motivations

   To simplify implementation, the architecture discussed in this
   document builds over an existing and widely adopted identity
   management framework: OpenID Connect [OpenID.Core].  However, that
   framework fails short of several of the requirements and objectives
   set forth in the previous section.

   The proposal thus uses a pillar of the Internet, the Domain Name
   System [RFC1034], and a few purpose-developed specifications such as
   [I-D.sanz-openid-dns-discovery], to complete OpenID Connect and reach
   the desired objectives.

4.1.  Advantages and shortcomings of OpenID Connect

   OpenID Connect [OpenID.Core] is an identity management framework that
   has been recently gaining widespread adoption; it gets nearer than
   others to meeting the requirements.  Building on the OAuth 2.0
   [RFC6749] authorization framework, OpenID Connect provides
   authentication, authorization, and basic management of personal
   information; it is currently already being used by many big Internet
   access and content providers to offer authentication to third-party
   services, and many different implementations, both commercial and
   free, are readily available.

   However, OpenID Connect, in its current status, is aimed at the
   creation of individual and non-interoperable sets of identities,
   entirely controlled by a single identity provider.  While this design
   suits a company willing to provide single sign-on for all its
   websites, or an online service willing to let other services
   authenticate users against the credentials it provides, there is no
   easy way for multiple providers to offer identities in the same
   interoperable set, or for online services to support identities by
   multiple providers without explicitly implementing separate support
   for each and every provider; and there is no way to create a single,
   public, global identity set that can be used by the entire Internet
   without having to rely on a single and centralized identity provider.
   Also, once users adopt an identifier run by a specific provider,
   there is no way for them to move it transparently to another
   provider.

   In the end, the centralization of all three functions and of the
   ownership of the user's identifier in a single entity that cannot be



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   easily picked and changed by the user creates significant risks for
   privacy and security, and prevents competition and choice among
   multiple identity providers.  While users should be able to
   centralize these functions in a single entity that they really trust,
   they should also have the options of owning the identifier directly,
   of distributing these functions among more than one entity and of
   changing these entities as easily as possible.

4.2.  Motivations for the use of the Domain Name System

   To create a single identity framework for the entire Internet, a
   single namespace and a lookup service for the identities are
   necessary; and to prevent control by a single entity, they need to be
   implemented in a decentralized and federated manner that must also
   provide the necessary security features.

   The Internet already relies for its basic functioning on a single
   namespace and on a lookup service: the Domain Name System [RFC1034].
   The ubiquitousness of the DNS, the familiarity of Internet users with
   DNS-style hierarchical strings, and the increasing adoption of DNSSEC
   [RFC4033], make the DNS the proper container for a public, secure,
   decentralized and hierarchical identity naming and lookup service.

   By using DNS strings as identifiers for human identities, with the
   addition of a simple mapping mechanism such as that described in
   [I-D.sanz-openid-dns-discovery], it is immediate for anyone to know
   where and how to look up information about an identifier, without
   knowing any other piece of data - not even the identity provider that
   is managing it.

   Locating identity identifiers in the DNS has the additional advantage
   that users, rather than identity providers, can easily become the
   sole owners of their identifier by acquiring a personal domain name;
   the controller of that zone - the user - can point the identifier
   towards a different provider just by changing a record in the zone,
   even without the current provider's consent or action, much reducing
   the opportunities for user lock-in by the identity provider.

4.3.  Separation of roles

   While the current OpenID Connect implementations concentrate
   authentication, authorization and personal information management all
   in a single entity, a separation of roles is introduced to increase
   the decentralization and security of the system, mimicking the roles
   existing in the Domain Name System industry.  Two different entities
   - an "identity authority" and an "identity agent" - co-manage each
   online identity, fulfilling different functions, with the user being




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   free to choose and change each of them, and even to run directly one
   or both of these roles.

5.  Elements of the architecture

5.1.  User

   A user of the PIDI architecture is an entity of any kind - a physical
   person, a juridical person, a host, an application, or anything else
   - that needs to authenticate itself to gain access to online services
   and applications, and to provide and distribute over the Internet, in
   a controlled manner, information about itself.

5.2.  Online identity

   An online identity is a collection of personal information associated
   to an identifier that represents it.

   No assumption is made on whether distinct online identities belong to
   distinct physical persons, or even whether they belong to human
   beings at all.  Users may own any number of online identities; they
   should not be required to disclose the correlation between their
   different online identities.

   The personal information included in an online identity is entirely
   self-asserted by the controlling user; in the absence of appropriate
   additional mechanisms outside the purview of this document,
   assumptions should not be made on whether such information is "true"
   or "false" for any definition of these terms.  The only assumption
   that can be safely made about the personal information included in an
   online identity is that the controlling user is stating that
   information about himself, herself or itself.

5.3.  Identifier

   A PIDI identifier is a string, unique on a global Internet scale,
   that represents a distinct online identity in the PIDI architecture.

   PIDI identifiers MUST follow any syntax which is acceptable to the
   mapping mechanism described in [I-D.sanz-openid-dns-discovery].
   Specifically, an identifier MUST be one of the following:

   o  A fully qualified DNS name following the conventions set forth in
      section 2.3.1 of [RFC1035].

   o  A syntactically valid internationalized DNS name (IDN) as per
      [RFC5890].




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   o  An e-mail address following the syntax described in section 3.4.1
      of [RFC5322].

   o  A syntactically valid internationalized e-mail address within the
      framework of [RFC6530].

   In all these cases, no assumption is made on whether these strings
   actually correspond to existing network objects such as a host or a
   mailbox; they could not correspond to anything but the online
   identity that they represent.  However, when applying the mapping
   mechanism to an identifier, the resulting string MUST belong to an
   existing and working domain name, and MUST point to an existing DNS
   record of the appropriate type and syntax as specified in
   [I-D.sanz-openid-dns-discovery].

5.4.  Claim

   A claim is a piece of information associated to the online identity
   that is represented by an identifier.

   Claims are made by a standard claim name, to which a predefined claim
   type is associated, and by a claim value that contains the actual
   information.  To ensure interoperability, claim names and types are
   publicly standardized.

   Claims MUST follow the specification and format described in
   [OpenID.Core]; however, further claim names and types may be defined
   in additional specifications.

5.5.  Identity authority

   An identity authority is an entity responsible for the authentication
   and authorization functions of the PIDI identity management
   framework.

   More specifically, the identity authority MUST perform the following
   activities:

   o  Allow identity agents, on behalf of their users, to create, update
      and cancel identifiers, verifying the proper set up of the
      required DNS records in the identifier's domain name zone,
      including an appropriate proof that the user has write access to
      that zone.

   o  Allow the user to set the password or the other credentials that
      will be used for authentication, and store them securely.





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   o  Authenticate the user whenever necessary; to this purpose, the
      authority should either ask the user to provide credentials and
      verify them, or rely on the secure storage of the results of a
      previous authentication.

   o  Whenever the user tries to log into an online service for the
      first time, or whenever the service requests access to additional
      claims, show the user the list of claims that the service would
      like to access, and ask the user for specific and separate consent
      on the sharing of each claim; then, authorize the service to
      access the consented claims at the appropriate identity agent.

   o  Allow the user to review and change the consent that was given for
      access to claims, for each claim and relying party.

   To perform these activities, the identity authority MUST act as the
   OpenID Provider defined in [OpenID.Core]; it MUST also allow third
   parties to retrieve its OpenID Configuration according to the
   specification in section 4 of [OpenID.Discovery].

   Moreover, the identity authority MUST allow relying parties to
   perform dynamic client registration as defined in
   [OpenID.Registration], and it MUST NOT require any Initial Access
   Token or other out-of-band mechanisms, though an authority may apply
   policies to prevent some clients from registering if these clients
   can be presumed to be abusive or malicious.  The identity authority
   MUST use the distributed claims mechanism described in section 5.6.2
   of [OpenID.Core] to direct a service requesting access to claims to
   the identity agent managing the personal information associated with
   the identifier.

   The identity authority, unless also acting as identity agent, should
   not have access to any claim associated to the online identity,
   except the identifier, the authentication credentials and any
   personal information necessary to verify them, or that the user has
   voluntarily shared with the identity authority to allow it to provide
   its services.

   After each login attempt by the user, the identity authority SHOULD
   communicate to the identity agent that such attempt has happened and
   what was its outcome.  Details for such communication will be
   specified separately.

5.6.  Identity agent

   An identity agent is an entity responsible for the personal
   information management function of the PIDI identity management




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   framework, as well as for the management of the relationship with
   final users.

   More specifically, the identity agent MUST perform the following
   activities:

   o  Allow users to acquire, move and cancel their identifiers,
      performing the necessary technical operations.

   o  Allow users to enter, update and delete the value for any claim
      supported by the architecture and by the agent.

   o  Provide to any relying party that shows a valid authorization,
      received by the appropriate identity authority, access to the
      claims that the user has consented to share with that relying
      party.

   The identity agent should also perform the following activities:

   o  Allow users to verify which claims have been shared with each
      relying party.

   o  Allow users to retrieve a list and history of their logins, unless
      such information has not been made available to the identity
      agent.

   To perform these activities, the identity agent MUST act as a
   provider of distributed claims as defined in [OpenID.Core], running
   an appropriate UserInfo Endpoint; it MUST allow access to such
   endpoint to any relying party that has been successfully authorized
   to do so by the identity authority.  The identity agent MUST also
   allow third parties to retrieve its OpenID Configuration according to
   the specification in section 4 of [OpenID.Discovery].  It SHOULD also
   provide to identity authorities and relying parties an endpoint to
   communicate user logins.

   The identity agent, unless also acting as identity authority, should
   not have access to the user's password; it also should not have
   access to other credentials used for the authentication process,
   unless they are claims that can be legitimately used for other
   purposes (e.g. a mobile phone number).  The identity agent should use
   the PIDI identifier to grant access to its PIDI services, relying on
   the identity authority for authentication.








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5.7.  Relying party

   A relying party is any online service, website or application willing
   to accept PIDI identifiers to recognize and authenticate its users.

   A relying party can accept PIDI identifiers natively, using them as
   the sole identification method for its accounts, or can use PIDI
   identifiers as a pointer towards an internal username in its own
   accounting system.  In both cases, the relying party should allow
   users to register and authenticate with any valid PIDI identifier,
   though the relying party may apply policies to reject or discriminate
   against specific identity agents or identity authorities that are
   credibly presumed to be abusive or malicious.  Moreover, a relying
   party may apply its own policies and requirements to determine which
   users should be disallowed from using its services, even if they show
   up with a valid PIDI identifier.

   More specifically, the relying party MUST perform the following
   activities:

   o  Allow users to enter a PIDI identifier in its login and
      registration forms or procedures.

   o  Perform the mapping described in [I-D.sanz-openid-dns-discovery]
      and then an OpenID Connect authentication flow, to authenticate
      the user, to gain authorization to access the user's claims, to
      retrieve such claims as authorized, and optionally to use them to
      create or update a local account for the user.

   To perform these activities, the relying party MUST act as the
   Relying Party defined in [OpenID.Core]; it MUST also perform a
   dynamic client registration as defined in [OpenID.Registration],
   every time it encounters an identity authority never seen before.  To
   do so, the relying party MUST be able to retrieve the OpenID
   configuration of the identity authority and of the identity agent,
   according to the specification in section 4 of [OpenID.Discovery].

   The relying party, unless also acting as identity authority, should
   not have access to the user's password; it also should not have
   access to other credentials used for the authentication process,
   unless they are claims that the user has authorized the relying party
   to access.  Moreover, the relying party should never have access to
   any user claims different from those that the user has authorized the
   relying party to access, and it should honor any request by the user
   to update or delete the claims that he or she already provided.

   After each login attempt by the user, the relying party SHOULD
   communicate to the identity agent that such attempt has happened and



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   what was its outcome.  Details for such communication will be
   specified separately.

6.  Interaction flows

   The following sections provide a high-level description of the
   sequence of steps that has to be followed jointly by the various
   actors to perform some basic actions.  The sequence of steps is meant
   to be normative, but the detailed technical specification of each
   step can be found in the standards referenced in the previous
   section, or in further standards that will be specified separately.

6.1.  Identifier creation flow

   To create a valid identifier, the actors have to follow this
   procedure:

   1.  The user approaches an identity agent and requests the provision
       of an identifier, agreeing with the agent on the identity
       authority that will manage it.

   2.  If necessary, the identity agent registers and/or sets up the
       domain name in which the identifier will be created.

   3.  The identity agent or the user, depending on who operates the
       domain name, sets up the appropriate DNS record for the mapping
       of the identifier.

   4.  The identity agent requests the creation of the identifier at the
       agreed identity authority.

   5.  The identity authority verifies that the DNS record has been
       successfully set up and that the user, either directly or through
       the identity agent, has write access to the domain name zone of
       the identifier.

   6.  If verifications are successful, the identity authority creates
       the identifier, in inactive state, and communicates success to
       the agent.

   7.  The agent communicates success to the user and redirects the user
       to the identity authority to set up the authentication
       credentials.

   8.  The user approaches the identity authority and sets up the
       authentication credentials.





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   9.  Upon successful setup of the authentication credentials, the
       identity authority activates the identifier and communicates
       success to the user.

   After the conclusion of this procedure, the identifier is ready for
   use for authentication.

6.2.  Authentication flow

   To authenticate and log the user into a relying party, the actors
   have to follow this procedure:

   1.  The relying party asks the user to provide the identifier.

   2.  The user provides an identifier of choice, corresponding to the
       online identity that the user chooses to use for this login, to
       the relying party.

   3.  The relying party performs a DNS lookup to identify the identity
       authority and the identity agent that manage the identifier.

   4.  If the relying party has never performed a login towards that
       specific identity authority, or if for any reason (e.g.
       expiration) it does not possess any valid credentials towards
       that identity authority, the relying party performs OpenID
       Connect Discovery section 4 and then OpenID Dynamic Client
       Registration towards the identity authority, to acquire valid
       OpenID Connect client credentials; the acquired credentials may
       be stored for future use.

   5.  The relying party and the user perform an OpenID Connect
       authentication using the Authorization Code Flow, at the end of
       which the relying party receives an Identity Token and, if claims
       need to be accessed, an Access Token.  Optionally, at the end of
       this step, the identity authority communicates to the identity
       agent that a login has been made by the user towards that relying
       party.  During the Authorization Code Flow, the identity
       authority must ask the user for separate and specific consent to
       share each claim that has been requested by the relying party,
       and store this consent for future reference.

   6.  If the relying party has been granted access to any claims, but
       has never performed a connection towards that specific identity
       agent, the relying party performs OpenID Connect Discovery
       section 4 towards the identity agent.

   7.  If the relying party has been granted access to any claims, it
       performs a connection to the UserInfo Endpoint of the identity



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       authority, that will use the Distributed Claims mechanism to
       redirect the relying party to the identity agent; the relying
       party then connects to the UserInfo Endpoint of the identity
       agent and retrieves the claims.

   8.  Optionally, if appropriate, the relying party creates a local
       account for the user and stores the identifier and the values of
       the claims into it.  If necessary, this step can be subject to
       further direct interaction between the user and the relying
       party, for example to ask the user to accept the relying party's
       terms and conditions.

   After the conclusion of this procedure, the user has logged into the
   relying party and provided it with the appropriate personal
   information; if necessary, the relying party has created a new local
   account for the user.

7.  Security Considerations

   tbd

8.  IANA Considerations

   tbd

9.  Normative References

   [I-D.sanz-openid-dns-discovery]
              Bertola, V. and M. Sanz, "OpenID Connect DNS-based
              Discovery", draft-sanz-openid-dns-discovery-00 (work in
              progress), October 2017.

   [OpenID.Core]
              Sakimura, N., Bradley, J., Jones, M., de Medeiros, B., and
              C. Mortimore, "OpenID Connect Core 1.0", November 2014,
              <http://openid.net/specs/openid-connect-core-1_0.html>.

   [OpenID.Discovery]
              Sakimura, N., Bradley, J., Jones, M., and E. Jay, "OpenID
              Connect Discovery 1.0", November 2014,
              <http://openid.net/specs/
              openid-connect-discovery-1_0.html>.

   [OpenID.Registration]
              Sakimura, N., Bradley, J., and M. Jones, "OpenID Connect
              Dynamic Client Registration 1.0", November 2014,
              <https://openid.net/specs/
              openid-connect-registration-1_0.html>.



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   [RFC1034]  Mockapetris, P., "Domain names - concepts and facilities",
              STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
              <https://www.rfc-editor.org/info/rfc1034>.

   [RFC1035]  Mockapetris, P., "Domain names - implementation and
              specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
              November 1987, <https://www.rfc-editor.org/info/rfc1035>.

   [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>.

   [RFC4033]  Arends, R., Austein, R., Larson, M., Massey, D., and S.
              Rose, "DNS Security Introduction and Requirements",
              RFC 4033, DOI 10.17487/RFC4033, March 2005,
              <https://www.rfc-editor.org/info/rfc4033>.

   [RFC5322]  Resnick, P., Ed., "Internet Message Format", RFC 5322,
              DOI 10.17487/RFC5322, October 2008,
              <https://www.rfc-editor.org/info/rfc5322>.

   [RFC5890]  Klensin, J., "Internationalized Domain Names for
              Applications (IDNA): Definitions and Document Framework",
              RFC 5890, DOI 10.17487/RFC5890, August 2010,
              <https://www.rfc-editor.org/info/rfc5890>.

   [RFC6530]  Klensin, J. and Y. Ko, "Overview and Framework for
              Internationalized Email", RFC 6530, DOI 10.17487/RFC6530,
              February 2012, <https://www.rfc-editor.org/info/rfc6530>.

   [RFC6749]  Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
              RFC 6749, DOI 10.17487/RFC6749, October 2012,
              <https://www.rfc-editor.org/info/rfc6749>.

Authors' Addresses

   Vittorio Bertola
   Open-Xchange
   Via Treviso 12
   Torino  10144
   Italy

   Email: vittorio.bertola@open-xchange.com
   URI:   https://www.open-xchange.com






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   Marcos Sanz
   DENIC eG
   Kaiserstrasse 75 - 77
   Frankfurt am Main  60329
   Germany

   Email: sanz@denic.de
   URI:   https://www.denic.de











































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