Internet DRAFT - draft-bertola-dns-openid-pidi-architecture
draft-bertola-dns-openid-pidi-architecture
Network Working Group V. Bertola
Internet-Draft Open-Xchange
Intended status: Informational M. Sanz
Expires: September 6, 2018 DENIC eG
March 5, 2018
An Architecture for a Public Identity Infrastructure Based on DNS and
OpenID Connect
draft-bertola-dns-openid-pidi-architecture-01
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
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This Internet-Draft will expire on September 6, 2018.
Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements Notation and Conventions . . . . . . . . . . . . 3
3. Key features . . . . . . . . . . . . . . . . . . . . . . . . 3
4. Technical design and motivations . . . . . . . . . . . . . . 4
4.1. Advantages and shortcomings of OpenID Connect . . . . . . 5
4.2. Motivations for the use of the Domain Name System . . . . 5
4.3. Separation of roles . . . . . . . . . . . . . . . . . . . 6
5. Elements of the architecture . . . . . . . . . . . . . . . . 6
5.1. User . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5.2. Online identity . . . . . . . . . . . . . . . . . . . . . 7
5.3. Identifier . . . . . . . . . . . . . . . . . . . . . . . 7
5.4. Identity handle . . . . . . . . . . . . . . . . . . . . . 8
5.5. Claim . . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.6. Identity authority . . . . . . . . . . . . . . . . . . . 8
5.7. Identity agent . . . . . . . . . . . . . . . . . . . . . 10
5.8. Relying party . . . . . . . . . . . . . . . . . . . . . . 11
6. Interaction flows . . . . . . . . . . . . . . . . . . . . . . 12
6.1. Identifier creation flow . . . . . . . . . . . . . . . . 12
6.2. Authentication flow . . . . . . . . . . . . . . . . . . . 13
6.3. Identifier deletion flow . . . . . . . . . . . . . . . . 14
6.4. Change of Identity Agent flow . . . . . . . . . . . . . . 15
7. Security Considerations . . . . . . . . . . . . . . . . . . . 16
8. Privacy Considerations . . . . . . . . . . . . . . . . . . . 16
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
10. Normative References . . . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18
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
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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
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
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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
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.
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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
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].
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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.
Moreover, other provider discovery mechanisms that rely on different
protocols, such as HTTP, still require the client to query the DNS to
find the IP address of the server that it has to connect to; by
storing the necessary information in the DNS, the initial DNS query
is all that is needed to perform the discovery, avoiding the need to
implement additional protocols and procedures in the client and in
the server.
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
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
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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 at
any given time, 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].
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
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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].
As the ownership of domain names may change over time, the identity
pointed at by a PIDI identifier may change as well. Relying parties
should not assume that the same PIDI identifier, over time, will
always refer to the same identity.
5.4. Identity handle
An identity handle is a string of alphanumeric characters which
uniquely and permanently identifies a specific online identity.
Identity handles are generated and maintained by identity
authorities, which provide them to each relying party during the
authentication flow. The autority can assign one or more handles to
the same online identity; however, the identity authority MUST always
provide the same identity handle to the same relying party for the
same online identity.
Identity authorities MUST NOT reuse an identity handle for a
different online identity, even after the identity that was
originally associated to that handle has been permanently deleted.
5.5. 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.
5.6. Identity authority
An identity authority is an entity responsible for the authentication
and authorization functions of the PIDI identity management
framework.
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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.
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
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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.
5.7. Identity agent
An identity agent is an entity responsible for the personal
information management function of the PIDI identity management
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.
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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.
5.8. 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,
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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
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.
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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.
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. The Identity Token will
also include the identity handle associated to the identifier;
the relying party should then use the identity handle, rather
than the identifier, as the key to refer to the online identity
in its own local datasets. 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
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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
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 identity handle 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.
6.3. Identifier deletion flow
To delete an existing identifier the actors have to follow this
procedure:
1. The user requests the deletion of the identifier at the identity
agent (the user might also request deletion of the domain name in
which the identifier resides, but this is out of scope). The
identity agent stops delivering any claims about the user on its
UserInfo Endpoint.
2. The identity agent or the user, depending on who operates the
domain name, deletes the DNS record for the mapping of the
identifier.
3. The identify agent notifies the identity authority about the
deletion request, so that deletion of stored credentials is
triggered.
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4. The identity authority verifies that the source of the deletion
request, either directly or through the identity agent, has write
access to the domain name zone of the identifier.
5. The identity authority communicates success to the agent.
6. The agent communicates success to the user and redirects the user
to the identity authority to confirm deletion.
7. The user approaches the identity authority and deletes all
authentication credentials, together with all potentially stored
consents for sharing claims. From this point on, the identity
authority should reject any authentication requests for this user
by any relying parties.
It must be noted that, although from step 2 on (or more exactly,
after expiration of the pertinent DNS information) the identifier
should have been rendered useless because no discovery information is
publicly available anymore, this does not suffice for a complete
identifier deletion: Relying parties might have cached discovery
information (s. Section 6.2 step 3), which would leave the
identifier operating in authentication flows for an uncertain amount
of time.
It must also be noted that any local accounts that might have been
created at relying parties during past usage of the now deleted
identifier (and that might be directly associated to its identity
handle) are left intact after this flow. [NOTE: Discuss risks in
security considerations, specially wrt identifier reregistration].
6.4. Change of Identity Agent flow
The user might want to move the identifier from one identity agent
(losing agent) to another (gaining agent). It is a requirement that
the functionality of the identifier (specially for authentication
flows) is not affected during this change. A change in the identity
authority during this workflow is not foreseen. Actors have to
follow this procedure:
1. The user approaches the gaining agent and requests the provision
of the identifier.
2. The gaining agent sets up the domain name in which the identifier
will be created.
3. The gaining agent or the user, depending on who operates the
domain name, sets up a new DNS record for the mapping of the
identifier.
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4. The gaining agent requests the sponsorship of the domain name, in
which the identifier resides, at the domain name registry. This
might happen via EPP transfer command (s. [RFC5731]); details
are out of scope in this document.
5. If the transfer of sponsorship is successful, the new DNS mapping
will become authoritative and relying parties will start
discovering the gaining agent when requesting user claims.
Additionally, for considerations on DNS operator change procedures
that maintain consistency and validation under DNSSEC please refer to
[draft-koch-dnsop-dnssec-operator-change-06].
7. Security Considerations
tbd
8. Privacy Considerations
About rogue Identity Authority monitoring
About Whois information on the identifiers
9. IANA Considerations
There is no IANA action required for this document.
10. 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>.
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[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>.
[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>.
[RFC5731] Hollenbeck, S., "Extensible Provisioning Protocol (EPP)
Domain Name Mapping", STD 69, RFC 5731,
DOI 10.17487/RFC5731, August 2009,
<https://www.rfc-editor.org/info/rfc5731>.
[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>.
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Authors' Addresses
Vittorio Bertola
Open-Xchange
Via Treviso 12
Torino 10144
Italy
Email: vittorio.bertola@open-xchange.com
URI: https://www.open-xchange.com
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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