Identity Trust System
draft-sbriz-identity-trust-system-00
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| Last updated | 2024-04-27 (Latest revision 2023-11-17) | ||
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draft-sbriz-identity-trust-system-00
Web Authorization Protocol L. Sbriz
Internet-Draft Cybersecurity & Privacy Senior Consultant
Intended status: Standards Track 16 November 2023
Expires: 19 May 2024
Identity Trust System
draft-sbriz-identity-trust-system-00
Abstract
This document describes the identity trust system, which is an open
identity authentication system that does not require federation of
authentication domains. It is based on a symmetric authentication
protocol and a specific infrastructure to ensure trust in the
identity providers (IdPs). Regarding the main components:
1. Symmetric authentication protocol - Both entities MUST recognize
each other and are authenticated by their identity provider
according to a symmetric scheme. This protocol builds on and
extends the OAuth Authorization Framework RFC6749.
2. Trustees' network - A special network, dedicated to creating a
protected environment for exchanging authentication messages
between IdPs, constitutes the infrastructure to avoid domain
federation.
3. Custodian concept - IdPs are divided into two typologies to
better protect personal data. A generic IdP (called trustee) for
pure digital authentication and a specific IdP (called custodian)
under the control of the country's authority with legal right to
the individual's real data to ensure physical identity.
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."
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This Internet-Draft will expire on 19 May 2024.
Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Use cases of both authentication schemes . . . . . . . . 3
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 5
3. Symmetric authentication protocol . . . . . . . . . . . . . . 7
4. Identity Provider - Trustee Concepts . . . . . . . . . . . . 10
5. Identity Provider - Custodian Concepts . . . . . . . . . . . 11
5.1. Issuing of a New Digital Identity . . . . . . . . . . . . 12
6. Sustainable Digital Identity Trust Schema . . . . . . . . . . 14
7. Security Considerations . . . . . . . . . . . . . . . . . . . 16
7.1. User registration . . . . . . . . . . . . . . . . . . . . 16
7.1.1. Registration with an identity custodian (IdC). . . . 17
7.1.2. Registration with an identity provider (IdP). . . . . 17
7.1.3. Registration with a service provider (SP). . . . . . 17
8. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 17
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.1. Normative References . . . . . . . . . . . . . . . . . . 18
10.2. Informative References . . . . . . . . . . . . . . . . . 18
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 19
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction
The current model of access to Internet protected resources requires
that the identity of the user, i.e. the *_resource owner_*, be
authenticated by the resource manager, i.e. the *_service provider_*.
Authentication can be indirect, this means that there is a trusted
third party for both, called *_identity provider_*, which performs
the authentication process. The mechanism is defined by [RFC6749].
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This mechanism is asymmetrical, only the resource owner needs to be
recognized but not vice versa. Furthermore, the digital identity has
value only within its own digital ecosystem (authentication domain or
set of domains in a relationship of trust between each other).
Changing digital ecosystem, a new user is needed for the resource
owner.
It is possible to improve this process by requiring equal dignity in
recognition, i.e. each entity must be recognized by the other.
Consequently, the identity recognition process will be symmetrical
and presents a great advantage. It is no longer necessary to define
a trust between domains or create new users to be able to operate in
an ecosystem different from your own.
It is necessary to modify the authentication protocol to implement
symmetric recognition of the digital identity. Furthermore, a
network infrastructure dedicated to identity providers is required to
guarantee confidentiality and reliability in the exchange of messages
between them. Additionally, dividing IdPs into two categories
improves security. One category will be made up of those who are
only authorized to recognize digital identity, while the other
category is that of identity providers with the legal authority to
also manage real identity.
1.1. Use cases of both authentication schemes
Figure 1 shows a use case describing the components of the classic
identity recognition method with asymmetry in the authentication
process [RFC6749]. A SVG image is available here
(https://github.com/Luigi-Sbriz/identity/images/1_Asymmetric-
depiction.svg). The scenario depicted represents a resource owner
who needs to retrieve a resource from the service provider. The
identity provider MUST verify the identity of the resource owner
before accessing the resource server.
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┌───────────┐
│Identity │
│ │
│Provider │
└─────┬─────┘
Digital │ecosystem
.........│..............................
: ┌─────┴─────┐ :
: │Authorizati│ :
: │ │ :
: │on Server │ :
: └─────┬─────┘ :
: │ :
: │ :
┌───────────┐ : ┌─────┴─────┐ ┌───────────┐ : ┌───────────┐
│Resource │ : │User │ │Relying │ : │Service │
│ ├─────┤ ├────────┤ ├─────┤ │
│Owner │ : │Agent │ │Party │ : │Provider │
└───────────┘ : └───────────┘ └─────┬─────┘ : └───────────┘
: │ :
: │ :
: ┌─────┴─────┐ :
: │Resource │ :
: │ │ :
: │Server │ :
: └───────────┘ :
:......................................:
Figure 1: Abstract Authorization Flow - Asymmetrical Case
Figure 2 shows a use case describing the components necessary to
enable the identity authentication process in a symmetrical way that
can operate in different digital ecosystems. A SVG image is
available here (https://github.com/Luigi-Sbriz/identity/
images/2_Symmetric-depiction.svg). The new scenario depicts two
different ecosystems, one for the resource owner and the other for
the service provider. This means there MUST be two different
identity providers interacting with each other to ensure the
authentication process.
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┌───────────┐ ┌───────────┐
│Identity │ │Identity │
│ │ │ │
│Provider C │ │Provider S │
└─────┬─────┘ └─────┬─────┘
Digital │ecosystem Digital │ecosystem
│C │S
.........│......... .........│.........
: ┌─────┴─────┐ : : ┌─────┴─────┐ :
: │Authorizati│ : : │Authorizati│ :
: │ ╞════════╡ │ :
: │on Server C│ : : │on Server S│ :
: └─────┬─────┘ : : └─────┬─────┘ :
: │ : : │ :
: │ : : │ :
┌───────────┐ : ┌─────┴─────┐ : : ┌─────┴─────┐ : ┌───────────┐
│Resource │ : │User │ : : │Relying │ : │Service │
│ ├─────┤ ├────────┤ ├─────┤ │
│Owner │ : │Agent │ : : │Party │ : │Provider │
└───────────┘ : └───────────┘ : : └─────┬─────┘ : └───────────┘
: : : │ :
: : : │ :
: : : ┌─────┴─────┐ :
: : : │Resource │ :
: : : │ │ :
: : : │Server │ :
: : : └───────────┘ :
:.................: :.................:
Figure 2: Abstract Authorization Flow - Symmetrical Case
The two representations are very similar to each other but it is
noted that the symmetric protocol introduces direct communication
between the identity providers' authentication servers to allow the
circular transit of authentication messages. Therefore, no trust is
needed between domains. The idea was first exposed in some articles
published on ISACA Journal (see [LS1], [LS2], [LS3], [LS4]) with some
specific use cases and examples.
2. Conventions and Definitions
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.
Some terms are used with a precise meaning.
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* "*_resource owner_*": An entity capable of granting access to a
protected resource. When the resource owner is a person, it is
referred to as an end-user or an individual. This is sometimes
abbreviated as "*_RO_*".
* "*_service provider_*": An entity capable of managing access to a
protected resource. It is generally a legal person. This is
sometimes abbreviated as "*_SP_*".
* "*_identity provider_*": An entity capable of managing and
recognizing the identity of registered entities. The set of all
entities registered by the identity provider is also known as the
IdP's digital ecosystem. This is sometimes abbreviated as
"*_IdP_*".
* "*_resource server_*": The server hosting the protected resources,
capable of accepting and responding to protected resource requests
using access tokens. The resource server is often accessible via
an API. This is sometimes abbreviated as "*_RS_*".
* "*_client_*" or "*_user agent_*": An application making protected
resource requests on behalf of the resource owner and with its
authorization. The term "client" does not imply any particular
implementation characteristics (e.g., whether the application
executes on a server, a desktop, or other devices).
* "*_relying party_*": An application making protected resource
authorization on behalf of the service provider and also managing
its identity. The "relying party" acts as the "client" but on
service provider side. This is sometimes abbreviated as "*_RP_*".
* "*_authorization server_*": The server issuing access tokens to
the client after successfully authenticating the resource owner
and obtaining authorization. This is sometimes abbreviated as
"*_AS_*".
* "*_access token_*": The concept is the same of the [RFC6749], a
tiny piece of code that contains the necessary authentication
data, issued by the authorization server.
* "*_identity token_*" or "*_ID token_*": The structure is similar
to access token but it is used as proof that the user has been
authenticated. The ID token may have additional information about
the user and, it is signed by the issuer with its private key. To
verify the token, the issuer's public key is used.
* "*_digital ecosystem_*": Internet environment composed of all
entities based on the same identity provider.
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The detail of the information exchanged in the interactions between
the authorization server and the requesting client, or between
relying party and resource server, or the composition of tokens, is
beyond the scope of this specification.
3. Symmetric authentication protocol
The symmetric authentication flow is conceptually not too dissimilar
from the classic one on a single ecosystem [RFC5234], except that the
authentication is dual because the two flows reflect the same
operations symmetrically. Both the *client* (_resource owner_) and
the *server* (_service provider_) MUST authenticate their identity
through their IdP. The details of each basic operation are the same
as the corresponding individual ecosystem specification [RFC6749] and
maintain alignment with it over time.
Considering two entities, a consumer and a resource provider, each
must authenticate to the other's environment. The sequence will be:
*_1._* Entities exchange the access tokens received from their
authentication server with each other.
*_2._* Entities send the received token to their authentication
server.
*_3._* Authentication servers exchange access tokens with each other.
*_4._* Authentication servers verify tokens with their original.
*_5._* Authentication servers send the result to their own entity.
*_6._* Entities are authenticated and can now exchange information.
Conceptually, in a client-server schema, the authentication process
begins with the resource owner requesting access to the protected
resource to the service provider. Both respond with their access
tokens and request their IdP to validate the received token. The
IdPs exchange tokens for validation and send the result to their
entity. On success, access to the resource is allowed.
Figure 3 shows the abstract depiction of the symmetric authentication
sequence. A SVG image is available here (https://github.com/Luigi-
Sbriz/identity/images/3_Symmetric-sequence-diagram.svg).
┌───────────┐ ┌───────────┐
│Relying ├-(1)--Request Authentication--------------->│Authorizati│
│ │ │ │
│Party │<-(2)-Return Server Token-------------------┤on Server S│
└───────────┘ └───────────┘
┌───────────┐ ┌───────────┐ ┌───────────┐ ┌───────────┐
│Resource │ │User │ │Authorizati│ │Relying │
│ │ │ │ │ │ │ │
│Owner │ │Agent │ │on Server C│ │Party │
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└─────┬─────┘ └─────┬─────┘ └─────┬─────┘ └─────┬─────┘
| Request | | |
├-(3)--Protected-->+-(4)--Send Access Request----------->|
| Resource | | |
| |<-(5)-Return Server Token------------┘
| | |
| ├(6)-Request Client|
| | Token & Send |
| | Server Token--->|
| | |
|<-(7)-Request Credentials via UA-----┤
| | |
└-(8)--Present Credentials via UA---->|
| |
└<-(9)---Return |
Client Token----┘
┌───────────┐ ┌───────────┐ ┌───────────┐ ┌───────────┐
│User │ │Authorizati│ │Authorizati│ │Relying │
│ │ │ │ │ │ │ │
│Agent │ │on Server C│ │on Server S│ │Party │
└─────┬─────┘ └─────┬─────┘ └─────┬─────┘ └─────┬─────┘
| | | |
├-(10)--Request Protected Resource & Send Client Token-->|
| | | |
| |<-(12)---Send |<-(11)---Send |
| | Client Token----┤ Client Token----┤
| | | |
| ├-(13)---Return | |
| | Server Token--->| |
| | | |
└<-(14)--Return of | └-(15)--Return of |
Authorization---┘ Authorization-->┘
┌───────────┐ ┌───────────┐ ┌───────────┐ ┌───────────┐
│Resource │ │User │ │Relying │ │Resource │
│ │ │ │ │ │ │ │
│Owner │ │Agent │ │Party │ │Server │
└─────┬─────┘ └─────┬─────┘ └─────┬─────┘ └─────┬─────┘
| | | |
| | ├(16)Call Protected|
| | | Resource-------->|
| | | |
└<-(19)-----Return |<-(18)-----Return |<-(17)-----Return |
Protect.Resource-┘ Protect.Resource-┘ Protect.Resource-┘
Figure 3: Symmetric Authentication Protocol - Sequence diagram
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(1) - (2) The *_RP_* requests authentication to its *_AS_* (marked
"S" as server) and receives the server token (access token from the
service provider's AS). The relying party must be provided with its
own access token to resolve multiple requests.
(3) - (5) The *_RO_* requests access to the protected resource via
the user agent. The *_UA_* activates the authentication process by
requesting access to the *_RP_*, which responds by providing the
server token. The response may also include the server ID token.
(6) - (9) The *_UA_* requests the client token (access token from the
client's AS) to its *_AS_* (marked "C" as client), sending also the
server token received from *_RP_*. The client's *_AS_* requests
credentials from the *_RO_* and returns the client token to the
*_UA_*.
(10) - (11) The *_UA_* requests the protected resource from the
*_RP_* by sending the client token. Then, relying party requests to
service provider's AS to verify the client token.
(12) - (15) Both authentication servers must verify that the tokens
received match the originals. Then, client's AS informs the *_UA_*
of the outcome and the same is done by the service provider's AS to
the *_RP_*. The outcome sent to the relying party may also include
the client ID token.
(16) - (17) The *_RP_* notifies the *_RS_* of the legitimate request
of '*_UA_*. The *_RS_* returns the protected resource to *_RP_*.
(18) - (19) The *_RP_* sends the protected resource to *_UA_*, which
then presents it to the requester *_RO_*.
*_Notes regarding some steps:_*
(4) If the server token is not available at this time, sequence (1) -
(2) will be executed between steps (4) and (5) to provide the server
token. Additionally, this change may also be necessary for a
periodic refresh of the server token or if the entities are both
clients.
(6) The client's authorization could be performed in advance and the
client token stored securely by the user agent for handling multiple
authentication requests. This means performing only the server token
communication here, avoiding the following steps (7) - (9) because
already done.
The verification of the authenticity of the tokens is carried out by
the IdPs who exchange messages on a dedicated network to reduce the
risk of intrusion. Security is strengthened by the presence of two
interfaces for the exchange of tokens, one is for the party in trust
and the other is for the opposing party. If one is compromised, the
other interrupts the flow avoiding authorization. The trust placed
in the mutual validation of messages avoids having to merge
authentication domains, leaving great flexibility to the system as a
whole.
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Identity recognition information resides only with the trusted
identity provider. This reduces the need to store too much personal
information in Internet registrations. Furthermore, to easily
identify which IdP holds the entity's authentication credentials, it
can be easily extracted from the username structure if this is
defined following the same technique used to compose an email address
[RFC5322], that means an username, an @ sign, and a domain name.
4. Identity Provider - Trustee Concepts
An IdP is a service provider that verifies the authenticity of a
digital identity so that it is truly what it claims to be. The
service provided is the guarantee of recognition of the identity of
natural or legal persons in digital communication. For this role as
an identity guarantor it can also be called an *ID trustee*. When
processing personal data, the laws of the country to which the data
subject belongs must be considered. It could also provide additional
services (e-mail, voice mail, anonymous account,...) but always in
full compliance with current legislation and only if they do not
present a risk for the data subject.
The infrastructure underlying symmetric communication is a dedicated
network to the exchange of authentication messages between IdPs.
Ideally, each IdP always has two connectors, one to communicate with
its trusted entity and the other to exchange messages with another
IdP. With its own entity the mechanism is exactly the one defined by
[RFC6749]. With other IdPs, a reserved channel is required for the
exchange of tokens, which provides guarantees on the integrity of the
messages and their origin. This channel SHOULD have low latency
because it represents an additional step compared to the single
ecosystem authentication scheme. The intended mechanism for sharing
messages is that of a mail server [RFC5321].
The dedicated network for the identity providers is not technically
necessary for the authentication protocol but is essential for
security, to reduce the risk of fraud or identity theft and, to
ensure trust in lawful behavior. There MUST also be an international
control body for the IdPs and the IdP network, an authority with the
task of governing the overall system, i.e. defining technical
standards, or carrying out audits to ensure compliance with the
rules, or acting to exclude nodes in case of violation of the rules.
An IdP MUST be a legal person subject to both the laws of the country
where it is established and international certifications to protect
data treatment and service provision in terms of security and
quality.
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5. Identity Provider - Custodian Concepts
The identity provider must carry out a recognition and registration
of the user's personal data before being able to guarantee its
identity. The collection of data from legal entities, as they are
public, is not particularly critical, while for the natural person
the protection provided by the law in force for the holder of the
digital identity must be enforced. Consequently, it is useful to
divide the set of IdPs into two categories, in the first the set of
IdPs (also called trustees) that only manage the operation of digital
identities and in the second those that guarantee to the trustees
that the identity of the user is real. This last category of IdPs,
called custodians (IdCs), should operate under the responsibility of
the legal authority that manages the real identity of the individual
(i.e. who issues the identity card). IdCs are the only guarantors of
the link between physical and digital identity, the only ones to
issue a digital identity with legal value. IdCs do not provide
guarantees on identities associated with legal entities, which are
managed directly by IdPs.
Through the legal digital identity, each user can request the issuing
of a new digital identity to the trusted IdP. The latter will
request the IdC to confirm the authenticity of the identification
data received from the user, that is, the user could send an ID token
with the contact information of its IdC. The request will be handled
entirely online and will not require any additional data from the
data subject other than the identification information that it
decides to provide. The new identity will be useful to satisfy the
typical needs of Internet transactions by providing precise
guarantees.
* The *_identity custodian_* is the guarantor of the existence of
the natural person and has the ability to uniquely identify them
but only following a formal request from the relevant authority.
* The *_identity provider_* receives the identification data that
the data subject has decided to provide and will match these to
the digital identity.
* The *_service provider_* will have the guarantee that the user is
linked to a real person for security, contractual or legal
reasons.
* The *_data subject_* can provide personal information according to
their need, also maintaining anonymity.
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* The *_public authority_* that manages the real data will be able
to identify the individual with certainty in case of violations of
the law (i.e. to protect the service provider).
5.1. Issuing of a New Digital Identity
Figure 4 shows a use case describing the request of a new digital
identity from an identity provider. A SVG image is available here
(https://github.com/Luigi-Sbriz/identity/images/4_New-identity-use-
case.svg).
┌───────────┐ ┌───────────┐
│Identity │ │Identity │
│ │ │ │
│Custodian │ │Provider │
└─────┬─────┘ └─────┬─────┘
Digital │ecosystem Digital │ecosystem
│IdC │IdP
.........│......... .........│.........
: ┌─────┴─────┐ : : ┌─────┴─────┐ :
: │Authorizat.│ : : │Authorizat.│ :
: │ ╞════════╡ │ :
: │Server IdC │ : : │Server IdP │ :
: └─────┬─────┘ : : └─────┬─────┘ :
: │ : : │ :
: │ : : │ :
┌───────────┐ : ┌─────┴─────┐ : : ┌─────┴─────┐ :
│Data │ : │User │ : : │Relying │ :
│ ├─────┤ ├────────┤ │ :
│Subject │ : │Agent │ : : │Party IdP │ :
└───────────┘ : └───────────┘ : : └───────────┘ :
:.................: :.................:
Figure 4: Abstract of New Digital Identity Request
Figure 5 shows the abstract representation of the message exchange
sequence to request a new digital identity. A SVG image is available
here (https://github.com/Luigi-Sbriz/identity/images/5_New-identity-
sequence-diagram.svg).
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┌───────────┐ ┌───────────┐ ┌───────────┐ ┌───────────┐
│Data │ │User │ │Authorizat.│ │Relying │
│ │ │ │ │ │ │ │
│Subject │ │Agent │ │Server IdC │ │Party IdP │
└───────────┘ └─────┬─────┘ └─────┬─────┘ └─────┬─────┘
| | | |
├-(1)-Request New->+-(2)--Send New Identity Request----->|
| Identity | | |
| |<--(3)--Return IdP Token-------------┘
| | |
| ├(4)--Request IdC |
| | Token & Send |
| | IdP Token--->|
| | |
|<-(5)-Request Credentials via UA-----┤
| | |
└-(6)--Present Credentials via UA---->|
| |
└<--(7)--Return |
IdC Token-┘
┌───────────┐ ┌───────────┐ ┌───────────┐ ┌───────────┐
│User │ │Authorizat.│ │Authorizat.│ │Relying │
│ │ │ │ │ │ │ │
│Agent │ │Server IdC │ │Server IdP │ │Party IdP │
└─────┬─────┘ └─────┬─────┘ └─────┬─────┘ └─────┬─────┘
| | | |
├-(8)--Request New Identity & Send IdC Token------------>|
| | | |
| |<--(10)--Send IdC |<--(9)--Send IdC |
| | Token----┤ Token-----┤
| | | |
| ├-(11)--Return IdP | |
| | Token & Send | |
| | ID Token---->| |
| | | |
└<-(12)---Return | └-(13)---Return |
ID Token-┘ Client Token--->┘
┌───────────┐ ┌───────────┐ ┌───────────┐
│Data │ │User │ │Relying │
│ │ │ │ │ │
│Subject │ │Agent │ │Party IdP │
└─────┬─────┘ └─────┬─────┘ └─────┬─────┘
| | |
└<-(15)------Return ID Token-┘<-(14)-Return Client Token-┘
Figure 5: New Digital Identity Request - Sequence diagram
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(1) - (3) The *_data subject_* requests the new digital identity via
the user agent to the identity provider. The *_UA_* activates the
authentication process by requesting the new identity to the *_RP_*,
which responds by providing the IdP token (access token from IdP's
AS).
(4) - (7) The *_UA_* requests the IdC token (access token from the
custodian's AS) to its *_AS_*, sending also the IdP token received
from *_RP_*. The custodian's *_AS_* requests credentials from the
*_data subject_* and returns the IdC token to the *_UA_*.
(8) - (9) The *_UA_* requests the new digital identity from the
*_RP_* by sending the IdC token. Then, relying party requests to
identity provider's AS to verify the IdC token.
(10) - (11) Both authentication servers must verify that the tokens
received match the originals. If required by data subject, the
custodian's AS will send an additional ID token with personal data.
(12) - (13) Custodian's AS informs the *_UA_* of the outcome and, if
required, sends also a copy of the ID token. The identity provider's
AS sends to the *_RP_* the client token (related the new identity
provided by IdP).
(14) - (15) The *_RP_* sends the client token to *_UA_*, which then
informs the *_data subject_* of the outcome and, if required, sends a
readable copy of the ID token to check the personal information
shared.
*_Notes regarding some steps:_*
(3) If the relying party does not have the IdP token available, this
will be requested from the authentication server after step (2).
(4) IdC token does not contains any real identity information as
default. If requested, an ID token with a standard set of real
information can be included during this step.
Any new digital identity with legal value is issued according to the
rules defined by the relevant authority. It is presumable that there
is also physical recognition of the data subject before the provision
of credentials but no reference model is defined in this document.
6. Sustainable Digital Identity Trust Schema
For the effectiveness of the identity trust system based on the
paradigm of trust towards a third party recognizable as reliable, it
is necessary to guarantee a transparent and verifiable mechanism.
The objective is to achieve universal participation and it is only
possible if trust in the system as a whole is demonstrable. For this
reason it is necessary to establish founding principles that guide
the rules to guarantee equal dignity and balance in all components of
the system. The following nine principles are established:
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1. The digital identity can be cancelled or deleted without
impacting the physical identity.
2. The digital identity must be linkable to the physical identity in
a verifiable manner.
3. Only the authority that legally manages the individual's physical
identity can verify this link.
4. The authentication system must be flexible (i.e., able to adapt
to technological evolutions or emerging needs).
5. The authentication system must be accessible to all (i.e.,
without discriminatory costs).
6. The authentication system must be secure (i.e., continuously
aligned with security best practices).
7. The authentication system must be privacy-friendly (i.e., not
requiring any personal information unless strictly necessary).
8. The authentication system must be resilient (i.e., with
availability appropriate for needs and the ability to cope with
adversity).
9. The authentication system technology must be open (i.e., able to
evolve based on transparent shared standards and verifiable
developments).
To guarantee the principles set out, the requirements of the
authentication system MUST include the protection of personal data
and the guarantee of anonymity for lawful purposes, that is:
1. Ensure mutual recognition to guarantee the identity of the
provider to the consumer.
2. Ensure the ability to authenticate the digital identities of
consumers and providers against their real-world identity without
exposing real data
Naturally, the ability to validate the authenticity of the
relationship between digital identity and physical identity lies only
with the public authority responsible for managing the citizen's
identity.
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7. Security Considerations
Integrity and resilience are the most critical parameters. Symmetric
authentication should avoid the risk of man-in-the-middle attack
because it should successfully attack both message flows at the same
time. The trustee is a critical component and must be subjected to
rigorous checks on compliance with the standards. Referring to the
term identification, we mean at least three different types, the
device, the digital user and the individual.
* The *_device_* is identified with technical methods suited to the
various needs. For example, geolocalization using International
Mobile Equipment Identity (IMEI) [ITU1] and Integrated Circuit
Card ID (ICCID) [ITU2].
* The *_digital user_* is well managed by [RFC6749] but inside the
digital ecosystem. To manage users of multiple domains, either
the user registrations are duplicated for each domain involved, or
the domains involved are joined in a trust relationship.
* The *_individual_* is well managed with classic physical methods
(e.g. photo ID) but the link with the digital identity needs to be
improved because the quality is not satisfactory. This topic is
beyond the scope of this specification and it was explored for
example in [LS3].
An in-depth defense system SHOULD consider all the components
involved and in this case not just the pure digital authentication of
the user. In this document only the digital user is treated but
extensions applicable to mixed situations with multiple types are
certainly welcome to improve the overall security profile.
7.1. User registration
It is important to control the amount of data exchanged during the
authentication process but also that the data required to issue a new
digital identity are the only ones strictly necessary. To assign
access credentials to a protected resource to a user, a process of
recording the user's identification and contact data is necessary, as
they are necessary for the authentication of the digital identity and
for the attribution of access rights to the resource. Data provided
or exchanged with IdPs MUST comply with the need-to-know principle.
Three ways of recording are required.
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7.1.1. Registration with an identity custodian (IdC).
The IdC has the legal authority to retain all personal data essential
to complete the process of recognizing the real individual.
Consequently it also has full authority over digital identity data
and registration is subject to the law of the individual's country of
origin.
7.1.2. Registration with an identity provider (IdP).
The IdP has to guarantee the authenticity of the digital identity and
the collection of personal data SHOULD be limited to the sole purpose
of this operation. For the registration of a natural person, the IdP
requests confirmation from the IdC of the real identity of the
applicant before issuing the digital identity. The process is
completely online and does not require any physical recognition. For
legal entities, the data is provided by the owner or a delegate.
7.1.3. Registration with a service provider (SP).
The service provider SHOULD know only the data necessary to build the
authorization roles to govern access to resources and nothing more.
These are provided directly by the user or by an ID token, in
addition to those received automatically from their IdP relating to
digital identity.
8. Conclusions
The identity management system, to operate in different digital
ecosystems, should rely on a common authentication protocol that
symmetrically performs the same operations in complete transparency,
entrusting the decision on recognition to a trusted third party. The
trust in the reliability of the recognition carried out by the
identity guarantor (IdP or IdC) cannot be based on the technological
component alone. It is therefore necessary to involve a supervisory
authority of the overall system for technological aspects and the
authorities of the data subject's country for data protection.
To improve trust between two entities, in this identification scheme,
the objective is to provide three guarantees:
1. The mutual recognition between consumer and supplier.
2. The control and minimization of the personal information
processed
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3. In case of legal need, the ability to match the digital
identities of consumer and supplier against their real-world
identity.
Technically, due to the strong synergy obtained it is advisable to
maintain alignment with [RFC6749] and the related specifications.
9. IANA Considerations
This document has no IANA actions.
10. References
10.1. Normative References
[RFC6749] Hardt, D., Ed., "The OAuth 2.0 Authorization Framework",
RFC 6749, DOI 10.17487/RFC6749, October 2012,
<https://www.rfc-editor.org/rfc/rfc6749>.
[RFC5322] Resnick, P., Ed., "Internet Message Format", RFC 5322,
DOI 10.17487/RFC5322, October 2008,
<https://www.rfc-editor.org/rfc/rfc5322>.
[RFC5321] Klensin, J., "Simple Mail Transfer Protocol", RFC 5321,
DOI 10.17487/RFC5321, October 2008,
<https://www.rfc-editor.org/rfc/rfc5321>.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/rfc/rfc5234>.
[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/rfc/rfc2119>.
[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/rfc/rfc8174>.
10.2. Informative References
[ITU1] International Telecommunications Union, "QTR-RLB-IMEI -
Reliability of International Mobile Station Equipment
Identity (IMEI), Technical Report", July 2020,
<https://www.itu.int/dms_pub/itu-t/opb/tut/T-TUT-CCICT-
2020-PDF-E.pdf>. Switzerland
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[ITU2] International Telecommunications Union, "E.118: The
International Telecommunication Charge Card", May 2006,
<https://www.itu.int/rec/T-REC-E.118>.
[LS1] Sbriz, L., "A Symmetrical Framework for the Exchange of
Identity Credentials Based on the Trust Paradigm, Part 1:
Identity Trust Abstract Model, ISACA Journal, vol.2",
April 2022, <https://www.isaca.org/resources/isaca-
journal/issues/2022/volume-2/a-symmetrical-framework-for-
the-exchange-of-identity-credentials-based-on-the-trust-
paradigm-part-1>.
[LS2] Sbriz, L., "A Symmetrical Framework for the Exchange of
Identity Credentials Based on the Trust Paradigm, Part 2:
Identity Trust Service Implementation, ISACA Journal,
vol.2", April 2022, <https://www.isaca.org/resources/
isaca-journal/issues/2022/volume-2/a-symmetrical-
framework-for-the-exchange-of-identity-credentials-based-
on-the-trust-paradigm-part-2>.
[LS3] Sbriz, L., "How to Digitally Verify Human Identity: The
Case of Voting, ISACA Journal, vol.1", January 2023,
<https://www.isaca.org/resources/isaca-
journal/issues/2023/volume-1/how-to-digitally-verify-
human-identity>.
[LS4] Sbriz, L., "Modeling an Identity Trust System, ISACA
Journal, vol.6", November 2023,
<https://www.isaca.org/resources/isaca-
journal/issues/2023/volume-6/modeling-an-identity-trust-
system>.
Acknowledgments
This document was prepared using text editor with Markdown syntax
(kramdown-rfc dialect).
Author's Address
Luigi Sbriz
Cybersecurity & Privacy Senior Consultant
Email: luigi@sbriz.eu
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