< draft-ietf-abfab-arch-05.txt   draft-ietf-abfab-arch-06.txt >
ABFAB J. Howlett ABFAB J. Howlett
Internet-Draft JANET(UK) Internet-Draft JANET(UK)
Intended status: Informational S. Hartman Intended status: Informational S. Hartman
Expires: August 29, 2013 Painless Security Expires: October 20, 2013 Painless Security
H. Tschofenig H. Tschofenig
Nokia Siemens Networks Nokia Siemens Networks
E. Lear E. Lear
Cisco Systems GmbH Cisco Systems GmbH
J. Schaad J. Schaad
Soaring Hawk Consulting Soaring Hawk Consulting
February 25, 2013 April 18, 2013
Application Bridging for Federated Access Beyond Web (ABFAB) Application Bridging for Federated Access Beyond Web (ABFAB)
Architecture Architecture
draft-ietf-abfab-arch-05.txt draft-ietf-abfab-arch-06.txt
Abstract Abstract
Over the last decade a substantial amount of work has occurred in the Over the last decade a substantial amount of work has occurred in the
space of federated access management. Most of this effort has space of federated access management. Most of this effort has
focused on two use-cases: network access and web-based access. focused on two use cases: network access and web-based access.
However, the solutions to these use-cases that have been proposed and However, the solutions to these use cases that have been proposed and
deployed tend to have few common building blocks in common. deployed tend to have few common building blocks in common.
This memo describes an architecture that makes use of extensions to This memo describes an architecture that makes use of extensions to
the commonly used security mechanisms for both federated and non- the commonly used security mechanisms for both federated and non-
federated access management, including the Remote Authentication Dial federated access management, including the Remote Authentication Dial
In User Service (RADIUS) and the Diameter protocol, the Generic In User Service (RADIUS) and the Diameter protocol, the Generic
Security Service (GSS), the GS2 family, the Extensible Authentication Security Service (GSS), the GS2 family, the Extensible Authentication
Protocol (EAP) and the Security Assertion Markup Language (SAML). Protocol (EAP) and the Security Assertion Markup Language (SAML).
The architecture addresses the problem of federated access management The architecture addresses the problem of federated access management
to primarily non-web-based services, in a manner that will scale to to primarily non-web-based services, in a manner that will scale to
large numbers of identity providers, relying parties, and large numbers of identity providers, relying parties, and
federations. federations.
Status of this Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 29, 2013. This Internet-Draft will expire on October 20, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
1.1.1. Channel Binding . . . . . . . . . . . . . . . . . . . 6 1.1.1. Channel Binding . . . . . . . . . . . . . . . . . . . 6
1.2. An Overview of Federation . . . . . . . . . . . . . . . . 7 1.2. An Overview of Federation . . . . . . . . . . . . . . . . 7
1.3. Challenges for Contemporary Federation . . . . . . . . . . 10 1.3. Challenges for Contemporary Federation . . . . . . . . . 10
1.4. An Overview of ABFAB-based Federation . . . . . . . . . . 11 1.4. An Overview of ABFAB-based Federation . . . . . . . . . . 10
1.5. Design Goals . . . . . . . . . . . . . . . . . . . . . . . 13 1.5. Design Goals . . . . . . . . . . . . . . . . . . . . . . 13
2. Architecture . . . . . . . . . . . . . . . . . . . . . . . . . 15 2. Architecture . . . . . . . . . . . . . . . . . . . . . . . . 14
2.1. Relying Party to Identity Provider . . . . . . . . . . . . 16 2.1. Relying Party to Identity Provider . . . . . . . . . . . 15
2.1.1. AAA, RADIUS and Diameter . . . . . . . . . . . . . . . 17 2.1.1. AAA, RADIUS and Diameter . . . . . . . . . . . . . . 16
2.1.2. Discovery and Rules Determination . . . . . . . . . . 19 2.1.2. Discovery and Rules Determination . . . . . . . . . . 18
2.1.3. Routing and Technical Trust . . . . . . . . . . . . . 20 2.1.3. Routing and Technical Trust . . . . . . . . . . . . . 19
2.1.4. AAA Security . . . . . . . . . . . . . . . . . . . . . 21 2.1.4. AAA Security . . . . . . . . . . . . . . . . . . . . 20
2.1.5. SAML Assertions . . . . . . . . . . . . . . . . . . . 22 2.1.5. SAML Assertions . . . . . . . . . . . . . . . . . . . 21
2.2. Client To Identity Provider . . . . . . . . . . . . . . . 24 2.2. Client To Identity Provider . . . . . . . . . . . . . . . 23
2.2.1. Extensible Authentication Protocol (EAP) . . . . . . . 24 2.2.1. Extensible Authentication Protocol (EAP) . . . . . . 23
2.2.2. EAP Channel Binding . . . . . . . . . . . . . . . . . 25 2.2.2. EAP Channel Binding . . . . . . . . . . . . . . . . . 25
2.3. Client to Relying Party . . . . . . . . . . . . . . . . . 26 2.3. Client to Relying Party . . . . . . . . . . . . . . . . . 25
2.3.1. GSS-API . . . . . . . . . . . . . . . . . . . . . . . 26 2.3.1. GSS-API . . . . . . . . . . . . . . . . . . . . . . . 26
2.3.2. Protocol Transport . . . . . . . . . . . . . . . . . . 28 2.3.2. Protocol Transport . . . . . . . . . . . . . . . . . 27
2.3.3. Reauthentication . . . . . . . . . . . . . . . . . . . 28 2.3.3. Reauthentication . . . . . . . . . . . . . . . . . . 28
3. Application Security Services . . . . . . . . . . . . . . . . 29 3. Application Security Services . . . . . . . . . . . . . . . . 28
3.1. Authentication . . . . . . . . . . . . . . . . . . . . . . 29 3.1. Authentication . . . . . . . . . . . . . . . . . . . . . 28
3.2. GSS-API Channel Binding . . . . . . . . . . . . . . . . . 30 3.2. GSS-API Channel Binding . . . . . . . . . . . . . . . . . 29
3.3. Host-Based Service Names . . . . . . . . . . . . . . . . . 31 3.3. Host-Based Service Names . . . . . . . . . . . . . . . . 30
3.4. Additional GSS-API Services . . . . . . . . . . . . . . . 33 3.4. Additional GSS-API Services . . . . . . . . . . . . . . . 32
4. Privacy Considerations . . . . . . . . . . . . . . . . . . . . 34
4.1. Entities and their roles . . . . . . . . . . . . . . . . . 34 4. Privacy Considerations . . . . . . . . . . . . . . . . . . . 32
4.2. Relationship between user and entities . . . . . . . . . . 35 4.1. Entities and their roles . . . . . . . . . . . . . . . . 33
4.3. Data and Identifiers in use . . . . . . . . . . . . . . . 35 4.2. Privacy Aspects of ABFAB Communication Flows . . . . . . 34
4.3.1. NAI . . . . . . . . . . . . . . . . . . . . . . . . . 35 4.2.1. Client to RP . . . . . . . . . . . . . . . . . . . . 34
4.3.2. Identity Information . . . . . . . . . . . . . . . . . 36 4.2.2. Client to IdP (via Federation Substrate) . . . . . . 35
4.3.3. Accounting Information . . . . . . . . . . . . . . . . 36 4.2.3. IdP to RP (via Federation Substrate) . . . . . . . . 36
4.3.4. Collection and retention of data and identifiers . . . 36 4.3. Relationship between User and Entities . . . . . . . . . 36
4.4. User Participation . . . . . . . . . . . . . . . . . . . . 37 4.4. Accounting Information . . . . . . . . . . . . . . . . . 37
5. Deployment Considerations . . . . . . . . . . . . . . . . . . 38 4.5. Collection and retention of data and identifiers . . . . 37
5.1. EAP Channel Binding . . . . . . . . . . . . . . . . . . . 38 4.6. User Participation . . . . . . . . . . . . . . . . . . . 38
5.2. AAA Proxy Behavior . . . . . . . . . . . . . . . . . . . . 38 5. Deployment Considerations . . . . . . . . . . . . . . . . . . 38
6. Security Considerations . . . . . . . . . . . . . . . . . . . 39 5.1. EAP Channel Binding . . . . . . . . . . . . . . . . . . . 38
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 41 5.2. AAA Proxy Behavior . . . . . . . . . . . . . . . . . . . 38
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 42 6. Security Considerations . . . . . . . . . . . . . . . . . . . 38
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 43 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 40
9.1. Normative References . . . . . . . . . . . . . . . . . . . 43 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 40
9.2. Informative References . . . . . . . . . . . . . . . . . . 43 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 40
Editorial Comments . . . . . . . . . . . . . . . . . . . . . . . . 9.1. Normative References . . . . . . . . . . . . . . . . . . 40
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 49 9.2. Informative References . . . . . . . . . . . . . . . . . 41
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 43
1. Introduction 1. Introduction
The Internet uses numerous security mechanisms to manage access to The Internet uses numerous security mechanisms to manage access to
various resources. These mechanisms have been generalized and scaled various resources. These mechanisms have been generalized and scaled
over the last decade through mechanisms such as Simple Authentication over the last decade through mechanisms such as Simple Authentication
and Security Layer (SASL) with the Generic Security Server and Security Layer (SASL) with the Generic Security Server
Application Program Interface (GSS-API) (known as the GS2 family) Application Program Interface (GSS-API) (known as the GS2 family)
[RFC5801], Security Assertion Markup Language (SAML) [RFC5801], Security Assertion Markup Language (SAML)
[OASIS.saml-core-2.0-os], and the Authentication, Authorization, and [OASIS.saml-core-2.0-os], and the Authentication, Authorization, and
Accounting (AAA) architecture as embodied in RADIUS [RFC2865] and Accounting (AAA) architecture as embodied in RADIUS [RFC2865] and
Diameter [RFC3588]. Diameter [RFC3588].
A Relying Party (RP) is the entity that manages access to some A Relying Party (RP) is the entity that manages access to some
resource. The actor that is requesting access to that resource is resource. The entity that is requesting access to that resource is
often described as the Client. Many security mechanisms are often described as the Client. Many security mechanisms are
manifested as an exchange of information between these actors. The manifested as an exchange of information between these entities. The
RP is therefore able to decide whether the Client is authorized, or RP is therefore able to decide whether the Client is authorized, or
not. not.
Some security mechanisms allow the RP to delegate aspects of the Some security mechanisms allow the RP to delegate aspects of the
access management decision to an actor called the Identity Provider access management decision to an entity called the Identity Provider
(IdP). This delegation requires technical signaling, trust and a (IdP). This delegation requires technical signaling, trust and a
common understanding of semantics between the RP and IdP. These common understanding of semantics between the RP and IdP. These
aspects are generally managed within a relationship known as a aspects are generally managed within a relationship known as a
'federation'. This style of access management is accordingly 'federation'. This style of access management is accordingly
described as 'federated access management'. described as 'federated access management'.
Federated access management has evolved over the last decade through Federated access management has evolved over the last decade through
specifications like SAML [OASIS.saml-core-2.0-os], OpenID [1], OAuth specifications like SAML [OASIS.saml-core-2.0-os], OpenID [1], OAuth
[RFC5849], [I-D.ietf-oauth-v2] and WS-Trust [WS-TRUST]. The benefits [RFC5849], [I-D.ietf-oauth-v2] and WS-Trust [WS-TRUST]. The benefits
of federated access management include: of federated access management include:
Single or Simplified sign-on: Single or Simplified sign-on:
An Internet service can delegate access management, and the An Internet service can delegate access management, and the
associated responsibilities such as identity management and associated responsibilities such as identity management and
credentialing, to an organisation that already has a long-term credentialing, to an organization that already has a long-term
relationship with the Subject. This is often attractive for relationship with the Client. This is often attractive for
Relying Parties who frequently do not want these responsibilities. Relying Parties who frequently do not want these responsibilities.
The Subject also requires fewer credentials, which is also The Client also requires fewer credentials, which is also
desirable. desirable.
Data Minimization and User Participation: Data Minimization and User Participation:
Often a Relying Party does not need to know the identity of a Often a Relying Party does not need to know the identity of a
Subject to reach an access management decision. It is frequently Client to reach an access management decision. It is frequently
only necessary for the Relying Party know specific attributes only necessary for the Relying Party know specific attributes
about the subject, for example, that the Subject is affiliated about the subject, for example, that the Subject is affiliated
with a particular organisation or has a certain role or with a particular organization or has a certain role or
entitlement. Sometimes the RP only needs to know a pseudonym of entitlement. Sometimes the RP only needs to know a pseudonym of
the Subject. the Subject.
Prior to the release of attributes to the IdP from the IdP, the Prior to the release of attributes to the RP from the IdP, the IdP
IdP will check configuration and policy to determine if the will check configuration and policy to determine if the attributes
attributes are to be released. There is currently no direct are to be released. There is currently no direct client
client participation in this decision. participation in this decision.
Provisioning Provisioning:
Sometimes a Relying Party needs, or would like, to know more about Sometimes a Relying Party needs, or would like, to know more about
a subject than an affiliation or a pseudonym. For example, a a client than an affiliation or a pseudonym. For example, a
Relying Party may want the Subject's email address or name. Some Relying Party may want the Client's email address or name. Some
federated access management technologies provide the ability for federated access management technologies provide the ability for
the IdP to supply this information, either on request by the RP or the IdP to supply this information, either on request by the RP or
unsolicited. unsolicited.
This memo describes the Application Bridging for Federated Access This memo describes the Application Bridging for Federated Access
Beyond the Web (ABFAB) architecture. This architecture makes use of Beyond the Web (ABFAB) architecture. This architecture makes use of
extensions to the commonly used security mechanisms for both extensions to the commonly used security mechanisms for both
federated and non-federated access management, including the RADIUS federated and non-federated access management, including the RADIUS
and the Diameter protocols, the Generic Security Service (GSS), the and the Diameter protocols, the Generic Security Service (GSS), the
GS2 family, the Extensible Authentication Protocol (EAP) and SAML. GS2 family, the Extensible Authentication Protocol (EAP) and SAML.
skipping to change at page 5, line 45 skipping to change at page 5, line 28
This document uses identity management and privacy terminology from This document uses identity management and privacy terminology from
[I-D.iab-privacy-considerations]. In particular, this document uses [I-D.iab-privacy-considerations]. In particular, this document uses
the terms identity provider, relying party, identifier, pseudonymity, the terms identity provider, relying party, identifier, pseudonymity,
unlinkability, and anonymity. unlinkability, and anonymity.
In this architecture the IdP consists of the following components: an In this architecture the IdP consists of the following components: an
EAP server, a RADIUS or a Diameter server, and optionally a SAML EAP server, a RADIUS or a Diameter server, and optionally a SAML
Assertion service. Assertion service.
This document uses the term Network Access Identifier (NAI), as This document uses the term Network Access Identifier (NAI), as
defined in [RFC4282]. An NAI consists of a realm identifier, which defined in [I-D.ietf-radext-nai]. An NAI consists of a realm
is associated with an IdP and a username which is associated with a identifier, which is associated with an IdP and a username which is
specific client of the IdP. associated with a specific client of the IdP.
One of the problems people will find with reading this document is One of the problems people will find with reading this document is
that the terminology sometimes appears to be inconsistent. This is that the terminology sometimes appears to be inconsistent. This is
due the fact that the terms used by the different standards we are due the fact that the terms used by the different standards we are
picking up don't use the same terms. In general the document uses referencing are not consistent. In general the document uses either
either a consistent term or the term associated with the standard a the ABFAB term or the term associated with the standard under
under discussion as appropriate. For reference we include this table discussion as appropriate. For reference we include this table which
which maps the different terms into a single table. maps the different terms into a single table.
+----------+-----------+--------------------+-----------------------+ +--------------+--------------+-----------------+-------------------+
| Protocol | Subject | Relying Party | Identity Provider | | Protocol | Subject | Relying Party | Identity Provider |
+----------+-----------+--------------------+-----------------------+ +--------------+--------------+-----------------+-------------------+
| ABFAB | Client | Relying Party (RP) | Identity Provider | | ABFAB | Client | Relying Party | Identity Provider |
| | | | (IdP) | | | | (RP) | (IdP) |
| | | | | | | | | |
| | Initiator | Acceptor | | | | Initiator | Acceptor | |
| | | | | | | | | |
| | | Server | | | | | Server | |
| | | | | | | | | |
| SAML | Subject | Service Provider | Issuer | | SAML | Subject | Service | Issuer |
| | | | | | | | Provider | |
| GSS-API | Initiator | Acceptor | | | | | | |
| | | | | | GSS-API | Initiator | Acceptor | |
| EAP | EAP peer | | EAP server | | | | | |
| | | | | | EAP | EAP peer | | EAP server |
| AAA | | AAA Client | AAA server | | | | | |
| | | | | | AAA | | AAA Client | AAA server |
| RADIUS | user | NAS | RADIUS server | | | | | |
| | | | | | RADIUS | user | NAS | RADIUS server |
| | | RADIUS client | | | | | | |
+----------+-----------+--------------------+-----------------------+ | | | RADIUS client | |
+--------------+--------------+-----------------+-------------------+
Note that in some cases a cell has been left empty, in these cases Note that in some cases a cell has been left empty; in these cases
there is no direct name that represents this concept. there is no direct name that represents this concept.
Note to reviewers - I have most likely missed some entries in the
table. Please provide me with both correct names from the protocol
and missing names that are used in the text below.
1.1.1. Channel Binding 1.1.1. Channel Binding
This document uses the term channel binding with two different This document uses the term channel binding with two different
meanings. meanings.
EAP channel binding, also called channel binding, is used to provide EAP channel binding is used to provide GSS-API naming semantics.
GSS-API naming semantics. Channel binding sends a set of attributes Channel binding sends a set of attributes from the peer to the EAP
from the peer to the EAP server either as part of the EAP server either as part of the EAP conversation or as part of a secure
converstaion or as part of a secure association protocol. In association protocol. In addition, attributes are sent in the
addition, attributes are sent in the baackend protocol from the backend protocol from the authenticator to the EAP server. The EAP
authenticator to the EAP server. The EAP server confirms the server confirms the consistency of these attributes and provides the
consistency of these attributes and provides the confirmation back to confirmation back to the peer. In this document, channel binding
the peer. without qualification refers to EAP channel binding.
GSS-API channel binding provides protection against man-in-the-middle GSS-API channel binding provides protection against man-in-the-middle
attacks when GSS-API is used for authentication inside of some attacks when GSS-API is used for authentication inside of some
tunnel; it is similar to a facility called cryptographic binding in tunnel; it is similar to a facility called cryptographic binding in
EAP. The binding works by each side deriving a cryptographic value EAP. The binding works by each side deriving a cryptographic value
from the tunnel itself and then using that cyrptographic value to from the tunnel itself and then using that cryptographic value to
prove to the otherside that it knows the value. prove to the other side that it knows the value.
See [RFC5056] for a discussion of the differences between these two See [RFC5056] for a discussion of the differences between these two
facilities. facilities.
Typically when considering channel binding, people think of channel Typically when considering channel binding, people think of channel
binding in combination with mutual authentication. This is binding in combination with mutual authentication. This is
sufficiently common that without additional qualification channel sufficiently common that without additional qualification channel
binding should be assumed to imply mutual authentication. Without binding should be assumed to imply mutual authentication. Without
mutual authentication, only one party knows that the endpoints are mutual authentication, only one party knows that the endpoints are
correct. That's sometimes useful. Consider for example a user who correct. That's sometimes useful. Consider for example a user who
wishes to access a protected resource from a shared whiteboard in a wishes to access a protected resource from a shared whiteboard in a
conference room. The whiteboard is the initiator; it does not need conference room. The whiteboard is the initiator; it does not need
to actually authenticate that it is talking to the correct resource to actually authenticate that it is talking to the correct resource
because the user will be able to recognize whether the displayed because the user will be able to recognize whether the displayed
content is correct. If channel binding were used without mutual content is correct. If channel binding is used without mutual
authentication, it would in effect be a request to only disclose the authentication, it is effectively a request to disclose the resource
resource in the context of a particular channel. Such an in the context of a particular channel. Such an authentication would
authentication would be similar in concept to a holder-of-key SAML be similar in concept to a holder-of-key SAML assertion. However,
assertion. However, also note that while it is not happening in the also note that while it is not happening in the protocol, mutual
protocol, mutual authentication is happening in the overall system: authentication is happening in the overall system: the user is able
the user is able to visually authenticate the content. This is to visually authenticate the content. This is consistent with all
consistent with all uses of channel binding without protocol level uses of channel binding without protocol level mutual authentication
mutual authentication found so far. found so far.
1.2. An Overview of Federation 1.2. An Overview of Federation
In the previous section we introduced the following actors: In the previous section we introduced the following entities:
o the Client, o the Client,
o the Identity Provider, and o the Identity Provider, and
o the Relying Party. o the Relying Party.
One additional actor in can be an Individual. An individual is a The final entity that needs to be introduced is the Individual. An
human being that is using a client. Individuals may or may not exist Individual is a human being that is using the Client. In any given
in any given deployment. The client may be either a front end on an situation, an Individual may or may not exist. Clients can act
individual or an independent automated entity. either as front ends for Individuals or they may be independent
entities that are setup and allowed to run autonomously. An example
of such an entity can be found in the trust routing protocol where
the routers use ABFAB to authenticate to each other.
These entities and their relationships are illustrated graphically in These entities and their relationships are illustrated graphically in
Figure 1. Figure 1.
,----------\ ,---------\ ,----------\ ,---------\
| Identity | Federation | Relying | | Identity | Federation | Relying |
| Provider + <-------------------> + Party | | Provider + <-------------------> + Party |
`----------' '---------' `----------' '---------'
< <
\ \
skipping to change at page 8, line 30 skipping to change at page 8, line 14
+---------+ / \ +---------+ / \
Figure 1: Entities and their Relationships Figure 1: Entities and their Relationships
The relationships between the entities in Figure 1 are: The relationships between the entities in Figure 1 are:
Federation Federation
The Identity Provider and the Relying Parties are part of a The Identity Provider and the Relying Parties are part of a
Federation. The relationship may be direct (they have an explicit Federation. The relationship may be direct (they have an explicit
trust relationship) or transitive (the trust releationship is trust relationship) or transitive (the trust relationship is
mediated by one or more entities). The federation relationship is mediated by one or more entities). The federation relationship is
governed by a federation agreement. Within a single federation, governed by a federation agreement. Within a single federation,
there may be multiple Identity Providers as well as multiple there may be multiple Identity Providers as well as multiple
Relying Parties. A federation is governed by a federation Relying Parties. A federation is governed by a federation
agreement. agreement.
Authentication Authentication
There is a direct relationship between the Client and the Identity There is a direct relationship between the Client and the Identity
Provider by which the entities trust and can securely authenticate Provider by which the entities trust and can securely authenticate
each other. each other.
A federation agreement typically encompasses operational A federation agreement typically encompasses operational
specifications and legal rules: specifications and legal rules:
Operational Specifications: Operational Specifications:
These includes the technical specifications (e.g. protocols used These include the technical specifications (e.g. protocols used
to communicate between the three parties), process standards, to communicate between the three parties), process standards,
policies, identity proofing, credential and authentication policies, identity proofing, credential and authentication
algorithm requirements, performance requirements, assessment and algorithm requirements, performance requirements, assessment and
audit criteria, etc. The goal of operational specifications is to audit criteria, etc. The goal of operational specifications is to
provide enough definition that the system works and provide enough definition that the system works and
interoperability is possible. interoperability is possible.
Legal Rules: Legal Rules:
The legal rules take the legal framework into consideration and The legal rules take the legal framework into consideration and
provides contractual obligations for each entity. The rules provide contractual obligations for each entity. The rules define
define the responsibilities of each party and provide further the responsibilities of each party and provide further
clarification of the operational specifications. These legal clarification of the operational specifications. These legal
rules regulate the operational specifications, make operational rules regulate the operational specifications, make operational
specifications legally binding to the participants, define and specifications legally binding to the participants, define and
govern the rights and responsibilities of the participants. The govern the rights and responsibilities of the participants. The
legal rules may, for example, describe liability for losses, legal rules may, for example, describe liability for losses,
termination rights, enforcement mechanisms, measures of damage, termination rights, enforcement mechanisms, measures of damage,
dispute resolution, warranties, etc. dispute resolution, warranties, etc.
The Operational Specifications can demand the usage of a The Operational Specifications can demand the usage of a
sophisticated technical infrastructure, including requirements on the sophisticated technical infrastructure, including requirements on the
message routing intermediaries, to offer the required technical message routing intermediaries, to offer the required technical
functionality. In other environments, the Operational Specifications functionality. In other environments, the Operational Specifications
require fewer technical components in order to meet the required require fewer technical components in order to meet the required
technical functionality. technical functionality.
The Legal Rules include many non-technical aspects of federation, The Legal Rules include many non-technical aspects of federation,
such as business practices and legal arrangements, which are outside such as business practices and legal arrangements, which are outside
the scope of the IETF. The Legal Rules can still have an impact the the scope of the IETF. The Legal Rules can still have an impact on
architectural setup or on how to ensure the dynamic establishment of the architectural setup or on how to ensure the dynamic establishment
trust. of trust.
While a federation agreement is often discussed within the context of While a federation agreement is often discussed within the context of
formal relationships, such as between an enterprise and an employee formal relationships, such as between an enterprise and an employee
or a government and a citizen, a federation agreement does not have or a government and a citizen, a federation agreement does not have
to require any particular level of formality. For an IdP and a to require any particular level of formality. For an IdP and a
Client, it is sufficient for a relationship to be established by Client, it is sufficient for a relationship to be established by
something as simple as using a web form and confirmation email. For something as simple as using a web form and confirmation email. For
an IdP and an RP, it is sufficient for the IdP to publish contact an IdP and an RP, it is sufficient for the IdP to publish contact
information along with a public key and for the RP to use that data. information along with a public key and for the RP to use that data.
With in the framework of ABFAB, it will generally be required that a Within the framework of ABFAB, it will generally be required that a
mechanism exists for the IdP to be able to trust the identity of the mechanism exists for the IdP to be able to trust the identity of the
RP, if this is not present then the IdP cannot provide the assurances RP, if this is not present then the IdP cannot provide the assurances
to the client that the identity of the RP has been established. to the client that the identity of the RP has been established.
The nature of federation dictates that there is some form of The nature of federation dictates that there is some form of
relationship between the identity provider and the relying party. relationship between the identity provider and the relying party.
This is particularly important when the relying party wants to use This is particularly important when the relying party wants to use
information obtained from the identity provider for access management information obtained from the identity provider for access management
decisions and when the identity provider does not want to release decisions and when the identity provider does not want to release
information to every relying party (or only under certain information to every relying party (or only under certain
skipping to change at page 11, line 14 skipping to change at page 10, line 46
to allow for such ambiguities. For instance, in the case of an email to allow for such ambiguities. For instance, in the case of an email
provider, the use of SMTP and IMAP protocols do not have the ability provider, the use of SMTP and IMAP protocols do not have the ability
for the server to get additional information, beyond the clients NAI, for the server to get additional information, beyond the clients NAI,
in order to provide additional input to decide between multiple in order to provide additional input to decide between multiple
federations it may be associated with. However, the building blocks federations it may be associated with. However, the building blocks
do exist to add this functionality. do exist to add this functionality.
1.4. An Overview of ABFAB-based Federation 1.4. An Overview of ABFAB-based Federation
The previous section described the general model of federation, and The previous section described the general model of federation, and
its the application of federated access management. This section the application of federated access management. This section
provides a brief overview of ABFAB in the context of this model. provides a brief overview of ABFAB in the context of this model.
In this example, a client is attempting to connect to a server in In this example, a client is attempting to connect to a server in
order to either get access to some data or perform some type of order to either get access to some data or perform some type of
transaction. In order for the client to mutually authenticate with transaction. In order for the client to mutually authenticate with
the server, the following steps are taken in an ABFAB federated the server, the following steps are taken in an ABFAB federated
architecture: architecture:
1. Client Configuration: The Client Application is configured with 1. Client Configuration: The Client Application is configured with
an NAI assigned by the IdP. It is also configured with any an NAI assigned by the IdP. It is also configured with any
skipping to change at page 11, line 36 skipping to change at page 11, line 24
information needed to run the EAP protocols between it and the information needed to run the EAP protocols between it and the
IdP. IdP.
2. Authentication mechanism selection: The GSS-EAP GSS-API 2. Authentication mechanism selection: The GSS-EAP GSS-API
mechanism is selected for authentication/authorization. mechanism is selected for authentication/authorization.
3. Client provides an NAI to RP: The client application sets up a 3. Client provides an NAI to RP: The client application sets up a
transport to the RP and begins the GSS-EAP authentication. In transport to the RP and begins the GSS-EAP authentication. In
response, the RP sends an EAP request message (nested in the response, the RP sends an EAP request message (nested in the
GSS-EAP protocol) asking for the Client's name. The Client GSS-EAP protocol) asking for the Client's name. The Client
sends an EAP response with an NAI name form that at a minimum, sends an EAP response with an NAI name form that, at a minimum,
contains the realm portion of it's full NAI. contains the realm portion of its full NAI.
4. Discovery of federated IdP: The RP uses pre-configured 4. Discovery of federated IdP: The RP uses pre-configured
information or a federation proxy to determine what IdP to use information or a federation proxy to determine what IdP to use
based on policy and the realm portion of the provided Client based on policy and the realm portion of the provided Client
NAI. This is discussed in detail below (Section 2.1.2). NAI. This is discussed in detail below (Section 2.1.2).
5. Request from Relying Party to IdP: Once the RP knows who the IdP 5. Request from Relying Party to IdP: Once the RP knows who the IdP
is, it (or its agent) will send a RADIUS/Diameter request to the is, it (or its agent) will send a RADIUS/Diameter request to the
IdP. The RADIUS/Diameter access request encapsulates the EAP IdP. The RADIUS/Diameter access request encapsulates the EAP
response. At this stage, the RP will likely have no idea who response. At this stage, the RP will likely have no idea who
the client is. The RP sends its identity to the IdP in AAA the client is. The RP sends its identity to the IdP in AAA
attributes, and it may send a SAML Attribute Requests in a AAA attributes, and it may send a SAML Attribute Requests in a AAA
attribute. The AAA network checks that the identity claimed by attribute. The AAA network checks that the identity claimed by
the RP is valid. the RP is valid.
6. IdP begins EAP with the client: The IdP sends an EAP message to 6. IdP begins EAP with the client: The IdP sends an EAP message to
the client with an EAP method to be run. The IdP may re-request the client with an EAP method to be used. The IdP SHOULD NOT
the clients name in this message, but this is unexpected re-request the clients name in this message, but clients need to
behavior. The available and appropriate methods are discussed be able to handle it. In this case the IdP MUST accept a realm
below in this memo (Section 2.2.1). only in order to protect the client's name from the RP. The
available and appropriate methods are discussed below in this
memo (Section 2.2.1).
7. The EAP protocol is run: A bunch of EAP messages are passed 7. The EAP protocol is run: A bunch of EAP messages are passed
between the client (EAP peer) and the IdP (EAP server), until between the client (EAP peer) and the IdP (EAP server), until
the result of the authentication protocol is determined. The the result of the authentication protocol is determined. The
number and content of those messages depends on the EAP method number and content of those messages depends on the EAP method
selected. If the IdP is unable to authenticate the client, the selected. If the IdP is unable to authenticate the client, the
IdP sends a EAP failure message to the RP. As part of the EAP IdP sends a EAP failure message to the RP. As part of the EAP
protocol, the client sends a channel bindings EAP message to the protocol, the client sends a channel bindings EAP message to the
IdP (Section 2.2.2). In the channel binding message the client IdP (Section 2.2.2). In the channel binding message the client
identifies, among other things, the RP to which it is attempting identifies, among other things, the RP to which it is attempting
skipping to change at page 12, line 38 skipping to change at page 12, line 27
cryptographic keys: a Master Session Key (MSK), and an Extended cryptographic keys: a Master Session Key (MSK), and an Extended
MSK (EMSK). At this point the client has a level of assurance MSK (EMSK). At this point the client has a level of assurance
about the identity of the RP based on the name checking the IdP about the identity of the RP based on the name checking the IdP
has done using the RP naming information from the AAA framework has done using the RP naming information from the AAA framework
and from the client (by the channel binding data). and from the client (by the channel binding data).
9. Local IdP Policy Check: At this stage, the IdP checks local 9. Local IdP Policy Check: At this stage, the IdP checks local
policy to determine whether the RP and client are authorized for policy to determine whether the RP and client are authorized for
a given transaction/service, and if so, what if any, attributes a given transaction/service, and if so, what if any, attributes
will be released to the RP. If the IdP gets a policy failure, will be released to the RP. If the IdP gets a policy failure,
it sends an EAP failure message to the RP.[anchor4] (The RP will it sends an EAP failure message to the RP.[[Should this be an
have done its policy checks during the discovery process.) EAP failure to the client as well?]] (The RP will have done its
policy checks during the discovery process.)
10. IdP provide the RP with the MSK: The IdP sends a positive result 10. IdP provide the RP with the MSK: The IdP sends a positive result
EAP to the RP, along with an optional set of AAA attributes EAP to the RP, along with an optional set of AAA attributes
associated with the client (usually as one or more SAML associated with the client (usually as one or more SAML
assertions). In addition, the EAP MSK is returned to the RP. assertions). In addition, the EAP MSK is returned to the RP.
11. RP Processes Results: When the RP receives the result from the 11. RP Processes Results: When the RP receives the result from the
IdP, it should have enough information to either grant or refuse IdP, it should have enough information to either grant or refuse
a resource access request. It may have information that a resource access request. It may have information that
associates the client with specific authorization identities. associates the client with specific authorization identities.
skipping to change at page 14, line 12 skipping to change at page 13, line 46
Our key design goals are as follows: Our key design goals are as follows:
o Each party of a transaction will be authenticated, although o Each party of a transaction will be authenticated, although
perhaps not identified, and the client will be authorized for perhaps not identified, and the client will be authorized for
access to a specific resource. access to a specific resource.
o Means of authentication is decoupled so as to allow for multiple o Means of authentication is decoupled so as to allow for multiple
authentication methods. authentication methods.
o Hence, the architecture requires no sharing of long term private o The architecture requires no sharing of long term private keys
keys between clients and servers. between clients and servers.
o The system will scale to large numbers of identity providers, o The system will scale to large numbers of identity providers,
relying parties, and users. relying parties, and users.
o The system will be designed primarily for non-Web-based o The system will be designed primarily for non-Web-based
authentication. authentication.
o The system will build upon existing standards, components, and o The system will build upon existing standards, components, and
operational practices. operational practices.
Designing new three party authentication and authorization protocols Designing new three party authentication and authorization protocols
is hard and fraught with risk of cryptographic flaws. Achieving is hard and fraught with risk of cryptographic flaws. Achieving
widespead deployment is even more difficult. A lot of attention on widespread deployment is even more difficult. A lot of attention on
federated access has been devoted to the Web. This document instead federated access has been devoted to the Web. This document instead
focuses on a non-Web-based environment and focuses on those protocols focuses on a non-Web-based environment and focuses on those protocols
where HTTP is not used. Despite the increased excitement for where HTTP is not used. Despite the increased excitement for
layering every protocol on top of HTTP there are still a number of layering every protocol on top of HTTP there are still a number of
protocols available that do not use HTTP-based transports. Many of protocols available that do not use HTTP-based transports. Many of
these protocols are lacking a native authentication and authorization these protocols are lacking a native authentication and authorization
framework of the style shown in Figure 1. framework of the style shown in Figure 1.
2. Architecture 2. Architecture
We have already introduced the federated access architecture, with We have already introduced the federated access architecture, with
skipping to change at page 15, line 19 skipping to change at page 14, line 39
did not expand on the specifics of providing support for non-Web did not expand on the specifics of providing support for non-Web
based applications. This section details this aspect and motivates based applications. This section details this aspect and motivates
design decisions. The main theme of the work described in this design decisions. The main theme of the work described in this
document is focused on re-using existing building blocks that have document is focused on re-using existing building blocks that have
been deployed already and to re-arrange them in a novel way. been deployed already and to re-arrange them in a novel way.
Although this architecture assumes updates to the relying party, the Although this architecture assumes updates to the relying party, the
client application, and the Identity Provider, those changes are kept client application, and the Identity Provider, those changes are kept
at a minimum. A mechanism that can demonstrate deployment benefits at a minimum. A mechanism that can demonstrate deployment benefits
(based on ease of update of existing software, low implementation (based on ease of update of existing software, low implementation
effort, etc.) is preferred and there may be a need to specify effort, etc.) is preferred and there may be a need to specify
multiple mechanisms to support the range of different deployment multiple mechanisms to support the range of different deployment
scenarios. scenarios.
There are a number of ways for encapsulating EAP into an application There are a number of ways for encapsulating EAP into an application
protocol. For ease of integration with a wide range of non-Web based protocol. For ease of integration with a wide range of non-Web based
application protocols the usage of the GSS-API was chosen. A application protocols the usage of the GSS-API was chosen. A
description of the technical specification can be found in description of the technical specification can be found in
[I-D.ietf-abfab-gss-eap]. Other alternatives exist as well and may [I-D.ietf-abfab-gss-eap].
be considered later, such as "TLS using EAP Authentication"
[I-D.nir-tls-eap]. [anchor7]
The architecture consists of several building blocks, which is shown The architecture consists of several building blocks, which is shown
graphically in Figure 2. In the following sections, we discuss the graphically in Figure 2. In the following sections, we discuss the
data flow between each of the entities, the protocols used for that data flow between each of the entities, the protocols used for that
data flow and some of the trade-offs made in choosing the protocols. data flow and some of the trade-offs made in choosing the protocols.
+--------------+ +--------------+
| Identity | | Identity |
| Provider | | Provider |
| (IdP) | | (IdP) |
skipping to change at page 17, line 38 skipping to change at page 16, line 38
protocol provide the pieces necessary to establish the identities protocol provide the pieces necessary to establish the identities
of the RP and the client, while EAP provides the cryptographic of the RP and the client, while EAP provides the cryptographic
methods for the RP and the client to validate they are talking to methods for the RP and the client to validate they are talking to
each other. each other.
o A method exists for carrying SAML packets within RADIUS o A method exists for carrying SAML packets within RADIUS
[I-D.ietf-abfab-aaa-saml] and Diameter (work in progress) which [I-D.ietf-abfab-aaa-saml] and Diameter (work in progress) which
allows the RP to query attributes about the client from the IdP. allows the RP to query attributes about the client from the IdP.
Future protocols that support the same framework but do different Future protocols that support the same framework but do different
routing may be used in the future. Once such effort is to setup a routing may be used in the future. One such effort is to setup a
framework that creates a trusted point-to-point channel on the fly. framework that creates a trusted point-to-point channel on the fly.
2.1.1. AAA, RADIUS and Diameter 2.1.1. AAA, RADIUS and Diameter
Interestingly, for network access authentication the usage of the AAA Interestingly, for network access authentication the usage of the AAA
framework with RADIUS [RFC2865] and Diameter [RFC3588] was quite framework with RADIUS [RFC2865] and Diameter [RFC3588] was quite
successful from a deployment point of view. To map the terminology successful from a deployment point of view. To map to the
used in Figure 1 to the AAA framework the IdP corresponds to the AAA terminology used in Figure 1 to the AAA framework the IdP corresponds
server, the RP corresponds to the AAA client, and the technical to the AAA server, the RP corresponds to the AAA client, and the
building blocks of a federation are AAA proxies, relays and redirect technical building blocks of a federation are AAA proxies, relays and
agents (particularly if they are operated by third parties, such as redirect agents (particularly if they are operated by third parties,
AAA brokers and clearing houses). The front-end, i.e. the end host such as AAA brokers and clearing houses). The front-end, i.e. the
to AAA client communication, is in case of network access end host to AAA client communication, is in case of network access
authentication offered by link layer protocols that forward authentication offered by link layer protocols that forward
authentication protocol exchanges back-and-forth. An example of a authentication protocol exchanges back-and-forth. An example of a
large scale RADIUS-based federation is EDUROAM [2]. large scale RADIUS-based federation is EDUROAM [2].
By using the AAA framework, ABFAB gets a lot of mileage as many of By using the AAA framework, ABFAB gets a lot of mileage as many of
the federation agreements already exist and merely need to be the federation agreements already exist and merely need to be
expanded to cover the ABFAB additions. The AAA framework has already expanded to cover the ABFAB additions. The AAA framework has already
addressed some of the problems outlined above. For example, addressed some of the problems outlined above. For example,
o It already has a method for routing requests based on a domain. o It already has a method for routing requests based on a domain.
skipping to change at page 18, line 28 skipping to change at page 17, line 28
The astute reader will notice that RADIUS and Diameter have The astute reader will notice that RADIUS and Diameter have
substantially similar characteristics. Why not pick one? RADIUS and substantially similar characteristics. Why not pick one? RADIUS and
Diameter are deployed in different environments. RADIUS can often be Diameter are deployed in different environments. RADIUS can often be
found in enterprise and university networks, and is also in use by found in enterprise and university networks, and is also in use by
fixed network operators. Diameter, on the other hand, is deployed by fixed network operators. Diameter, on the other hand, is deployed by
mobile operators. Another key difference is that today RADIUS is mobile operators. Another key difference is that today RADIUS is
largely transported upon UDP. We leave as a deployment decision, largely transported upon UDP. We leave as a deployment decision,
which protocol will be appropriate. The protocol defines all the which protocol will be appropriate. The protocol defines all the
necessary new AAA attributes as RADIUS attributes. A future document necessary new AAA attributes as RADIUS attributes. A future document
would defined the same AAA attributes for a Diameter environment. We would define the same AAA attributes for a Diameter environment. We
also note that there exist proxies which convert from RADIUS to also note that there exist proxies which convert from RADIUS to
Diameter and back. This makes it possible for both to be deployed in Diameter and back. This makes it possible for both to be deployed in
a single federation substrate. a single federation substrate.
Through the integrity protection mechanisms in the AAA framework, the Through the integrity protection mechanisms in the AAA framework, the
identity provider can establish technical trust that messages are identity provider can establish technical trust that messages are
being sent by the appropriate relying party. Any given interaction being sent by the appropriate relying party. Any given interaction
will be associated with one federation at the policy level. The will be associated with one federation at the policy level. The
legal or business relationship defines what statements the identity legal or business relationship defines what statements the identity
provider is trusted to make and how these statements are interpreted provider is trusted to make and how these statements are interpreted
skipping to change at page 19, line 6 skipping to change at page 18, line 6
about the subject by the identity provider, statements made about the about the subject by the identity provider, statements made about the
relying party and other information are transported as attributes. relying party and other information are transported as attributes.
One demand that the AAA substrate makes of the upper layers is that One demand that the AAA substrate makes of the upper layers is that
they must properly identify the end points of the communication. It they must properly identify the end points of the communication. It
must be possible for the AAA client at the RP to determine where to must be possible for the AAA client at the RP to determine where to
send each RADIUS or Diameter message. Without this requirement, it send each RADIUS or Diameter message. Without this requirement, it
would be the RP's responsibility to determine the identity of the would be the RP's responsibility to determine the identity of the
client on its own, without the assistance of an IdP. This client on its own, without the assistance of an IdP. This
architecture makes use of the Network Access Identifier (NAI), where architecture makes use of the Network Access Identifier (NAI), where
the IdP is indicated by the realm component [RFC4282]. The NAI is the IdP is indicated by the realm component [I-D.ietf-radext-nai].
represented and consumed by the GSS-API layer as GSS_C_NT_USER_NAME The NAI is represented and consumed by the GSS-API layer as
as specified in [RFC2743]. The GSS-API EAP mechanism includes the GSS_C_NT_USER_NAME as specified in [RFC2743]. The GSS-API EAP
NAI in the EAP Response/Identity message. mechanism includes the NAI in the EAP Response/Identity message.
2.1.2. Discovery and Rules Determination 2.1.2. Discovery and Rules Determination
While we are using the AAA protocols to communicate with the IdP, the While we are using the AAA protocols to communicate with the IdP, the
RP may have multiple federation substrates to select from. The RP RP may have multiple federation substrates to select from. The RP
has a number of criteria that it will use in selecting which of the has a number of criteria that it will use in selecting which of the
different federations to use: different federations to use:
o The federation selected must be able to communicate with the IdP. o The federation selected must be able to communicate with the IdP.
o The federation selected must match the business rules and o The federation selected must match the business rules and
technical policies required for the RP security requirements. technical policies required for the RP security requirements.
The RP needs to discover which federation will be used to contact the The RP needs to discover which federation will be used to contact the
IdP. The first selection criteria in discovery is going to be the IdP. The first selection criteria used during discovery is going to
name of the IdP to be contacted. The second selection criteria in be the name of the IdP to be contacted. The second selection
discovery is going to be the set of business rules and technical criteria used during discovery is going to be the set of business
policies governing the relationship; this is called rules rules and technical policies governing the relationship; this is
determination. The RP also needs to establish technical trust in the called rules determination. The RP also needs to establish technical
communications with the IdP. trust in the communications with the IdP.
Rules determination covers a broad range of decisions about the Rules determination covers a broad range of decisions about the
exchange. One of these is whether the given RP is permitted to talk exchange. One of these is whether the given RP is permitted to talk
to the IdP using a given federation at all, so rules determination to the IdP using a given federation at all, so rules determination
encompasses the basic authorization decision. Other factors are encompasses the basic authorization decision. Other factors are
included, such as what policies govern release of information about included, such as what policies govern release of information about
the principal to the RP and what policies govern the RP's use of this the client to the RP and what policies govern the RP's use of this
information. While rules determination is ultimately a business information. While rules determination is ultimately a business
function, it has significant impact on the technical exchanges. The function, it has significant impact on the technical exchanges. The
protocols need to communicate the result of authorization. When protocols need to communicate the result of authorization. When
multiple sets of rules are possible, the protocol must disambiguate multiple sets of rules are possible, the protocol must disambiguate
which set of rules are in play. Some rules have technical which set of rules are in play. Some rules have technical
enforcement mechanisms; for example in some federations enforcement mechanisms; for example in some federations
intermediaries validate information that is being communicated within intermediaries validate information that is being communicated within
the federation. the federation.
At the time of writing no protocol mechanism has been specified to At the time of writing no protocol mechanism has been specified to
allow a AAA client to determine whether a AAA proxy will indeed be allow a AAA client to determine whether a AAA proxy will indeed be
able to route AAA requests to a specific IdP. The AAA routing is able to route AAA requests to a specific IdP. The AAA routing is
impacted by business rules and technical policies that may be quite impacted by business rules and technical policies that may be quite
complex and atpresent time, the route selection is based on manual complex and at the present time, the route selection is based on
configuration. manual configuration.
2.1.3. Routing and Technical Trust 2.1.3. Routing and Technical Trust
Several approaches to having messages routed through the federation Several approaches to having messages routed through the federation
substrate are possible. These routing methods can most easily be substrate are possible. These routing methods can most easily be
classified based on the mechanism for technical trust that is used. classified based on the mechanism for technical trust that is used.
The choice of technical trust mechanism constrains how rules The choice of technical trust mechanism constrains how rules
determination is implemented. Regardless of what deployment strategy determination is implemented. Regardless of what deployment strategy
is chosen, it is important that the technical trust mechanism be able is chosen, it is important that the technical trust mechanism be able
to validate the names of both parties to the exchange. The trust to validate theg identities of both parties to the exchange. The
mechanism must to ensure that the entity acting as IdP for a given trust mechanism must to ensure that the entity acting as IdP for a
NAI is permitted to be the IdP for that realm, and that any service given NAI is permitted to be the IdP for that realm, and that any
name claimed by the RP is permitted to be claimed by that entity. service name claimed by the RP is permitted to be claimed by that
Here are the categories of technical trust determination: entity. Here are the categories of technical trust determination:
AAA Proxy: AAA Proxy:
The simplest model is that an RP supports a request directly to an The simplest model is that an RP is an AAA client and can send the
AAA proxy. The hop-by-hop integrity protection of the AAA fabric request directly to an AAA proxy. The hop-by-hop integrity
provides technical trust. An RP can submit a request directly to protection of the AAA fabric provides technical trust. An RP can
a federation. Alternatively, a federation disambiguation fabric submit a request directly to a federation. Alternatively, a
can be used. Such a fabric takes information about what federation disambiguation fabric can be used. Such a fabric takes
federations the RP is part of and what federations the IdP is part information about what federations the RP is part of and what
of and routes a message to the appropriate federation. The federations the IdP is part of and routes a message to the
routing of messages across the fabric plus attributes added to appropriate federation. The routing of messages across the fabric
requests and responses provides rules determination. For example, plus attributes added to requests and responses provides rules
when a disambiguation fabric routes a message to a given determination. For example, when a disambiguation fabric routes a
federation, that federation's rules are chosen. Name validation message to a given federation, that federation's rules are chosen.
is enforced as messages travel across the fabric. The entities Name validation is enforced as messages travel across the fabric.
near the RP confirm its identity and validate names it claims. The entities near the RP confirm its identity and validate names
The fabric routes the message towards the appropriate IdP, it claims. The fabric routes the message towards the appropriate
validating the IdP's name in the process. The routing can be IdP, validating the IdP's name in the process. The routing can be
statically configured. Alternatively a routing protocol could be statically configured. Alternatively a routing protocol could be
developed to exchange reachability information about given IdPs developed to exchange reachability information about given a IdP
and to apply policy across the AAA fabric. Such a routing and to apply policy across the AAA fabric. Such a routing
protocol could flood naming constraints to the appropriate points protocol could flood naming constraints to the appropriate points
in the fabric. in the fabric.
Trust Broker: Trust Broker:
Instead of routing messages through AAA proxies, some trust broker Instead of routing messages through AAA proxies, some trust broker
could establish keys between entities near the RP and entities could establish keys between entities near the RP and entities
near the IdP. The advantage of this approach is efficiency of near the IdP. The advantage of this approach is efficiency of
message handling. Fewer entities are needed to be involved for message handling. Fewer entities are needed to be involved for
each message. Security may be improved by sending individual each message. Security may be improved by sending individual
messages over fewer hops. Rules determination involves decisions messages over fewer hops. Rules determination involves decisions
made by trust brokers about what keys to grant. Also, associated made by trust brokers about what keys to grant. Also, associated
with each credential is context about rules and about other with each credential is context about rules and about other
aspects of technical trust including names that may be claimed. A aspects of technical trust including names that may be claimed. A
routing protocol similar to the one for AAA proxies is likely to routing protocol similar to the one for AAA proxies is likely to
skipping to change at page 21, line 40 skipping to change at page 21, line 5
provide a traditional AAA proxy interface even if they also provide provide a traditional AAA proxy interface even if they also provide
another mechanism for increased efficiency or security. another mechanism for increased efficiency or security.
2.1.4. AAA Security 2.1.4. AAA Security
For the AAA framework there are two different places where security For the AAA framework there are two different places where security
needs to be examined. The first is the security that is in place for needs to be examined. The first is the security that is in place for
the links in the AAA backbone being used. The second is the nodes the links in the AAA backbone being used. The second is the nodes
that the backbone consists of. that the backbone consists of.
The default link security for RADIUS is showing it's age as it uses The default link security for RADIUS is showing its age as it uses
MD5 and a shared secret to both obfuscate passwords and to provide MD5 and a shared secret to both obfuscate passwords and to provide
integrity on the RADIUS messages. In many environments this is integrity on the RADIUS messages. While some EAP methods have
considered to be insufficient, especially as not all attributes are designed in the ability to protect the client authentication
obfuscated and can thus leak information to a passive eavesdropper. credentials, the MSK returned from the IDP to the RP is protected
The use of RADIUS with TLS [RFC6614] and/or DTLS only by the RADIUS security. In many environments this is considered
[I-D.ietf-radext-dtls] addresses these attacks. The same level of to be insufficient, especially as not all attributes are obfuscated
security is included in the base Diameter specifications. and can thus leak information to a passive eavesdropper. The use of
RADIUS with TLS [RFC6614] and/or DTLS [I-D.ietf-radext-dtls]
TBD - Put in text - Not all nodes can be eliminated - proxy nodes may addresses these attacks. The same level of security is included in
be required Trust router looks for a way to shorten the list of inner the base Diameter specifications.
nodes. Reference DYNAMIC and say that it does or does not help and
why. Talk about Diameter in the same context - does it have the same
set of issues or not?
2.1.5. SAML Assertions 2.1.5. SAML Assertions
For the traditional use of AAA frameworks, network access, the only For the traditional use of AAA frameworks, network access, the only
requirement that was necessary to grant access was an affirmative requirement that was necessary to grant access was an affirmative
response from the IdP. In the ABFAB world, the RP may need to get response from the IdP. In the ABFAB world, the RP may need to get
additional information about the client before granting access. additional information about the client before granting access.
ABFAB therefore has a requirement that it can transport an arbitrary ABFAB therefore has a requirement that it can transport an arbitrary
set of attributes about the client from the IdP to the RP. set of attributes about the client from the IdP to the RP.
Security Assertions Markup Language (SAML) [OASIS.saml-core-2.0-os] Security Assertions Markup Language (SAML) [OASIS.saml-core-2.0-os]
was designed in order to carry an extensible set of attributes about was designed in order to carry an extensible set of attributes about
a subject. Since SAML is extensible in the attribute space, ABFAB a subject. Since SAML is extensible in the attribute space, ABFAB
has no immediate needs to update the core SAML specifications for our has no immediate needs to update the core SAML specifications for our
work. It will be necessary to update IdPs that need to return SAML work. It will be necessary to update IdPs that need to return SAML
assertions to IdPs and for both the IdP and the RP to implement a new assertions to RPs and for both the IdP and the RP to implement a new
SAML profile designed to carry SAML assertions in AAA. The new SAML profile designed to carry SAML assertions in AAA. The new
profile can be found in RFCXXXX [I-D.ietf-abfab-aaa-saml]. As SAML profile can be found in RFCXXXX [I-D.ietf-abfab-aaa-saml]. As SAML
statements will frequently be large, RADIUS servers and clients that statements will frequently be large, RADIUS servers and clients that
deal with SAML statements will need to implement RFC XXXX deal with SAML statements will need to implement RFC XXXX
[I-D.perez-radext-radius-fragmentation] [I-D.perez-radext-radius-fragmentation]
There are several issues that need to be highlighted: There are several issues that need to be highlighted:
o The security of SAML assertions. o The security of SAML assertions.
skipping to change at page 23, line 11 skipping to change at page 22, line 20
Attributes placed in SAML assertions can have different namespaces Attributes placed in SAML assertions can have different namespaces
assigned to the same name. In many, but not all, cases the assigned to the same name. In many, but not all, cases the
federation agreements will determine what attributes can be used in a federation agreements will determine what attributes can be used in a
SAML statement. This means that the RP needs to map from the SAML statement. This means that the RP needs to map from the
federation names, types and semantics into the ones that the policies federation names, types and semantics into the ones that the policies
of the RP are written in. In other cases the federation substrate of the RP are written in. In other cases the federation substrate
may modify the SAML assertions in transit to do the necessary may modify the SAML assertions in transit to do the necessary
namespace, naming and semantic mappings as the assertion crosses the namespace, naming and semantic mappings as the assertion crosses the
different boundaries in the federation. If the proxies are modifying different boundaries in the federation. If the proxies are modifying
the SAML Assertion, then will obviously remove any signatures on the the SAML Assertion, then they will obviously remove any signatures as
SAML assertions as they would no longer validate. In this case the they would no longer validate. In this case the technical trust is
technical trust is the required mechanism for validating the the required mechanism for validating the integrity of the assertion.
integrity of the assertion. Finally, the attributes may still be in Finally, the attributes may still be in the namespace of the
the namespace of the originating IdP. When this occurs the RP will originating IdP. When this occurs the RP will need to get the
need to get the required mapping operations from the federation required mapping operations from the federation agreements and do the
agreements and do the appropriate mappings itself. appropriate mappings itself.
As of this writing, no one has defined a SAML name format that The RADIUS SAML RFC [I-D.ietf-abfab-aaa-saml] has define a new SAML
corresponds to the NAI structure defined by RFC 4282 [RFC4282]. This name format that corresponds to the NAI name form defined by RFC XXXX
means that there is no method to directly place the same NAI used in [I-D.ietf-radext-nai]. This allows for easy name matching in many
RADIUS or Diameter as the subject name of a SAML assertion. It is a cases as the name form in the SAML statement and the name form used
requirement on the EAP server that it validate that the subject of in RADIUS or Diameter will be the same. In addition to the NAI name
the SAML name, if any, is equivalent to the subject identified by the form, the document also defines a pair of implicit name forms
NAI used in the RADIUS or Diameter session. corresponding to the Client and the Client's machine. These implicit
name forms are based on the Identity-Type enumeration defined in TEAP
[I-D.ietf-emu-eap-tunnel-method]. If the name form returned in a
SAML statement is not based on the NAI, then it is a requirement on
the EAP server that it validate that the subject of the SAML
assertion, if any, is equivalent to the subject identified by the NAI
used in the RADIUS or Diameter session.
RADIUS has the ability to deal with multiple SAML queries for those RADIUS has the ability to deal with multiple SAML queries for those
EAP Servers which follow RFC 5080 [RFC5080]. In this case a State EAP Servers which follow RFC 5080 [RFC5080]. In this case a State
attribute will always been returned with the Access-Accept. The EAP attribute will always be returned with the Access-Accept. The EAP
client can then send a new Access-Request with the State attribute client can then send a new Access-Request with the State attribute
and the new SAML request Multiple SAML queries can them be done by and the new SAML Request Multiple SAML queries can then be done by
making a new Access-Request using the State attribute returned in the making a new Access-Request using the State attribute returned in the
last Access-Accept to link together the different RADIUS sessions. last Access-Accept to link together the different RADIUS sessions.
Some RPs need to ensure that specfic criteria are met during the Some RPs need to ensure that specific criteria are met during the
authentication process. This need is met by using Levels of authentication process. This need is met by using Levels of
Assurance. The way a Level of Assurance is communicated to from the Assurance. The way a Level of Assurance is communicated to the RP
RP to the EAP server is by the use of a SAML Authentication Request from the EAP server is by the use of a SAML Authentication Request
using the Authentication Profile from RFC XXX using the Authentication Profile from RFC XXX
[I-D.ietf-abfab-aaa-saml] When crossing boundaries between different [I-D.ietf-abfab-aaa-saml] When crossing boundaries between different
federations, either the policy specfied will need to be shared federations, either the policy specified will need to be shared
between the two federations, the policy will need to be mapped by the between the two federations, the policy will need to be mapped by the
proxy server on the boundary or the proxy server on the boundary will proxy server on the boundary or the proxy server on the boundary will
need to supply infomration the EAP server so that it can do the need to supply information the EAP server so that it can do the
required mapping. If this mapping is not done, then the EAP server required mapping. If this mapping is not done, then the EAP server
will not be able to enforce the desired Level of Assurance as it will will not be able to enforce the desired Level of Assurance as it will
not understand the policy requirements. not understand the policy requirements.
2.2. Client To Identity Provider 2.2. Client To Identity Provider
Looking at the communications between the client and the IdP, the Looking at the communications between the client and the IdP, the
following items need to be dealt with: following items need to be dealt with:
o The client and the IdP need to mutually authenticate each other. o The client and the IdP need to mutually authenticate each other.
skipping to change at page 24, line 30 skipping to change at page 23, line 41
framework with that provided by the client. framework with that provided by the client.
2.2.1. Extensible Authentication Protocol (EAP) 2.2.1. Extensible Authentication Protocol (EAP)
Traditional web federation does not describe how a subject interacts Traditional web federation does not describe how a subject interacts
with an identity provider for authentication. As a result, this with an identity provider for authentication. As a result, this
communication is not standardized. There are several disadvantages communication is not standardized. There are several disadvantages
to this approach. Since the communication is not standardized, it is to this approach. Since the communication is not standardized, it is
difficult for machines to correctly enter their credentials with difficult for machines to correctly enter their credentials with
different authentications, where Individuals can correctly identify different authentications, where Individuals can correctly identify
the entyr mechanism on the fly. The use of browsers for the entire mechanism on the fly. The use of browsers for
authentication restricts the deployment of more secure forms of authentication restricts the deployment of more secure forms of
authentication beyond plaintext username and password known by the authentication beyond plaintext username and password known by the
server. In a number of cases the authentication interface may be server. In a number of cases the authentication interface may be
presented before the subject has adequately validated they are presented before the subject has adequately validated they are
talking to the intended server. By giving control of the talking to the intended server. By giving control of the
authentication interface to a potential attacker, then the security authentication interface to a potential attacker, the security of the
of the system may be reduced and phishing opportunities introduced. system may be reduced and phishing opportunities introduced.
As a result, it is desirable to choose some standardized approach for As a result, it is desirable to choose some standardized approach for
communication between the subject's end-host and the identity communication between the subject's end-host and the identity
provider. There are a number of requirements this approach must provider. There are a number of requirements this approach must
meet. meet.
Experience has taught us one key security and scalability Experience has taught us one key security and scalability
requirement: it is important that the relying party not get requirement: it is important that the relying party not get
possession of the long-term secret of the client. Aside from a possession of the long-term secret of the client. Aside from a
valuable secret being exposed, a synchronization problem can develop valuable secret being exposed, a synchronization problem can develop
when the client changes keys with the IdP. when the client changes keys with the IdP.
Since there is no single authentication mechanism that will be used Since there is no single authentication mechanism that will be used
everywhere there is another associated requirement: The everywhere there is another associated requirement: The
authentication framework must allow for the flexible integration of authentication framework must allow for the flexible integration of
authentication mechanisms. For instance, some IdPs require hardware authentication mechanisms. For instance, some IdPs require hardware
tokens while others use passwords. A service provider wants to tokens while others use passwords. A service provider wants to
provide support for both authentication methods, and other methods provide support for both authentication methods, and other methods
from IdPs not yet seen. from IdPs not yet seen.
Fortunately, these requirements can be met by utilizing standardized These requirements can be met by utilizing standardized and
and successfully deployed technology, namely by the Extensible successfully deployed technology, namely by the Extensible
Authentication Protocol (EAP) framework [RFC3748]. Figure 2 Authentication Protocol (EAP) framework [RFC3748]. Figure 2
illustrates the integration graphically. illustrates the integration graphically.
EAP is an end-to-end framework; it provides for two-way communication EAP is an end-to-end framework; it provides for two-way communication
between a peer (i.e,service client or principal) through the between a peer (i.e. client or individual) through the authenticator
authenticator (i.e., service provider) to the back-end (i.e., (i.e., relying party) to the back-end (i.e., identity provider).
identity provider). Conveniently, this is precisely the Conveniently, this is precisely the communication path that is needed
communication path that is needed for federated identity. Although for federated identity. Although EAP support is already integrated
EAP support is already integrated in AAA systems (see [RFC3579] and in AAA systems (see [RFC3579] and [RFC4072]) several challenges
[RFC4072]) several challenges remain: remain:
o The first is how to carry EAP payloads from the end host to the o The first is how to carry EAP payloads from the end host to the
relying party. relying party.
o Another is to verify statements the relying party has made to the o Another is to verify statements the relying party has made to the
subject, confirm these statements are consistent with statements subject, confirm these statements are consistent with statements
made to the identity provider and confirm all the above are made to the identity provider and confirm all the above are
consistent with the federation and any federation-specific policy consistent with the federation and any federation-specific policy
or configuration. or configuration.
skipping to change at page 27, line 35 skipping to change at page 27, line 17
the application is well defined. Also, the set of assumptions the the application is well defined. Also, the set of assumptions the
application is permitted to make is generally well defined. As a application is permitted to make is generally well defined. As a
result, an application protocol that supports GSS-API or SASL is very result, an application protocol that supports GSS-API or SASL is very
likely to be usable with a new approach to authentication including likely to be usable with a new approach to authentication including
this one with no required modifications. In some cases, support for this one with no required modifications. In some cases, support for
a new authentication mechanism has been added using plugin interfaces a new authentication mechanism has been added using plugin interfaces
to applications without the application being modified at all. Even to applications without the application being modified at all. Even
when modifications are required, they can often be limited to when modifications are required, they can often be limited to
supporting a new naming and authorization model. For example, this supporting a new naming and authorization model. For example, this
work focuses on privacy; an application that assumes it will always work focuses on privacy; an application that assumes it will always
obtain an identifier for the principal will need to be modified to obtain an identifier for the client will need to be modified to
support anonymity, unlinkability or pseudonymity. support anonymity, unlinkability or pseudonymity.
So, we use GSS-API and SASL because a number of the application So, we use GSS-API and SASL because a number of the application
protocols we wish to federate support these strategies for security protocols we wish to federate support these strategies for security
integration. What does this mean from a protocol standpoint and how integration. What does this mean from a protocol standpoint and how
does this relate to other layers? This means we need to design a does this relate to other layers? This means we need to design a
concrete GSS-API mechanism. We have chosen to use a GSS-API concrete GSS-API mechanism. We have chosen to use a GSS-API
mechanism that encapsulates EAP authentication. So, GSS-API (and mechanism that encapsulates EAP authentication. So, GSS-API (and
SASL) encapsulate EAP between the end-host and the service. The AAA SASL) encapsulate EAP between the end-host and the service. The AAA
framework encapsulates EAP between the relying party and the identity framework encapsulates EAP between the relying party and the identity
provider. The GSS-API mechanism includes rules about how principals provider. The GSS-API mechanism includes rules about how initiators
and services are named as well as per-message security and other and services are named as well as per-message security and other
facilities required by the applications we wish to support. facilities required by the applications we wish to support.
2.3.2. Protocol Transport 2.3.2. Protocol Transport
The transport of data between the client and the relying party is not The transport of data between the client and the relying party is not
provided by GSS-API. GSS-API creates and consumes messages, but it provided by GSS-API. GSS-API creates and consumes messages, but it
does not provide the transport itself, instead the protocol using does not provide the transport itself, instead the protocol using
GSS-API needs to provide the transport. In many cases HTTP or HTTPS GSS-API needs to provide the transport. In many cases HTTP or HTTPS
is used for this transport, but other transports are perfectly is used for this transport, but other transports are perfectly
skipping to change at page 30, line 33 skipping to change at page 29, line 45
GSS-API acceptor, providing anonymity between the initiator and the GSS-API acceptor, providing anonymity between the initiator and the
acceptor. At this time, whether the identity is disclosed is acceptor. At this time, whether the identity is disclosed is
determined by EAP server policy rather than by an indication from the determined by EAP server policy rather than by an indication from the
initiator. Also, initiators are unlikely to be able to determine initiator. Also, initiators are unlikely to be able to determine
whether anonymous communication will be provided. For this reason, whether anonymous communication will be provided. For this reason,
initiators are unlikely to set the anonymous return flag from initiators are unlikely to set the anonymous return flag from
GSS_Init_Sec_context. GSS_Init_Sec_context.
3.2. GSS-API Channel Binding 3.2. GSS-API Channel Binding
[RFC5056] defines a concept of channel binding to which is used [RFC5056] defines a concept of channel binding which is used prevent
prevent man-in-the-middle attacks. The channel binding works by man-in-the-middle attacks. The channel binding works by taking a
taking a cryptographic value from the transport security and checks cryptographic value from the transport security and checks that both
that both sides of the GSS-API conversation know this value. sides of the GSS-API conversation know this value. Transport Layer
Transport Layer Security (TLS) is the most common transport security Security (TLS) is the most common transport security layer used for
layer used for this purpose. this purpose.
It needs to be stressed that RFC 5056 channel binding (also called It needs to be stressed that RFC 5056 channel binding (also called
GSS-API channel binding when GSS-API is involved) is not the same GSS-API channel binding when GSS-API is involved) is not the same
thing as EAP channel binding. GSS-API channel binding is used for thing as EAP channel binding. GSS-API channel binding is used for
detecting Man-In-The-Middle attacks. EAP channel binding is used for detecting Man-In-The-Middle attacks. EAP channel binding is used for
mututal authentication and acceptor naming checks. Details are mutual authentication and acceptor naming checks. Details are
discussed in the mechanisms specification [I-D.ietf-abfab-gss-eap]. discussed in the mechanisms specification [I-D.ietf-abfab-gss-eap].
A fuller discription of the differences between the factilities cn be A fuller description of the differences between the facilities can be
found in RFC 5056 [RFC5056]. found in RFC 5056 [RFC5056].
The use of TLS can provide both encryption and integrity on the The use of TLS can provide both encryption and integrity on the
channel. It is common to provide SASL and GSS-API with these other channel. It is common to provide SASL and GSS-API with these other
security services. security services.
On of the benifits that the use of TLS provides, is that client has One of the benefits that the use of TLS provides, is that client has
the ability to validate the name of the server. However this the ability to validate the name of the server. However this
validation is predicated on on a couple of things. The TLS sessions validation is predicated on a couple of things. The TLS sessions
needs to be using certificates and not be an anonymous session. The needs to be using certificates and not be an anonymous session. The
client and the TLS need to share a common trust point for the client and the TLS need to share a common trust point for the
certificate used in validating the server. TLS provides its own certificate used in validating the server. TLS provides its own
server authentication. However there are a variety of situations server authentication. However there are a variety of situations
where this authentication is not checked for policy or usability where this authentication is not checked for policy or usability
reasons. Even when it is checked, if the trust infrastructure behind reasons. Even when it is checked, if the trust infrastructure behind
the TLS authentication is different from the trust infrastructure the TLS authentication is different from the trust infrastructure
behind the GSS-API mutual authentication then confirming the end- behind the GSS-API mutual authentication then confirming the end-
points using both trust infrastructures is likely to enhance points using both trust infrastructures is likely to enhance
security. If the endpoints of the GSS-API authentication are security. If the endpoints of the GSS-API authentication are
skipping to change at page 31, line 46 skipping to change at page 31, line 10
applications that use GSS-API (including SSH, NFS, IMAP, LDAP and applications that use GSS-API (including SSH, NFS, IMAP, LDAP and
XMPP) have chosen to use a more restricted naming convention based on XMPP) have chosen to use a more restricted naming convention based on
the host name. The GSS-EAP mechanism needs to support host-based the host name. The GSS-EAP mechanism needs to support host-based
service names in order to work with existing IETF protocols. service names in order to work with existing IETF protocols.
The use of host-based service names leads to a challenging trust The use of host-based service names leads to a challenging trust
delegation problem. Who is allowed to decide whether a particular delegation problem. Who is allowed to decide whether a particular
host name maps to a specific entity. Possible solutions to this host name maps to a specific entity. Possible solutions to this
problem have been looked at. problem have been looked at.
The public-key infrastructure (PKI) used by the web has chosen to o The public-key infrastructure (PKI) used by the web has chosen to
have a number of trust anchors (root certificate authorities) each have a number of trust anchors (root certificate authorities) each
of which can map any host name to a public key. of which can map any host name to a public key.
A number of GSS-API mechanisms, such as Kerberos [RFC1964], have o A number of GSS-API mechanisms, such as Kerberos [RFC1964], have
split the problem into two parts. A new concept called a realm is split the problem into two parts. A new concept called a realm is
introduced, the realm is responsible for host mapping within that introduced, the realm is responsible for host mapping within that
realm. The mechanism then decides what realm is responsible for a realm. The mechanism then decides what realm is responsible for a
given name. This is the approach adopted by ABFAB. given name. This is the approach adopted by ABFAB.
GSS-EAP defines a host naming convention that takes into account the GSS-EAP defines a host naming convention that takes into account the
host name, the realm, the service and the service parameters. An host name, the realm, the service and the service parameters. An
example of GSS-API service name is "xmpp/foo@example.com". This example of GSS-API service name is "xmpp/foo@example.com". This
identifies the XMPP service on the host foo in the realm example.com. identifies the XMPP service on the host foo in the realm example.com.
Any of the components, except for the service name may be omitted Any of the components, except for the service name may be omitted
skipping to change at page 32, line 40 skipping to change at page 32, line 4
validated will depend on both what information was provided by the validated will depend on both what information was provided by the
client, and what information is considered significant. If the client, and what information is considered significant. If the
client only cares about getting a specific service, then the host and client only cares about getting a specific service, then the host and
realm that provides the service does not need to be validated. realm that provides the service does not need to be validated.
In many cases applications may retrieve information about providers In many cases applications may retrieve information about providers
of services from DNS. When Service Records (SRV) and Naming of services from DNS. When Service Records (SRV) and Naming
Authority Pointer (NAPTR) records are used to help find a host that Authority Pointer (NAPTR) records are used to help find a host that
provides a service, the security requirements on the referrals is provides a service, the security requirements on the referrals is
going to interact with the information used in the service name. If going to interact with the information used in the service name. If
the a host name is returned from the DNS referrals, and the host name a host name is returned from the DNS referrals, and the host name is
is to be validated by GS-EAP, then it makes sense that the referrals to be validated by GS-EAP, then it makes sense that the referrals
themselves should be secure. On the other hand, if the host name themselves should be secure. On the other hand, if the host name
returned is not validated, i.e. only the service is passed in, then returned is not validated, i.e. only the service is passed in, then
it is less important that the host name be obtained in a secure it is less important that the host name be obtained in a secure
manner. manner.
Another issue that needs to be addressed for host-based service names Another issue that needs to be addressed for host-based service names
is that they do not work ideally when different instances of a is that they do not work ideally when different instances of a
service are running on different ports. If the services are service are running on different ports. If the services are
equivalent, then it does not matter. However if there are equivalent, then it does not matter. However if there are
substantial differences in the quality of the service that substantial differences in the quality of the service that
information needs to be part of the validation process. If one has information needs to be part of the validation process. If one has
just a host name and not a port in the information being validated, just a host name and not a port in the information being validated,
skipping to change at page 34, line 24 skipping to change at page 33, line 17
communications and what exposure they have to identity information. communications and what exposure they have to identity information.
In discussing these privacy considerations in this section, we use In discussing these privacy considerations in this section, we use
terminology and ideas from [I-D.iab-privacy-considerations]. terminology and ideas from [I-D.iab-privacy-considerations].
Note that the ABFAB architecture uses at its core several existing Note that the ABFAB architecture uses at its core several existing
technologies and protocols; detailed privacy discussion around these technologies and protocols; detailed privacy discussion around these
is not examined. This section instead focuses on privacy is not examined. This section instead focuses on privacy
considerations specifically related to overall architecture and usage considerations specifically related to overall architecture and usage
of ABFAB. of ABFAB.
+--------+ +---------------+ +--------------+
| Client | <---> | RP | <---> | AAA Client |
+--------+ +---------------+ +--------------+
^
|
v
+---------------+ +--------------+
| SAML Server | | AAA Proxy(s) |
+---------------+ +--------------+
^ ^
| |
v v
+------------+ +---------------+ +--------------+
| EAP Server | <---> | IdP | <---> | AAA Server |
+------------+ +---------------+ +--------------+
Figure 3: Entities and Data Flow
4.1. Entities and their roles 4.1. Entities and their roles
In an ABFAB environment, there are four distinct types of entities Categorizing the ABFAB entities shown in the Figure 3 according to
involved in communication paths. Figure 2 shows the ABFAB the taxonomy of terms from [I-D.iab-privacy-considerations] the
architecture with these entity types. We have: entities shown in Figure 3 is somewhat complicated as during the
various phases of ABFAB communications the roles of each entity
changes. The three main phases of relevance are the Client to RP
communication phase, the Client to IdP (via the Federation Substrate)
phase, and the IdP to RP (via the Federation Substrate) phase.
o The client application: usually a piece of software running on a In the Client to RP communication phase, we have:
user's device. This communicates with a service (the Relying
Party) that the user wishes to interact with.
o The Identity Provider: The home AAA server for the user. Initiator: Client.
o The Relying Party: The service the user wishes to connect to. Observers: Client, RP.
o The federation substrate: A set of entities through which messages Recipient: RP.
pass on their path between RP and AAA server.
As described in detail earlier in this document, when a user wishes In the Client to IdP (via the Federation Substrate) communication
to access a Relying Party, a secure tunnel is set up between their phase, we have:
client application and their Identity Provider (via the Relying Party
and the federation substrate) through which credentials are
exchanged. An indication of success or failure, alongside a set of
AAA attributes about a principal is then passed from the Identity
Provider to the Relying Party (usually in the form of a SAML
assertion).
4.2. Relationship between user and entities Initiator: Client.
o Between User and Identity Provider - the identity Provider is an Observers: Client, RP, AAA Client, AAA Proxy(s), AAA Server, IdP.
entity the user will have a direct relationship with, created when
the organisation that operates the entity provisioned and
exchanged the user's credentials. Privacy and data protection
guarantees may form a part of this relationship.
o Between User and Relying Party - the Relying Party is an entity Recipient: IdP
the user may or may not have a direct relationship with, depending
on the service in question. Some services may only be offered to
those users where such a direct relationship exists (for
particularly sensitive services, for example), while some may not
require this and would instead be satisfied with basic federation
trust guarantees between themselves and the Identity Provider).
This may well include the option that the user stays anonymous
with respect to the Relying Party (though obviously not to the
Identity Provider). If attempting to preserve privacy through the
mitigation of data minimisation, then the only attribute
information about individuals exposed to the Relying Party should
be that which is strictly necessary for the operation of the
service.
o Between User and Federation substrate - the user is highly likely In the IdP to Relying party (via the Federation Substrate)
to have no knowledge of, or relationship with, any entities communication phase, we have:
involved with the federation substrate (not that the Identity
Provider and/or Relying Party may, however). Knowledge of
attribute information about individuals for these entities is not
necessary, and thus such information should be protected in such a
way as to prevent access to this information from being possible.
4.3. Data and Identifiers in use Initiator: IdP.
Observers: IdP, AAA Server, AAA Proxy(s), AAA Client, RP.
Recipient: RP
Eavesdroppers and Attackers can reside on any communication link
between entities in Figure 3.
The Federation Substrate consists of all of the AAA entities. In
some cases the AAA Proxies entities may not exist as the AAA Client
can talk directly to the AAA Server. Specifications such as the
Trust Router Protocol and RADIUS dynamic discovery
[I-D.ietf-radext-dynamic-discovery] can be used to shorten the path
between the AAA client and the AAA server (and thus stop these AAA
Proxies from being Observers), however even in these circumstances
there may be AAA Proxies in the path.
In Figure 3 the IdP has been divided into multiple logical pieces, in
actual implementations these pieces will frequently be tightly
coupled. The links between these pieces provide the greatest
opportunity for attackers and eavesdroppers to acquire information,
however, as they are all under the control of a single entity they
are also the easiest to have tightly secured.
4.2. Privacy Aspects of ABFAB Communication Flows
In the ABFAB architecture, there are a few different types of data In the ABFAB architecture, there are a few different types of data
and identifiers in use. and identifiers in use. The best way to understand them, and the
potential privacy impacts of them, is to look at each phase of
communication in ABFAB.
4.3.1. NAI 4.2.1. Client to RP
In order for the Relying Party to be able to route messages to enable The flow of data between the client and the RP is divided into two
an EAP transaction to occur between client application and the parts. The first part consists of all of the data exchanged as part
correct identity Provider, it is necessary for the client application of the ABFAB authentication process. The second part consists of all
to provide enough information to the Relying Party to enable the of the data exchanged after the authentication process has been
identification of the correct Identity Provider. This takes the form finished.
of an Network Access Identifier (NAI) (as specified in [RFC4282]).
Note that an NAI can have inner and outer forms in a AAA
architecture.
o The outer part of NAI is exposed to the Relying Party; this can During the initial communications phase, the client sends an NAI (see
simply contain realm information. Doing so (i.e. not including [I-D.ietf-radext-nai]) to the RP. Many EAP methods (but not all)
user identification details such as a username) minimises the data allow for the client to disclose an NAI to the in a form that
given to the Relying Part to that which is purely necessary to includes only a realm during this communications phase. This is the
support the necessary routing decision. minimum amount of identity information necessary for ABFAB to work -
it indicates an IdP that the principal has a relationship with. EAP
methods that do not allow this will necessarily also reveal an
identifier for the principal in the IdP realm (e.g. a username).
o The inner part of NAI is sent through the secure tunnel as The data exchanged after the authentication process can have privacy
established by the EAP protocol; this form of the NAI will contain and authentication using the GSS-API services. If the overall
credentials for the user suitable for authenticating them application protocol allows for the process of re-authentication,
successfully (e.g. a username and password). Since the entire then the same privacy impliciations as discussed in previous
purpose of the secure tunnel is to protect communications between paragraph apply.
client application (EAP client) and Identity Provider (EAP
server), then it is considered secure from eavesdroppers or
malicious intermediaries and no further privacy discussion is
necessary.
4.3.2. Identity Information 4.2.2. Client to IdP (via Federation Substrate)
As a part of the ABFAB process, after a successful authentication has This phase sees a secure TLS tunnel initiated between the Client and
occurred between client application and Identity Provider, an the IdP via the RP and federation substrate. The process is
indication of this success is sent to the Relying Party. Alongside initiated by the RP using the realm information given to it by the
this message, information about the user may be returned through AAA client. Once set up, the tunnel is used to send credentials to IdP
attributes, usually in form of a SAML assertion. This information is to authenticate.
arbitrary and may include either only attributes that prevent an
individual from being identified by the Relying Party (thus enabling
anonymous or pseudonymous access) or attributes that contain
personally identifiable information.
Depending on the method used, this information carried through AAA Various operational information is transported between RP and IdP,
attributes may or may not be accessible to intermediaries involved in over the AAA infrastructure, for example using RADIUS headers. As no
communications - e.g. in the case of RADIUS and unencrypted SAML, end-to-end security is provided by AAA, all AAA entities on the path
these headers are plain text and could be seen by any observer, between the RP and IdP have the ability to eavesdrop on this
whereas if using RADSEC or encrypted SAML, these headers are information unless additional security measures are taken (such as
protected from observers. Obviously, where the protection of the the use of TLS for RADIUS [I-D.ietf-radext-dtls]). Some of this
privacy of an individual is required then this information needs to information may form identifiers or explicit identity information:
be protected by some appropriate means.
4.3.3. Accounting Information o The Relying Party knows the IP address of the Client. It is
possible that the Relying Party could choose to expose this IP
address by including it in a RADIUS header such as Calling Station
ID. This is a privacy consideration to take into account of the
application protocol.
o The EAP MSK is transported between the IdP and the RP over the AAA
infrastructure, for example through RADIUS headers. This is a
particularly important privacy consideration, as any AAA Proxy
that has access to the EAP MSK is able to decrypt and eavesdrop on
any traffic encrypted using that EAP MSK (i.e. all communications
between the Client and IdP).
o Related to the above, the AAA server has access to the material
necessary to derive the session key, thus the AAA server can
observe any traffic encrypted between the Client and RP. This
"feature" was" chosen as a simplification and to make performance
faster; if it was decided that this trade-off was not desireable
for privacy and security reasons, then extensions to ABFAB that
make use of techniques such as Diffie-Helman key exchange would
mitigate against this.
The choice of EAP method used has other potential privacy
implications. For example, if the EAP method in use does not support
trust anchors to enable mutual authentication, then there are no
guarantees that the IdP is who it claims to be, and thus the full NAI
including a username and a realm might be sent to any entity
masquerading as a particular IdP.
Note that ABFAB has not specified any AAA accounting requirements.
Implementations that use the accounting portion of AAA should
consider privacy appropriately when designing this aspect.
4.2.3. IdP to RP (via Federation Substrate)
In this phase, the IdP communicates with the RP informing it as to
the success or failure of authentication of the user, and optionally,
the sending of identity information about the principal.
As in the previous flow (Client to IdP), various operation
information is transported between IdP and RP over the AAA
infrastructure, and the same privacy considerations apply. However,
in this flow, explicit identity information about the authenticated
principal can be sent from the IdP to the RP. This information can
be sent through RADIUS headers, or using SAML
[I-D.ietf-abfab-aaa-saml]. This can include protocol specific
identitifiers, such as SAML NameIDs, as well as arbitrary attribute
information about the principal. What information will be released
is controlled by policy on the Identity Provider. As before, when
sending this through RADIUS headers, all AAA entities on the path
between the RP and IdP have the ability to eavesdrop unless
additional security measures are taken (such as the use of TLS for
RADIUS [I-D.ietf-radext-dtls]). When sending this using SAML, as
specified in [I-D.ietf-abfab-aaa-saml], confidentiality of the
information should however be guaranteed as [I-D.ietf-abfab-aaa-saml]
requires the use of TLS for RADIUS.
4.3. Relationship between User and Entities
o Between User and IdP - the IdP is an entity the user will have a
direct relationship with, created when the organisation that
operates the entity provisioned and exchanged the user's
credentials. Privacy and data protection guarantees may form a
part of this relationship.
o Between User and RP - the RP is an entity the user may or may not
have a direct relationship with, depending on the service in
question. Some services may only be offered to those users where
such a direct relationship exists (for particularly sensitive
services, for example), while some may not require this and would
instead be satisfied with basic federation trust guarantees
between themselves and the IdP). This may well include the option
that the user stays anonymous with respect to the RP (though
obviously never to the IdP). If attempting to preserve privacy
through the mitigation of data minimisation, then the only
attribute information about individuals exposed to the RP should
be that which is strictly necessary for the operation of the
service.
o Between User and Federation substrate - the user is highly likely
to have no knowledge of, or relationship with, any entities
involved with the federation substrate (not that the IdP and/or RP
may, however). Knowledge of attribute information about
individuals for these entities is not necessary, and thus such
information should be protected in such a way as to prevent access
to this information from being possible.
4.4. Accounting Information
Alongside the core authentication and authorization that occurs in Alongside the core authentication and authorization that occurs in
AAA communications, accounting information about resource consumption AAA communications, accounting information about resource consumption
may be delivered as part of the accounting exchange during the may be delivered as part of the accounting exchange during the
lifetime of the granted application session. lifetime of the granted application session.
4.3.4. Collection and retention of data and identifiers 4.5. Collection and retention of data and identifiers
In cases where Relying Parties do not require to identify a In cases where Relying Parties do not require to identify a
particular individual when an individual wishes to make use of their particular individual when an individual wishes to make use of their
service, the ABFAB architecture enable anonymous or pseudonymous service, the ABFAB architecture enable anonymous or pseudonymous
access. Thus data and identifiers other than pseudonyms and access. Thus data and identifiers other than pseudonyms and
unlinkable attribute information need not be stored and retained. unlinkable attribute information need not be stored and retained.
However, in cases where Relying Parties require the ability to However, in cases where Relying Parties require the ability to
identify a particular individual (e.g. so they can link this identity identify a particular individual (e.g. so they can link this
information to a particular account in their service, or where identity information to a particular account in their service, or
identity information is required for audit purposes), the service where identity information is required for audit purposes), the
will need to collect and store such information, and to retain it for service will need to collect and store such information, and to
as long as they require. Deprovisioning of such accounts and retain it for as long as they require. Deprovisioning of such
information is out of scope for ABFAB, but obviously for privacy accounts and information is out of scope for ABFAB, but obviously for
protection any identifiers collected should be deleted when they are privacy protection any identifiers collected should be deleted when
no longer needed. they are no longer needed.
4.4. User Participation 4.6. User Participation
In the ABFAB architecture, by its very nature users are active In the ABFAB architecture, by its very nature users are active
participants in the sharing of their identifiers as they initiate the participants in the sharing of their identifiers as they initiate the
communications exchange every time they wish to access a server. communications exchange every time they wish to access a server.
They are, however, not involved in control of the set of information They are, however, not involved in control of the set of information
related to them that transmitted from Identity Provider to Relying related to them that transmitted from the IdP to RP for authorisation
Party for authorisation purposes. purposes; rather, this is under the control of policy on the IdP.
Due to the nature of the AAA communication flows, with the current
ABFAB architecture there is no place for a process of gaining user
consent for the information to be released from IdP to RP.
5. Deployment Considerations 5. Deployment Considerations
5.1. EAP Channel Binding 5.1. EAP Channel Binding
Discuss the implications of needing EAP channel binding. Discuss the implications of needing EAP channel binding.
5.2. AAA Proxy Behavior 5.2. AAA Proxy Behavior
Discuss deployment implications of our proxy requirements. Discuss deployment implications of our proxy requirements.
skipping to change at page 39, line 25 skipping to change at page 38, line 49
the final message (i.e., a cryptographic token for the channel). the final message (i.e., a cryptographic token for the channel).
Authentication may be provided by the RP to the client but a Authentication may be provided by the RP to the client but a
deployment without authentication at the TLS layer is possible as deployment without authentication at the TLS layer is possible as
well. In addition, there is a channel between the GSS requestor well. In addition, there is a channel between the GSS requestor
and the GSS acceptor, but the keying material is provided by a and the GSS acceptor, but the keying material is provided by a
"third party" to both entities. The client can derive keying "third party" to both entities. The client can derive keying
material locally, but the RP gets the material from the IdP. In material locally, but the RP gets the material from the IdP. In
the absence of a transport that provides encryption and/or the absence of a transport that provides encryption and/or
integrity, the channel between the client and the RP has no integrity, the channel between the client and the RP has no
ability to have any cryptographic protection until the EAP ability to have any cryptographic protection until the EAP
authentication has been completed and the MSK is transfered from authentication has been completed and the MSK is transferred from
the IdP to the RP. the IdP to the RP.
RP-to-IdP Channel: RP-to-IdP Channel:
The security of this communication channel is mainly provided by The security of this communication channel is mainly provided by
the functionality offered via RADIUS and Diameter. At the time of the functionality offered via RADIUS and Diameter. At the time of
writing there are no end-to-end security mechanisms standardized writing there are no end-to-end security mechanisms standardized
and thereby the architecture has to rely on hop-by-hop security and thereby the architecture has to rely on hop-by-hop security
with trusted AAA entities or, as an alternative but possible with trusted AAA entities or, as an alternative but possible
deployment variant, direct communication between the AAA client to deployment variant, direct communication between the AAA client to
skipping to change at page 40, line 15 skipping to change at page 39, line 41
responsible during this process to determine that the RP that is responsible during this process to determine that the RP that is
communication to the client over the RP-to-IdP channel is the same communication to the client over the RP-to-IdP channel is the same
one talking to the IdP. This is accomplished via the EAP channel one talking to the IdP. This is accomplished via the EAP channel
binding. binding.
Partial list of issues to be addressed in this section: Privacy, Partial list of issues to be addressed in this section: Privacy,
SAML, Trust Anchors, EAP Algorithm Selection, Diameter/RADIUS/AAA SAML, Trust Anchors, EAP Algorithm Selection, Diameter/RADIUS/AAA
Issues, Naming of Entities, Protection of passwords, Channel Binding, Issues, Naming of Entities, Protection of passwords, Channel Binding,
End-point-connections (TLS), Proxy problems End-point-connections (TLS), Proxy problems
When a psuedonym is generated as a unique long term identifier for a When a pseudonym is generated as a unique long term identifier for a
Subject by an IdP, care MUST be taken in the algorithm that it cannot Subject by an IdP, care MUST be taken in the algorithm that it cannot
easily be reverse engineered by the service provider. If it can be easily be reverse engineered by the service provider. If it can be
reversed then the service provider can consult an oracle to determine reversed then the service provider can consult an oracle to determine
if a given unique long term identifier is associated with a different if a given unique long term identifier is associated with a different
known identifier. known identifier.
7. IANA Considerations 7. IANA Considerations
This document does not require actions by IANA. This document does not require actions by IANA.
skipping to change at page 43, line 13 skipping to change at page 40, line 28
the pre-00 draft version. the pre-00 draft version.
9. References 9. References
9.1. Normative References 9.1. Normative References
[RFC2743] Linn, J., "Generic Security Service Application Program [RFC2743] Linn, J., "Generic Security Service Application Program
Interface Version 2, Update 1", RFC 2743, January 2000. Interface Version 2, Update 1", RFC 2743, January 2000.
[RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson, [RFC2865] Rigney, C., Willens, S., Rubens, A., and W. Simpson,
"Remote Authentication Dial In User Service (RADIUS)", "Remote Authentication Dial In User Service (RADIUS)", RFC
RFC 2865, June 2000. 2865, June 2000.
[RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J. [RFC3588] Calhoun, P., Loughney, J., Guttman, E., Zorn, G., and J.
Arkko, "Diameter Base Protocol", RFC 3588, September 2003. Arkko, "Diameter Base Protocol", RFC 3588, September 2003.
[RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
Levkowetz, "Extensible Authentication Protocol (EAP)", Levkowetz, "Extensible Authentication Protocol (EAP)", RFC
RFC 3748, June 2004. 3748, June 2004.
[RFC3579] Aboba, B. and P. Calhoun, "RADIUS (Remote Authentication [RFC3579] Aboba, B. and P. Calhoun, "RADIUS (Remote Authentication
Dial In User Service) Support For Extensible Dial In User Service) Support For Extensible
Authentication Protocol (EAP)", RFC 3579, September 2003. Authentication Protocol (EAP)", RFC 3579, September 2003.
[RFC4072] Eronen, P., Hiller, T., and G. Zorn, "Diameter Extensible [RFC4072] Eronen, P., Hiller, T., and G. Zorn, "Diameter Extensible
Authentication Protocol (EAP) Application", RFC 4072, Authentication Protocol (EAP) Application", RFC 4072,
August 2005. August 2005.
[RFC4282] Aboba, B., Beadles, M., Arkko, J., and P. Eronen, "The
Network Access Identifier", RFC 4282, December 2005.
[I-D.ietf-abfab-gss-eap] [I-D.ietf-abfab-gss-eap]
Hartman, S. and J. Howlett, "A GSS-API Mechanism for the Hartman, S. and J. Howlett, "A GSS-API Mechanism for the
Extensible Authentication Protocol", Extensible Authentication Protocol", draft-ietf-abfab-gss-
draft-ietf-abfab-gss-eap-09 (work in progress), eap-09 (work in progress), August 2012.
August 2012.
[I-D.ietf-abfab-aaa-saml] [I-D.ietf-abfab-aaa-saml]
Howlett, J. and S. Hartman, "A RADIUS Attribute, Binding Howlett, J. and S. Hartman, "A RADIUS Attribute, Binding,
and Profiles for SAML", draft-ietf-abfab-aaa-saml-04 (work Profiles, Name Identifier Format, and Confirmation Methods
in progress), October 2012. for SAML", draft-ietf-abfab-aaa-saml-05 (work in
progress), February 2013.
[I-D.ietf-radext-nai]
DeKok, A., "The Network Access Identifier", draft-ietf-
radext-nai-02 (work in progress), January 2013.
[RFC6677] Hartman, S., Clancy, T., and K. Hoeper, "Channel-Binding [RFC6677] Hartman, S., Clancy, T., and K. Hoeper, "Channel-Binding
Support for Extensible Authentication Protocol (EAP) Support for Extensible Authentication Protocol (EAP)
Methods", RFC 6677, July 2012. Methods", RFC 6677, July 2012.
9.2. Informative References 9.2. Informative References
[RFC2903] de Laat, C., Gross, G., Gommans, L., Vollbrecht, J., and [RFC2903] de Laat, C., Gross, G., Gommans, L., Vollbrecht, J., and
D. Spence, "Generic AAA Architecture", RFC 2903, D. Spence, "Generic AAA Architecture", RFC 2903, August
August 2000. 2000.
[I-D.nir-tls-eap] [I-D.nir-tls-eap]
Nir, Y., Sheffer, Y., Tschofenig, H., and P. Gutmann, "A Nir, Y., Sheffer, Y., Tschofenig, H., and P. Gutmann, "A
Flexible Authentication Framework for the Transport Layer Flexible Authentication Framework for the Transport Layer
Security (TLS) Protocol using the Extensible Security (TLS) Protocol using the Extensible
Authentication Protocol (EAP)", draft-nir-tls-eap-13 (work Authentication Protocol (EAP)", draft-nir-tls-eap-13 (work
in progress), December 2011. in progress), December 2011.
[I-D.ietf-oauth-v2] [I-D.ietf-oauth-v2]
Hardt, D., "The OAuth 2.0 Authorization Framework", Hardt, D., "The OAuth 2.0 Authorization Framework", draft-
draft-ietf-oauth-v2-31 (work in progress), August 2012. ietf-oauth-v2-31 (work in progress), August 2012.
[I-D.iab-privacy-considerations] [I-D.iab-privacy-considerations]
Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., Cooper, A., Tschofenig, H., Aboba, B., Peterson, J.,
Morris, J., Hansen, M., and R. Smith, "Privacy Morris, J., Hansen, M., and R. Smith, "Privacy
Considerations for Internet Protocols", Considerations for Internet Protocols", draft-iab-privacy-
draft-iab-privacy-considerations-03 (work in progress), considerations-03 (work in progress), July 2012.
July 2012.
[I-D.perez-radext-radius-fragmentation] [I-D.perez-radext-radius-fragmentation]
Perez-Mendez, A., Lopez, R., Pereniguez-Garcia, F., Lopez- Perez-Mendez, A., Lopez, R., Pereniguez-Garcia, F., Lopez-
Millan, G., Lopez, D., and A. DeKok, "Support of Millan, G., Lopez, D., and A. DeKok, "Support of
fragmentation of RADIUS packets", fragmentation of RADIUS packets", draft-perez-radext-
draft-perez-radext-radius-fragmentation-05 (work in radius-fragmentation-05 (work in progress), February 2013.
progress), February 2013.
[RFC4017] Stanley, D., Walker, J., and B. Aboba, "Extensible [RFC4017] Stanley, D., Walker, J., and B. Aboba, "Extensible
Authentication Protocol (EAP) Method Requirements for Authentication Protocol (EAP) Method Requirements for
Wireless LANs", RFC 4017, March 2005. Wireless LANs", RFC 4017, March 2005.
[RFC5106] Tschofenig, H., Kroeselberg, D., Pashalidis, A., Ohba, Y., [RFC5106] Tschofenig, H., Kroeselberg, D., Pashalidis, A., Ohba, Y.,
and F. Bersani, "The Extensible Authentication Protocol- and F. Bersani, "The Extensible Authentication Protocol-
Internet Key Exchange Protocol version 2 (EAP-IKEv2) Internet Key Exchange Protocol version 2 (EAP-IKEv2)
Method", RFC 5106, February 2008. Method", RFC 5106, February 2008.
[RFC1964] Linn, J., "The Kerberos Version 5 GSS-API Mechanism", [RFC1964] Linn, J., "The Kerberos Version 5 GSS-API Mechanism", RFC
RFC 1964, June 1996. 1964, June 1996.
[RFC2203] Eisler, M., Chiu, A., and L. Ling, "RPCSEC_GSS Protocol [RFC2203] Eisler, M., Chiu, A., and L. Ling, "RPCSEC_GSS Protocol
Specification", RFC 2203, September 1997. Specification", RFC 2203, September 1997.
[RFC3645] Kwan, S., Garg, P., Gilroy, J., Esibov, L., Westhead, J., [RFC3645] Kwan, S., Garg, P., Gilroy, J., Esibov, L., Westhead, J.,
and R. Hall, "Generic Security Service Algorithm for and R. Hall, "Generic Security Service Algorithm for
Secret Key Transaction Authentication for DNS (GSS-TSIG)", Secret Key Transaction Authentication for DNS (GSS-TSIG)",
RFC 3645, October 2003. RFC 3645, October 2003.
[RFC2138] Rigney, C., Rigney, C., Rubens, A., Simpson, W., and S. [RFC2138] Rigney, C., Rigney, C., Rubens, A.C., Simpson, W.A., and
S. Willens, "Remote Authentication Dial In User Service
Willens, "Remote Authentication Dial In User Service
(RADIUS)", RFC 2138, April 1997. (RADIUS)", RFC 2138, April 1997.
[RFC4462] Hutzelman, J., Salowey, J., Galbraith, J., and V. Welch, [RFC4462] Hutzelman, J., Salowey, J., Galbraith, J., and V. Welch,
"Generic Security Service Application Program Interface "Generic Security Service Application Program Interface
(GSS-API) Authentication and Key Exchange for the Secure (GSS-API) Authentication and Key Exchange for the Secure
Shell (SSH) Protocol", RFC 4462, May 2006. Shell (SSH) Protocol", RFC 4462, May 2006.
[RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and [RFC4422] Melnikov, A. and K. Zeilenga, "Simple Authentication and
Security Layer (SASL)", RFC 4422, June 2006. Security Layer (SASL)", RFC 4422, June 2006.
skipping to change at page 45, line 41 skipping to change at page 43, line 8
[RFC5849] Hammer-Lahav, E., "The OAuth 1.0 Protocol", RFC 5849, [RFC5849] Hammer-Lahav, E., "The OAuth 1.0 Protocol", RFC 5849,
April 2010. April 2010.
[RFC6614] Winter, S., McCauley, M., Venaas, S., and K. Wierenga, [RFC6614] Winter, S., McCauley, M., Venaas, S., and K. Wierenga,
"Transport Layer Security (TLS) Encryption for RADIUS", "Transport Layer Security (TLS) Encryption for RADIUS",
RFC 6614, May 2012. RFC 6614, May 2012.
[OASIS.saml-core-2.0-os] [OASIS.saml-core-2.0-os]
Cantor, S., Kemp, J., Philpott, R., and E. Maler, Cantor, S., Kemp, J., Philpott, R., and E. Maler,
"Assertions and Protocol for the OASIS Security Assertion "Assertions and Protocol for the OASIS Security Assertion
Markup Language (SAML) V2.0", OASIS Standard saml-core- Markup Language (SAML) V2.0", OASIS Standard saml-
2.0-os, March 2005. core-2.0-os, March 2005.
[RFC2904] Vollbrecht, J., Calhoun, P., Farrell, S., Gommans, L., [RFC2904] Vollbrecht, J., Calhoun, P., Farrell, S., Gommans, L.,
Gross, G., de Bruijn, B., de Laat, C., Holdrege, M., and Gross, G., de Bruijn, B., de Laat, C., Holdrege, M., and
D. Spence, "AAA Authorization Framework", RFC 2904, D. Spence, "AAA Authorization Framework", RFC 2904, August
August 2000. 2000.
[I-D.ietf-emu-crypto-bind] [I-D.ietf-emu-crypto-bind]
Hartman, S., Wasserman, M., and D. Zhang, "EAP Mutual Hartman, S., Wasserman, M., and D. Zhang, "EAP Mutual
Cryptographic Binding", draft-ietf-emu-crypto-bind-02 Cryptographic Binding", draft-ietf-emu-crypto-bind-03
(work in progress), February 2013. (work in progress), March 2013.
[I-D.ietf-emu-eap-tunnel-method] [I-D.ietf-emu-eap-tunnel-method]
Zhou, H., Cam-Winget, N., Salowey, J., and S. Hanna, Zhou, H., Cam-Winget, N., Salowey, J., and S. Hanna,
"Tunnel EAP Method (TEAP) Version 1", "Tunnel EAP Method (TEAP) Version 1", draft-ietf-emu-eap-
draft-ietf-emu-eap-tunnel-method-05 (work in progress), tunnel-method-05 (work in progress), February 2013.
February 2013.
[I-D.ietf-radext-dtls] [I-D.ietf-radext-dtls]
DeKok, A., "DTLS as a Transport Layer for RADIUS", DeKok, A., "DTLS as a Transport Layer for RADIUS", draft-
draft-ietf-radext-dtls-03 (work in progress), ietf-radext-dtls-03 (work in progress), January 2013.
January 2013.
[I-D.ietf-radext-dynamic-discovery]
Winter, S. and M. McCauley, "NAI-based Dynamic Peer
Discovery for RADIUS/TLS and RADIUS/DTLS", draft-ietf-
radext-dynamic-discovery-06 (work in progress), February
2013.
[WS-TRUST] [WS-TRUST]
Lawrence, K., Kaler, C., Nadalin, A., Goodner, M., Gudgin, Lawrence, K., Kaler, C., Nadalin, A., Goodner, M., Gudgin,
M., Barbir, A., and H. Granqvist, "WS-Trust 1.4", OASIS M., Barbir, A., and H. Granqvist, "WS-Trust 1.4", OASIS
Standard ws-trust-200902, February 2009, <http:// Standard ws-trust-200902, February 2009, <http://docs
docs.oasis-open.org/ws-sx/ws-trust/v1.4/ws-trust.html>. .oasis-open.org/ws-sx/ws-trust/v1.4/ws-trust.html>.
[NIST-SP.800-63] [NIST-SP.800-63]
Burr, W., Dodson, D., and W. Polk, "Electronic Burr, W., Dodson, D., and W. Polk, "Electronic
Authentication Guideline", NIST Special Authentication Guideline", NIST Special Publication
Publication 800-63, April 2006. 800-63, April 2006.
URIs
[1] <http://www.openid.net>
[2] <http://www.eduroam.org>
Editorial Comments
[anchor4] JLS: Should this be an EAP failure to the client as well?
[anchor7] JLS: I don't believe this is a true statement - check it
with Josh and Sam.
Authors' Addresses Authors' Addresses
Josh Howlett Josh Howlett
JANET(UK) JANET(UK)
Lumen House, Library Avenue, Harwell Lumen House, Library Avenue, Harwell
Oxford OX11 0SG Oxford OX11 0SG
UK UK
Phone: +44 1235 822363 Phone: +44 1235 822363
Email: Josh.Howlett@ja.net Email: Josh.Howlett@ja.net
Sam Hartman Sam Hartman
Painless Security Painless Security
Phone:
Email: hartmans-ietf@mit.edu Email: hartmans-ietf@mit.edu
Hannes Tschofenig Hannes Tschofenig
Nokia Siemens Networks Nokia Siemens Networks
Linnoitustie 6 Linnoitustie 6
Espoo 02600 Espoo 02600
Finland Finland
Phone: +358 (50) 4871445 Phone: +358 (50) 4871445
Email: Hannes.Tschofenig@gmx.net Email: Hannes.Tschofenig@gmx.net
 End of changes. 124 change blocks. 
419 lines changed or deleted 511 lines changed or added

This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/