Internet Engineering Task Force (IETF) G. Zorn, Ed.
Request for Comments: 6697 Network Zen
Category: Informational Q. Wu
ISSN: 2070-1721 T. Taylor
Huawei
Y. Nir
Check Point
K. Hoeper
Motorola Solutions, Inc.
S. Decugis
INSIDE Secure
July 2012
Handover Keying (HOKEY) Architecture Design
Abstract
The Handover Keying (HOKEY) Working Group seeks to minimize handover
delay due to authentication when a peer moves from one point of
attachment to another. Work has progressed on two different
approaches to reduce handover delay: early authentication (so that
authentication does not need to be performed during handover), and
reuse of cryptographic material generated during an initial
authentication to save time during re-authentication. A basic
assumption is that the mobile host or "peer" is initially
authenticated using the Extensible Authentication Protocol (EAP),
executed between the peer and an EAP server as defined in RFC 3748.
This document defines the HOKEY architecture. Specifically, it
describes design objectives, the functional environment within which
handover keying operates, the functions to be performed by the HOKEY
architecture itself, and the assignment of those functions to
architectural components. It goes on to illustrate the operation of
the architecture within various deployment scenarios that are
described more fully in other documents produced by the HOKEY Working
Group.
Zorn, et al. Informational [Page 1]RFC 6697 HOKEY Architecture Design July 2012
Status of This Memo
This document is not an Internet Standards Track specification; it is
published for informational purposes.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Not all documents
approved by the IESG are a candidate for any level of Internet
Standard; see Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc6697.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Zorn, et al. Informational [Page 2]
RFC 6697 HOKEY Architecture Design July 2012
Table of Contents
1. Introduction ....................................................3
2. Terminology .....................................................6
3. Design Goals ....................................................6
3.1. Reducing Signaling Overhead ................................7
3.1.1. Minimized Communications with Home Servers ..........7
3.1.2. Minimized User Interaction for Authentication .......7
3.2. Integrated Local Domain Name (LDN) Discovery ...............7
3.3. Fault-Tolerant Re-Authentication ...........................8
3.4. Improved Deployment Scalability ............................8
4. Required Functionality ..........................................8
4.1. Authentication Subsystem Functional Overview ...............8
4.2. Pre-Authentication Function (Direct or Indirect) ...........9
4.3. EAP Re-Authentication Function .............................9
4.4. EAP Authentication Function ...............................10
4.5. Authenticated Anticipatory Keying (AAK) Function ..........10
4.6. Management of EAP-Based Handover Keys .....................10
5. Components of the HOKEY Architecture ...........................11
5.1. Functions of the Peer .....................................12
5.2. Functions of the Serving Authenticator ....................13
5.3. Functions of the Candidate Authenticator ..................14
5.4. Functions of the EAP Server ...............................15
5.5. Functions of the ER Server ................................16
6. Usage Scenarios ................................................16
6.1. Simple Re-Authentication ..................................16
6.2. Intra-Domain Handover .....................................17
6.3. Inter-Domain Handover .....................................17
6.4. Inter-Technology Handover .................................17
7. AAA Considerations .............................................17
7.1. Authorization .............................................17
7.2. Transport Aspect ..........................................18
8. Security Considerations ........................................18
9. Acknowledgments ................................................18
10. References ....................................................18
10.1. Normative References .....................................18
10.2. Informative References ...................................19
1. Introduction
The Extensible Authentication Protocol (EAP) [RFC3748] is an
authentication framework that supports different types of
authentication methods. Originally designed for dial-up connections,
EAP is now commonly used for authentication in a variety of access
networks.
Zorn, et al. Informational [Page 3]RFC 6697 HOKEY Architecture Design July 2012
When a host (or "peer", the term used from this point onward) changes
its point of attachment to the network, it must be re-authenticated.
If a full EAP authentication must be repeated, several message round
trips between the peer and the home EAP server may be involved. The
resulting delay will result in degradation -- or, in the worst case,
loss of any service session in progress -- if communication is
suspended while re-authentication is carried out. The delay is worse
if the new point of attachment is in a visited network rather than
the peer's home network because of the extra procedural steps
involved as well as the probable increase in round-trip time.
Clancy, et al. [RFC5169] describe this problem more fully and
establish design goals for solutions to reduce re-authentication
delay for transfers within a single administrative domain. They also
suggest a number of ways to achieve a solution:
o specification of a method-independent, efficient re-authentication
protocol based upon EAP;
o reuse of keying material from the initial EAP authentication;
o deployment of re-authentication servers local to the peer to
reduce round-trip delay; and
o specification of the additional protocol needed to allow the EAP
server to pass authentication information to the local
re-authentication servers.
Salowey, et al. [RFC5295] tackle the problem of the reuse of keying
material by specifying how to derive a hierarchy of cryptographically
independent purpose-specific keys from the results of the original
EAP authentication, while Cao, et al. [RFC6696] specify a method-
independent re-authentication protocol (the EAP Re-authentication
Protocol (ERP)) applicable to two specific deployment scenarios:
o where the peer's home EAP server also performs re-authentication;
and
o where a local re-authentication server exists but is co-located
with an Authentication, Authorization, and Accounting (AAA) proxy
within the domain.
Other work provides further pieces of the solution or insight into
the problem. For the purpose of this memo, Hoeper, et al. [RFC5749]
provide an abstract mechanism for distribution of keying material
from the EAP server to re-authentication servers. Ohba,
et al. [RFC5836] contrast the EAP Re-authentication (ER) strategy
provided by ERP with an alternative strategy called "early
Zorn, et al. Informational [Page 4]RFC 6697 HOKEY Architecture Design July 2012
authentication". RFC 5836 defines EAP early authentication as the
use of EAP by a mobile peer to establish authenticated keying
material on a target attachment point prior to its arrival. Hence,
the goal of EAP early authentication is to complete all EAP-related
communications, including AAA signaling, in preparation for the
handover, before the mobile device actually moves. Early
authentication includes direct and indirect pre-authentication as
well as Authenticated Anticipatory Keying (AAK). All three early
authentication mechanisms provide means to securely establish
authenticated keying material on a Candidate Attachment Point (CAP)
while still being connected to the Serving Attachment Point (SAP) but
vary in their respective system assumptions and communication paths.
In particular, direct pre-authentication assumes that clients are
capable of discovering CAPs and all communications are routed through
the SAP. On the other hand, indirect pre-authentication assumes an
existing relationship between the SAP and CAP, whereas the discovery
and selection of CAPs is outside the scope of AAK. Furthermore, both
direct and indirect pre-authentication require a full EAP execution
to occur before the handover of the peer takes place, while AAK
techniques (like ERP [RFC6696]) use keys derived from the initial EAP
authentication.
Both EAP re-authentication and early authentication enable faster
inter-authenticator handovers. However, it is currently unclear how
the necessary handover infrastructure can be deployed and integrated
into existing EAP infrastructures. In particular, previous work has
not described how ER servers that act as endpoints in the
re-authentication process should be integrated into local and home
domain networks. Furthermore, how EAP infrastructure can support the
timely triggering of early authentications and aid with the selection
of CAPs is currently unspecified.
This document proposes a general HOKEY architecture and demonstrates
how it can be adapted to different deployment scenarios. To begin
with, Section 3 recalls the design objectives for the HOKEY
architecture. Section 4 reviews the functions that must be supported
within the architecture. Section 5 describes the components of the
HOKEY architecture. Section 6 describes the different deployment
scenarios that the HOKEY Working Group has addressed and the
information flows that must occur within those scenarios, by
reference to the documents summarized above where possible and
otherwise within this document itself. Finally, Section 7 provides
an analysis of how AAA protocols can be applied in the HOKEY
architecture.
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2. Terminology
This document reuses terms defined in Section 2 of Ohba,
et al. [RFC5836] and Section 2 of Cao, et al. [RFC6696]. In
addition, it defines the following:
DS-rRK
Domain-Specific re-authentication Root Key.
pMSK
pre-established Master Session Key.
EAP Early Authentication
The use of EAP by a mobile peer to establish authenticated keying
material on a target attachment point prior to its arrival; see
Ohba, et al. [RFC5836].
ER Key Management
An instantiation of the mechanism described in Hoeper,
et al. [RFC5749] for creating and delivering root keys from an EAP
server to an ER server.
EAP Re-authentication (ER)
The use of keying material derived from an initial EAP
authentication to enable single-round-trip re-authentication of a
mobile peer. For a detailed description of the keying material,
see Section 4 of Cao, et al. [RFC6696].
ER Server
A component of the HOKEY architecture that terminates the EAP
re-authentication exchange with the peer.
3. Design Goals
This section investigates the design goals for the HOKEY
architecture. These include reducing the signaling overhead for
re-authentication and early authentication, integrating local domain
name discovery, enabling fault-tolerant re-authentication, and
improving deployment scalability. These goals supplement those
discussed in Section 4 of RFC 5169. Note that the identification and
selection of CAPs is not a goal of the architecture, since those
operations are generally specific to the lower layer in use.
Zorn, et al. Informational [Page 6]RFC 6697 HOKEY Architecture Design July 2012
3.1. Reducing Signaling Overhead
3.1.1. Minimized Communications with Home Servers
ERP [RFC6696] requires only one round trip; however, this round trip
may require communication between a peer and its home ER and/or home
AAA server in explicit bootstrapping and communication between local
servers and the home server in implicit bootstrapping even if the
peer is currently attached to a visited (local) network. As a
result, even this one round trip may introduce long delays because
the home ER and home AAA servers may be distant from the peer and the
network to which it is attached. To lower signaling overhead,
communication with the home ER server and home AAA server should be
minimized. Ideally, a peer should only need to communicate with
local servers and other local entities.
3.1.2. Minimized User Interaction for Authentication
When the peer is initially attached to the network or moves between
heterogeneous networks, full EAP authentication between the peer and
EAP server occurs and user interaction may be needed, e.g., a dialog
to prompt the user for credentials. To reduce latency, user
interaction for authentication at each handover should be minimized.
Ideally, user involvement should take place only during initial
authentication and subsequent re-authentication should occur
transparently.
3.2. Integrated Local Domain Name (LDN) Discovery
ERP bootstrapping must occur before (implicit) or during (explicit) a
handover to transport the necessary keys to the local ER server
involved. Implicit bootstrapping is preferable because it does not
require communication with the home ER server during handover, but it
requires that the peer know the domain name of the ER server before
the subsequent local ERP exchange happens in order to derive the
necessary re-authentication keying material. ERP [RFC6696] does not
specify such a domain name discovery mechanism and suggests that the
peer may learn the domain name through the EAP-Initiate/Re-auth-Start
message or via lower-layer announcements. However, domain name
discovery happens after the implicit bootstrapping completes, which
may introduce extra latency. To allow more efficient handovers, a
HOKEY architecture should support an efficient domain name discovery
mechanism (for example, see Zorn, Wu & Wang [RFC6440]) and allow its
integration with ERP implicit bootstrapping. Even in the case of
explicit bootstrapping, LDN discovery should be optimized such that
it does not require contacting the home AAA server, as is currently
the case.
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RFC 6697 HOKEY Architecture Design July 2012
3.3. Fault-Tolerant Re-Authentication
If all authentication services depend upon a remote server, a network
partition can result in the denial of service to valid users.
However, if for example an ER server exists in the local network,
previously authenticated users can re-authenticate even though a link
to the home or main authentication server doesn't exist.
3.4. Improved Deployment Scalability
To provide better deployment scalability, there should be no
requirement for the co-location of entities providing handover keying
services (e.g., ER servers) and AAA servers or proxies. Separation
of these entities may cause problems with routing but allows greater
flexibility in deployment and implementation.
4. Required Functionality
4.1. Authentication Subsystem Functional Overview
The operation of the authentication subsystem provided by HOKEY also
depends on the availability of a number of discovery functions:
o discovery of CAPs by the peer, by the SAP, or by some other
entity;
o discovery of the authentication services supported at a given CAP;
o discovery of the required server in the home domain when a CAP is
not in the same domain as the SAP, or no local server is
available;
o peer discovery of the LDN when EAP re-authentication is used with
a local server.
It is assumed that these functions are provided by the environment
within which the authentication subsystem operates and are outside
the scope of the authentication subsystem itself. LDN discovery is a
possible exception.
The major functions comprising the authentication subsystem and their
interdependencies are discussed in greater detail below.
o When AAA is invoked to authorize network access, it uses one of
two services offered by the authentication subsystem: full EAP
authentication or EAP re-authentication. Note that although AAA
may perform authentication directly in some cases, when EAP is
Zorn, et al. Informational [Page 8]RFC 6697 HOKEY Architecture Design July 2012
utilized AAA functions only as a transport for EAP messages and
the encryption keys (if any) resulting from successful EAP
authentication.
o Pre-authentication triggers AAA network access authorization at
each CAP, which in turn causes full EAP authentication to be
invoked.
o EAP re-authentication invokes ER key management at the time of
authentication to create and distribute keying material to ER
servers.
o AAK relies on ER key management to establish keying material on
ER/AAK servers but uses an extension to ER key management to
derive and establish keying material on candidate authenticators.
AAK uses an extension to EAP re-authentication to communicate with
ER/AAK servers.
EAP authentication, EAP re-authentication, and handover key
distribution depend on the routing and secure transport service
provided by AAA. Discovery functions and the function of
authentication and authorization of network entities (access points,
ER servers) are not shown. As stated above, these are external to
the authentication subsystem.
4.2. Pre-Authentication Function (Direct or Indirect)
The pre-authentication function is responsible for discovery of CAPs
and completion of network access authentication and authorization at
each CAP in advance of handover. The operation of this function is
described in general terms in Ohba, et al. [RFC5836]. No document is
yet available to describe the implementation of pre-authentication in
terms of specific protocols; pre-authentication support for the
Protocol for Carrying Authentication for Network Access (PANA)
[RFC5873] could be part of the solution.
4.3. EAP Re-Authentication Function
The EAP re-authentication function is responsible for authenticating
the peer at a specific access point using keying material derived
from a prior full EAP authentication. RFC 5169 [RFC5169] provides
the design objectives for an implementation of this function. ERP
[RFC6696] describes a protocol to implement EAP re-authentication.
Zorn, et al. Informational [Page 9]RFC 6697 HOKEY Architecture Design July 2012
4.4. EAP Authentication Function
The EAP authentication function is responsible for authenticating the
peer at a specific access point using a full EAP exchange. Aboba,
et al. [RFC3748] define the associated protocol, while Ohba,
et al. [RFC5836] describe the use of EAP as part of
pre-authentication. Note that the HOKEY Working Group has not
specified the non-AAA protocol required to transport EAP frames over
IP that is shown in Figures 3 and 5 of Ohba, et al. [RFC5836],
although PANA [RFC5873] is a candidate.
4.5. Authenticated Anticipatory Keying (AAK) Function
The AAK function is responsible for pre-placing keying material
derived from an initial full EAP authentication on CAPs. The
operation is carried out in two steps: ER key management (with
trigger not currently specified) places root keys derived from
initial EAP authentication onto an ER/AAK server associated with the
peer. When requested by the peer, the ER/AAK server derives and
pushes predefined master session keys to one or more CAPs. The
operation of the AAK function is described in very general terms in
Ohba, et al. [RFC5836]. A protocol specification exists (see Cao,
et al. [RFC6630]).
4.6. Management of EAP-Based Handover Keys
Handover key management consists of EAP method-independent key
derivation and distribution and comprises the following specific
functions:
o handover key derivation
o handover key distribution
The derivation of handover keys is specified in Salowey,
et al. [RFC5295], and AAA-based key distribution is specified in
Hoeper, Nakhjiri & Ohba [RFC5749].
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RFC 6697 HOKEY Architecture Design July 2012
5. Components of the HOKEY Architecture
This section describes the components of the HOKEY architecture in
terms of the functions they perform. The components cooperate as
described in this section to carry out the functions described in the
previous section. Section 6 describes the different deployment
scenarios that are possible using these functions.
The components of the HOKEY architecture are as follows:
o the peer;
o the authenticator, which is a part of the SAP and CAPs;
o the EAP server;
o the ER server; and
o the ER/AAK server [RFC6630], either in the home domain or local to
the authenticator.
Zorn, et al. Informational [Page 11]RFC 6697 HOKEY Architecture Design July 2012
5.1. Functions of the Peer
The peer participates in the functions described in Section 4, as
shown in Table 1.
+--------------------+----------------------------------------------+
| Function | Peer Role |
+--------------------+----------------------------------------------+
| EAP authentication | Determines that full EAP authentication is |
| | needed based on context (e.g., initial |
| | authentication), prompting from the |
| | authenticator, or discovery that only EAP |
| | authentication is supported. Participates |
| | in the EAP exchange with the EAP server. |
| - | - |
| Direct | Discovers CAPs. Initiates |
| pre-authentication | pre-authentication with each, followed by |
| | EAP authentication as above, but using IP |
| | rather than L2 transport for the EAP frames. |
| - | - |
| Indirect | Enters into a full EAP exchange when |
| pre-authentication | triggered, using either L2 or L3 transport |
| | for the frames. |
| - | - |
| EAP | Determines that EAP re-authentication is |
| re-authentication | possible based on discovery or authenticator |
| | prompting. Participates in ERP exchange |
| | with the ER server. |
| - | - |
| AAK | Determines that AAK is possible based on |
| | discovery or serving authenticator |
| | prompting. Discovers CAPs. Participates in |
| | ERP/AAK exchange, requesting distribution of |
| | keying material to the CAPs. |
| - | - |
| ER key management | No role. |
+--------------------+----------------------------------------------+
Table 1: Functions of the Peer
Zorn, et al. Informational [Page 12]RFC 6697 HOKEY Architecture Design July 2012
5.2. Functions of the Serving Authenticator
The serving authenticator participates in the functions described in
Section 4, as shown in Table 2.
+--------------------+----------------------------------------------+
| Function | Serving Authenticator Role |
+--------------------+----------------------------------------------+
| EAP authentication | No role. |
| - | - |
| Direct | No role. |
| pre-authentication | |
| - | - |
| Indirect | Discovers CAPs. Initiates an EAP exchange |
| pre-authentication | between the peer and the EAP server through |
| | each candidate authenticator. Mediates |
| | between L2 transport of EAP frames on the |
| | peer side and a non-AAA protocol over IP |
| | toward the CAP. |
| - | - |
| EAP | No role. |
| re-authentication | |
| - | - |
| AAK | Mediates between L2 transport of AAK frames |
| | on the peer side and AAA transport toward |
| | the ER/AAK server. |
| - | - |
| ER key management | No role. |
+--------------------+----------------------------------------------+
Table 2: Functions of the Serving Authenticator
Zorn, et al. Informational [Page 13]RFC 6697 HOKEY Architecture Design July 2012
5.3. Functions of the Candidate Authenticator
The candidate authenticator participates in the functions described
in Section 4, as shown in Table 3.
+--------------------+----------------------------------------------+
| Function | Candidate Authenticator Role |
+--------------------+----------------------------------------------+
| EAP authentication | Invokes AAA network access authentication |
| | and authorization upon handover/initial |
| | attachment. Mediates between L2 transport |
| | of EAP frames on the peer link and AAA |
| | transport toward the EAP server. |
| - | - |
| Direct | Invokes AAA network access authentication |
| pre-authentication | and authorization when the peer initiates |
| | authentication. Mediates between non-AAA L3 |
| | transport of EAP frames on the peer side and |
| | AAA transport toward the EAP server. |
| - | - |
| Indirect | Same as direct pre-authentication, except |
| pre-authentication | that it communicates with the serving |
| | authenticator rather than the peer. |
| - | - |
| EAP | Invokes AAA network access authentication |
| re-authentication | and authorization upon handover. Discovers |
| | or is configured with the address of the ER |
| | server. Mediates between L2 transport of |
| | ERP frames on the peer side and AAA |
| | transport toward the ER server. |
| - | - |
| AAK | Receives and saves the pMSK. |
| - | - |
| ER key management | No role. |
+--------------------+----------------------------------------------+
Table 3: Functions of the Candidate Authenticator
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5.4. Functions of the EAP Server
The EAP server participates in the functions described in Section 4,
as shown in Table 4.
+--------------------+----------------------------------------------+
| Function | EAP Server Role |
+--------------------+----------------------------------------------+
| EAP authentication | Terminates EAP signaling between it and the |
| | peer via the candidate authenticator. |
| | Determines whether network access |
| | authentication succeeds or fails. Provides |
| | the MSK to the authenticator (via AAA). |
| - | - |
| Direct | Same as for EAP authentication. |
| pre-authentication | |
| - | - |
| Indirect | Same as for EAP authentication. |
| pre-authentication | |
| - | - |
| EAP | Provides an rRK or DS-rRK to the ER server |
| re-authentication | (via AAA). |
| - | - |
| AAK | Same as for EAP re-authentication. |
| - | - |
| ER key management | Creates an rRK or DS-rRK and distributes it |
| | to the ER server requesting the information. |
+--------------------+----------------------------------------------+
Table 4: Functions of the EAP Server
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5.5. Functions of the ER Server
The ER server participates in the functions described in Section 4,
as shown in Table 5.
+--------------------+----------------------------------------------+
| Function | ER Server Role |
+--------------------+----------------------------------------------+
| EAP authentication | No role. |
| - | - |
| Direct | No role. |
| pre-authentication | |
| - | - |
| Indirect | No role. |
| pre-authentication | |
| - | - |
| EAP | Acquires an rRK or DS-rRK as applicable when |
| re-authentication | necessary. Terminates ERP signaling between |
| | it and the peer via the candidate |
| | authenticator. Determines whether network |
| | access authentication succeeds or fails. |
| | Provides an MSK to the authenticator. |
| - | - |
| AAK | Acquires an rRK or DS-rRK as applicable when |
| | necessary. Derives pMSKs and passes them to |
| | the CAPs. |
| - | - |
| ER key management | Receives and saves an rRK or DS-rRK as |
| | applicable. |
+--------------------+----------------------------------------------+
Table 5: Functions of the ER Server
6. Usage Scenarios
Depending upon whether a change in a domain or access technology is
involved, we have the following usage scenarios.
6.1. Simple Re-Authentication
The peer remains stationary and re-authenticates to the original
access point. Note that in this case, the SAP takes the role of the
CAP in the discussion above.
Zorn, et al. Informational [Page 16]RFC 6697 HOKEY Architecture Design July 2012
6.2. Intra-Domain Handover
The peer moves between two authenticators in the same domain. In
this scenario, the peer communicates with the ER server via the ER
authenticator within the same network.
6.3. Inter-Domain Handover
The peer moves between two different domains. In this scenario, the
peer communicates with more than one ER server via one or two
different ER authenticators. One ER server is located in the current
network as the peer, and one is located in the previous network from
which the peer moves. Another ER server is located in the home
network to which the peer belongs.
6.4. Inter-Technology Handover
The peer moves between two heterogeneous networks. In this scenario,
the peer needs to support at least two access technologies. The
coverage of two access technologies usually is overlapped during
handover. In this case, only authentication corresponding to
intra-domain handover is required; i.e., the peer can communicate
with the same local ER server to complete authentication and obtain
keying material corresponding to the peer.
7. AAA Considerations
This section provides an analysis of how the AAA protocol can be
applied in the HOKEY architecture in accordance with Section 4.1
("Authentication Subsystem Functional Overview").
7.1. Authorization
Authorization is a major issue in deployments. Wherever the peer
moves around, the home AAA server provides authorization for the peer
during its handover. However, it is unnecessary to couple
authorization with authentication at every handover, since
authorization is only needed when the peer is initially attached to
the network or moves between two different AAA domains. The EAP key
management document [RFC5247] discusses several vulnerabilities that
are common to handover mechanisms. One important issue arises from
the way that the authorization decisions might be handled at the AAA
server during network access authentication. For example, if AAA
proxies are involved, they may also influence authorization
decisions. Furthermore, the reasons for choosing a particular
decision are not communicated to the AAA clients. In fact, the AAA
client only knows the final authorization result. Another issue
relates to session management. In some circumstances, when the peer
Zorn, et al. Informational [Page 17]RFC 6697 HOKEY Architecture Design July 2012
moves from one authenticator to another, the peer may be
authenticated by the different authenticator during a period of time,
and the authenticator to which the peer is currently attached needs
to create a new AAA user session; however, the AAA server should not
view these handoffs as different sessions. Otherwise, this may
affect user experience and also cause accounting or logging issues.
For example, session ID creation, in most cases, is done by each
authenticator to which the peer attaches. In this sense, the new
authenticator acting as AAA client needs to create a new AAA user
session from scratch, which forces its corresponding AAA server to
terminate the existing user session with the previous authenticator
and set up a new user session with the new authenticator. This may
complicate the setup and maintenance of the AAA user session.
7.2. Transport Aspect
The existing AAA protocols can be used to carry EAP and ERP messages
between the AAA server and AAA clients. AAA transport of ERP
messages is specified in Hoeper, Nakhjiri & Ohba [RFC5749] and
Bournelle, et al. [DIAMETER-ERP]. AAA transport of EAP messages is
specified in [RFC4072]. Key transport also can be performed through
a AAA protocol. Zorn, Wu & Cakulev [DIAMETER-AVP] specify a set of
Attribute-Value Pairs (AVPs) providing native Diameter support of
cryptographic key delivery.
8. Security Considerations
This document does not introduce any new security vulnerabilities.
9. Acknowledgments
The authors would like to thank Mark Jones, Zhen Cao, Semyon
Mizikovsky, Stephen Farrell, Ondrej Sury, Richard Barnes, Jari Arkko,
and Lionel Morand for their reviews and comments.
10. References
10.1. Normative References
[RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H.
Levkowetz, Ed., "Extensible Authentication Protocol
(EAP)", RFC 3748, June 2004.
[RFC5169] Clancy, T., Nakhjiri, M., Narayanan, V., and L. Dondeti,
"Handover Key Management and Re-Authentication Problem
Statement", RFC 5169, March 2008.
Zorn, et al. Informational [Page 18]RFC 6697 HOKEY Architecture Design July 2012
[RFC5836] Ohba, Y., Ed., Wu, Q., Ed., and G. Zorn, Ed., "Extensible
Authentication Protocol (EAP) Early Authentication Problem
Statement", RFC 5836, April 2010.
[RFC6696] Cao, Z., He, B., Shi, Y., Wu, Q., Ed., and G. Zorn, Ed.,
"EAP Extensions for the EAP Re-authentication Protocol
(ERP)", RFC 6696, July 2012.
10.2. Informative References
[DIAMETER-AVP]
Zorn, G., Wu, Q., and V. Cakulev, "Diameter Attribute-
Value Pairs for Cryptographic Key Transport", Work
in Progress, August 2011.
[DIAMETER-ERP]
Bournelle, J., Morand, L., Decugis, S., Wu, Q., and G.
Zorn, "Diameter Support for the EAP Re-authentication
Protocol (ERP)", Work in Progress, June 2012.
[RFC4072] Eronen, P., Ed., Hiller, T., and G. Zorn, "Diameter
Extensible Authentication Protocol (EAP) Application",
RFC 4072, August 2005.
[RFC5247] Aboba, B., Simon, D., and P. Eronen, "Extensible
Authentication Protocol (EAP) Key Management Framework",
RFC 5247, August 2008.
[RFC5295] Salowey, J., Dondeti, L., Narayanan, V., and M. Nakhjiri,
"Specification for the Derivation of Root Keys from an
Extended Master Session Key (EMSK)", RFC 5295,
August 2008.
[RFC5749] Hoeper, K., Ed., Nakhjiri, M., and Y. Ohba, Ed.,
"Distribution of EAP-Based Keys for Handover and
Re-Authentication", RFC 5749, March 2010.
[RFC5873] Ohba, Y. and A. Yegin, "Pre-Authentication Support for the
Protocol for Carrying Authentication for Network Access
(PANA)", RFC 5873, May 2010.
[RFC6440] Zorn, G., Wu, Q., and Y. Wang, "The EAP Re-authentication
Protocol (ERP) Local Domain Name DHCPv6 Option", RFC 6440,
December 2011.
[RFC6630] Cao, Z., Deng, H., Wu, Q., and G. Zorn, Ed., "EAP
Re-authentication Protocol Extensions for Authenticated
Anticipatory Keying (ERP/AAK)", RFC 6630, June 2012.
Zorn, et al. Informational [Page 19]RFC 6697 HOKEY Architecture Design July 2012
Authors' Addresses
Glen Zorn (editor)
Network Zen
227/358 Thanon Sanphawut
Bang Na, Bangkok 10260
Thailand
Phone: +66 (0) 909 201060
EMail: glenzorn@gmail.com
Qin Wu
Huawei Technologies Co., Ltd.
101 Software Avenue, Yuhua District
Nanjing, JiangSu 210012
China
Phone: +86-25-84565892
EMail: bill.wu@huawei.com
Tom Taylor
Huawei Technologies Co., Ltd.
Ottawa, Ontario
Canada
EMail: tom.taylor.stds@gmail.com
Yoav Nir
Check Point
5 Hasolelim St.
Tel Aviv 67897
Israel
EMail: ynir@checkpoint.com
Katrin Hoeper
Motorola Solutions, Inc.
1301 E. Algonquin Road
Schaumburg, IL 60196
USA
EMail: khoeper@motorolasolutions.com>
Sebastien Decugis
INSIDE Secure
41 Parc Club du Golf
Aix-en-Provence 13856
France
Phone: +33 (0)4 42 39 63 00
EMail: sdecugis@freediameter.net
Zorn, et al. Informational [Page 20]
