EAP WG
Internet-Draft H. Tschofenig
D. Kroeselberg
Siemens
Y. Ohba
Toshiba
F. Bersani
France Telecom R&D
Document: draft-tschofenig-eap-ikev2-07.txt
Expires: January 18, 2006 July 2005
EAP IKEv2 Method
(EAP-IKEv2)
Status of this Memo
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Copyright (C) The Internet Society (2005).
Abstract
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EAP-IKEv2 is an EAP authentication method with cryptographic
properties and basic exchanges similar to the Internet Key
Exchange (IKEv2) protocol. It provides a flexible EAP method with
support for both symmetric and asymmetric authentication, as well
as a combination of both.
EAP-IKEv2 thereby offers the security benefits of the exchanges
for authentication and key agreement of IKEv2 within the AAA
framework defined by the IETF.
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Table of Contents
1. Introduction..................................................3
2. EAP-IKEv2 Overview............................................4
3. Terminology...................................................5
4. Protocol overview.............................................6
5. Identities used in EAP-IKEv2..................................9
6. Packet Format.................................................9
7. Fragmentation support........................................11
8. Retransmission...............................................12
9. Key derivation...............................................12
10. Error Handling..............................................14
11. Fast Reconnect..............................................14
12. Channel Binding.............................................17
12.1 Channel Binding Procedure in Full Authentication........17
12.2 Channel Binding Procedure in Fast Reconnect.............18
12.3 Channel Binding Error Indication........................18
12.4 Notify Payload Types for Channel Binding................19
12.5 Examples................................................20
13. Security Considerations.....................................24
13.1 General Considerations..................................24
13.2 Security Claims.........................................25
14. IANA Considerations.........................................26
15. Normative References........................................27
16. Informative References......................................27
Acknowledgments.................................................28
Author's Addresses..............................................28
Intellectual Property Statement.................................29
Disclaimer of Validity..........................................29
Copyright Statement.............................................30
Acknowledgment..................................................30
1. Introduction
This document specifies the EAP authentication method EAP-IKEv2.
The main design goal for EAP-IKEv2 is to provide a flexible and
efficient EAP method which makes security properties and exchanges
similar to these of the IKEv2 protocol available for all scenarios
using EAP-based authentication.
The main advantage of EAP-IKEv2 is that it does not define a new
cryptographic protocol, but re-uses the well-analyzed IKEv2
authentication exchanges within the EAP framework. Thereby, it
provides strong cryptographic properties as well as good
flexibility to support a large number of use cases.
EAP-IKEv2 especially provides an efficient shared-secret based
authentication method offering a high security level, and allows
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for password-derived shared secrets while protecting from
password-guessing attacks.
It provides mutual authentication between EAP peers. This may be
based on either symmetric-key methods using pre-shared keys, or
on asymmetric methods based on public/private key pairs,
Certificates and CRLs. It is possible to use different types of
authentication for the different directions, e.g. the server uses
certificate-based authentication whereas the client uses a
symmetric-key method.
By this, both AAA scenarios where public-key EAP-based
authentication as well as scenarios requiring symmetric-key
EAP-based authentication are flexibly supported.
2. EAP-IKEv2 Overview
EAP-IKEv2 is an EAP authentication method that offers security
features similar to those offered by the IKEv2 protocol defined
for Internet key exchange. It defines exchanges and message
formats similar to exchanges and payloads specified by IKEv2 for
establishment of an IKE-SA.
The basic successful EAP-IKEv2 exchange as specified in section
4 requires two roundtrips for authenticating EAP peer and server
that are followed by an EAP-Success message. An optional roundtrip
for exchanging EAP identities may precede the authentication
exchange.
In addition to the basic exchange, a fast reconnect method is
specified in section 11 to allow fast session resumption with
increased efficiency compared to an EAP-IKEv2 standard exchange.
Section 5 details the handling of identities for EAP-IKEv2, since
identities occur in both the basic EAP exchange as well as the
specific EAP-IKEv2 authentication exchange.
In section 6, the packet format for EAP-IKEv2 messages is
specified, which is composed of the standard EAP request/response
message and the EAP method specific formats that are derived from
the original IKEv2 protocol specification.
EAP-IKEv2 provides a secure fragmentation mechanism that is
detailed in section 7 and details retransmission aspects in
section 8.
Key derivation as an important part of any EAP authentication
method is specified in section 9 that details the method-specific
behavior according to the overall EAP keying framework.
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For security aspects, in section 12 a detailed discussion on
channel binding to avoid security issues related to misbehaving
EAP authenticators can be found. The general security
considerations for this EAP method are subsequently given in
section 13.
In general, although EAP-IKEv2 reuses parts of the original IKEv2
specification, it must be noted that the scenarios EAP-IKEv2 is
intended for are clearly different from the scenarios covered by
IKEv2. Therefore, a number of mechanisms available in IKEv2 are
not required, nor are they available, in EAP-IKEv2. For example,
the optional tunneling of IKEv2 (inner authentication method as
defined in [Kau04], section 3.16) is not supported by this version
of EAP-IKEv2.
EAP-IKEv2 provides authentication between an EAP server and an EAP
peer in a single authentication exchange, or phase. In contrast,
IKEv2 [Kau04] itself is a protocol which consists of two phases
that can be run (but are not necessarily run) subsequently:
(1) an authentication and key exchange phase which establishes an
IKE-SA.
(2) a phase for the negotiation of parameters in order to establish
IPsec security associations. Such exchanges contain e.g.
algorithm parameters and traffic selector fields, and are
protected by the security established in the first phase.
The EAP-IKEv2 method does not include any exchange similar to the
above phase (2), since such functionality is not a requirement in
the context of common AAA scenarios, consisting of an EAP peer,
an authenticator (NAS) and a back-end authentication server.
There, IPsec SA establishment may be required locally (i.e.,
between the EAP peer and some access server). However, SA
establishment within an EAP method could only provide SAs between
the EAP peer and the back-end authentication server. Other
approaches as, e.g., the IETF PANA framework are considered more
appropriate in this case.
3. Terminology
This document does not introduce new terms other than those defined
in [RFC3748] or in [Kau04].
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The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in
this document, are to be interpreted as described in [RFC2119].
4. Protocol overview
This section defines the basic EAP-IKEv2 message exchanges.
The given exchanges are based on IKEv2 [Kau04].
All message exchanges take place between two parties - between the
Initiator (I) and the Responder (R) of an exchange. In the context
of EAP the Initiator takes the role of the EAP server and the
responder matches the EAP peer.
The first message flow shows the EAP-IKEv2 full successful
authentication exchange. The core EAP-IKEv2 exchange (message (3)
to (6)) consists of four messages (two round trips)_only:
- Messages (3) and (4) negotiate cryptographic algorithms,
exchange nonces, and perform a Diffie-Hellman exchange. This
step is called EAP-IKE_SA_INIT exchange.
- Messages (5) and (6) authenticate the EAP-IKE_SA_INIT exchange,
and exchange the identities of Initiator and Responder (i.e.
the EAP server and peer) and certificates. This step is called
EAP-IKE_SA_AUTH exchange.
The first two messages (1) and (2) constitute the standard EAP
identity exchange and are optional; they are not required in case
the EAP server is known. The exchange is concluded with an
EAP-Success message (7) sent by the EAP server to the EAP peer.
In the exchange, the EAP server (B) takes the role of the Initiator
and the EAP peer (A) acts as the Responder.
1) A <-- B: EAP-Request/Identity
2) A --> B: EAP-Response/Identity(Id)
3) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(HDR(A,0), SAi1, KEi, Ni)
4) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SAr1, KEr, Nr, [CERTREQ])
5) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {IDi, [CERT,] [CERTREQ,] [IDr,], AUTH})
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6) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {IDr, [CERT,] AUTH})
7) A <-- B: EAP-Success
Figure 1: EAP-IKEv2 successful message flow
Descriptions of the EAP-IKEv2 message format, headers and payloads
are given in section 6.
Figure 2 shows the message flow in case the EAP peer fails to
authenticate the EAP server. The difference to the above
successful exchange is that in message (6) the EAP peer answers
to the EAP server with an AUTHENTICATION_FAILED error. In message
(7), EAP-Failure is returned from the EAP server.
1) A <-- B: EAP-Request/Identity
2) A --> B: EAP-Response/Identity(Id)
3) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(HDR(A,0), SAi1, KEi, Ni)
4) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SAr1, KEr, Nr, [CERTREQ])
5) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {IDi, [CERT,] [CERTREQ,] [IDr,], AUTH})
6) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {N(AUTHENTICATION_FAILED)})
7) A <-- B: EAP-Failure
Figure 2: EAP-IKEv2 with failed server authentication
Figure 3 shows the message flow in case the EAP server fails to
authenticate the EAP peer. Compared to the successful exchange,
one additional roundtrip is required. In message (7) the EAP server
answers with an AUTHENTICATION_FAILED error instead of sending
EAP-Successs. The EAP peer, after receiving message (7), MUST send
an empty EAP-IKEv2 (informational) message in reply to the EAP
server's error indication, as shown in (8). The EAP server answers
with an EAP-Failure.
1) A <-- B: EAP-Request/Identity
2) A --> B: EAP-Response/Identity(Id)
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3) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(HDR(A,0), SAi1, KEi, Ni)
4) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SAr1, KEr, Nr, [CERTREQ])
5) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {IDi, [CERT,] [CERTREQ,] [IDr,], AUTH})
6) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {IDr, [CERT,] AUTH})
7) A <-- B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {N(AUTHENTICATION_FAILED)})
8) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {})
9) A <-- B: EAP-Failure
Figure 3: EAP-IKEv2 with failed client authentication
Since the goal of this EAP method is not the goal of the original
IKEv2 protocol to establish IPsec security associations, some
payloads that are specified in IKEv2 are not specified for
EAP-IKEv2 (as they do not occur in the message exchanges specified
in this document). For example, the following messages and
payloads are not specified for EAP-IKEv2::
- Traffic Selector (TS) payloads ([Kau04], section 3.13).
- SA payloads ([Kau04], section 3.3) that carry SA proposals for
protocol IDs other than 1(IKE), i.e., SA payloads with protocol
ID 2 (ESP) or 3 (AH)
- Configuration payloads ([Kau04], section 3.15).
- EAP payloads ([Kau04], section 3.16), since EAP tunnelling
within EAP-IKEv2 is not supported in this version of EAP-IKEv2.
Consequently, mechanisms that are part of IKEv2 but are not
required nor specified within EAP-IKEv2 are:
- ECN Notifications as specified in section 2.24 of [Kau04].
- IKE-specific port handling
- NAT traversal
IKEv2 provides optional functionality for additional DoS
protection by adding a roundtrip to the initial exchanges, see
section 2.6 of [Kau04]. This is intended to protect the IKEv2
responder. Because in EAP-IKEv2 the EAP server takes the role of
the initiator, no similar feature is specified for EAP-IKEv2.
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5. Identities used in EAP-IKEv2
A number of different places allow to convey identity information
in IKEv2 as well as in EAP. This section describes identities and
their role within the different exchanges of EAP-IKEv2. Note that
EAP-IKEv2 does not introduce more identities than other
non-tunneling EAP methods. Figure 4 shows which identities are
used during the individual phases of the protocol.
+-------+ +-------------+ +---------+
|Client | |Front-End | |AAA |
| | |Authenticator| |Server |
+-------+ +-------------+ +---------+
EAP/Identity-Request
<---------------------
(a) EAP/Identity-Response
---------------------------------->
EAP-IKE_SA_INIT and AUTH exchange
(b) (Identities of IKEv2 are used)
Server (Network) Authentication
<----------------------------------
...
---------------------------------->
Figure 4: Identities used in EAP-IKEv2
a) The first part of the EAP message exchange provides information
about the identities of the EAP endpoints. This message exchange
mainly is an identity request/response. It is optional if the EAP
server is known already or can be learned by other means.
b) Identities IDi and IDr are exchanged within the EAP-IKE_SA_INIT
and AUTH exchanges for both the initiator and the responder (EAP
server and peer).
For carrying identities in EAP-IKEv2, implementations MUST follow
the rules given in [Kau04], section 3.5, i.e., MUST be configurable
to send at least one of ID_IPV4_ADDR, ID_FQDN, ID_RFC822_ADDR, or
ID_KEY_ID, and MUST be configurable to accept all of these types.
Implementations SHOULD be capable of generating and accepting all
of these types.
6. Packet Format
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The EAP-IKEv2 messages are EAP messages carrying the
authentication exchange embedded in the Data field of the standard
EAP Request/Response packets. The Code, Identifier, Length and
Type fields are described in [RFC3748]. These are followed by a
Type-Data field that carries one octet with method-specific Flags
as specified in section 7.
This EAP header is, embedded in the Data field, followed by the
method-specific header HDR and by one or more payloads of the
EAP-IKEv2 authentication data.
The EAP Type for this EAP method is <TBD>.
The general packet format is shown in Figure 5.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code | Identifier | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Flags | Message Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Length | HDR ... ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Integrity Checksum Data |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: EAP-IKEv2 general packet format
The HDR payload that heads the Data field is as shown in Figure
5Figure 6 below. The HDR fields given in Figure 6 are used according
to [Kau04], section 3.1, where the EAP server acts as the initiator
and the EAP peer acts as the responder.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! IKE_SA Initiator's SPI !
! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! IKE_SA Responder's SPI !
! !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload ! MjVer ! MnVer ! Exchange Type ! Flags !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Message ID !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Figure 6: HDR format
In contrast to the original IKEv2 protocol specified in [Kau04],
the HDR (IKE header data) is not carried within a UDP message, but
is directly embedded into the EAP message as shown above. However,
no additional packet formats other than those defined in [Kau04]
are required for this EAP method.
Following the header HDR are one or more payloads where each of
them is identified by a "Next Payload" field in the preceding
payload. Processing these payloads follows the rules specified by
[Kau04] section 3.2.
Each payload begins with a generic payload header as given in
Figure 7 followed by the payload data itself.
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
! Next Payload !C! RESERVED ! Payload Length !
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7: generic payload header format
All payloads used within the EAP-IKEv2 messages defined by this
document are specified in [Kau04], sections 3.3. to 3.12 and 3.14.
7. Fragmentation support
The Flags field in HDR (see section 6) is used for fragmentation
support. The S and F bits are reserved for future use.
Currently three bits of the eight bit flags field are defined. The
remaining bits are set to zero.
0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|L M I 0 0 0 0 0|
+-+-+-+-+-+-+-+-+
L = Length included
M = More fragments
I = Integrity Checksum Data included
With regard to fragmentation we adopt the mechanism given in
Section 2.8 of [PS+03]: The L indicates that a length field is
present and the M flag indicates fragments. The L flag MUST be set
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for the first fragment and the M flag MUST be set on all fragments
expect for the last one.
Reliable fragment delivery is provided by the retransmission
mechanism of EAP.
The Message Length field is four octets long and present only if
the L bit is set. This field provides the total message length that
is being fragmented (i.e., the length of the Data field.).
The Integrity Checksum Data is the cryptographic checksum of the
entire EAP message starting with the Code field through the Data
field. This field presents only if the I bit is set. The field
immediately follows the Data field without adding any padding
octet before or after itself. The checksum MUST be computed for
each fragment (including the case where the entire IKEv2 message
is carried in a single fragment) by using the same key (i.e., SK_ai
or SK_ar) that is used for computing the checksum for the IKEv2
Encrypted payload in the encapsulated IKEv2 message. The
Integrity Checksum Data field is omitted for other packets. To
minimize DoS attacks on fragmented packets, messages that are not
protected SHOULD NOT be fragmented.
Note that EAP-IKE_SA_INIT messages are not encrypted or integrity
protected. However, they are not likely to be fragmented since they
do not carry certificates.
8. Retransmission
Since EAP authenticators support a timer-based retransmission
mechanism for EAP Requests and EAP peers retransmit the last valid
EAP Response when receiving a duplicate EAP Request message, IKEv2
messages MUST NOT be retransmitted based on timers, when used as
EAP authentication method.
9. Key derivation
The EAP-IKEv2 method described in this document generates session
keys. On the one hand, these session keys are used within the
IKE-SA, for protection of EAP-IKEv2 payloads, e.g., AUTH exchanges
or notifications. On the other hand, additional keys are derived
to be exported as part of the EAP keying framework [AS+05] (i.e.,
MSK, EMSK and IV).
For key derivation, EAP-IKEv2 reuses the key derivation function
as specified in Section 2.17 of [Kau04] to create keying material
KEYMAT.
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The key derivation function defined is KEYMAT = prf+(SK_d, Ni |
Nr), where Ni and Nr are the Nonces from the EAP-IKE_SA_INIT
exchange.
Since the required amount of keying material is greater than the
size of the output of the prf algorithm the prf is used iteratively.
Iteration is applied as specified in section 2.13 of [Kau04].
The produced keying material for MSK, EMSK and IV MUST be 64 octets
long for each MSK, EMSK and IV.
Figure 8 describes the keying hierarchy of EAP-IKEv2 graphically.
This figure is adopted from Figure 2 of [AS+05].
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++ ---+
| | ^
| EAP-IKEv2 Method | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++ +------------------+ | |
| | EAP-IKEv2 Diffie-Hellmann | | EAP-IKEv2 prot. | | |
| | derived and authenticated key | | session specific | | |
| | SK_d | | state (Nonce i,j)| | |
| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-++ +-------------+----+ | |
| | | | Local |
| | | | to EAP |
| | | | Method |
| | | | |
| | | | |
| | | | |
| | | | |
| +---------------+-------------+ | | |
| | | | | | |
| +-+-+-+-+-++ +-+-+-+-+-++ +-+-+-+-+-++ | |
| | MSK | |EMSK | | IV | | |
| |Derivation| |Derivation| |Derivation| | |
| +-+-+-+-+-++ +-+-+-+-+-++ +-+-+-+-+-++ | |
| | | | | V
+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-++-+-+-+-+-------+-+-+----+ ---+
| | | ^
|MSK |EMSK |IV |
| | | |
| | | Exported |
| | | by EAP |
V V V Method |
+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+ |
| AAA Key Derivation | | Known | |
| Naming & Binding | |(Not Secret) | |
+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+ V
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Legend:
MSK = Master Session Key (512 Bit)
EMSK = Extended Master Session Key (512 Bit)
SK_d = Session key derived by EAP-IKEv2
IV = Initialization Vector
Figure 8: EAP-IKEv2 Keying Hierarchy
10. Error Handling
As described in the IKEv2 specification, there are many kinds of
errors that can occur during IKE processing (i.e., processing the
Data field of EAP-IKEv2 Request and Response messages) and
detailed processing rules. EAP-IKEv2 follows the error handling
rules specified in the IKEv2 specification for errors on the Data
field of EAP-IKEv2 messages, with the following additional rules:
For an IKEv2 error that triggers an initiation of an IKEv2 exchange
(i.e., an INFORMATIONAL exchange), an EAP-IKEv2 message that
contains the IKEv2 request that is generated for the IKEv2 exchange
MUST be sent to the peering entity. In this case, the EAP message
that caused the IKEv2 error MUST be treated as a valid EAP message.
For an IKEv2 error for which the IKEv2 message that caused the error
is discarded without triggering an initiation of an IKEv2
exchange, the EAP message that carries the erroneous IKEv2 message
MUST be treated as an invalid EAP message and discarded as if it
were not received at EAP layer.
For an error occurred outside the Data field of EAP-IKEv2 messages,
including defragmentation failures, integrity check failures,
errors in Flag and Message Length fields, the EAP message that
caused the error MUST be treated as an invalid EAP message and
discarded as if it were not received at EAP layer.
When the EAP-IKEv2 method runs on a backend EAP server, the error
handling rules defined in Section 2.2 of [RFC3579] are applied for
invalid EAP-IKEv2 messages.
11. Fast Reconnect
EAP-IKEv2 supports fast reconnect, i.e., a successful reconnect
exchange creates a new IKE-SA by using a method similar to the IKE
CHILD_SA exchange defined in [KAU04]. The purpose of a
re-authentication exchange is to allow for efficient re-keying
based on the existing IKE-SA in situations where (depending on the
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given security policy) no full authentication is required in case
of an existing EAP-IKEv2 security context.
The fast reconnect exchange is similar to the IKE-SA rekeying
procedure as specified in section 2.18 of [Kau04]. However, the
exchanges for EAP-IKEv2 that are specified below do not use
rekeying payloads other than IKE SAs:
- The TS (traffic selector) payloads are not used in EAP-IKEv2.
- The [N] payload (REKEY_SA notification) is not sent by EAP-IKEv2.
During fast re-authentication, the new IKE_SA is computed as
specified in [Kau04], section 2.18. The new keying material
derived from this IKE_SA is computed in the same way as in an
initial EAP-IKEv2 authentication exchange.
Fast re-authentication allows for an optional fresh
Diffie-Hellman exchange in case the payloads Kei and KEr are
included.
The following exchanges specify fast reconnect for EAP-IKEv2,
where A is the EAP peer (responder) and B is the EAP server
(initiator):
1) A <-- B: EAP-Request/Identity
2) A --> B: EAP-Response/Identity(Id)
3) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(
HDR, SK {SA, Ni, [KEi]})
4) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR, SK {SA, Nr, [KEr]})
5) A <-- B: EAP-Success
Figure 9: Fast Reconnect exchange
The first two messages constitute the standard EAP identity
exchange and are optional; they are not required in case the EAP
server is known. Messages (3) and (4) establish the new IKE SA.
The successful fast reconnect is concluded by an EAP-Success sent
by the EAP server.
Figure 10 shows the fast reconnect message flow in case the EAP
peer fails to re-authenticate the EAP server.
1) A <-- B: EAP-Request/Identity
2) A --> B: EAP-Response/Identity(Id)
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3) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2
(HDR, SK {SA, Ni, [KEi]})
4) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR, SK {N(AUTHENTICATION_FAILED)})
5) A <-- B: EAP-Failure
Figure 10: EAP-IKEv2 fast reconnect
(server authentication failed)
Figure 11 shows the fast reconnect message flow in case the EAP
server fails to re-authenticate the EAP peer. The EAP peer MUST
send an empty EAP-IKEv2 informational message (empty encrypted
payload) in reply to the EAP server's error indication, as shown
in (6) below. The EAP server answers with an EAP-Failure.
1) A <-- B: EAP-Request/Identity
2) A --> B: EAP-Response/Identity(Id)
3) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(
HDR, SK {SA, Ni, [KEi]})
4) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR, SK {SA, Nr, [KEr]})
5) A <-- B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {N(AUTHENTICATION_FAILED)})
6) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {})
7) A <-- B: EAP-Failure
Figure 11: EAP-IKEv2 fast reconnect
(client authentication failed)
Note: The original IKEv2 protocol supports fast rekeying to be
initiated by both peers. IKE_SAs do not have lifetimes. Such
lifetimes are therefore set by local policies. Typically the peer
setting the shorter lifetime will therefore trigger the reconnect
procedure in IKEv2.
In EAP-IKEv2, the EAP authenticator or server initiate the
rekeying as this results in the most efficient message flow. If
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the client initiates fast rekeying, it needs to indicate this to
the network by appropriate out-of-band (e.g. link-layer) means.
12. Channel Binding
EAP-IKEv2 provides a channel binding functionality [RFC3784] in
order for the EAP peer and EAP server to make sure that the both
entities are given the same network access attributes such as
Calling-Station-Id, Called-Station-Id, and NAS-Port-Type by the
NAS. This is achieved by using Notify payloads to exchange
attribute data between the EAP peer and EAP server.
A Notify payload that carries a null channel binding attribute is
referred to as a channel binding request. A Notify payload which
contains a non-null channel binding attribute and is sent in
response to a channel binding request is referred to as a channel
binding response. A pair of channel binding request and channel
binding response constitutes a channel binding exchange. A
distinct Notify payload type is used for a particular type of
channel binding attribute, which is referred to as a channel
binding attribute type. It is allowed to carry multiple channel
binding requests and/or responses with different channel binding
attribute types in a single IKEv2 message. A set of channel binding
exchanges performed in a single round of EAP-IKEv2 full
authentication or fast reconnect is referred to as a channel
binding procedure.
A Notify payload that is used for reporting an error occurred
during a channel binding exchange is referred to as a channel
binding error indication.
EAP-IKEv2 offers a protected result indication mechanism (see
section 13.2). To receive protected result indication, the EAP
server MUST initiate a channel binding exchange as specified in
Figure 12, message 5. As a result of this channel binding exchange,
the client will receive a protected result indication, because the
server will initiate an informational exchange as part of the
channel binding procedure (messages 7 and 8) through the new IKE-SA
that results from a successful reconnect procedure.
12.1 Channel Binding Procedure in Full Authentication
In the case of EAP-IKEv2 full authentication procedure, the
channel binding procedure is performed in the following way.
The EAP peer MAY include one or more channel binding request in
an IKE_SA_INIT response. The EAP server MAY include one or more
channel binding request in an IKE_AUTH request. When the EAP server
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receives an IKE_SA_INIT response with one or more channel binding
request, it MUST include the corresponding channel binding
response(s) an IKE_AUTH request (in addition to its channel
binding request(s) if any). When the EAP peer receives an IKE_AUTH
request with one or more channel binding request, it MUST include
the corresponding channel binding response(s) in an IKE_AUTH
response.
When the EAP server successfully validates all the channel binding
response(s) sent by the EAP server, it initiates an INFORMATIONAL
exchange, where an empty payload is used in both INFORMATIONAL
request and INFORMATIONAL response. This exchange serves as a
protected success indication. After completion of this
INFORMATIONAL exchange, the EAP server sends Success message.
12.2 Channel Binding Procedure in Fast Reconnect
In the case of EAP-IKEv2 fast reconnect, the channel binding
procedure is performed in the following way.
In the pair of CREATE_CHILD_SA exchange, the EAP peer and/or the
EAP server MAY include one or more channel binding request, one
for each channel binding attribute that needs validation. When
the EAP peer receives a CREATE_CHILD_SA request with containing
one or more channel binding request, it MUST contain channel
binding response(s) in the CREATE_CHILD_SA response, as well as
its channel binding request(s) if any. This piggybacking is
possible because the CREATE_CHILD_SA exchange is protected with
the old IKE_SA. When the EAP server receives a CREATE_CHILD_SA
response, if it has one or more channel binding response to send
to the EAP peer, it initiates an INFORMATIONAL exchange
immediately after completion of the CREATE_CHILD_SA exchange,
where one or more channel binding response is carried in the
INFORMATIONAL request. If the EAP peer successfully validates the
channel binding response(s), it MUST respond with an empty
INFORMATIONAL response. This exchange serves as a protected
success indication. After completion of this INFORMATIONAL
exchange, the EAP server sends Success message.
12.3 Channel Binding Error Indication
A channel binding error is detected by the EAP peer or EAP server
when (i) a channel binding response is not contained in the
expected IKEv2 message or (ii) a channel binding response is
contained in the expected IKEv2 message but the channel binding
attribute does not have the expected value. Whenever a channel
binding error is detected, the detecting entity MUST send a channel
binding error indication to its peering entity. In case of (ii),
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the channel binding error indication MUST contain the channel
binding attribute that caused the error.
When the EAP server detects a channel binding error, a channel
binding error indication MUST be carried in an INFORMATIONAL
request, and the EAP peer MUST respond with an empty INFORMATIONAL
response.
When the EAP peer detects a channel binding error, a channel
binding error indication MUST be carried in an IKEv2 error
reporting message for which the R-flag of the IKEv2 header MUST
be set. The EAP server MUST respond with EAP-Failure message when
it receives such a channel binding error indication.
12.4 Notify Payload Types for Channel Binding
The following Notify Payload types are defined for the purpose of
channel binding exchange.
CALLING_STATION_ID TBD
The payload data in a channel binding response of this type
contains octet string representation of
Calling-Station-Id value known to the EAP server by using
an external mechanism.
CALLED_STATION_ID TBD
The payload data in a channel binding response of this type
contains octet string representation of Called-Station-Id
value known to the EAP peer by using an external mechanism.
NAS_PORT_TYPE TBD
The payload data in a channel binding response of this type
contains 4-octet unsigned integer value of NAS-Port-Type
known to the EAP peer by using an external mechanism.
The following Notify Payload types are defined for the purpose of
reporting when there is an error in a channel binding exchange.
INVALID_CALLING_STATION_ID TBD
The payload data (if non-null) contains octet string
representation of Calling-Station-Id value that caused the
error.
INVALID_CALLED_STATION_ID TBD
The payload data (if non-null) contains octet string
representation of Called-Station-Id value that caused the
error.
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INVALID_NAS_PORT_TYPE TBD
The payload data (if non-null) contains 4-octet unsigned
integer value of NAS-Port-Type that caused the error.
Table 1 shows the entity that is allowed to send a channel binding
request for each channel binding attribute type.
channel binding The entity that is allowed to send
attribute type channel binding request
----------------------+---------------------------------------
CALLING_STATION_ID EAP server
CALLED_STATION_ID EAP peer
NAS_PORT_TYPE EAP server
Table 1: Channel Binding Attribute Types and Requesting
Entities
12.5 Examples
In the figures of this section, a Notify payload tagged with '*'
indicates a Notify payload with null data (i.e., a channel binding
request). a Notify payload no tagged with '*' indicates a Notify
payload with non-null data (i.e., a channel binding response).
Figure 12 shows an example of EAP-IKEv2 authentication sequence
with a successful channel binding procedure. The first two
messages constitute the standard EAP identity exchange and are
optional.
1) A <-- B: EAP-Request/Identity
2) A --> B: EAP-Response/Identity(Id)
3) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(HDR(A,0), SAi1, KEi, Ni)
4) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SAr1, KEr, Nr, [CERTREQ,]
N(CALLED_STATION_ID*))
5) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {IDi, [CERT,] [CERTREQ,] [IDr,], AUTH,
N(CALLED_STATION_ID),
N(CALLING_STATION_ID*),
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N(NAS_PORT_TYPE*)})
6) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {IDr, [CERT,] AUTH,
N(CALLING_STATION_ID),
N(NAS_PORT_TYPE)})
7) A <-- B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {})
8) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {})
9) A <-- B: EAP-Success
Figure 12: EAP-IKEv2 with successful channel binding
Figure 13 shows an example of EAP-IKEv2 authentication sequence
when the EAP server detects an error in a channel binding
procedure. The first two messages constitute the standard EAP
identity exchange and are optional. In this case, message 7) and
8) MUST constitute an INFORMATIONAL exchange.
1) A <-- B: EAP-Request/Identity
2) A --> B: EAP-Response/Identity(Id)
3) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(HDR(A,0), SAi1, KEi, Ni)
4) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SAr1, KEr, Nr, [CERTREQ,]
N(CALLED_STATION_ID*))
5) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {IDi, [CERT,] [CERTREQ,] [IDr,], AUTH,
N(CALLED_STATION_ID),
N(CALLING_STATION_ID*),
N(NAS_PORT_TYPE*)})
6) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {IDr, [CERT,] AUTH,
N(CALLING_STATION_ID),
N(NAS_PORT_TYPE)})
7) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {N(INVALID_CALLING_STATION_ID)})
8) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
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HDR(A,B), SK {})
9) A <-- B: EAP-Failure
Figure 13: EAP-IKEv2 with channel binding error
(detected by EAP server)
Figure 14 shows an example of EAP-IKEv2 authentication sequence
when the EAP peer detects an error in a channel binding procedure.
The first two messages constitute the standard EAP identity
exchange and are optional.
1) A <-- B: EAP-Request/Identity
2) A --> B: EAP-Response/Identity(Id)
3) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(HDR(A,0), SAi1, KEi, Ni)
4) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SAr1, KEr, Nr, [CERTREQ,]
N(CALLED_STATION_ID*))
5) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {IDi, [CERT,] [CERTREQ,] [IDr,], AUTH,
N(CALLED_STATION_ID),
N(CALLING_STATION_ID*),
N(NAS_PORT_TYPE*)})
6) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {N(INVALID_CALLED_STATION_ID)})
7) A <-- B: EAP-Failure
Figure 14: EAP-IKEv2 with channel binding error
(detected by EAP peer)
Figure 15 shows an example of EAP-IKEv2 fast reconnection sequence
with a successful channel binding procedure. The first two
messages constitute the standard EAP identity exchange and are
optional.
1) A <-- B: EAP-Request/Identity
2) A --> B: EAP-Response/Identity(Id)
3) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(HDR, SK {SA, Ni, [KEi,]
N(CALLING_STATION_ID*),
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N(NAS_PORT_TYPE*)})
4) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(HDR, SK {SA, Nr, [KEr,]
N(CALLED_STATION_ID*),
N(CALLING_STATION_ID),
N(NAS_PORT_TYPE)})
5) A <-- B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {N(CALLED_STATION_ID)})
6) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(HDR(A,B), SK {})
7) A <-- B: EAP-Success
Figure 15: Fast reconnect with channel binding error
(fast reconnect)
Figure 16 shows an example of EAP-IKEv2 fast reconnect sequence
when the EAP server detects an error in a channel binding
procedure. The first two messages constitute the standard EAP
identity exchange and are optional. In this case, message 7) and
8) MUST constitute an INFORMATIONAL exchange.
1) A <-- B: EAP-Request/Identity
2) A --> B: EAP-Response/Identity(Id)
3) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(HDR, SK {SA, Ni, [KEi,]
N(CALLING_STATION_ID*),
N(NAS_PORT_TYPE*)})
4) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(HDR, SK {SA, Nr, [KEr,]
N(CALLED_STATION_ID*),
N(CALLING_STATION_ID),
N(NAS_PORT_TYPE)})
5) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {N(INVALID_CALLING_STATION_ID)})
6) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {})
7) A <-- B: EAP-Failure
Figure 16: Fast reconnect with channel binding error
(detected by EAP server)
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Figure 17 shows an example of EAP-IKEv2 fast reconnect sequence
when the EAP peer detects an error in a channel binding procedure.
The first two messages constitute the standard EAP identity
exchange and are optional.
1) A <-- B: EAP-Request/Identity
2) A --> B: EAP-Response/Identity(Id)
3) A <-- B: EAP-Request/EAP-Type=EAP-IKEv2(HDR, SK {SA, Ni, [KEi,]
N(CALLING_STATION_ID*),
N(NAS_PORT_TYPE*)})
4) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(HDR, SK {SA, Nr, [KEr,]
N(CALLED_STATION_ID*),
N(CALLING_STATION_ID),
N(NAS_PORT_TYPE)})
5) A <-- B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {N(CALLED_STATION_ID)})
6) A --> B: EAP-Response/EAP-Type=EAP-IKEv2(
HDR(A,B), SK {N(INVALID_CALLED_STATION_ID)})
7) A <-- B: EAP-Failure
Figure 17: Fast reconnect with channel binding error
(detected by EAP peer)
13. Security Considerations
13.1 General Considerations
The security of EAP-IKEv2 is intentionally based on IKEv2 [Kau04].
Therefore, the security claims of EAP-IKEv2 are derived mainly
from the security offered by the supported features of IKEv2.
IKEv2 provides an improvement over IKEv1 [RFC2409] as described
in Appendix A of [Kau04]. Important for this document are the
reduced number of initial exchanges, decreased latency of the
initial exchange, and some other fixes (e.g., hash problem). IKEv2
is a cryptographically sound protocol that has received a
considerable amount of expert review and that benefits from a long
practical experience with IKE.
In addition, IKEv2 provides authentication and key exchange
capabilities which allow an entity to use symmetric as well as
asymmetric authentication within a single protocol. Such
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flexibility is considered important for an EAP method and is
provided by EAP-IKEv2.
[Per03] provides a good tutorial for IKEv2 design decisions.
13.2 Security Claims
Authentication mechanism:
Mutual authentication is supported based on either pre-shared
symmetric keys or public/private key pairs. Besides certificates,
plain public keys can be used. It is possible to use different types
of authentication for the different directions within one
authentication exchange. An example is the server using
certificate-based authentication and the client using pre-shared
secrets.
EAP-IKEv2 changes the roles regarding password usage: The EAP
server acts as initiator, the remote peer as responder. This
results in an exchange which protects user authentication (based
on a shared secret derived from a user password) to the network
through an already network (initiator-) authenticated, secured
IKEv2 SA (see e.g. message 6 of Figure 1). This prevents an attacker
from launching password-guessing attacks on the peer-generated
AUTH value.
Therefore, dictionary attacks are not applicable in the context
of EAP-IKEv2 in the case the EAP peer uses a password-derived
shared secret.
Man-in-the-middle attacks discovered in the context of tunneled
authentication protocols (see [AN03] and [PL+03]) are not
applicable to EAP-IKEv2 as the extended authentication feature of
IKEv2 is not supported by EAP-IKEv2. Hence, the cryptographic
binding claim is not applicable.
Ciphersuite negotiation is supported as specified in IKEv2 for
IKE-SAs. The negotiation for IPsec (Child) SAs is not supported,
as such SAs are not generated by EAP-IKEv2.
Protected result indication as described in section 7.16 of
[RFC3748] is optionally provided by EAP-IKEv2. In message 5 of
figure 1 (full successful authentication) the EAP server
authenticates to the client. Message 6 authenticates the client
to the server, and the client by authenticating the server and by
sending message 6 expresses that it is willing to accept access.
The client, however, does not get a protected result indication
from the server in this case. An attacker could potentially forge
an EAP success/failure message which could result in DoS to the
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client. In some situations, synchronization may be achieved by
lower layer indications.
Protected result indication is optionally provided as specified
in section 12.
If this mechanism is not used, the recommended behavior for the
client is to assume the correct establishment of a new IKE-SA after
sending message 6, independent of the receipt of an EAP
success/failure. In case of unsuccessful authentication, the
server would answer with a notification (which, in case of the fast
reconnect exchange, would be protected by the old IKE-SA). In case
of a lost message 6, the server would retransmit message 5,
indicating the message loss to the client.
The client implementation can minimize potential DoS risks due to
missing protected result indications by assuming the correct
establishment of a new IKE-SA after not receiving one of the above
messages within a certain time window after sending message 6. In
the fast reconnect case, the client needs to hold both the old and
the new IKE-SA in parallel during this time window.
Session independence is optionally provided if the fast reconnect
exchange includes the KE payloads (new Diffie-Hellman) as
described in section 11, Figure 9.
Security claims:
Ciphersuite negotiation: Yes
Mutual authentication: Yes
Integrity protection: Yes
Replay protection: Yes
Confidentiality: Yes
Key derivation: Yes
Key strength: Variable
Dictionary attack prot.: Yes
Fast reconnect: Yes
Crypt. binding: N/A
Protected result ind.: yes
Session independence: yes
Fragmentation: Yes
Channel binding: Yes
14. IANA Considerations
This section provides guidance to the IANA regarding registration
of values related to the EAP-IKEv2 protocol, in accordance with
[RFC2434].
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The following terms are used here with the meanings defined in
[RFC2434]: "name space" and "registration".
The following policies are used here with the meanings defined in
[RFC2434]: "Expert Review" and "Specification Required".
This document introduces one new Internet Assigned Numbers
Authority (IANA) consideration:
- It requires IANA to allocate an EAP-Request/Response Type for
EAP-IKEv2.
<TBD: IANA considerations for channel binding notify payloads>
15. Normative References
[RFC3748] Aboba, Blunk, Carlson and Levkowetz: "Extensible
Authentication Protocol (EAP)", RFC 3748, June 2004.
[Kau04] C. Kaufman: "Internet Key Exchange (IKEv2) Protocol",
internet draft, Internet Engineering Task Force, September 2004.
Work in progress.
[RFC2119] S. Bradner: "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, Internet Engineering Task Force,
March 1997.
[RFC2434] Narten, T. and H. Alvestrand, "Guidelines for Writing
an IANA Considerations Section in RFCs", BCP 26, RFC 2434, October
1998.
16. Informative References
[AN03] N. Asokan, V. Niemi, and K. Nyberg: "Man-in-the-middle in
tunnelled authentication", In the Proceedings of the 11th
International Workshop on Security Protocols, Cambridge, UK,
April 2003. To be published in the Springer-Verlag LNCS series.
[PL+03] J. Puthenkulam, V. Lortz, A. Palekar, D. Simon, and B.
Aboba, "The compound authentication binding problem," internet
draft, Internet Engineering Task Force, October 2003. Expired.
[RFC2409] D. Harkins, D. Carrel: "The Internet Key Exchange
(IKE)", RFC 2409, November 1998.
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Internet-Draft EAP-IKEv2 July 2005
[Per03] R. Perlman: "Understanding IKEv2: Tutorial, and rationale
for decisions", internet draft, Internet Engineering Task Force,
2003. Expired.
[AS+05] B. Aboba, D. Simon, J. Arkko, P. Eronen and H. Levkowetz:
"Extensible Authentication Protocol (EAP) Key Management
Framework", internet draft, Internet Engineering Task Force,
April, 2005. Work in progress.
[PS+03] A. Palekar, D. Simon, G. Zorn, H. Zhou and S. Josefsson:
"Protected EAP Protocol (PEAP)", internet draft, Internet
Engineering Task Force, July 2004. Work in progress.
Acknowledgments
We would like to thank Bernard Aboba, Jari Arkko, Guenther Horn,
Paoulo Pagliusi and John Vollbrecht for their comments to this
draft.
Additionally we would like to thank members of the PANA design team
(namely D. Forsberg and A. Yegin) for their comments and input to
the initial version of the draft.
Finally we would like to thank the members of the EAP keying design
team for their discussion in the area of the EAP Key Management
Framework.
Author's Addresses
Hannes Tschofenig
Siemens AG
Otto-Hahn-Ring 6
81739 Munich
Germany
EMail: Hannes.Tschofenig@siemens.com
Dirk Kroeselberg
Siemens AG
Otto-Hahn-Ring 6
81739 Munich
Germany
EMail: Dirk.Kroeselberg@siemens.com
Yoshihiro Ohba
Toshiba America Research, Inc.
1 Telcordia Drive
Piscataway, NJ 08854
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Internet-Draft EAP-IKEv2 July 2005
USA
Phone: +1 732 699 5305
EMail: yohba@tari.toshiba.com
Florent Bersani
France Telecom R&D
38, rue du General Leclerc
Issy-Les-Moulineaux 92794 Cedex 9
FR
EMail: florent.bersani@francetelecom.com
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Tschofenig et al. Expires û November 18, 2005 Page 29]
Internet-Draft EAP-IKEv2 July 2005
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Datatracker
draft-tschofenig-eap-ikev2-07
Internet-Draft
