draft-ietf-hokey-erp-aak-08.txt   draft-ietf-hokey-erp-aak-09.txt 
Network Working Group Z. Cao Network Working Group Z. Cao
Internet-Draft H. Deng Internet-Draft H. Deng
Intended status: Standards Track China Mobile Intended status: Standards Track China Mobile
Expires: August 11, 2012 Q. Wu Expires: August 15, 2012 Q. Wu
Huawei Huawei
G. Zorn G. Zorn, Ed.
Network Zen Network Zen
February 8, 2012 February 12, 2012
EAP Re-authentication Protocol Extensions for Authenticated Anticipatory EAP Re-authentication Protocol Extensions for Authenticated Anticipatory
Keying (ERP/AAK) Keying (ERP/AAK)
draft-ietf-hokey-erp-aak-08 draft-ietf-hokey-erp-aak-09
Abstract Abstract
The Extensible Authentication Protocol (EAP) is a generic framework The Extensible Authentication Protocol (EAP) is a generic framework
supporting multiple types of authentication methods. supporting multiple types of authentication methods.
The EAP Re-authentication Protocol (ERP) specifies extensions to EAP The EAP Re-authentication Protocol (ERP) specifies extensions to EAP
and the EAP keying hierarchy to support an EAP method-independent and the EAP keying hierarchy to support an EAP method-independent
protocol for efficient re-authentication between the peer and an EAP protocol for efficient re-authentication between the peer and an EAP
re-authentication server through any authenticator. re-authentication server through any authenticator.
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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 11, 2012. This Internet-Draft will expire on August 15, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 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
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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 . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 3 2.1. Standards Language . . . . . . . . . . . . . . . . . . . . 3
2.2. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2. Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. ERP/AAK Description . . . . . . . . . . . . . . . . . . . . . 4 3. ERP/AAK Description . . . . . . . . . . . . . . . . . . . . . 4
4. ERP/AAK Key Hierarchy . . . . . . . . . . . . . . . . . . . . 6 4. ERP/AAK Key Hierarchy . . . . . . . . . . . . . . . . . . . . 7
4.1. pRK, pMSK derivation . . . . . . . . . . . . . . . . . . . 7 4.1. Derivation of the pRK and pMSK . . . . . . . . . . . . . . 8
5. Packet and TLV Extension . . . . . . . . . . . . . . . . . . . 8 5. Packet and TLV Extension . . . . . . . . . . . . . . . . . . . 9
5.1. EAP-Initiate/Re-auth-Start Packet and TLV Extension . . . 8 5.1. EAP-Initiate/Re-auth-Start Packet and TLV Extension . . . 9
5.2. EAP-Initiate/Re-auth Packet and TLV Extension . . . . . . 8 5.2. EAP-Initiate/Re-auth Packet and TLV Extension . . . . . . 9
5.3. EAP-Finish/Re-auth packet and TLV extension . . . . . . . 10 5.3. EAP-Finish/Re-auth packet and TLV extension . . . . . . . 11
5.4. TV and TLV Attributes . . . . . . . . . . . . . . . . . . 13 5.4. TV and TLV Attributes . . . . . . . . . . . . . . . . . . 14
6. Lower Layer Considerations . . . . . . . . . . . . . . . . . . 13 6. Lower Layer Considerations . . . . . . . . . . . . . . . . . . 14
7. AAA Transport Considerations . . . . . . . . . . . . . . . . . 13 7. AAA Transport Considerations . . . . . . . . . . . . . . . . . 14
8. Security Considerations . . . . . . . . . . . . . . . . . . . 13 8. Security Considerations . . . . . . . . . . . . . . . . . . . 15
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16
10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 15 10. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 16
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 17
11.1. Normative References . . . . . . . . . . . . . . . . . . . 15 11.1. Normative References . . . . . . . . . . . . . . . . . . . 17
11.2. Informative References . . . . . . . . . . . . . . . . . . 16 11.2. Informative References . . . . . . . . . . . . . . . . . . 17
1. Introduction 1. Introduction
The Extensible Authentication Protocol (EAP) [RFC3748] is a generic The Extensible Authentication Protocol (EAP) [RFC3748] is a generic
framework supporting multiple types of authentication methods. In framework supporting multiple types of authentication methods. In
systems where EAP is used for authentication, it is desirable to not systems where EAP is used for authentication, it is desirable to not
repeat the entire EAP exchange with another authenticator. The EAP repeat the entire EAP exchange with another authenticator. The EAP
Re-authentication Protocol (ERP) [RFC5296] specifies extensions to Re-authentication Protocol (ERP) [RFC5296] specifies extensions to
EAP and the EAP keying hierarchy to support an EAP method-independent EAP and the EAP keying hierarchy to support an EAP method-independent
protocol for efficient re-authentication between the peer and an EAP protocol for efficient re-authentication between the EAP re-
re-authentication server through any authenticator. The re- authentication peer and an EAP re-authentication server through any
authentication server may be in the home network or in the local authenticator. The re-authentication server may be in the home
network to which the peer is connecting. network or in the local network to which the mobile host (i.e., the
EAP re-authentication peer) is connecting.
Authenticated Anticipatory Keying (AAK) [RFC5836] is a method by Authenticated Anticipatory Keying (AAK) [RFC5836] is a method by
which cryptographic keying materials may be established prior to which cryptographic keying materials may be established prior to
handover upon one or more candidate attachment points (CAPs). AAK handover upon one or more candidate attachment points (CAPs). AAK
utilizes the AAA infrastructure for key transport. utilizes the AAA infrastructure for key transport.
This document specifies the extensions necessary to enable AAK This document specifies the extensions necessary to enable AAK
support in ERP. support in ERP.
2. Terminology 2. Terminology
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The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
2.2. Acronyms 2.2. Acronyms
The following acronyms are used in this document; see the references The following acronyms are used in this document; see the references
for more details. for more details.
AAA Authentication, Authorization and Accounting [RFC3588] AAA
Authentication, Authorization and Accounting [RFC3588]
CAP Candidate Attachment Point [RFC5836] CAP
Candidate Attachment Point [RFC5836]
EA Abbreviation for "ERP/AAK"; used in figures EA
Abbreviation for "ERP/AAK"
MH Mobile Host EA Peer
An EAP peer that supports the ERP/AAK. Note that all references
to "peer" in this document imply an EA peer, unless specifically
noted otherwise.
SAP Serving Attachment Point [RFC5836] SAP
Serving Attachment Point [RFC5836]
3. ERP/AAK Description 3. ERP/AAK Description
ERP/AAK is intended to allow the establishment of cryptographic ERP/AAK is intended to allow the establishment of cryptographic
keying materials on a single Candidate Attachment Points prior to the keying materials on a single Candidate Attachment Point prior to the
arrival of the MH at the Candidate Access Network (CAN) upon request arrival of the peer at the Candidate Access Network (CAN) upon
by the peer. request by the peer.
In this document, ERP/AAK support for the peer is assumed. Also it In this document, ERP/AAK support by the peer is assumed. Also it is
is assumed that the peer has previously completed full EAP assumed that the peer has previously completed full EAP
authentication and the peer or SAP knows the identities of authentication and that either the peer or SAP knows the identities
neighboring attachment points. Note that the behavior of the peer of neighboring attachment points. Note that the behavior of a peer
that does not support the ERP-AAK scheme defined in this that does not support the ERP-AAK scheme defined in this
specification is out of the scope of this document.Figure 1 shows the specification is out of the scope of this document. Figure 1 shows
general protocol exchange by which the keying material is established the general protocol exchange by which the keying material is
on the CAP. established on the CAP.
+------+ +-----+ +-----+ +-----------+ +------+ +-----+ +-----+ +-----------+
| Peer | | SAP | | CAP | | EA Server | | Peer | | SAP | | CAP | | EA Server |
+--+---+ +--+--+ +--+--+ +-----+-----+ +--+---+ +--+--+ +--+--+ +-----+-----+
| | | | | | | |
a. | [EAP-Initiate/ | | | a. | [EAP-Initiate/ | | |
| Re-auth-start | | | | Re-auth-start | | |
| (E-flag) | | | | (E-flag) | | |
|<---------------| | | |<---------------| | |
| | | | | | | |
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| | | |
| | | |
Figure 2: Key Distribution for ERP/AAK Figure 2: Key Distribution for ERP/AAK
ERP/AAK re-uses the packet format defined by ERP, but specifies a new ERP/AAK re-uses the packet format defined by ERP, but specifies a new
flag to differentiate EAP early-authentication from EAP re- flag to differentiate EAP early-authentication from EAP re-
authentication. The peer initiates ERP/AAK itself, or does so in authentication. The peer initiates ERP/AAK itself, or does so in
response to an EAP-Initiate/Re-Auth-Start message from the SAP. response to an EAP-Initiate/Re-Auth-Start message from the SAP.
In the latter case, the SAP MAY send the identity of a candidate In the latter case, the SAP MAY send the identity of one or more
attachment point to the peer in the EAP-Initiate/Re-auth-Start Candidate Attachment Points to which the SAP is adjacent to the peer
message (see a. in the figure 1). If the EAP-Initiate/ Re-auth-Start in the EAP-Initiate/Re-auth-Start message (see a. in Figure 1). The
packet is not supported by the peer, it MUST be silently discarded. Peer SHOULD override the identity of CAP(s) carried in EAP-Initiate/
Re-auth-Start message by sending EAP-Initiate/Re-auth with the 'E'
flag set if it knows to which CAP it will move. If the EAP-Initiate/
Re-auth-Start packet is not supported by the peer, it MUST be
silently discarded.
If the peer initiate ERP/AAK, the peer MAY send an early- If the peer initiates ERP/AAK, the peer MAY send an early-
authentication request message (EAP-Initiate/ Re-auth with the 'E' authentication request message (EAP-Initiate/Re-auth with the 'E'
flag set) containing the keyName-NAI, the CAP- Identifier, rIK and flag set) containing the keyName-NAI, the CAP-Identifier, rIK and
sequence number (see b. in the figure 1). The realm in the keyName- sequence number (see b. in Figure 1). The realm in the keyName-NAI
NAI field is used to locate the peer's ERP/AAK server. The CAP- field is used to locate the peer's ERP/AAK server. The CAP-
Identifier is used to identify the CAP. The rIK is defined in Identifier is used to identify the CAP. The rIK is defined in
RFC5296 and used to protect the integrity of the message. The Narayanan & Dondeti [RFC5296] and used to protect the integrity of
sequence number is used for replay protection. the message. The sequence number is used for replay protection.
The SAP SHOULD verify the integrity of the message at step b. If The SAP SHOULD verify the integrity of thus message at step b. If
This verifications fail, the SAP MUST send an EAP- Finish/Re-auth this verification fails, the SAP MUST send an EAP-Finish/Re-auth
message with the Result flag set to '1' (Failure).In success case, message with the Result flag set to '1' (Failure). If the
the SAP SHOULD encapsulate the early-authentication message into a verification succeeds, the SAP SHOULD encapsulate the early-
AAA message and send it to the peer's ERP/AAK server in the realm authentication message into a AAA message and send it to the peer's
indicated in the keyName-NAI field (see c. in the figure 1). ERP/AAK server in the realm indicated in the keyName-NAI field (see
c. in Figure 1).
Upon receiving the message, the ERP/AAK server MUST first use the Upon receiving the message, the ERP/AAK server MUST first use the
keyName indicated in the keyName-NAI to look up the rIK and MUST keyName indicated in the keyName-NAI to look up the rIK and check the
check the integrity and freshness of the message. Then the ERP/AAK integrity and freshness of the message. Then the ERP/AAK server MUST
server MUST verify the identity of the peer by checking the username verify the identity of the peer by checking the username portion of
portion of the KeyName-NAI. If any of the checks fail, the server the KeyName-NAI. If any of the checks fail, the server MUST send an
MUST send an early- authentication finish message (EAP-Finish/Re-auth early- authentication finish message (EAP-Finish/Re-auth with E-flag
with E-flag set) with the Result flag set to '1'. Next, the server set) with the Result flag set to '1'. Next, the server MUST
MUST authorize the CAP specified in the CAP-Identifier TLV. In authorize the CAP specified in the CAP-Identifier TLV. In the
success case, the server MUST derive a pMSK from the pRK for each CAP success case, the server MUST derive a pMSK from the pRK for the CAP
carried in the the CAP-Identifier field using the sequence number carried in the the CAP-Identifier field using the sequence number
associated with CAP-Identifier as an input to the key derivation. associated with CAP-Identifier as an input to the key derivation.
(see d. in the figure 1) (see d. in Figure 1).
Then The ERP/AAK server MUST transport the pMSK to the authorized CAP Then the ERP/AAK server MUST transport the pMSK to the authorized CAP
via AAA Section 7 as described in figure 2 (see e.1,e.2 in the figure via AAA Section 7 as illustrated above (see e.1 and e.2 in Figure 2).
2). Note that key distribution in the figure 2 is one part of step Note that key distribution in Figure 2 is one part of step d. in
d. in the figure 1. Figure 1.
Finally, in response to the EAP-Initiate/Re-auth message, the ERP/AAK Finally, in response to the EAP-Initiate/Re-auth message, the ERP/AAK
server SHOULD send the early-authentication finish message (EAP- server SHOULD send the early-authentication finish message (EAP-
Finish/ Re-auth with E-flag set) containing the identity of the Finish/ Re-auth with E-flag set) containing the identity of the
authorized CAP to the peer via the SAP and associated lifetime of authorized CAP to the peer via the SAP along with the lifetime of the
pMSK, OPTIONALLY, if the peer also requests the server for the rRK pMSK. If the peer also requests the rRK lifetime, the ERP/AAK server
lifetime, the ERP/AAK server SHOULD send the rRK lifetime in the EAP- SHOULD send the rRK lifetime in the EAP-Finish/Re-auth message. (see
Finish/Re-auth message. (see f.,g. in the figure 1). f. and g. in Figure 1).
4. ERP/AAK Key Hierarchy 4. ERP/AAK Key Hierarchy
As an extension of ERP, ERP/AAK uses a key hierarchy similar to that ERP/AAK uses a key hierarchy similar to that of ERP. The ERP/AAK
of ERP. The ERP/AAK pre-established Root Key (pRK) is derived from pre-established Root Key (pRK) is derived from either the EMSK or the
either EMSK or DSRK as specified in the section 4.1. In general, the DSRK as specified below (see Section 4.1). In general, the pRK is
pRK is derived from the EMSK in case of the peer moving in the home derived from the EMSK if the peer is located in the home AAA realm
AAA realm and derived from the DRSK in case of the peer moving in a and derived from the DRSK if the peer is in a visited realm. The
visited realm. The DSRK is delivered from the EAP server to the ERP/ DSRK is delivered from the EAP server to the ERP/AAK server as
AAK server as specified in [I-D.ietf-dime-local-keytran]. If the specified in [I-D.ietf-dime-local-keytran]. If the peer has
peer has previously been authenticated by means of ERP or ERP/AAK, previously been authenticated by means of ERP or ERP/AAK, the DSRK
the DSRK SHOULD be directly re-used. SHOULD be directly re-used.
DSRK EMSK DSRK EMSK
| | | |
+---+---+---+---+ +---+---+---+---+
| |
pRK ... pRK ...
Figure 3: ERP/AAK Root Key Derivation Figure 3: ERP/AAK Root Key Derivation
Similarly,the pre-established Master Session Key (pMSK) are derived Similarly, the pre-established Master Session Key (pMSK) is derived
from the pRK. The pMSK is established for the CAP when the peer from the pRK. The pMSK is established for the CAP when the peer
early authenticates to the network. The hierarchy relationship is early authenticates to the network. The hierarchy relationship is
illustrated Figure 4, illustrated Figure 4,
pRK pRK
| |
+--------+--------+ +--------+--------+
| |
pMSK ... pMSK ...
Figure 4: ERP/AAK Key Hierarchy Figure 4: ERP/AAK Key Hierarchy
below. below.
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pRK pRK
| |
+--------+--------+ +--------+--------+
| |
pMSK ... pMSK ...
Figure 4: ERP/AAK Key Hierarchy Figure 4: ERP/AAK Key Hierarchy
below. below.
4.1. pRK, pMSK derivation 4.1. Derivation of the pRK and pMSK
The rRK is derived as specified in [RFC5295]. The rRK is derived as specified in [RFC5295].
pRK = KDF (K, S), where pRK = KDF (K, S), where
K = EMSK or K = DSRK and K = EMSK or K = DSRK and
S = pRK Label | "\0" | length S = pRK Label | "\0" | length
The pRK Label is an IANA-assigned 8-bit ASCII string: The pRK Label is an IANA-assigned 8-bit ASCII string:
EAP Early-Authentication Root Key@ietf.org EAP Early-Authentication Root Key@ietf.org
assigned from the "USRK key labels" name space in accordance with assigned from the "USRK key labels" name space in accordance with
[RFC5295]. The KDF and algorithm agility for the KDF are as defined Salowey, et al. [RFC5295]. The KDF and algorithm agility for the
in [RFC5295]. KDF are also defined in RFC 5295.
The pMSK is derived as follows. The pMSK is derived as follows:
pMSK = KDF (K, S), where pMSK = KDF (K, S), where
K = pRK and K = pRK and
S = pMSK label | "\0" | SEQ | length S = pMSK label | "\0" | SEQ | length
The pMSK label is the 8-bit ASCII string: The pMSK label is the 8-bit ASCII string:
Early-Authentication Master Session Key@ietf.org Early-Authentication Master Session Key@ietf.org
The length field refers to the length of the pMSK in octets encoded The length field refers to the length of the pMSK in octets encoded
as specified in [RFC5295]. SEQ is sent by either the peer or the as specified in RFC 5295. SEQ is sent by either the peer or the
server in the ERP/AAK message using SEQ field or Sequence number TLV server in the ERP/AAK message using the SEQ field or the Sequence
and encoded as an 8-bit number specified in the section 5.2 and number TLV and encoded as an 16-bit number as specified in
section 5.3. Section 5.2 and Section 5.3.
5. Packet and TLV Extension 5. Packet and TLV Extension
This section describes the packet and TLV extensions for the ERP/AAK This section describes the packet and TLV extensions for the ERP/AAK
exchange. exchange.
5.1. EAP-Initiate/Re-auth-Start Packet and TLV Extension 5.1. EAP-Initiate/Re-auth-Start Packet and TLV Extension
Figure 5 shows the changed parameters contained in the EAP-Initiate/ Figure 5 shows the changed parameters contained in the EAP-Initiate/
Re-auth-Start packet defined in RFC 5296 [RFC5296]. Re-auth-Start packet defined in RFC 5296 [RFC5296].
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 1 or more TVs or TLVs ~ | 1 or more TVs or TLVs ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Cryptosuite | Authentication Tag ~ | Cryptosuite | Authentication Tag ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6 Figure 6
Flags Flags
'x' - The x flag is reserved. It MUST be set to 0. 'x' - The x flag is reserved. It MUST be ignored on receipt.
'E' - The E flag is used to indicate early-authentication. 'E' - The E flag is used to indicate early-authentication.
The rest of the 4 bits (Resved) MUST be set to 0 and ignored on The final 4 bits (Resved) MUST be set to 0 and ignored on reception.
reception.
SEQ SEQ
As defined in Section 5.3.2 of [RFC5296],this field is 16-bit As defined in Section 5.3.2 of [RFC5296],this field is 16-bit
sequence number and used for replay protection. sequence number and used for replay protection.
TVs and TLVs TVs and TLVs
keyName-NAI: As defined in RFC 5296 [RFC5296], this is carried in a keyName-NAI: As defined in RFC 5296 [RFC5296], this is carried in a
TLV payload. The Type is 1. The NAI is variable in length, not TLV payload. The Type is 1. The NAI is variable in length, not
exceeding 253 octets. The username part of the NAI is the EMSKname exceeding 253 octets. The username part of the NAI is the EMSKname
used to identify the peer. The realm part of the NAI is the peer's used to identify the peer. The realm part of the NAI is the peer's
home domain name if the peer communicates with the home EA server or home domain name if the peer communicates with the home EA server or
the domain to which the peer is currently attached (i.e., local the domain to which the peer is currently attached (i.e., local
domain name) if the peer communicates with the local EA server. The domain name) if the peer communicates with a local EA server. The
SAP knows whether the KeyName-NAI carries the local domain name by SAP knows whether the KeyName-NAI carries the local domain name by
comparing the domain name carried in KeyName-NAI with local domain comparing the domain name carried in KeyName-NAI with the local
name which is associated with the SAP and SAP has already known. domain name which is associated with the SAP. Exactly one keyName-
Exactly one keyName-NAI attribute SHALL be present in an EAP- NAI attribute SHALL be present in an EAP-Initiate/Re-auth packet and
Initiate/Re-auth packet and The realm part of it SHOULD follows the the realm part of it SHOULD follow the use of internationalized
use of internationalized domain names defined in the RFC5890 domain names defined in RFC5890 [RFC5890].
[RFC5890].
CAP-Identifier: Carried in a TLV payload.The Type is TBD (less than CAP-Identifier: Carried in a TLV payload.The Type is TBD (less than
128). This field is used to indicate the FQDN of a CAP. The value 128). This field is used to indicate the FQDN of a CAP. The value
field MUST be encoded as specified in Section 8 of RFC 3315 field MUST be encoded as specified in Section 8 of RFC 3315
[RFC3315]. Exactly one instance of the CAP-Identifier TLV MUST be
[RFC3315]. There at least one instance of the CAP-Identifier TLV present in the ERP/AAK-Key TLV.
MUST be present in the ERP/AAK-Key TLV.
Sequence number: The Type is TBD (less than 128). The value field is Sequence number: The Type is TBD (less than 128). The value field is
a 16-bit field and used in the derivation of the pMSK for a CAP. If a 16-bit field and used in the derivation of the pMSK for a CAP.
multiple CAP-Identifiers are carried,each CAP-Identifier in the
packet MUST be associated with a unique sequence number and followed
by that sequence number.
Cryptosuite Cryptosuite
This field indicates the integrity algorithm used for ERP/AAK. Key This field indicates the integrity algorithm used for ERP/AAK. Key
lengths and output lengths are either indicated or obvious from the lengths and output lengths are either indicated or obvious from the
cryptosuite name, e.g., HMAC-SHA256-128 denotes HMAC computed using cryptosuite name, e.g., HMAC-SHA256-128 denotes HMAC computed using
the SHA-256 function [RFC4868] and with the 256 bit key length and the SHA-256 function [RFC4868] with 256-bit key length and the output
output truncated to 128 bits [RFC2104]. We specify some cryptosuites truncated to 128 bits [RFC2104]. We specify some cryptosuites below:
below:
0~1 RESERVED 0-1 RESERVED
2 HMAC-SHA256-128 2 HMAC-SHA256-128
3 HMAC-SHA256-256 3 HMAC-SHA256-256
HMAC-SHA256-128 is REQUIRED to implement and SHOULD be enabled in the HMAC-SHA256-128 is REQUIRED to implement and SHOULD be enabled in the
default configuration. default configuration.
Authentication Tag Authentication Tag
This field contains the integrity checksum over the ERP/AAK packet, This field contains an integrity checksum over the ERP/AAK packet
excluding the authentication tag field itself. The value field is from the first bit of the Code field to the last bit of the
calculated using the integrity algorithm indicated in the Cryptosuite Cryptosuite field, excluding the Authentication Tag field itself.
field and rIK specified in [RFC5296] as the secret key. The length The value field is calculated using the integrity algorithm indicated
of the field is indicated by the Cryptosuite. in the Cryptosuite field and rIK specified in [RFC5296] as the secret
key. The length of the field is indicated by the Cryptosuite.
The peer uses authentication tag to determine the validity of the The peer uses the Authentication Tag to determine the validity of the
EAP-Finish/Re-auth message originates at a server. EAP-Finish/Re-auth message from the server.
If the message doesn't pass verification or authentication tag is not If the message doesn't pass verification or the Authentication Tag is
included in the message, the message SHOULD be discarded silently. not included in the message, the message SHOULD be discarded
silently.
If the EAP-Initiate/Re-auth packet is not supported by the SAP, it If the EAP-Initiate/Re-auth packet is not supported by the SAP, it
SHOULD be discarded silently. SHOULD be discarded silently. The peer MUST maintain retransmission
timers for reliable transport of the EAP-Initiate/Re-auth message.
If there is no response to the EAP-Initiate/Re-auth message from the
server after the necessary number of retransmissions (see Section 6),
the peer MUST assume that ERP/AAK is not supported by the SAP.
5.3. EAP-Finish/Re-auth packet and TLV extension 5.3. EAP-Finish/Re-auth packet and TLV extension
Figure 7 shows the changed parameters contained in the EAP-Finish/ Figure 7 shows the changed parameters contained in the EAP-Finish/
Re-auth packet defined in [RFC5296]. Re-auth packet defined in [RFC5296].
0 1 2 3 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 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 | | Code | Identifier | Length |
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+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 1 or more TVs or TLVs ~ | 1 or more TVs or TLVs ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Cryptosuite | Authentication Tag ~ | Cryptosuite | Authentication Tag ~
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 7 Figure 7
Flags Flags
'x' - The x flag is reserved. It MUST be set to 0. 'x' - The x flag is reserved. It MUST be ignored on receipt.
'E' - The E flag is used to indicate early-authentication. 'E' - The E flag is used to indicate early-authentication.
The rest of the 4 bits (Resved) MUST be set to 0 and ignored on The final 4 bits (Resved) MUST be set to 0 and ignored on reception.
reception.
SEQ SEQ
As defined in Section 5.3.2 of [RFC5296], this field is 16-bit As defined in Section 5.3.2 of [RFC5296], this field is a 16-bit
sequence number and used for replay protection. sequence number and used for replay protection.
TVs and TLVs TVs and TLVs
keyName-NAI: As defined in RFC 5296 [RFC5296], this is carried in a keyName-NAI: As defined in RFC 5296 [RFC5296], this is carried in a
TLV payload. The Type is 1. The NAI is variable in length, not TLV payload. The Type is 1. The NAI is variable in length, not
exceeding 253 octets. Exactly one keyName-NAI attribute SHALL be exceeding 253 octets. Exactly one keyName-NAI attribute SHALL be
present in an EAP-Finish/Re-auth packet. present in an EAP-Finish/Re-auth packet.
ERP/AAK-Key: Carried in a TLV payload for the key container. The ERP/AAK-Key: Carried in a TLV payload for the key container. The
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{ sub-TLV: CAP-Identifier } { sub-TLV: CAP-Identifier }
{ sub-TLV: pMSK-lifetime } { sub-TLV: pMSK-lifetime }
{ sub-TLV: pRK-lifetime } { sub-TLV: pRK-lifetime }
{ sub-TLV: Cryptosuites } { sub-TLV: Cryptosuites }
CAP-Identifier CAP-Identifier
Carried in a sub-TLV payload. The Type is TBD (less than 128). Carried in a sub-TLV payload. The Type is TBD (less than 128).
This field is used to indicate the identifier of the candidate This field is used to indicate the identifier of the candidate
authenticator. The value field MUST be encoded as specified in authenticator. The value field MUST be encoded as specified in
Section 8 of RFC 3315 [RFC3315]. There at least one instance of Section 8 of RFC 3315 [RFC3315]. There at least one instance of
the CAP-Identifier TLV MUST be present in the ERP/ AAK-Key TLV. the CAP-Identifier TLV MUST be present in the ERP/AAK-Key TLV.
pMSK-lifetime pMSK-lifetime
Carried in a sub-TLV payload of EAP-Finish/Re-auth message. The Carried in a sub-TLV payload of the EAP-Finish/Re-auth message.
Type is TBD. The value field is an unsigned 32-bit field and The Type is TBD. The value field is an unsigned 32-bit field and
contains the lifetime of the pMSK in seconds. This value is contains the lifetime of the pMSK in seconds. This value is
calculated by the server after pRK-lifetime computation upon calculated by the server after pRK-lifetime computation upon
receiving EAP-Initiate/Re-auth message. The rIK SHOULD share the receiving the EAP-Initiate/Re-auth message. The rIK SHOULD share
same lifetime as pMSK.If the 'L' flag is set, the pMSK-Lifetime the same lifetime as the pMSK. If the 'L' flag is set, the pMSK-
attribute MUST be present. Lifetime attribute MUST be present.
pRK-lifetime pRK-lifetime
Carried in a sub-TLV payload of EAP-Finish/Re-auth message. The Carried in a sub-TLV payload of EAP-Finish/Re-auth message. The
Type is TBD. The value field is an unsigned 32-bit field and Type is TBD. The value field is an unsigned 32-bit field and
contains the lifetime of the pRK in seconds. This value is contains the lifetime of the pRK in seconds. This value is
calculated by the server before pMSK-lifetime computation upon calculated by the server before pMSK-lifetime computation upon
receiving EAP-Initiate/Re-auth message. If the 'L' flag is set, receiving a EAP-Initiate/Re-auth message. If the 'L' flag is set,
the pRK-Lifetime attribute MUST be present. the pRK-Lifetime attribute MUST be present.
List of Cryptosuites List of Cryptosuites
Carried in a sub-TLV payload. The Type is 5 [RFC5296]. The value Carried in a sub-TLV payload. The Type is 5 [RFC5296]. The value
field contains a list of cryptosuites (at least one cryptosuite field contains a list of cryptosuites (at least one cryptosuite
SHOULD be included), each 1 octet in length. The allowed SHOULD be included), each 1 octet in length. The allowed
cryptosuite values are as specified in Section 5.2, above. The cryptosuite values are as specified in Section 5.2, above. The
server SHOULD include this attribute if the cryptosuite used in server SHOULD include this attribute if the cryptosuite used in
the EAP-Initiate/Re-auth message was not acceptable and the the EAP-Initiate/Re-auth message was not acceptable and the
message is being rejected. The server MAY include this attribute message is being rejected. The server MAY include this attribute
in other cases. The server MAY use this attribute to signal to in other cases. The server MAY use this attribute to signal to
the peer about its cryptographic algorithm capabilities. the peer about its cryptographic algorithm capabilities.
Cryptosuite Cryptosuite
This field indicates the integrity algorithm and PRF used for ERP/ This field indicates the integrity algorithm and PRF used for ERP/
AAK. HMAC-SHA256-128 is mandatory to implement and should be enabled AAK. HMAC-SHA256-128 is mandatory to implement and SHOULD be enabled
in the default configuration. Key lengths and output lengths are in the default configuration. Key lengths and output lengths are
either indicated or obvious from the cryptosuite name. either indicated or obvious from the cryptosuite name.
Authentication Tag Authentication Tag
This field contains the integrity checksum over the ERP/AAK packet, This field contains the integrity checksum over the ERP/AAK packet
excluding the authentication tag field itself. The value field is from the first bit of the Code field to the last bit of the
calculated using the integrity algorithm indicated in the Cryptosuite Cryptosuite field excluding the Authentication Tag field itself. The
field and rIK [RFC5296] as the integrity key. The length of the value field is calculated using the integrity algorithm indicated in
field is indicated by the corresponding Cryptosuite. the Cryptosuite field and the rIK [RFC5296] as the integrity key.
The length of the field is indicated by the corresponding
Cryptosuite.
The peer uses authentication tag to determine the validity of the The peer uses the authentication tag to determine the validity of the
EAP-Finish/Re-auth message originates at a server. EAP-Finish/Re-auth message from a server.
If the message doesn't pass verification or authentication tag is not If the message doesn't pass verification or the authentication tag is
included in the message, the message SHOULD be discarded silently. not included in the message, the message SHOULD be discarded
silently.
If the EAP-Initiate/Re-auth packet is not supported by the SAP, it is If the EAP-Initiate/Re-auth packet is not supported by the SAP, it is
discarded silently. discarded silently. The peer MUST maintain retransmission timers for
reliable transport of EAP-Initiate/Re-auth message. If there is no
response to the EAP-Initiate/Re-auth message from the server after
the necessary number of retransmissions (See Section 6), the peer
MUST assume that ERP/AAK is not supported by the SAP.
5.4. TV and TLV Attributes 5.4. TV and TLV Attributes
With the exception of the rRK-Lifetime and rMSK-Lifetime TV payloads, With the exception of the rRK-Lifetime and rMSK-Lifetime TV payloads,
the attributes specified in Section 5.3.4 of [RFC5296] also apply to the attributes specified in Section 5.3.4 of [RFC5296] also apply to
this document. In this document, new attributes which may be present this document. In this document, new attributes which may be present
in the EAP-Initiate and EAP-Finish messages are defined as below: in the EAP-Initiate and EAP-Finish messages are defined as below:
o Sequence number: This is a TV payload. The type is TBD. o Sequence number: This is a TV payload. The type is 7.
o ERP/AAK-Key: This is a TLV payload. The type is TBD.
o pRK-Lifetime: This is a TV payload. The type is TBD. o ERP/AAK-Key: This is a TLV payload. The type is 8.
o pMSK-Lifetime: This is a TV payload. The type is TBD. o pRK-Lifetime: This is a TV payload. The type is 9.
o List of Cryptosuites: This is a TLV payload. The type is TBD. o pMSK-Lifetime: This is a TV payload. The type is 10.
6. Lower Layer Considerations 6. Lower Layer Considerations
Similar to ERP, some lower layer specifications may need to be Similar to ERP, some lower layer specifications may need to be
revised to support ERP/AAK; refer to of Section 6 [RFC5296] for revised to support ERP/AAK; refer to Section 6 of [RFC5296] for
additional guidance. additional guidance.
7. AAA Transport Considerations 7. AAA Transport Considerations
AAA transport of ERP/AAK messages is the same as AAA transport of the The AAA transport of ERP/AAK messages is the same as that of the ERP
ERP message [RFC5296]. In addition, the document requires AAA message [RFC5296]. In addition, this document requires AAA transport
transport of the ERP/AAK keying materials delivered by the ERP/AAK of the ERP/AAK keying materials delivered by the ERP/AAK server to
server to the CAP. Hence, a new AAA message for ERP/AAK application the CAP. Hence, a new AAA message for the ERP/AAK application should
should be specified to transport the keying materials. be specified to transport the keying materials.
8. Security Considerations 8. Security Considerations
This section provides an analysis of the protocol in accordance with This section provides an analysis of the protocol in accordance with
the AAA key management requirements specified in RFC 4962 [RFC4962]. the AAA key management requirements specified in RFC 4962 [RFC4962].
o Cryptographic algorithm independence: ERP-AAK satisfies this o Cryptographic algorithm independence: ERP-AAK satisfies this
requirement. The algorithm chosen by the peer for calculating the requirement. The algorithm chosen by the peer for calculating the
authentication tag is indicated in the EAP-Initiate/Re-auth authentication tag is indicated in the EAP-Initiate/Re-auth
message. If the chosen algorithm is unacceptable, the EAP server message. If the chosen algorithm is unacceptable, the EAP server
returns an EAP- Finish/Re-auth message with Failure indication. returns an EAP-Finish/Re-auth message with a Failure indication.
o Strong, fresh session keys: ERP-AAK results in the derivation of o Strong, fresh session keys: ERP-AAK results in the derivation of
strong, fresh keys that are unique for the given CAP. An pMSK is strong, fresh keys that are unique for the given CAP. An pMSK is
always derived on-demand when the peer requires a key with a new always derived on-demand when the peer requires a key with a new
CAP. The derivation ensures that the compromise of one pMSK does CAP. The derivation ensures that the compromise of one pMSK does
not result in the compromise of a different pMSK at any time. not result in the compromise of a different pMSK at any time.
o Limit key scope: The scope of all the keys derived by ERP-AAK is o Limit key scope: The scope of all the keys derived by ERP-AAK is
well defined. The pRK is used to derive the pMSK for the CAP. well defined. The pRK is used to derive the pMSK for the CAP.
Different sequence numbers for each CAP MUST be used to derive a Different sequence numbers for each CAP MUST be used to derive a
unique pMSK. unique pMSK.
o Replay detection mechanism: For replay protection of ERP-AAK o Replay detection mechanism: For replay protection a sequence
messages, a sequence number associated with the pMSK is used.The number associated with the pMSK is used.The peer increments the
peer increments the sequence number by one after it sends an ERP/ sequence number by one after it sends an ERP/AAK message. The
AAK message. The server sets the expected sequence number to the server sets the expected sequence number to the received sequence
received sequence number plus one after verifying the validity of number plus one after verifying the validity of the received
the received message and responds to the message. If multiple message and responds to the message.
CAP-identifier are carried, a unique sequence number for each pMSK
SHOULD be associated for each CAP-Identifier.
o Authenticate all parties: The EAP Re-auth Protocol provides mutual o Authenticate all parties: The EAP Re-auth Protocol provides mutual
authentication of the peer and the server. The peer and SAP are authentication of the peer and the server. The peer and SAP are
authenticated via ERP. The CAP is authenticated and trusted by authenticated via ERP. The CAP is authenticated and trusted by
the SAP. the SAP.
o Peer and authenticator authorization: The peer and authenticator o Peer and authenticator authorization: The peer and authenticator
demonstrate possession of the same key material without disclosing demonstrate possession of the same keying material without
it, as part of the lower layer secure authentication protocol. disclosing it, as part of the lower layer secure authentication
protocol.
o Keying material confidentiality: The peer and the server derive o Keying material confidentiality: The peer and the server derive
the keys independently using parameters known to each entity. the keys independently using parameters known to each entity.
o Uniquely named keys: All keys produced within the ERP context can o Uniquely named keys: All keys produced within the ERP context can
be referred to uniquely as specified in this document. be referred to uniquely as specified in this document.
o Prevent the domino effect: Different sequence numbers for each CAP o Prevent the domino effect: Different sequence numbers for each CAP
MUST be used to derive the unique pMSK. So the compromise of one MUST be used to derive the unique pMSK. So the compromise of one
pMSK does not hurt any other CAP. pMSK does not hurt any other CAP.
skipping to change at page 15, line 20 skipping to change at page 16, line 23
domain-specific keys are further restricted to be used only in the domain-specific keys are further restricted to be used only in the
domain for which the keys are derived. Any other restrictions of domain for which the keys are derived. Any other restrictions of
session keys may be imposed by the specific lower layer and are session keys may be imposed by the specific lower layer and are
out of scope for this specification. out of scope for this specification.
9. IANA Considerations 9. IANA Considerations
IANA is requested to assign four TLV type values from the registry of IANA is requested to assign four TLV type values from the registry of
EAP Initiate and Finish Attributes maintained at EAP Initiate and Finish Attributes maintained at
http://www.iana.org/assignments/eap-numbers/eap-numbers.xml. http://www.iana.org/assignments/eap-numbers/eap-numbers.xml.
with the following assigned number: with the following numbers:
o Sequence number: This is a TV payload. The type is 7. o Sequence number: This is a TV payload. The type is 7.
o ERP/AAK-Key: This is a TLV payload. The type is 8. o ERP/AAK-Key: This is a TLV payload. The type is 8.
o pRK Lifetime: This is a TLV payload. The type is 9. o pRK Lifetime: This is a TLV payload. The type is 9.
o pMSK Lifetime: This is a TLV payload. The type is 10. o pMSK Lifetime: This is a TLV payload. The type is 10.
This document reuses the crytosuites we have already created for 'Re- This document reuses the crytosuites have already created for 'Re-
authentication Cryptosuites' in [RFC5296]. authentication Cryptosuites' in [RFC5296].
Further, this document instructs IANA to add a new label in the User Further, this document instructs IANA to add a new label in the User
Specific Root Keys (USRK) Key Labels of the Extended Master Session Specific Root Keys (USRK) Key Labels of the Extended Master Session
Key (EMSK) Parameters registry, as follows: Key (EMSK) Parameters registry, as follows:
EAP Early-Authentication Root Key@ietf.org EAP Early-Authentication Root Key@ietf.org
10. Acknowledgement 10. Acknowledgement
In writing this document, Yungui Wang contributed to early versions In writing this document, Yungui Wang contributed to early versions
of this document and we have received reviews from many experts in of this document and we have received reviews from many experts in
the IETF, including Tom Taylor, Tena Zou, Tim Polk, Tan Zhang and the IETF, including Tom Taylor, Tena Zou, Tim Polk, Tan Zhang, Semyon
Semyon Mizikovsky, Stephen Farrell,Sujing Zhou. We apologize if we Mizikovsky, Stephen Farrell, Radia Perlman, Miguel A. Garcia and
miss some of those who have helped us. Sujing Zhou. We apologize if we miss some of those who have helped
us.
11. References 11. References
11.1. Normative References 11.1. Normative References
[RFC2119] Bradner, S., "Key words for use in [RFC2119] Bradner, S., "Key words for use in
RFCs to Indicate Requirement Levels", RFCs to Indicate Requirement Levels",
BCP 14, RFC 2119, March 1997. BCP 14, RFC 2119, March 1997.
[RFC3315] Droms, R., Ed., Bound, J., Volz, B., [RFC3315] Droms, R., Ed., Bound, J., Volz, B.,
Lemon, T., Perkins, C., and M. Carney, Lemon, T., Perkins, C., and M. Carney,
"Dynamic Host Configuration Protocol "Dynamic Host Configuration Protocol
for IPv6 (DHCPv6)", RFC 3315, for IPv6 (DHCPv6)", RFC 3315,
skipping to change at page 18, line 4 skipping to change at page 19, line 4
EMail: denghui02@gmail.com EMail: denghui02@gmail.com
Qin Wu Qin Wu
Huawei Huawei
Floor 12, HuiHong Mansion, No.91 BaiXia Rd. Floor 12, HuiHong Mansion, No.91 BaiXia Rd.
Nanjing, Jiangsu 210001 Nanjing, Jiangsu 210001
P.R. China P.R. China
Phone: +86 25 56623633 Phone: +86 25 56623633
EMail: sunseawq@huawei.com EMail: sunseawq@huawei.com
Glen Zorn Glen Zorn (editor)
Network Zen Network Zen
227/358 Thanon Sanphawut 227/358 Thanon Sanphawut
Bang Na, Bangkok 10260 Bang Na, Bangkok 10260
Thailand Thailand
Phone: +66 (0) 87-040-4617 Phone: +66 (0) 87-040-4617
EMail: glenzorn@gmail.com EMail: glenzorn@gmail.com
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