Network Working Group M. Jethanandani
Internet-Draft Ciena
Intended status: Standards Track B. Weis
Expires: August 29, 2013 K. Patel
Cisco Systems
D. Zhang
Huawei
S. Hartman
Painless Security
U. Chunduri
A. Tian
Ericsson Inc.
J. Touch
USC/ISI
February 25, 2013
Negotiation for Keying Pairwise Routing Protocols in IKEv2
draft-mahesh-karp-rkmp-03
Abstract
This document describes a mechanism to secure the routing protocols
which use unicast to transport their signaling messages. Most of
such routing protocols are TCP-based (e.g., BFD and LDP), and the TCP
Authentication Option (TCP-AO) is primarily employed for securing the
signaling messages of these routing protocols. There are also two
exceptions: BFD which is over UDP or MPLS, and RSVP-TE which is over
IP (but employs an integrated approach to protecting the signaling
messages instead of using IPsec). The proposed mechanism secures
pairwise TCP-based Routing Protocol (RP) associations, BFD
associations and RSVP-TE associations using the IKEv2 Key Management
Protocol (KMP) integrated with TCP-AO, BFD, and RSVP-TE respectively.
Included are extensions to IKEv2 and its Security Associations to
enable its key negotiation to support TCP-AO, BFD, and RSVP-TE.
Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 29, 2013.
Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminologies . . . . . . . . . . . . . . . . . . . . . . 4
1.2. Acronyms and Abbreviations . . . . . . . . . . . . . . . . 4
2. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. Types of Keys . . . . . . . . . . . . . . . . . . . . . . 6
3. Protocol Exchanges . . . . . . . . . . . . . . . . . . . . . . 7
3.1. IKE_SA_INIT . . . . . . . . . . . . . . . . . . . . . . . 7
3.2. IKE_AUTH . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.3. CREATE_CHILD_SA . . . . . . . . . . . . . . . . . . . . . 8
3.4. INFORMATIONAL . . . . . . . . . . . . . . . . . . . . . . 9
4. Operation Details . . . . . . . . . . . . . . . . . . . . . . 10
4.1. General . . . . . . . . . . . . . . . . . . . . . . . . . 10
4.2. Initial Key Specific Data Exchange . . . . . . . . . . . . 11
4.3. Key Selection, Rollover and Protocol Interaction . . . . . 11
5. Key Management Database . . . . . . . . . . . . . . . . . . . 11
6. Header and Payload Formats . . . . . . . . . . . . . . . . . . 12
6.1. Header and Payload Formats for TCP-AO . . . . . . . . . . 12
6.1.1. Security Association Payload for TCP-AO . . . . . . . 12
6.1.1.1. Transforms Substructures for TCP-AO . . . . . . . 12
6.1.1.2. Example Proposal Exchange . . . . . . . . . . . . 13
6.1.2. Derivation of TCP-AO Keying Material . . . . . . . . . 14
6.2. Security Association Payload for BFD . . . . . . . . . . . 14
6.2.1. Transforms Substructures for BFD Authentication . . . 15
6.3. Security Association Payload for RSVP-TE . . . . . . . . . 16
6.3.1. Transforms Substructures for RSVP-TE Authentication . 16
6.4. Notify and Delete Payloads . . . . . . . . . . . . . . . . 17
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
8. Security Considerations . . . . . . . . . . . . . . . . . . . 18
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 18
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
10.1. Normative References . . . . . . . . . . . . . . . . . . . 18
10.2. Informative References . . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 20
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1. Introduction
Existing routing protocols using unicast pairwise communication model
(e.g., BGP, LDP, RSVP-TE, and BFD) have cryptographic authentication
mechanisms that use a key shared between the network devices (devices
for short) on the both sides of the model to protect routing message
exchanges between endpoints. The unicast key management for these
protocols today is limited to statically configured master keys in
individual network devices. This document defines a mechanism to
secure such pairwise Routing Protocol (RP) associations using IKEv2
[RFC5996], allowing network devices to automatically exchange keying
material related information between the network devices. To benefit
the discussion, it is implied that the routing protocols mentioned in
the remainder of this memo use unicast pair-wise communication model,
unless otherwise mentioned.
This memo assumes that network devices need to be provisioned with
some credentials for a one-to-one authentication protocol. Any
method for a pairwise security protocol specified for use with IKEv2
is applicable.
When two network devices running a routing protocol have not yet
established a secure association, the two endpoints need to select a
KMP solution that meets their mutual requirements and use that KMP
solution to establish the required security before sending out any
routing protocol packets. The KMP solution typically enables the
network devices to perform mutual authentication using their
provisioned credentials and to agree upon certain keying material as
the result of an successful authentication. The keying material then
can be applied to secure the routing protocol.
1.1. Terminologies
This section lists the key terminologies used throughout the memo.
Network Device: In this memo, a router or any other type of device
participating in routing protocols is referred to as a network
device.
Key Management Database (KDMB): A KDMB is a conceptual database which
locates in the middle of a key management protocol and a routing
protocol to provide the long-term key management service. Therefore,
the RP and the KMP need not to cooperate directly.
1.2. Acronyms and Abbreviations
The following acronyms and abbreviations are used throughout this
memo.
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IKEv2 Internet Key Exchange Protocol Version 2
RP Routing Protocol
SA Security Association
KMP Key Management Protocol
2. Overview
As illustrated in Figure 1, this work makes use the state machine of
IKEv2. Assume a network device and its peer device are in State 1.
That is, the device has not authenticated its peer device and does
not have the keys to secure the routing protocol packets which it
would like to exchange with the peer. Before sending any routing
protocol packets, the two devices need to perform a IKE_SA_INIT
exchange. If the IKE_SA_INIT exchange succeeds, both network devices
are transferred to State 2 where they have agreed upon certain keying
material but have decided how to use the material to derive keys to
secure routing protocols. To achieve this objective, the two network
devices perform an IKE_AUTH exchange, in which both endpoints try to
authenticate each other and generate security associations for the
routing protocol they intend to support. If the IKE_AUTH exchange
succeeds, the network devices transfer their state to State 3 where
both endpoints are authenticated and keys for securing the routing
protocols are generated. If the endpoints intend to generate new SAs
for routing protocols by using the keying material already generated,
they can just perform an CREATE_CHILD_SA exchange. A discussion in
more details can be found in Section 4.
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-----------------------
=======> | Not Authenticated |==========
|| | No RP Keys | ||
|| ----------------------- IKE_SA_INIT exchange
|| State 1 ||
|| ||
INFORMATIONAL VV
|| --------------------------
|| | Privacy Keys Exchanged |
|| | No RP Keys |
|| --------------------------
|| || State 2
|| ||
|| |-------------------- IKE_AUTH exchange
=========| Authenticated | <============
| RP Keys Derived | ====
-------------------- ||
State 3 ^^ ||
|| CREATE_CHILD_SA
|| ||
===============
Figure 1: State Diagram
2.1. Types of Keys
Three types of keys mentioned the discussion of this memo are listed
as follows:
o PSK (Pre-Shared Key) : a PSK is a pair-wise unique key, which can
be used for securing the routing protocol exchanges or be used for
authenticating a network device by a KMP. These keys are
configured by some mechanism such as manual configuration or a
management application outside of the scope of KMP.
o Protocol master key: A protocol master key is a key exported by a
KMP for use by a routing protocol. This is the key that is shared
in the KMDB between the routing protocol and KMP. A routing
protocol may use a protocol master key directly or derive traffic
keys from it.
o Traffic key: A traffic key is the key actually used to protect the
integrity of the routing messages exchanged in a routing protocol.
In existing cryptographic authentication mechanisms for routing
protocols, the traffic key can be the same as or derived from the
protocol master key. If there is no KMP provided, a traffic key
can be the same as or derived from a pre-shared key.
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3. Protocol Exchanges
The KARP analysis in BGP, LDP, PCEP, and MSDP indicates that all of
these routing protocols need a dedicated key management protocol
[I-D.ietf-karp-routing-tcp-analysis] to confidentially exchange
keying material between endpoints. There is no need to define an
entirely new protocol for this purpose, when existing mature protocol
exchanges and methods have been vetted. This draft makes use of the
IKEv2 protocol exchanges, state machine, and policy definitions to
define a dedicated key management protocol.
The notations contained in the IKEv2 message are defined as follows.
+----------+------------------------------+
| Notation | Payload |
+----------+------------------------------+
| AUTH | Authentication |
| CERT | Certificate |
| CERTREQ | Certificate Request |
| D | Delete |
| HDR | IKEv2 Header (not a payload) |
| IDi | Identification - Initiator |
| IDr | Identification - Responder |
| KE | Key Exchange |
| Ni, Nr | Nonce |
| N | Notify |
| SA | Security Association |
| SK | Encrypted and Authenticated |
| TSi | Traffic Selector - Initiator |
| TSr | Traffic Selector - Responder |
+----------+------------------------------+
Acronyms Used in Protocol Exchange
3.1. IKE_SA_INIT
A network device desiring to negotiate a key and other associated
parameters for a pair-wise routing protocol to a peer initiates an
IKE_SA_INIT exchange defined in IKEv2 [RFC5996]. The IKE_SA_INIT
exchange is a two-message exchange that allows the network devices to
negotiate cryptographic algorithms, exchange nonce information, and
do a Diffie-Hellman (DH) [DH] exchange, for their routing protocols,
after which protocols on these network devices can communicate
privately. Note that at the end of a IKE_SA_INIT exchange the
endpoints on the both sides have not authenticated each other yet.
For the details of this exchange, refer to IKE_SA_INIT in IKEv2
[RFC5996].
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Peer (Initiator) Peer (Responder)
-------------------- ------------------
HDR, SAi1, KEi, Ni -->
<-- HDR, SAr1, KEr, Nr, [CERTREQ,]
IKE_SA_INIT
Up to this step, this work introduces no change to IKEv2.
3.2. IKE_AUTH
Next, the network devices perform an IKE_AUTH exchange defined in
IKEv2 [RFC5996]. The SA payloads contain the security policies for a
key and the associated parameters (as defined in Header and Payload
Formats (Section 6)), and the TS payloads contains traffic selectors
as defined in IKEv2 [RFC5996]. For the details of the exchange
please refer to IKE_AUTH in IKEv2 [RFC5996].
Peer (Initiator) Peer (Responder)
-------------------- ------------------
HDR, SK {IDi, [CERT,] [CERTREQ,]
[IDr,] AUTH, SAi2, TSi, TSr} -->
<-- HDR, SK {IDr, [CERT,] AUTH,
SAr2, TSi, TSr}
IKE_AUTH
In the IKE_AUTH exchange, the Initiator proposes one or more sets of
policies for the key used for securing a routing protocol in the
SAi2. The SA payload indicates that the supported policies
associated with the key are being proposed. The Responder returns
the one policy contained in SAr2 that it accepts. Based on this
policy, appropriate keying material is derived from the existing
shared keying material. At the successful conclusion of the IKE_AUTH
exchange, the initiator and responder have agreed upon a single set
of policy and keying material for a particular routing protocol.
3.3. CREATE_CHILD_SA
The network devices may then destroy the state associated with the
IKEv2 SA, continuing to use the RP policy and keying material, or
they may choose to retain them for further usages. Note that this
policy differs from IKEv2/IPsec, where the deletion of the IKEv2 SA
necessitates the deletion of the IPsec SAs. If both the network
devices choose to retain them, they may use the IKEv2 SA to
subsequently agree upon replacement policy for the same RP, or agree
upon the policy and keying material for another routing protocol.
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Either case will require the use of the IKEv2 CREATE_CHILD_SA
exchange as defined in IKEv2 [RFC5996].
A CREATE_CHILD_SA exchange therefore can be triggered in order to
1. Rekey an antique RP master key and establish a new equivalent
one,
2. Generate needed keying material for a newly executed routing
protocol based on an existing SA, or
3. Rekey an IKEv2 SA and establish a new equivalent IKEv2 SA.
Peer (Initiator) Peer (Responder)
-------------------- ------------------
HDR, SK {[N], SA, Ni, [KEi],
[TSi, TSr]} -->
<-- HDR, SK {SA, Nr, [KEr],
[TSi, TSr]}
CREATE_CHILD_SA
A CREATE_CHILD_SA exchange MAY be initiated by either end of the SA
after the initial exchanges are completed. All messages in a
CREATE_CHILD_SA exchange are cryptographically protected using the
cryptographic algorithms and keys negotiated in the initial exchange.
For details on the exchange, refer to the CREATE_CHILD_SA exchange as
defined in IKEv2 [RFC5996].
3.4. INFORMATIONAL
The IKEv2 INFORMATIONAL exchange is also useful for deleting specific
IKEv2 SAs or sending status information. The Notify (N) and Delete
(D) payloads are as those defined by IKEv2 [IKEV2-PARAMS]. For
example, if the Responder refused to accept one of Proposals sent by
the Initiator, it would return an INFORMATIONAL exchange of type
NO_PROPOSAL_CHOSEN instead of the response to CREATE_CHILD_SA.
Peer (Initiator) Peer (Responder)
------------------- ------------------
HDR, SK {[N,] [D,] ... } -->
<-- HDR, SK {[N,] [D,] ... }
INFORMATIONAL
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4. Operation Details
4.1. General
IKEv2 is used to dynamically derive keying material information
between the two network devices trying to establish or maintain a
routing protocol neighbor adjacency. Typically network devices
running the routing protocols establish neighbor adjacencies at the
routing protocol level. These routing protocols may run different
security algorithms that provide transport level security for the
protocol neighbor adjacencies. Depending on the security algorithm
used, the routing protocols are configured with security algorithm
specific keys that are either long term keys or short term session
keys. These keys are specific to the security algorithms used to
enforce transport level security for the routing protocols.
A routing protocol causes IKEv2 to execute when it needs keying
material to establish neighbor adjacency. This can be as a result of
the routing protocol neighbor being configured, neighbor changed or
updated, a local rekey policy decision, or some other event dictated
by the implementation. The keying material would allow the network
devices to then independently generate the same key and establish an
IKEv2 session between them. This is typically done by the Initiator
(IKEv2 speaker) initiating an IKEv2 IKE_SA_INIT exchange mentioned in
the section 2.1 towards its IKEv2 peer. As part of IKEv2_INIT
exchange, IKEv2 will send a message to the peer's IKEv2 port. The
format of the message is explained in Section 6. The procedure to
exchange key information is explained in Section 6. Once the keying
material information is successfully exchanged by both of the IKEv2
speakers, the IKEv2 neighbor adjacency may be torn down or kept
around as explained in Section 6.
The master key data received from IKEv2 peers is stored in the
separate Key Management Database known as KMDB. KMDB follows the
guidelines in Database of Long Lived Symmetric Cryptographic Keys
[I-D.ietf-karp-crypto-key-table], and each entry consists of Key
specific information, Security algorithm to which the Key is
applicable to, Routing Protocol Clients of interest, and the
announcing KMP Peer. KMDB is also used to notify the routing
protocols about the key updates. Typically keying material
information is exchanged whenever a routing protocol is about to
create a new neighbor adjacency. This is considered as an Initial
Key exchange mode. Keying material information is also exchanged to
refresh existing key data on an already existing neighbor adjacency.
This is considered as Key rollover exchange mode. The following
sections describes their detail behavior.
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4.2. Initial Key Specific Data Exchange
Routing protocols informs IKEv2 of its new neighbor adjacency. It
does so by creating a local entry in KMDB which consists of a
Security algorithm, Key specific information, routing protocol client
and the routing protocol neighbor. Upon a successful creation of
such an entry IKEv2 initiates KMP peering with the neighbor and
starts an initial IKE_SA_INIT exchange explained in Section 3.1
followed by the RP_AUTH exchanged explained in Section 3.2. Once the
key related information is successfully exchanged, KMDB may invoke
the routing protocol client to provide key specific information
updates if any.
4.3. Key Selection, Rollover and Protocol Interaction
A routing protocol may need to perform the key selection and rollover
in cooperation with KMDB. Such a procedure is described in Section 3
of Database of Long-Lived Symmetric Cryptographic Keys
[I-D.ietf-karp-crypto-key-table]. Details of how RP interact with
KMDB and deals with multiple keys during rollover are also described
in that section. When a routing protocol uses TCP-AO to secure its
message exchanges, conditions could be a little more complex.
Typically, a TCP-AO implementation has its own key tables. TCP-AO
may only carry out key management operations on the key tables if the
key information maintained in KDMB needs not to be updated. In
[I-D.chunduri-karp-using-ikev2-with-tcp-ao], a Gatekeeper (GK)
mechanism is provided to orchestrate the key management operations on
the TCP-AO key tables and KMDB.
5. Key Management Database
Protocol interaction between KMP and its client routing protocols is
typically done using KMDB. Routing protocols may be able to update
KMDB by performing key selection and rollover operations. During a
key selection, if there is no appropriate key found in the conceptual
database, as a part of the KMDB update, IKEv2 is initiated to connect
with its appropriate IKEv2 peer so as to generate a new key. When a
key needs to be revoked, it is also the responsibility of IKEv2 to
inform its peer to guarantee the synchronization of the databases on
the both sides. In addition, when a key is obsoleted for some
reasons when it is being used by a client routing protocol, the
routing protocol may need to be informed of this update. For the
routing protocols which using TCP-AO to secure their message
exchanges, a Gatekeeper mechanism is provided to trigger the update
of keys and manage the key revocation
[I-D.chunduri-karp-using-ikev2-with-tcp-ao].
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6. Header and Payload Formats
The protocol defined in this memo uses IKEv2 payload definitions.
However, new security policy definitions are described to support
security transforms and policy defined by routing protocol documents.
6.1. Header and Payload Formats for TCP-AO
6.1.1. Security Association Payload for TCP-AO
The TCP Authentication Option (TCP-AO) [RFC5925] is primarily
intended for BGP and other TCP-based routing protocols. In order for
IKEv2 to negotiate TCP-AO policy, a new Security Protocol Identifier
needs to be defined in the IANA registry for "IKEv2 Security Protocol
Identifiers" Magic Numbers' for ISAKMP Protocol [IKEV2-PROTOCOL-IDS].
This memo proposes adding a new Protocol Identifier to the table,
with a Protocol Name of "TCP_AO" and a value of 6.
The Security Association (SA) payload contains a list of Proposals,
which describe one or more sets of policies that a network device is
willing to use to protect a routing protocol. In the Initiator's
message, the SAi2 payload contains a list of Proposal payloads (as
defined in the next sections), each of which contains a single set of
policy that can be applied to the packets described in the Traffic
Selector (TS) payloads in the same exchange. Each set of policy is
given a particular "Proposal Number" uniquely identifying this set of
policy.
The responder includes a single Proposal payload in it's SA policy,
which denotes the choice it has made amongst the initiator's list of
Proposals. Any attributes of a selected transform MUST be returned
unmodified as explained in IKEv2 [RFC5996] section 3.3.6. The
initiator of an exchange MUST check that the accepted offer is
consistent with one of its proposals, and if not MUST terminate the
exchange.
6.1.1.1. Transforms Substructures for TCP-AO
Each Proposal has a list of Transform (T) substructures, each of
which describe a particular set of cryptographic policy choices. A
TCP-AO proposal uses the INTEG transform to negotiate the MKT Message
Authentication Code (MAC) algorithm. Cryptographic Algorithms for
TCP-AO [RFC5926] describes HMAC-SHA-1-96, AES-128-CMAC-96, which map
to the existing INTEG transform IDs of AUTH_HMAC_SHA1_96 and
AUTH_AES_CMAC_96 respectively. The use of each INTEG algorithm
implies the use of a specific KDF (deriving session keys from a
master key), and so the choice of a particular INTEG transform ID
also specifies the required KDF transform. This will be true for
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every transform ID used with TCP-AO, as required in RFC 5926 (see
Section 3.2 where the "KDF_Alg" is a fixed element of a MAC algorithm
definition for TCP-AO).
A TCP-AO proposal also requires a new type of transform, which
describes whether TCP options are to be protected by the integrity
algorithm. This memo proposes adding a new Transform Type in the
IANA registry for "Transform Type Values" [IKEV2-TRANSFORM-TYPES]
+-------+---------------------------------+
|Number | Name |
+-------+---------------------------------+
| 0 |Options Not Integrity Protected |
| 1 |Options Integrity Protected |
+-------+---------------------------------
Figure 2: Transform Type 6 - TCP Authentication Option Transform IDs
The TCP-AO KeyID is sent in the SPI field of an IKEv2 proposal. A
KeyID for TCP-AO has the same purpose as an IPsec SPI value, so it is
natural to place it in this portion of the proposal. If the KeyID
values in a responder's Proposal does not mach the KeyID values
initiator's Proposal, then they have chosen to use different KeyID
values to represent the same master key and associated proposal
policy. This is consistent with how IPsec uses the SPI value, and
the semantic of initiator and responder using different SendIDs is
supported by RFC 5925.
The following table shows the Transforms that can be negotiated for a
TCP-AO protocol.
Protocol Mandatory Types Optional Types
---------------------------------------------------
TCP-AO INTEG, TCP D-H
Figure 3: Mandatory and Optional Transforms for TCP-AO
6.1.1.2. Example Proposal Exchange
Figure 4 shows an example of IKEv2 SA Payload including a single
Proposal sent in the first message of an IKE_AUTH or CREATE_CHILD_SA
exchange. It indicates a willingness to use either of the two MAC
algorithms defined in RFC 5926, and is willing to either protect TCP
options or not. The SPI value represents the new SendID it is
associating with the TCP-AO Master Key Tuple (MKT) policy being
negotiated.
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SA Payload
|
+--- Proposal #1 ( Proto ID = TCP-AO(T6), SPI size = 1,
| 4 transforms, SPI = 0x01 )
|
+-- Transform INTEG ( Name = AUTH_HMAC_SHA1_96 )
+-- Transform INTEG ( Name = AUTH_AES_CMAC_96 )
+-- Transform TCP ( Name = PROTECT_OPTIONS )
+-- Transform TCP ( Name = NO_PROTECT_OPTIONS )
Figure 4: Example Initiator SA Payload for TCP-AO
The responder will record the SPI value to be the RecvID of the MKT.
It chooses its own SendID value, one of each Transform type, and
returns this policy in the response message. For example, if the
responder chose HMAC-SHA-1-96 and chose to protect the TCP options,
the corresponding SA payload would be:
SA Payload
|
+--- Proposal #1 ( Proto ID = TCP-AO(6), SPI size = 1,
| 2 transforms, SPI = 0x11 )
|
+-- Transform INTEG ( Name = AUTH_HMAC_SHA1_96 )
+-- Transform TCP ( Name = PROTECT_OPTIONS )
Figure 5: Example Responder SA Payload for TCP-AO
In this example, the Proposal responder chose to use a different SPI
value (0x11) as its SendID. This is possible because Section 2.2 of
[RFC5925] declares that "KeyID values MAY be the same in both
directions of a connection, but do not have to be and there is no
special meaning when they are."
6.1.2. Derivation of TCP-AO Keying Material
Each TCP-AO MAC algorithm specification in Section 3.2 of Crypto for
TCP-AO [RFC5926] defines the Key_Length as a number of bits <n>
needed as keying material for the MAC algorithm.
6.2. Security Association Payload for BFD
In order for IKEv2 to negotiate BFD authentication policy, a new
Security Protocol Identifier needs to be defined in the IANA registry
for "IKEv2 Security Protocol Identifiers" Magic Numbers' for ISAKMP
Protocol [IKEV2-PROTOCOL-IDS]. This memo proposes adding a new
Protocol Identifier to the table, with a Protocol Name of "BFD" and a
value of 7.
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6.2.1. Transforms Substructures for BFD Authentication
The base BFD specification [RFC5880] defines five authentication
mechanisms: Password, Keyed MD5, Meticulous Keyed MD5, Keyed SHA1,
and Meticulous Keyed SHA1. Because Password does not use keys, the
support of this mechanism is out of the scope of this work. In the
other four mechanisms, Keyed MD5 and Meticulous Keyed MD5 use MD5 as
the Message Authentication Code (MAC) algorithm, while Keyed SHA1 and
Meticulous Keyed SHA1 use SHA1. In
[I-D.ietf-bfd-generic-crypto-auth], a generic authentication
mechanism and a generic meticulous authentication mechanism which can
support various MAC algorithms is proposed.
Therefore, a BFD proposal also requires a new type of transform to
identify the type of BFD authentication. This memo proposes adding a
new Transform Type in the IANA registry for "Transform Type
Values"[IKEV2-TRANSFORM-TYPES]
+-------+---------------------------------+
|Number | Name |
+-------+---------------------------------+
| 0 |Base Authentication |
| 1 |Base Meticulous Authentication |
| 2 |Generic Authentication |
| 3 |Generic Meticulous Authentication|
+-------+---------------------------------+
Figure 6: Transform Type 7 - BFD Authentication Option Transform IDs
Base Authentication in Figure 6 indicates the keyed (MD5 or SHA-1)
authentication mechanism defined in the base BFD specification
[RFC5880]. Base Meticulous Authentication indicates the meticulous
keyed (MD5 or SHA-1) authentication mechanism defined in the base BFD
specification. Generic Authentication and Generic Meticulous
Authentication indicate the generic keyed authentication and the
generic keyed meticulous authentication mechanisms defined in
[I-D.ietf-bfd-generic-crypto-auth] respectively.
A BFD proposal uses INTEG transforms to negotiate Message
Authentication Code (MAC) algorithms. In the base BFD [RFC5880],
keyed MD5 and keyed SHA-1 are adopted. The two algorithms can be
identified using existing INTEG transform IDs of AUTH_HMAC_MD5_96 and
AUTH_HMAC_SHA1_96 respectively. In [I-D.ietf-bfd-hmac-sha], it is
specified that a BFD using the authentication mechanisms defined in
[I-D.ietf-bfd-generic-crypto-auth] MUST support HMAC-SHA-256 which
can be identified using existing INTEG transform IDs of
AUTH_HMAC_SHA2_256_128 [RFC4868].
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The BFD KeyID is sent in the SPI field of an IKEv2 proposal. Note
that according to [RFC5880], the length of KeyID is 8 bits.
Because in BFD the transport key is the same as the protocol master
key, no KDF needs to be negotiated.
The following figure shows the Transforms that can be negotiated for
a BFD implementation.
Protocol Mandatory Types Optional Types
---------------------------------------------------
BFD BFD, INTEG D-H
Figure 7: Mandatory and Optional Transforms for BFD
6.3. Security Association Payload for RSVP-TE
In order for IKEv2 to negotiate RSVP-TE authentication policy, a new
Security Protocol Identifier needs to be defined in the IANA registry
for "IKEv2 Security Protocol Identifiers" Magic Numbers' for ISAKMP
Protocol [IKEV2-PROTOCOL-IDS]. This memo proposes adding a new
Protocol Identifier to the table, with a Protocol Name of "RSVP-TE"
and a value of 8.
6.3.1. Transforms Substructures for RSVP-TE Authentication
In the authentication mechanism for RSVP-TE [RFC2747], only HMAC-MD5
is mandated. Therefore, no INTG transform needs to be included in a
RSVP-TE proposal.
A RSVP-TE proposal requires a new type of transform, which indicates
whether the integrity handshake (which is used to collect the latest
sequence number associated with a key ID) is permitted. This memo
proposes adding a new Transform Type in the IANA registry for
"Transform Type Values" [IKEV2-TRANSFORM-TYPES]
+-------+---------------------------------+
|Number | Name |
+-------+---------------------------------+
| 0 |Not Allowed |
| 1 |Allowed |
+-------+---------------------------------+
Figure 8: Transform Type 8 - RSVP-TE Transform IDs
The RSVP-TE KeyID is sent in the SPI field of an IKEv2 proposal.
The following figure shows the Transforms that can be negotiated for
a RSVP-TE implementation.
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Protocol Mandatory Types Optional Types
---------------------------------------------------
RSVP-TE RSVP-TE, D-H
Figure 9: Mandatory and Optional Transforms for BFD
6.4. Notify and Delete Payloads
A Notify Payload (IKEv2 [RFC5996] Section 3.10) or Delete Payload
(IKEv2 [RFC5996] Section 3.11) contains a Protocol ID field. The
Protocol ID is set to TCP_AO (6) when a notify message is relevant to
the TCP-AO KeyID value contained in the SPI field. Similarly, the
Protocol ID is set to BFD (7) when a notify message is relevant to
the BFD KeyID value contained in the SPI field, and the Protocol ID
is set to RSVP-TE (8) when a notify message is relevant to the
RSVP-TE KeyID value contained in the SPI field.
7. IANA Considerations
In order for IKEv2 to negotiate TCP-AO authentication policies, a new
Security Protocol Identifier needs to be defined in the IANA registry
for "IKEv2 Security Protocol Identifiers" Magic Numbers' for ISAKMP
Protocol [IKEV2-PROTOCOL-IDS]. IANA is requested to add a new
Protocol Identifier to the table, with a Protocol Name of "TCP-AO"
and a value of 6. A TCP-AO proposal also requires a new type of
transform, which describes whether TCP options are to be protected by
the integrity algorithm. This memo proposes adding a new Transform
Type 6 for this transform in the IANA registry for "Transform Type
Values".
In order for IKEv2 to negotiate BFD authentication policies, a new
Security Protocol Identifier needs to be defined in the IANA registry
for "IKEv2 Security Protocol Identifiers" Magic Numbers' for ISAKMP
Protocol [IKEV2-PROTOCOL-IDS]. IANA is requested to add a new
Protocol Identifier to the table, with a Protocol Name of "BFD" and a
value of 7. A BFD proposal also requires a new type of transform,
which identifies the type of BFD authentication mechanism. This memo
proposes adding a new Transform Type 7 in the IANA registry for
"Transform Type Values".
In order for IKEv2 to negotiate RSVP-TE authentication policies, a
new Security Protocol Identifier needs to be defined in the IANA
registry for "IKEv2 Security Protocol Identifiers" Magic Numbers' for
ISAKMP Protocol [IKEV2-PROTOCOL-IDS]. IANA is requested to add a new
Protocol Identifier to the table, with a Protocol Name of "RSVP-TE"
and a value of 8. A RSVP-TE proposal requires a new type of
transform, which indicates whether the integrity handshake (which is
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used to collect the latest sequence number associated with a key ID)
is permitted. This memo proposes adding a new Transform Type 8 in
the IANA registry for "Transform Type Values".
8. Security Considerations
TBD
9. Acknowledgements
During the development of TCP-AO, Gregory Lebovitz noted that a
protocol based on an IKEv2 exchange would be a good automated key
management method for deriving a TCP-AO master key.
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2747] Baker, F., Lindell, B., and M. Talwar, "RSVP Cryptographic
Authentication", RFC 2747, January 2000.
[RFC4868] Kelly, S. and S. Frankel, "Using HMAC-SHA-256, HMAC-SHA-
384, and HMAC-SHA-512 with IPsec", RFC 4868, May 2007.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, June 2010.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", RFC 5925, June 2010.
[RFC5926] Lebovitz, G. and E. Rescorla, "Cryptographic Algorithms
for the TCP Authentication Option (TCP-AO)", RFC 5926,
June 2010.
[RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,
"Internet Key Exchange Protocol Version 2 (IKEv2)",
RFC 5996, September 2010.
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10.2. Informative References
[DH] Diffie, W. and M. Hellman, "New Directions in
Cryptography", IEEE Transactions on Information
Theory, V.IT-22 n. 6, June 1977.
[I-D.chunduri-karp-using-ikev2-with-tcp-ao]
Chunduri, U., Tian, A., and J. Touch, "Using IKEv2 with
TCP-AO", draft-chunduri-karp-using-ikev2-with-tcp-ao-03
(work in progress), January 2013.
[I-D.ietf-bfd-generic-crypto-auth]
Bhatia, M., Manral, V., and D. Zhang, "BFD Generic
Cryptographic Authentication",
draft-ietf-bfd-generic-crypto-auth-03 (work in progress),
October 2012.
[I-D.ietf-bfd-hmac-sha]
Zhang, D., Bhatia, M., and V. Manral, "Authenticating BFD
using HMAC-SHA-2 procedures", draft-ietf-bfd-hmac-sha-02
(work in progress), October 2012.
[I-D.ietf-karp-crypto-key-table]
Housley, R., Polk, T., Hartman, S., and D. Zhang,
"Database of Long-Lived Symmetric Cryptographic Keys",
draft-ietf-karp-crypto-key-table-06 (work in progress),
February 2013.
[I-D.ietf-karp-routing-tcp-analysis]
Jethanandani, M., Patel, K., and L. Zheng, "Analysis of
BGP, LDP, PCEP and MSDP Issues According to KARP Design
Guide", draft-ietf-karp-routing-tcp-analysis-06 (work in
progress), December 2012.
[IKEV2-PARAMS]
"Internet Key Exchange Version 2 (IKEv2) Parameters", <htt
p://www.iana.org/assignments/ikev2-parameters/
ikev2-parameters.xml>.
[IKEV2-PROTOCOL-IDS]
"'Magic Numbers' for ISAKMP Protocol", <http://
www.iana.org/assignments/ikev2-parameters/
ikev2-parameters.xml#ikev2-parameters-18>.
[IKEV2-TRANSFORM-TYPES]
"'Magic Numbers' for ISAKMP Protocol", <http://
www.iana.org/assignments/ikev2-parameters/
ikev2-parameters.xml#ikev2-parameters-3>.
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[TCP-AO-REG]
"Internet Key Exchange Version 2 (IKEv2) Parameters", <htt
p://www.iana.org/assignments/tcp-parameters/
tcp-parameters.xml>.
Authors' Addresses
Mahesh Jethanandani
Ciena
Phone:
Fax:
Email: mjethanandani@gmail.com
URI:
Brian Weis
Cisco Systems
170 W. Tasman Drive
San Jose, California 95134
USA
Phone: +1 (408) 526-4796
Fax:
Email: bew@cisco.com
URI:
Keyur Patel
Cisco Systems
170 Tasman Drive
San Jose, California 95134
USA
Phone: +1 (408) 526-7183
Fax:
Email: keyupate@cisco.com
URI:
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Dacheng Zhang
Huawei
Beijing,
China
Phone:
Fax:
Email: zhangdacheng@huawei.com
URI:
Sam Hartman
Painless Security
Phone:
Fax:
Email: hartmans@painless-security.com
URI:
Uma Chunduri
Ericsson Inc.
300 Holger Way
San Jose, California 95134
USA
Phone:
Fax:
Email: uma.chunduri@ericsson.com
URI:
Albert Tian
Ericsson Inc.
300 Holger Way
San Jose, California 95134
USA
Phone:
Fax:
Email: albert.tian@ericsson.com
URI:
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Joe Touch
USC/ISI
4676 Admiralty Way
Marina del Rey, California 90292-6695
USA
Phone:
Fax:
Email: touch@isi.edu
URI:
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