Internet DRAFT - draft-ietf-manet-nhdp-sec
draft-ietf-manet-nhdp-sec
Mobile Ad hoc Networking (MANET) U. Herberg
Internet-Draft Fujitsu Laboratories of America
Intended status: Standards Track T. Clausen
Expires: November 30, 2012 LIX, Ecole Polytechnique
May 29, 2012
Using Integrity Check Values and Timestamps For Router Admittance in
NHDP
draft-ietf-manet-nhdp-sec-02
Abstract
This document specifies a security extension to the MANET
Neighborhood Discovery Protocol (NHDP). The extension introduces the
use of Integrity Check Values (ICVs) and Timestamps in HELLO messages
in order to provide a router admittance mechanism, and therefore to
counter a selection of security threats to NHDP.
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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This Internet-Draft will expire on November 30, 2012.
Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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include Simplified BSD License text as described in Section 4.e of
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the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Applicability Statement . . . . . . . . . . . . . . . . . . . 4
4. Protocol Overview and Functioning . . . . . . . . . . . . . . 5
5. HELLO Message Content . . . . . . . . . . . . . . . . . . . . 5
6. HELLO Message Generation . . . . . . . . . . . . . . . . . . . 6
7. HELLO Message Processing . . . . . . . . . . . . . . . . . . . 6
7.1. Invalidating a Message Based on ICVs . . . . . . . . . . . 7
7.2. Invalidating a Message Based on Timestamps . . . . . . . . 8
8. Provisioning of NHDP Routers . . . . . . . . . . . . . . . . . 9
9. Summary of NHDP Interaction . . . . . . . . . . . . . . . . . 9
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
11. Security Considerations . . . . . . . . . . . . . . . . . . . 9
11.1. Alleviated Attacks . . . . . . . . . . . . . . . . . . . . 10
11.1.1. Identity Spoofing . . . . . . . . . . . . . . . . . . 10
11.1.2. Link Spoofing . . . . . . . . . . . . . . . . . . . . 10
11.1.3. Replay Attack . . . . . . . . . . . . . . . . . . . . 10
11.2. Limitations . . . . . . . . . . . . . . . . . . . . . . . 10
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
13.1. Normative References . . . . . . . . . . . . . . . . . . . 11
13.2. Informative References . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
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1. Introduction
This document specifies the use of Integrity Check Values (ICVs) for
router admittance in the MANET Neighborhood Discovery Protocol (NHDP)
[RFC6130]. It specifies the use of such ICVs for validating the
identity of the originator of a HELLO message, for validating of the
content (i.e., the links being advertised) of a HELLO message, and
for validating the message integrity.
This document uses the TLVs defined in [RFC6622] within NHDP HELLO
messages, and specifies extensions (as enabled by Section 16 in
[RFC6130]) to the HELLO message processing.
Schematically, the mechanism specified in this document inserts
itself between [RFC6130] processing/generation of HELLO messages and
[RFC5444] encoding/decoding as illustrated in Figure 1.
Incoming | | Outgoing
HELLO Message | /|\ HELLO Message
| |
| |
\|/ |
| |
+--------------------------------+
| |
| RFC5444 Parser / Generator |
| |
+--------------------------------+
| |
Hello Message \|/ /|\ RFC6622 ICVs
Parsed | | added
D +--------------------------------+
R /_________________ | |
O \ICV not | This Specification |
P Verified | |
+--------------------------------+
| |
ICV verified \|/ /|\ HELLO Message
| | Generated
+--------------------------------+
| |
| RFC6130 |
| Processing/Generation |
+--------------------------------+
Figure 1: Relationship with RFC5444 and RFC6130.
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2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC
2119 [RFC2119].
Additionally, this document uses the terminology of [RFC5444],
[RFC6130], and [RFC6622].
Additionally, this document introduces the following terminology:
NHDP Router:
A MANET router, running NHDP as specified in [RFC6130].
3. Applicability Statement
[RFC6130] enables extensions to recognize additional reasons for
rejecting a message as "badly formed and therefore invalid for
processing", and mentions security as an explicit example.
This document:
o Specifies an extension to [RFC6130] by providing a framework for
associating ICVs to messages and for using such invalid ICVs as
one such "additional reason" for rejecting a message as "badly
formed and therefore invalid for processing".
o Uses the containers for carrying ICVs and timestamps, as well as
the registries for cryptographic code-points, specified in
[RFC6622].
o Is applicable where ICVs are an appropriate security solution.
Note that the choice of the cryptographic function are to be made
for each given deployment, and that the choice of such is out of
scope for this document.
o Assumes that a router which is able to generate correct ICVs
(e.g., has valid cryptographic keys), is considered trusted.
o Assumes that the TLV type extension of the ICV Message TLV, as
defined in [RFC6622] is 1, i.e., that an ICV is composed of a
cryptographic function over a hash value of the message as defined
in Section 12 of [RFC6622].
This document does NOT:
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o Specify how to distribute cryptographic keys, shared secrets,
parameters for cryptographic functions, etc.
o Specify how to detect compromised routers with valid keys.
o Specify how to handle compromised routers with valid keys, i.e.,
key-revocation etc.
4. Protocol Overview and Functioning
The framework presented in this document provides two
functionalities:
o Generation of an ICV for an outgoing HELLO message.
o Verification of an ICV in order to determine if an incoming HELLO
message MUST be rejected as "badly formed and therefore invalid
for processing" [RFC6130].
When an NHDP Router generates a HELLO message on an interface, this
extension:
o Specifies how to calculate an ICV for the message.
o Specifies how to include that ICV by way of a TLV.
The framework allows for adding several ICVs with different hash and
cryptographic functions.
[RFC6130] allows for rejecting incoming HELLO messages prior to
processing by NHDP. This extension specifies that for each ICV TLV
in the Message TLV Block of an incoming message, the message MUST be
rejected if the ICV can not be verified.
5. HELLO Message Content
HELLO messages MUST have the content as specified in [RFC6130]. In
addition, in order to conform to this specification, each HELLO
message MUST contain:
o A <msg-orig-addr> element (as specified in [RFC5444]).
o A <msg-seq-num> element (as specified in [RFC5444]).
o One or more ICV TLVs (as specified in [RFC6622]), generated
according to Section 6.
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If protection against replay attacks is desired, then a HELLO message
MUST also contain:
o A TIMESTAMP TLV (as specified in [RFC6622]).
6. HELLO Message Generation
After HELLO message generation ([RFC6130] Section 11.1) and before
HELLO message transmission ([RFC6130] Section 11.2), as permitted by
[RFC6130] Section 12.1, the additional elements specified in
Section 5 MUST (unless already present) be added to an outgoing HELLO
message.
The following processing steps MUST be taken for each cryptographic
algorithm that is used for generating ICVs for a HELLO message:
1. All existing TLVs (if any) of type ICV are temporarily removed
from the message. Any temporarily removed TLVs MUST be stored,
for being reinserted into the message in step 5.
2. The message size is recalculated to the size of the message
without the temporarily removed ICV TLVs.
3. The ICV value is calculated over the whole message (as resulting
after step 2) according to the chosen hash and cryptographic
function and according to Section 12.1 of [RFC6622].
4. A TLV of type ICV and with type extension 1 is added in the
Message TLV block, with the content according to Section 12.1 of
[RFC6622].
5. All other ICV TLVs that have been temporary removed, are
restored.
6. The message size is recalculated, including the new ICV TLV as
well as any restored temporarily removed ICV TLVs.
7. HELLO Message Processing
[RFC6130] specifies that:
"On receiving a HELLO message, a router MUST first check if the
message is invalid for processing by this router"
[RFC6130] proceeds to give a number of conditions that, each, will
lead to a rejection of the HELLO message as "badly formed and
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therefore invalid for processing". This document adds the following
conditions to that list which, if true, MUST cause NHDP to consider
the HELLO message as invalid for processing:
o The HELLO message does not include a <msg-orig-addr> element.
o The HELLO message does not include a <msg-seq-num> element.
o The Message TLV block of the HELLO message contains more than one
TIMESTAMP TLV with the same type extension.
o Validation of ICVs in the Message TLV block of the HELLO message
fails, according to Section 7.1.
o If protection against replay attacks is desired, validation of the
TIMESTAMP TLV of the message fails, according to Section 7.2.
7.1. Invalidating a Message Based on ICVs
1. For each ICV Message TLV in the HELLO message, the ICV TLV is
temporarily removed if:
* The ICV Message TLV type extension is not equal to 1; OR
* The ICV Message TLV type extension is equal to 1, AND the hash
function and the cryptographic function indicated in that ICV
Messsage TLV are unknown to the NHDP Router.
2. If no ICV Message TLVs remain after step 1, then validation
fails:
* The HELLO message MUST be considered "badly formed and
therefore invalid for processing", and MUST be discarded.
3. Otherwise, the HELLO message with the remaining ICV Message TLVs
(henceforth: "Known ICV Message TLVs") is processed as follows:
1. All Known ICV Message TLVs are temporarily removed from the
message, and the message size is recalculated.
2. Each of the temporarily removed Known ICV Message TLVs from
the step above is, then, processed as follows:
+ Calculate the message-hash-value over the HELLO message,
using the hash function indicated by <hash-function> in
the Known ICV Message TLV.
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+ Calculate the message-ICV-Value over the resulting
message-hash-value, using the cryptographic function, and
the key ID, indicated by <cryptographic-function> and
<key-id> in the Known ICV Message TLV.
+ If message-ICV-Value differs from the value of <ICV-data>
in the Known ICV Message TLV, then validation fails:
- The HELLO message MUST be considered "badly formed and
therefore invalid for processing", and MUST be
discarded.
4. Otherwise, the message is considered (with respect to this
specification) "valid for processing", and:
A. All temporarily removed ICV Message TLVs (i.e., all ICV TLVs
temporarily removed in both step 1 and step 3) are restored.
B. The message size is restored.
7.2. Invalidating a Message Based on Timestamps
An NHDP Router which requires protection against replay attacks MUST:
o Be configured with a list of TIMESTAMP type extensions, which it
supports.
o For each of these TIMESTAMP type extensions, define
MAX_TIMESTAMP_DIFF as the maximum allowed difference between the
"expected timestamp value" and the "timestamp value" encoded in
the TIMESTAMP TLV of an incoming HELLO message (e.g., to
accommodate for propagation delays across a network).
A HELLO message MUST be considered "badly formed and therefore
invalid for processing", and MUST be discarded if either of the two
following conditions are true:
o The Message TLV Block of the HELLO message does not contain a
TIMESTAMP TLV with a type extension matching (one of) the
timestamp types, known by the receiving NHDP Router.
o The Message TLV Block of the HELLO message does contain a
TIMESTAMP TLV with a type extension matching (one of) the
timestamp types, known by the receiving NHDP Router, but where the
value of that TIMESTAMP TLV differs from the expected value by
more than MAX_TIMESTAMP_DIFF.
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8. Provisioning of NHDP Routers
Before an NHDP Router is able to generate ICVs or validate messages,
it MUST acquire the cryptographic key(s) and any parameters of the
cryptographic function from all other routers that are to participate
in the network. This document does not specify how a router acquires
the cryptographic keys and parameters used in the MANET.
9. Summary of NHDP Interaction
When using the NHDP security extension, specified in this document,
the following MUST be observed:
o HELLO messages MUST be generated according to [RFC6130].
o Outgoing HELLO messages, generated by [RFC6130], MUST be processed
according to Section 6 after their generation and prior to their
transmission by [RFC6130], in order that (an) ICV TLV(s) can be
generated and inserted, as allowed by Section 16 in [RFC6130].
o Any other extension to [RFC6130] which adds information to a HELLO
message MUST do so prior to the HELLO message being handed off for
ICV generation according to this specification.
o An incoming HELLO message MUST be processed according to Section 7
prior to processing by [RFC6130] as allowed in Section 16 in
[RFC6130].
o Any other NHDP extension, which has added information to a HELLO
message and which wishes that the HELLO message is rejected if an
ICV is not valid, MUST likewise process the HELLO message only
after its processing according to this specification.
10. IANA Considerations
This document has no actions for IANA.
11. Security Considerations
This document specifies a protocol extension to NHDP which allows for
alleviating some of the security threats of NHDP analyzed in
[NHDP-sec-threats].
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11.1. Alleviated Attacks
This section briefly summarizes which of the security threats, from
among those detailed in [NHDP-sec-threats], that are alleviated by
the framework presented in this document.
11.1.1. Identity Spoofing
As only NHDP Routers possessing valid cryptographic keys are able to
add ICV TLVs HELLO messages, in a way which permits that these be
validated successfully, identity spoofing is counteracted.
11.1.2. Link Spoofing
Link spoofing is counteracted by the framework specified in this
document, with the same argument as in Section 11.1.1. A router
without access to valid cryptographic keys cannot generate valid ICVs
for inclusion in a HELLO message.
11.1.3. Replay Attack
Replay attacks are only counteracted if TIMESTAMP TLVs are included
in HELLO messages. This is optional, and depends on synchronized
clocks of all routers in the MANET. An attacker which records
messages to replay them later can only do so in the time interval
between the timestamp that is contained in the TIMESTAMP TLV and
MAX_TIMESTAMP_DIFF later. As an attacker cannot modify the content
of the TIMESTAMP TLV (since it does not possess the valid
cryptographic keys for generating valid ICV TLVs), it cannot replay
messages after this time interval. Within this time interval,
however, it is still possible to perform replay attacks.
11.2. Limitations
Since jamming is a physical layer issue, it cannot be alleviated by
protocols on the routing layer. This framework does not counteract
jamming attacks.
If no synchronized clocks are available in the MANET, replay attacks
cannot be counteracted by the framework provided by this document.
The framework provided by this document does not avoid or detect
security attacks by routers possessing the cryptographic keys that
are used to generate ICVs for messages.
This document depends on the quality of the used cipher algorithm and
hash function, and is as such subject the same security
considerations as applies to these.
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This document relies on an out-of-band protocol or mechanism for
distributing keys and cryptographic parameters. The security
considerations of such protocol or mechanism also apply.
This document does also not provide a key revocation mechanism.
12. Acknowledgments
The authors would like to thank Jiazi Yi (Ecole Polytechnique) for
his review and comments to this document.
13. References
13.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5444] Clausen, T., Dearlove, C., Dean, J., and C. Adjih,
"Generalized MANET Packet/Message Format", RFC 5444,
February 2009.
[RFC6130] Clausen, T., Dearlove, C., and J. Dean, "Mobile Ad Hoc
Network (MANET) Neighborhood Discovery Protocol (NHDP)",
RFC 6130, March 2011.
[RFC6622] Herberg, U. and T. Clausen, "Integrity Check Value and
Timestamp TLV Definitions for Mobile Ad Hoc Networks
(MANETs)", RFC 6622, May 2012.
13.2. Informative References
[NHDP-sec-threats]
Herberg, U., Clausen, T., and J. Yi, "Security Threats for
NHDP", work in
progress draft-ietf-manet-nhdp-sec-threats-00.txt,
April 2012.
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Authors' Addresses
Ulrich Herberg
Fujitsu Laboratories of America
1240 E. Arques Ave.
Sunnyvale, CA, 94085,
USA
Email: ulrich@herberg.name
URI: http://www.herberg.name/
Thomas Heide Clausen
LIX, Ecole Polytechnique
91128 Palaiseau Cedex,
France
Phone: +33 6 6058 9349
Email: T.Clausen@computer.org
URI: http://www.thomasclausen.org/
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