2004-06-28
IEEE C802.20-04/62
Project
IEEE 802.20 Working Group on Mobile Broadband Wireless Access
<http://grouper.ieee.org/groups/802/20/>
Title
Moving forward on IEEE 802.20 security: where are we and where do we want to go?
Date
Submitted
2004-06-28
Source(s)
Florent Bersani
Re:
MBWA Call for Contributions
Abstract
Providing security to wireless communication technologies is a rather well-understood problem from a
theoretical point of view. However, effectively delivering it in real world standards is something quite different.
Security must de done by experts to which a clear set of requirements is provided.
Purpose
Prompt the 802.20 WG to refine its security requirements and plan the way it will want security to be handled.
Notice
This document has been prepared to assist the IEEE 802.20 Working Group. It is offered as a basis for discussion and is not binding on the
contributing individual(s) or organization(s). The material in this document is subject to change in form and content after further study. The
contributor(s) reserve(s) the right to add, amend or withdraw material contained herein.
Release
The contributor grants a free, irrevocable license to the IEEE to incorporate material contained in this contribution, and any modifications thereof, in
the creation of an IEEE Standards publication; to copyright in the IEEE’s name any IEEE Standards publication even though it may include portions of
this contribution; and at the IEEE’s sole discretion to permit others to reproduce in whole or in part the resulting IEEE Standards publication. The
contributor also acknowledges and accepts that this contribution may be made public by IEEE 802.20.
Patent Policy
The contributor is familiar with IEEE patent policy, as outlined in Section 6.3 of the IEEE-SA Standards Board Operations Manual
<http://standards.ieee.org/guides/opman/sect6.html#6.3> and in Understanding Patent Issues During IEEE Standards Development
<http://standards.ieee.org/board/pat/guide.html>.
Email: florent.bersani@francetelecom.com
2004-06-28
IEEE C802.20-04/XX
What this presentation is about:
• The previous contributions to MBWA on
security
• The way the security of MBWA is perceived
by a newbie
• How security could/should be handled by
MBWA
2004-06-28
IEEE C802.20-04/XX
What this presentation is not
about:
• The state of the art on the security for
wireless communication technologies
2004-06-28
IEEE C802.20-04/XX
Caveat (1/2)
• When you listen to a presentation on
security: be paranoid and use your brain!
– Never trust a speaker that is not recognized as a
security expert, for instance, do not trust this
presentation ;-)
– Even if the speaker is recognized as a security
expert, make sure there are no
misunderstandings with him and that his
position reflects a consensus
2004-06-28
IEEE C802.20-04/XX
Caveat (2/2)
• This presentation is not made by:
– A security expert
– A networking expert
– An IEEE 802 expert
• Feel free to correct or interrupt!
2004-06-28
IEEE C802.20-04/XX
The security contributions to
802.20 so far (1/2)
• IEEE C802.20-03/06&07 - Wireless Security
Threats
– A tentative threat model and some solutions?
• IEEE C802.0-03/21 - Distributed Security
Proposal Certicom
– Distributed vs. Centralized security architecture
• IEEE C802.20-03/74&88 - An Alternative
Approach for Enhancing Security of WMANs
using Physical Layer Encryption
– Physical layer encryption
2004-06-28
IEEE C802.20-04/XX
The security contributions to
802.20 so far (2/2)
• IEEE C802.20-04/09 - DoD Wireless Security
Requirements for Sensitive but Unclassified
information
– Prompting 802.20 to meet US DoD requirements
• IEEE C802.20-04/41- IEEE 802.20 MBWA
Security Architecture
– Security Requirements and proposed solutions
• IEEE C802.20-04/56r1 - On Security Issues In
Wireless Communications Systems
– Selection of cryptographic primitives (AES and/or
RC4)
2004-06-28
IEEE C802.20-04/XX
The way 802.20 security is
perceived by a newbie (1/5)
• The PAR:
– « Security Support AES (Advanced Encryption
Standard) »
• The 802.20 requirements document:
– « 4.1.11 Network Security
• Network security in MBWA systems shall protect the service
provider from theft of service, the user’s privacy and mitigate
against denial of service attacks. Provision shall be made for
authentication of both base station and mobile terminal, for
privacy, and for data integrity consistent with the best current
commercial practice. 802.20 security is expected to be a partial
solution complemented by end-to-end solutions at higher
protocol layers such as EAP, TLS, SSL, IPSec, etc. »
2004-06-28
IEEE C802.20-04/XX
The way 802.20 security is
perceived by a newbie (2/5)
• The 802.20 requirements document (continued):
– «
• 4.1.11.1 Access Control
– Access control shall be provided using a cryptographic method.
• 4.1.11.2 Privacy Methods
– A method that will provide message integrity across the air
interface to protect user data traffic, as well as signaling
messages from unauthorized modification will be specified.
– Encryption across the air interface to protect user data traffic, as
well as signaling messages, from unauthorized disclosure will be
incorporated.
• 4.1.11.3 User Privacy
– The system will prevent the unauthorized disclosure of the user
identity. »
2004-06-28
IEEE C802.20-04/XX
The way 802.20 security is
perceived by a newbie (3/5)
• The 802.20 requirements document (continued):
– «
• 4.1.11.4 Denial of Service Attacks
– It shall be possible to prevent replay attacks by minimizing the
likelihood that authentication signatures are reused.
– It shall be possible to provide protection against Denial of
Service (DOS) attacks.
• 4.1.11.5
Security Algorithm
– The authentication and encryption algorithms shall be publicly
available on a fair and non-discriminatory basis.
– National or international standards bodies shall have approved
the algorithms.
• The algorithms shall have been extensively analysed by the
cryptographic community to resist all currently known
attacks. »
2004-06-28
IEEE C802.20-04/XX
The way 802.20 security is
perceived by a newbie (4/5)
• The security contributions
– A collection of motley documents:
• Large tutorials vs. concrete propositions
• Correct vs. Incorrect assertions*
• Low level vs. High level preoccupations
* The latter is really a major concern!!!
2004-06-28
IEEE C802.20-04/XX
The way 802.20 security is
perceived by a newbie (5/5)
• Yet another standard that does not take into
account:
– The lessons of the past?
• IPsec (http://www.schneier.com/paper-ipsec.html*)
• IEEE 802.11 (http://www.drizzle.com/~aboba/IEEE/wep-draft.zip*)
– The work that is going/has gone on elsewhere?
• IEEE 802.1AE&AF (http://www.ieee802.org/1/pages/802.1ae.html)
• IEEE 802.16&IEEE 802.11i…
* among others
2004-06-28
IEEE C802.20-04/XX
How security could/should be
handled by MBWA
• Further refine the security requirements so that
they can fed as unique input to security experts, in
an ad-hoc group?
• Organize the security experts group that will be
fed the input requirements and the proposed
solution outputs?
• Keep up the good work and the positive attitude
demonstrated so far towards security , e.g.
– Taking security into account right from the start
– Requiring « standard » and public security solutions
2004-06-28
IEEE C802.20-04/XX
Example questions to be
discussed (1/7)
• What is the target architecture?
– Ad-hoc networks, e.g. IBSS in 802.11 jargon
(only STAs)
– Infrastructure networks, e.g. BSS in 802.11
jargon (STAs communicating thanks to an AP)
• What is the time-line for 802.20?
– Tentative answer in IEEE C802.20-04/59
– Necessary if 802.20 wishes to reuse security
standards that are not yet finished like .1ae&.1af
2004-06-28
IEEE C802.20-04/XX
Example questions to be
discussed (2/7)
• How much flexibility in the security?
– Supporting many cipher suites and versions
• Expected performances of the cryptographic&security
algorithms:
– Latency, Throughput, Resource consumption (on
which devices?)
– Ease of deployment&ease of use
Example questions to be
discussed (3/7)
• Placement of the of the security sublayer and interface to it
– Where does the security sublayer fit in?
• Below the MAC, at the PHY? C802.20-03/74&88
• Just below LLC? – see e.g. IEEE 802.10-1998*
• Integrated to the MAC?
– Which frames shall be protected?
• Data
• Control
• Management
– Which different types of protection will be available?
• Confidentiality and Integrity/Replay protection
• Only Integrity/Replay protection
*withdrawn standard
Example questions to be
discussed (4/7)
• Broadcast/multicast handling
– Many ways to secure this trafic: how to compare them:
• Bandwidth consumption
• Resource requirements
• Security/Functional issues (e.g., synchronization)
• Handover impacts
– Delay possibly added to handover by security
– Various ways to deal with this (architectural,
protocolary,…)
Example questions to be
discussed (5/7)
• Security architecture: « . 802.20 security is
expected to be a partial solution complemented by
end-to-end solutions at higher protocol »
– To what extent is the solution partial?
• Denial of service attacks
– Be prepared to much discussion on what is a
serious DoS attack and what is not
– Anyway, there still is the bovine jamming
attack
Example questions to be
discussed (6/7)
• Identity protection: « system will prevent the
unauthorized disclosure of the user identity »
– Current wording allows protocol that prompt authorized
disclosure of identity ;-)
– Anyway what is the user’s identity?
• MAC address? See the debate on this in 802.1 Link Sec
• Other, e.g., NAI for EAP?
• How many bytes per frame can be sent on
security?
– Security typically needs a Nonce, a MIC tag, a SPI…
– Can be problematic, see discussions between 802.1ae
and 802.3ah!
Example questions to be
discussed (7/7)
• Random numbers vs. Counters/timestamps
– Any preference?
• Key management is currently not evoked in
the requirements document ! 
– It MUST be included with the corresponding
requirements…
– What are the requirements on a key
management scheme?
2004-06-28
IEEE C802.20-04/XX
Questions?