10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 1Submission

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Submission Title: Security Suite Comparative CharacteristicsDate Submitted: 10 March, 2002Source: Bob Huang Company: Sony ElectronicsAddress: One Sony Drive TA3-12, Park Ridge, NJ 07656Voice: 201-358-4409, FAX: 201-9306397, E-Mail: robert.huang@am.sony.com

Re: P802.15.3 Security Suite

Abstract: This presentation identifies and discusses some differences in the proposed security suites. The information on the suites was drawn from contributions presented at the Schaumburg ad hoc meeting (February ’02) and related at that meeting discussions. The specific contributions were 02106-08, 02111-12 and 02114r2. Also considered were the meeting minutes (02122), the Security Sub-committee Status Report (02121) and some personal notes of mine. This contribution provides a practical perspective on the differences in the security suite proposals.

Purpose: For information and guidance to 802.15.3 prior to the Security Suite selection.

Notice: This document has been prepared to assist the IEEE P802.15. 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 acknowledges and accepts that this contribution becomes the property of IEEE and may be made publicly available by P802.15.

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 2Submission

802.15 TG3 Security Suite Comparative Characteristics

A Perspective

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 3Submission

(My) Baseline Thoughts

• The cryptographic algorithms proposed are hard to break – offer high security

• Greater attention should be paid to the strength of the protocol

• It will be difficult to thoroughly evaluate the protocol(s) in a short time

• It is best to evaluate the fit of the security suites against the applications:

‘‘Where the rubber meets the road’Where the rubber meets the road’

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 4Submission

Presentation Outline

• (My) Baseline Thoughts

• Approach to Evaluation

• What are the Major Differences?

• Look at the Trust Models

• Look at Security Topology

• Summary & Conclusions

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 5Submission

(My) Baseline Thoughts (cont.)

• The MAC (draft) standard – Must have a mandatory security suite– May have an optional security suite– Message structure (public key object) to allow

• The standards text to accommodate divergent architectures as mandatory and optional

• Either architecture to be mandatory or optional

– Based on the assertion that the security manager implementation was ‘basically free’, the security manager will be included in devices in the distributed system

– Agreed to at ad hoc in Schaumburg (Feb ’02)

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 6Submission

Approach to Evaluation

Focus on differences

• How well do the differences support the applications?

• How do the differences impact the user?

• How do the differences impact the manufacturer?

First: Identify and understand the First: Identify and understand the differencesdifferences

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 7Submission

What are the Major Differences?

Basic premeses for this comparison:• Not considering differences in cryptographic

algorithms or protocols• All approaches have flexibility in implementation

to allow ‘changing’ the fundamental characteristics– Therefore, must compare ‘native mode*’

• Most used/natural mode• Most efficient mode

* Assumption: operation outside of the ‘native mode’ will cost more

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 8Submission

What are the Major Differences?

Fundamental differences

• Trust model:– Digital certificates (fixed model or

infrastructure based)– Consumer/user trust model

• Security topology– Centralized (with PNC)– Distributed

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 9Submission

Framework for Considering Trust Models

• When is the first trust decision made?

• Interoperability

• When activated

• Control/flexibility

• Typical use model

Next: Consider trust models against this framework

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 10Submission

Trust model: Fixed model digital certificates• Imbedded at manufacture (royalty fee applies)

– Example given at Schaumburg ad hoc: $0.05 each

• Interoperability: Manufacturers must act in unison

• Activated at manufacture (fixed trust) • Control/flexibility

– Fixed by definition, therefore no flexibility after deployment

– What to accept any device that can authenticate (not restricted to a particular device)

– Consumer can not control (who is in the network)

• Typical use: DVB, 5C

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 11Submission

Trust model: Infrastructure model digital certificates

• Imbedded at manufacture (royalty)• Interoperability: typically closed system• Activated/deactivated ‘On-line’

– Implies communications infrastructure– Allows tracking of device use

• Infrastructure model allows strong central control– Single controlling party: a service provider

• not the consumer, • not the manufacture

• Typical use: Cable system

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Bob Huang, Sony ElectronicsSlide 12Submission

Trust model: Consumer/user

• Interoperability: – Dependent on P802.15.3, not on implementation or

industry agreements– Immediate interoperability

• Activated by user/consumer– At startup– At addition of new devices

• Control/flexibility– Consumer has control control

• Typical use: modeled on user controlled wired security

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 13Submission

Trust models: Conclusions

• Digital certificate trust: fixed or infrastructure based– Some additional cost at manufacture– Control

• By infrastructure• No consumer control in typical model (native mode*)

• Consumer/user trust– Similar to physical wired security: consumer controlled

* Assumption: operation outside of the ‘native mode’ will cost more • Which model applies to 802.15.3 applications?

your

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 14Submission

What are the Major Differences?

Fundamental differences

• Trust model:– Digital certificates (fixed model or

infrastructure based)– Consumer/user trust model

• Security topology– Centralized (on PNC)– Distributed

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 15Submission

Security Topology

• Security manager implementation is– More complex (costly) than simple device

security– More responsibility than simple device

• Different security topologies– Centralized (with PNC)– Distributed (each device is security manager)

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 16Submission

Centralized Security Topology

• Security manager located with PNC– Complexity centralized in one powerful device (the

PNC)– Simple to activate by user– Some critical tasks performed infrequently (n

times), therefore process power may be ‘borrowed’ from other PNC activities

• Authentication?• Key provisioning/re-provisioning

• Provides unified network wide security• Allows additional (individual) link security to

be applied

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 17Submission

Distributed Security TopologySecurity manager (capability) located in every device• Piconet is divided into logical security networks• Each device decides who it will connect to• Less exposure than centralized security manager

– Compartmentalized: Not higher security, more complex

• Each device has security manager complexity– Memory, processing power

• Critical tasks performed multiple times – up to n x n times (n x n relationships)– Authentication– Key provisioning/re-provisioning

How?

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 18Submission

Security Topology Conclusions

• Centralized topology– Less complex/lower cost– Easy to use (less user action)– Fewer authentications (better use of radio

resources)

• Distributed topology– Each device makes trust decision– Compartmentalizes security

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 19Submission

Security TopologyNumber of sequential authentications for 5 devices:

• Distributed =

SM: Security Manager

01

2

3

Display& SM

Camcorder& SM

DVD Player& SM

01

2

3

Display

Camcorder

DVD Player

• Centralized =

PNC & SM

Receiver

4DTR

PNC & SM

Receiver

4DTR& SM

4 1358Each authentication consumes channel time,

takes CPU cycles and adds delay.

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 20Submission

Security TopologyHow does the security topology overlay the MAC

control structure?

• Distributed =

SM: Security Manager

• Centralized =

PNC & SM

DTR

01

2

3

Display

Camcorder

DVD Player

Receiver

4

01

2

3

Display& SM

Camcorder& SM

DVD Player & SM

PNC & SM

Receiver

4DTR& SM

4 1358

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 21Submission

What are the Major Differences?

Fundamental differences

• Trust model:– Digital certificates (fixed model or

infrastructure based)– Consumer/user trust model

• Security topology– Centralized (on PNC)– Distributed

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 22Submission

Conclusion on Major DifferencesFramework success:1. Different approaches have different advantages

2. If the first big application of 802.15.3 fails, it will be harder for the second application to succeed.

3. Therefore consider the first applications that will make 802.15.3 a success.

4. Later consider the second applications that will make 802.15.3 a success.

5. Choose an appropriate security suite for overall success.

Go with your longest and your strongest !Closing note

10 March 2002 doc.: IEEE 802.15-02/126r0

Bob Huang, Sony ElectronicsSlide 23Submission

Conclusion on Major Differences?

Framework success:1. Different approaches have different advantages

2. If the first big application of 802.15.3 fails, it will be harder for the second application to succeed.

3. Therefore consider the first applications that will make 802.15.3 a success.

4. Later consider the second applications that will make 802.15.3 a success.

5. Choose an appropriate security suite for overall success.

Go with your longest and your strongest !Closing note