1. An Example Protocol for FastAKM
January 2010
doc.: IEEE /0059r0
January 2010
An Example Protocol for FastAKM
Date:
Authors:
Name
Company
Address
Phone
Hiroki NAKANO
Trans New Technology, Inc.
Sumitomo-Seimei Kyoto Bldg. 8F,
62 Tukiboko-cho Shimogyo-ku,
Kyoto JAPAN
Hitoshi MORIOKA
ROOT Inc.
#33 Ito Bldg.
Tenjin, Chuo-ku,
Fukuoka JAPAN
Hiroshi MANO
8F TOC2 Bldg Nishi-Gotanda, Shinagawa-ku,
Tokyo JAPAN
This is Hiroki Nakano. My affiliation is Trans New Technology, Inc in Japan.
Hiroki Nakano, Trans New Technology, Inc.
Hiroki Nakano, Trans New Technology, Inc.

2. January 2010
doc.: IEEE /0059r0
January 2010
Abstract
FastAKM framework reduces time to set up association between AP and non-AP STA. This results in reduction of blackout time on handover and enables us to use VoIP in “mobile” environment.
We show its technical possibility in this presentation by introducing a trial of example implementation of FastAKM, which establishes an association between AP and non-AP STA by single round-trip exchange of management frames.
Hiroki Nakano, Trans New Technology, Inc.
Hiroki Nakano, Trans New Technology, Inc.

3. Requirements Employ just ONE round-trip exchange of frames
January 2010
Requirements
Employ just ONE round-trip exchange of frames
STA to AP, then AP to STA
Do all things to start user’s data exchange
Association
Authentication
Key Exchange
No direct contract between AP and non-AP STA
‘Authentication Server’ mediates between AP and non-AP STA
For separation of service providers and AP infrastructure
Possibly compatible with existing framework
Old STAs can be still operated together.
Hiroki Nakano, Trans New Technology, Inc.

4. An Example Procedure by 802.11-2007
January 2010
An Example Procedure by
STA AP
RADIUS Server
Beacon
Probe Request
Probe Response
Open System Authentication
Open System Authentication
Association Request
Association Accept
EAPOL-Start
EAP-Request/Identity
EAP-Response/Identity
RADIUS-Access-Request/Identity
RADIUS-Access-Challenge/TLS-Start
EAP-Request/TLS-Start
EAP-Response/TLS-client Hello
RADIUS-Access-Request/Pass Through
RADIUS-Access-Challenge/ Server Certificate
EAP-Request/Pass Through
EAP-Response/Client Certificate
RADIUS-Access-Request/Pass Through
RADIUS-Access-Challenge/Encryption Type
EAP-Request/Pass Through
EAP-Response
RADIUS-Access-Request
RADIUS-Access-Accept
EAP-Success
EAP-Key
Hiroki Nakano, Trans New Technology, Inc.

5. Complaint about the Procedure…
January 2010
Complaint about the Procedure…
STA AP
RADIUS Server
Beacon
Probe process is optional
Open System auth. is meaningless
Probe Request
Probe Response
Open System Authentication
Open System Authentication
Association Request
Association Accept
Any other framework than EAPOL??
EAPOL-Start
EAP-Request/Identity
EAP-Response/Identity
RADIUS-Access-Request/Identity
RADIUS-Access-Challenge/TLS-Start
EAP-Request/TLS-Start
EAP-Response/TLS-client Hello
RADIUS-Access-Request/Pass Through
RADIUS-Access-Challenge/ Server Certificate
EAP-Request/Pass Through
EAP-Response/Client Certificate
RADIUS-Access-Request/Pass Through
RADIUS-Access-Challenge/Encryption Type
EAP-Request/Pass Through
EAP-Response
RADIUS-Access-Request
RADIUS-Access-Accept
EAP-Success
EAP-Key
Hiroki Nakano, Trans New Technology, Inc.

6. Solution? We investigated and tried implementing two ideas below.
January 2010
Solution?
We investigated and tried implementing two ideas below.
Trial 1: Omit Pre-RSNA Auth. Process
Trial 2: Piggyback Auth. Info. onto Association Request/Response
Hiroki Nakano, Trans New Technology, Inc.

7. Trial 1: Omit Pre-RSNA Auth. Process
January 2010
Trial 1: Omit Pre-RSNA Auth. Process
We use “Open System” authentication on Pre-RSNA framework at anytime.
Anyone using Shared Key auth?
“Open System auth. is a null auth. algorithm. Any STA requesting Open System auth. may be authenticated”
Quoted from section
Nevertheless, it takes ONE round-trip time to do that!
Standard should be changed to allow to run Association process without Open System authentication process.
Any problem occurs?
Hiroki Nakano, Trans New Technology, Inc.

8. Reason of existence of Open System auth.
January 2010
Reason of existence of Open System auth.
“NOTE 3—IEEE Open System authentication provides no security, but is included to maintain backward compatibility with the IEEE state machine (see 11.3).”
Quoted from section b)
Hiroki Nakano, Trans New Technology, Inc.

9. January 2010
Figure 11-6
Hiroki Nakano, Trans New Technology, Inc.

10. Modified Figure? January 2010 Successful Association with FastAKM
Hiroki Nakano, Trans New Technology, Inc.

11. Trial 2: Piggyback Auth. Info. onto Association Request/Response
January 2010
Trial 2: Piggyback Auth. Info. onto Association Request/Response
Can “Mutual Authentication” be done by just A round-trip of Association Request/Response?
“Single Round-trip Authentication” is a common problem.
STA AP
Authentication Server
Beacon
(Probe Request)
(Probe Response)
Authentication (Open System)
Authentication (Open System)
Association Request
Access Request
Access Response
Association Response (Accept)
Hiroki Nakano, Trans New Technology, Inc.

12. Supposed Service Model
January 2010
Supposed Service Model
Authentication Server
(Service Provider)
Non-AP STA
(Customer) AP
(Infrastructure)
Contract to provide wireless access to users specified by Authentication Server (i.e. Service Provider)
Set up secure communication channel to exchange information about users
Contract to provide wireless access via AP infrastructure.
Share information to identify each other properly, e.g. username, password, digital certificate, etc.
No Contract
Real wireless communication channel
Provide wireless access in request of Service Provider
Hiroki Nakano, Trans New Technology, Inc.

13. Technical Prerequisite
January 2010
Technical Prerequisite
Information shared
- to identify each other and
- to exchange data securely
Station
(non-AP STA)
Authentication
Server (AS)
Wireless
communication
Access Point
(AP)
Secure communication pipe
- Information shared to identify each other
Hiroki Nakano, Trans New Technology, Inc.

14. Association and Authentication Procedure
January 2010
Association and Authentication Procedure
STA  AP (piggyback on Association Request)
Auth. Server Selector = name of Auth. Server
User Information pack passed through AP toward Auth. Server
User Identifier and a kind of digital signature
Session key encrypted by secret shared with Auth. Server
Countermeasure against replay attack
AP  AS
User Information pack
AP  AS
Plain (decrypted) session key
STA  AP (piggyback on Association Response)
Proof of AP having legitimate session key
Group key
Hiroki Nakano, Trans New Technology, Inc.

15. Frame Exchange for Authentication
January 2010
Frame Exchange for Authentication
User Information pack
- User Identifier
- a kind of digital signature
- Session key encrypted by secret shared with Auth. Server
- Countermeasure against replay attack 1
Station
(non-AP STA)
Authentication
Server (AS)
Auth. Server Selector
Access Point
(AP)
- Proof of AP having legitimate session key
- Group key
Plain (decrypted) session key 3 2
Hiroki Nakano, Trans New Technology, Inc.

16. An Example Implemetation
January 2010
An Example Implemetation
OS: NetBSD (i386)
Upper MAC Layer: NetBSD’s net80211
WLAN Chipset: Atheros Communications AR5212
Add about 200 lines in C.
Hiroki Nakano, Trans New Technology, Inc.

17. January 2010
Difference from
Additional state transition to skip Open System Auth.
Figure 11-6—Relationship between state variables and services
Two additional elements to Table 7-26 Element IDs
Authentication Server Selector (240 temporally)
User Information Pack (241 temporally)
RSN with key obtained by new FastAKM framework
RSN information element (for beacon and probe resp.)
Both Group and Pairwise Cipher Suites are set to CCMP.
AKM Suite is set to the brand-new one!
Define new AKM Suite (00-d is used temporally.)
Assign officially on Table 7-34 AKM suite selectors in future…
Hiroki Nakano, Trans New Technology, Inc.

18. Conclusion Not-so-many changes enables FastAKM framework.
January 2010
Conclusion
Not-so-many changes enables FastAKM framework.
We need more technical discussion
to build and verify authentication method
about any effect of changing standard
to write down detailed specification
Hiroki Nakano, Trans New Technology, Inc.

19. January 2010
Straw Poll
“Does WNG think that we need tutorial session exploring the need for support for mobile communication ?”
Yes:
No: 0
Don’t Care:
Hiroki Nakano, Trans New Technology, Inc.