Measuring of the time consumption of the WLAN’s security functions

Jaroslav Kadlec, Radek Kuchta, Radimír Vrba

kadlecja@feec.vutbr.cz Dept. of MicroelectronicsBrno University of Technology, Faculty of Electrical Engineering and Communication Technologies, Brno, Czech Republic

Content

•Introduction•Measuring scenario•Results

▫WEP 64▫WEP 128▫WPA▫WPA2

•Conclusion

Introduction• Wireless digital communication starts to increase its

prominence for the industrial automation domain. • Still more and more producers of automation systems

try to offer complete wireless solution.• Problems with:

▫ harsh noise environment,▫ undefined network parameters,▫ real-time applications.

• To design remote mechanisms (telemonitoring, teleservice etc.) using wireless communication, an increasing number of communication technologies is available, ▫ limited by strict quality of service and performance

requirements.

Introduction• Automation application

▫Hard real-time▫Soft real-time▫Non real-time

Standard wireless communication protocols (WiFi, ZigBee etc.)

▫Communication speed X Security level

▫Manufacturers don’t provide information about time parameters

Measuring scenario• Measurement scenario is

mixture of:▫ software based packet

sniffers,▫ special network

development boards.• For controlling these boards

a special software was written.

• Lowest network function handling allows us to have precise control of all packets in the network.

• This packet size 146 bytes (100 bytes payload and 46 bytes packet header) was determined as an optimal value by several tests.

ASUS WL-566gM

Standard test packet

Standard test packet

EB200-1172.16.30.4255.255.0.0

EB200-2172.16.30.8255.255.0.0

Computer equipped with EB200 board and

measuring software tool

Computer equipped with EB200 board and

measuring software tool

Notebook equiped with WiFi connection

Local WiFi Access Point

172.16.30.2255.255.0.0

172.16.30.5255.255.0.0

Internal time synchronization

Measuring scenario

ResultsWEP 64-bit

• Stream cipher RC4▫ 64-bit key

IV 24-bit Key 40-bit

• CRC-32 checksum• Average latency = 142 ms.• Time = 12,8 ms

ResultsWEP 128-bit

• Stream cipher RC4▫ 128-bit key

IV 24-bit Key 104-bit

• CRC-32 checksum• Average latency = 146 ms.• Time = 16,8 ms

ResultsWPA

• RC4▫ 128-bit key

IV 48-bit Key 80-bit

• TKIP – Wired Equivalent Privacy

• Michael checksum algorithm▫ Using sender and

receiver MAC addresses• Average latency = 152 ms• Time = 22,3 ms

ResultsWPA2

• AES block cipher▫ 128-bit key

• CCMP (Counter mode with Cipher Block Chining Message Authentication Protocol)

• Average latency = 177 ms• Time = 47,9 ms

Results

Security function

Mean [ms]

Deviation [ms]

Time consumption [ms]

WEP64 142,761 1645,948 12,799

WEP128 146,798 1693,578 16,836

WPA 152,359 1789,710 22,396

WPA2 177,946 2049,761 47,983

No encryption 129,962 1773,390 -

Results

Conclusions• A sophisticated tool with high precision

resolution and absolute control of network traffic was created.

• Our measured results are unique due to their precision. ▫Manufacturers of wireless network devices do not

provide this kind of measurements which are very important for real time automation applications.

• We can simply decide for which level of real time application measured device can be applied.

• Based on those findings it is possible to develop wireless automation system with well defined parameters of wireless communication link.