1. Measuring of the time consumption of the WLAN’s security functions Jaroslav Kadlec, Radek Kuchta, Radimír Vrba kadlecja@feec.vutbr.cz Dept. of Microelectronics Brno University of Technology, Faculty of Electrical Engineering and Communication Technologies, Brno, Czech Republic

2. Content Introduction Measuring scenario Results ▫WEP 64 ▫WEP 128 ▫WPA ▫WPA2 Conclusion

3. 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.

4. 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

5. 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

6. Measuring scenario

7. Results WEP 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

8. Results WEP 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

9. Results WPA 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

10. Results WPA2 AES block cipher ▫128-bit key CCMP (Counter mode with Cipher Block Chining Message Authentication Protocol) Average latency = 177 ms Time = 47,9 ms

11. Results Security function Mean [ms] Deviation [ms] Time consumption [ms] WEP64142,7611645,94812,799 WEP128146,7981693,57816,836 WPA152,3591789,71022,396 WPA2177,9462049,76147,983 No encryption129,9621773,390-

12. Results

13. 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.