1. 15 November 2004 1 Wireless Security Issues Cheyenne Hollow Horn SFS Presentation 2004

2. 15 November 2004 2 Presentation Outline WEP WPA TKIP Optical Wireless Solution

3. 15 November 2004 3 WEP Wired Equivalency Protocol First WLAN security protocol. Four major categories of flaws: –No forgery protection. –No protection against replays. –RC4 encryption exposes protocol to weak key attacks. –Encrypted data can be decrypted with out learning encryption key.

4. 15 November 2004 4 WEP Encryption Each packet is encrypted with a RC4 cipher stream. The key uses an initialization vector and 40 – bit WEP key. The data is bitwise XOR-ed with the key. IV chosen by sender and sent with each packet.

5. 15 November 2004 5 WEP Encryption Flaws Key management and size IV is too small Authentication messages can be easily forged.

6. 15 November 2004 6 WPA Wi-Fi Protected Access Wi-Fi Alliance created early 2003 Based on IEEE 802.11i WPA specifies user authentication, better encryption, and data validation.

7. 15 November 2004 7 WPA Authentication: –Uses 802.1x protocol –802.1x based on EAP –Alternate PSK Data encryption: –TKIP Data validity: –MIC

8. 15 November 2004 8 TKIP Cryptographic message integrity code, MIC New IV sequencing discipline Pre-packet key mixing function Rekeying mechanism

9. 15 November 2004 9 MIC Three components: –Authentication key K –Tagging function –Verification predicate The tagging function takes key and message and generates tag. Receiver uses K, M, and T.

10. 15 November 2004 10 IV Sequence Enforcement When transmission begins sender and receiver initialize to zero The IV field used as packet sequence number. Receiver is required to increment sequence number If out of order packet is discarded

11. 15 November 2004 11 Key Mixing Two phases Phase I: –Temporal key and MAC address of local wireless interface used. Phase II: –Uses tiny cipher to “encrypt” each packet.

12. 15 November 2004 12 Rekeying Delivers fresh keys consumed by the various TKIP algorithms Eliminates attacks by guessing static keys.

13. 15 November 2004 13 Optical Wireless Communications Layer 1 advantage LIGHTPOINTE Works near infrared wavelengths Information relayed at several hundred THz Narrow beam, hard to intercept signal

14. 15 November 2004 14 More on Optical Wireless Military organizations use this Blocking the beam stops transmission Utilizes WPA to have a stronger system

15. 15 November 2004 15 Questions?