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Wireless Security Issues. Cheyenne Hollow Horn SFS Presentation 2004. Presentation Outline. WEP WPA TKIP Optical Wireless Solution. WEP. Wired Equivalency Protocol First WLAN security protocol. Four major categories of flaws: No forgery protection. No protection against replays.
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Wireless Security Issues Cheyenne Hollow Horn SFS Presentation 2004
Presentation Outline • WEP • WPA • TKIP • Optical Wireless Solution
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.
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.
WEP Encryption Flaws • Key management and size • IV is too small • Authentication messages can be easily forged.
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.
WPA • Authentication: • Uses 802.1x protocol • 802.1x based on EAP • Alternate PSK • Data encryption: • TKIP • Data validity: • MIC
TKIP • Cryptographic message integrity code, MIC • New IV sequencing discipline • Pre-packet key mixing function • Rekeying mechanism
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.
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
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.
Rekeying • Delivers fresh keys consumed by the various TKIP algorithms • Eliminates attacks by guessing static keys.
Optical Wireless Communications • Layer 1 advantage • LIGHTPOINTE • Works near infrared wavelengths • Information relayed at several hundred THz • Narrow beam, hard to intercept signal
More on Optical Wireless • Military organizations use this • Blocking the beam stops transmission • Utilizes WPA to have a stronger system