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| Wireless Encryptions |
WEP - Wired Equivalent Privacy (WEP) algorithm
- See page 13 and pg 28 for pics ( Acsac.org )
- WEP uses 40-bit RC4 encryption
- uses 64 or 128-bit encryption keys
- WEP key is static
- RC4 is a stream cipher commonly used by SSL
- WEP is already cracked (in Feb 2001 ) by Scott Fluhrer, Mantin, Shamir
- Those exploit scripts was posted around Aug 2001 by someone
- WEP keys can be reversed in as little as 15 minutes ( Jerry Wang )
- the 24-bit IV (initialization vector) is used by 64-bit and 128-bit keys
- short IV subjectto brute force attacks
- subject to man-in-the-middle attacks
- the message can be modified
- no user authentication
- no key management
TKIP - Temporal Key Integrity Protocol (replaces WEP )
- See page 13 and pg 28 for pic Acsac.org )
- initially referred to as WEP2
- uses 48bit Initialzation Vector
- starts with a shared 128-bit key among clients and access points
- combines the temporal key with the client's MAC address
- adds a relatively large 16-octet initialization vector
- still uses the RC4 to perform the encryption
- changes temporal keys every 10,000 packets
AES - Advanced Encryption Standard (to replace TKIP )
EAP - Extensible Authentication Protocol ( RFC-2284 )
EAP-MD0n login and passwd
EAP-Cisco ( LEAP ) uses MS-CHAPv1 w/ known vulnerabilities
EAP-TLS uses X.509 digital certificates
EAP-TTLS ( PEAP ) alternative to EAP-TLS
WPA - Wi-Fi Protected Access ( Wi-Fi.org )
- up to 256-bit encryption keys
- WPA key is dynamic, changes every 50min on linksys
- WPA-Personal mode, aka Pre-Shared Key (WPA-PSK)
- WPA-Enterprise mode, aka WPA-RADIUS
- WPA automatically generates a new unique encryption key periodically for each client
- uses temporal keys ( TKIP )
- user authentication ( Radius, LDAP )
- Supports MIC - Message integrity code - 64-bit cryptographic tag
- WPA2 uses AES instead of RC4
MIC - Message Integrity Check ( aka Michael )
SSN - Simple Secure Networks
RSA/HiFn - proposal include Ron Rivest
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| WEP Example Key |
WlanResearch.com Cisco LEAP vs IPSec VPN
Mail-Archive.com
Change your key often to minimize WEP vulnerabilities
In WF1 the 802.11 WEP keys would be changed many times each hour, say
every 10 minutes. A parameter, P , determines how many time per hour
the key is to be changed, where P must divide 3600 evenly. The WEP
keys are derived from a master key, M, by taking the low order N
bits (N = 40, 104, whatever) of the SHA1 hash of the master key with
the date and time (UTC) of the key change appended.
WF1 - WEP fix-1
WEPkey = Bits[0-N](SHA1(M | yyyymmddhhmmss))
WF2 - WEP fix-2
WEPkey = Bits[0-N](SHA1(M | Sender's address | yyyymmddhhmmss))
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