wired equivalent privacy (wep): the first ‘confidentiality’ algorithm for the wireless ieee...
TRANSCRIPT
Wired Equivalent Privacy (WEP):
The first ‘confidentiality’ algorithm for the wireless IEEE 802.11 standard.
PRESENTED BY:PRESENTED BY:Samuel Grush and Barry PrestonSamuel Grush and Barry Preston
WEP Components1) Secret Key and Plaintext2) Initialization Vector (IV)3) RC4 Stream Cipher
1) Key Scheduling Algorithm (KSA)Seeded by IV+Secret Key Passes 'State' Array to PRGA
2) Pseudo-Random Generation Algorithm (PRGA)Uses 'State' Array to generate a keystream, while also mixing the Array.
4) Plaintext is combined with its checksum.5) Bitwise-XOR
• [when encrypting] Plaintext is bitwise-XOR'd with keystream data to generate cyphertext.
KSA PRGA
Packet
ciphertext
IV
XOR
CRC-32 ICV
Seed
plaintext
Secret Key
InitializationVector (IV)
WEP Decryption
CRC-32
SeedKSAPRGAPacket
ciphertext
IV
Secret Key
XORplaintext
Received ICV
≟
Key Scheduling Algorithm
Pseudo-Random Generation Algorithm
Weaknesses
• The Initialization Vector (IV) 24-bit length limits the IV's entropy to 2²⁴, or about 16.7 million combinations.
● Certain characters in the 802.11 header are known or can be predicted, leading to a lessened effective entropy.
● The 'Shared Key' authentication system of WEP exposes the beginning of the keystream.