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

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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.