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Design and Implementation of RC4 stream for WI-FI

In Cryptography the main feature is to work out with problems, which associated with secrecy, authentication and integrity. In order to handle all the cryptographic problems many kinds of cryptographic algorithms have been invented. The complexity of these problems made several categories of cryptographic algorithms. A much known is the RC4 stream cipher. The project deals with the design of RC4 stream cipher for wireless LAN security.

The 802.11 is a wire LAN, uses a collision avoidance (CSMA/CA) mechanism together with a positive acknowledges scheme and critical carrier sense as well as physical carrier sense methods. The important part of wireless MAC layer design is the security (WEP/RC4 algorithm) implementation. The security protocol is the part of the data link layer. This protocol uses RC4 cryptographic algorithm and its intention is to prevent attempts of thefts and invasions. RC4 is the most widely-used software stream cipher and is used in popular protocols such as Secure Sockets Layer (SSL) (to protect Internet traffic) and WEP (to secure wireless networks) and is remarkable for its simplicity and speed in software.

RC4 uses a variable key from 1 to 256 bytes to initialize a 256-byte array. the array is used for subsequent generation of pseudo-random bytes and then generates a pseudorandom stream, which is XORed with the plaintext/cipher text to give the cipher text/plain text. The RC4 stream cipher works in two phases the key setup phase and the pseudorandom key stream generator phase. Both phases must be performed for every new key. The primary functions are generation of 256-bytes key data from variable key length (6to16bytes), initialization of the key setup, swapping of 256-bytes between two blocks of 256 bytes (to randomize the bytes). Control and storage blocks design and implementation and key stream cipher bytes generation.