Abstract: Wireless 802.11 has many flaws that expose the medium to various types of attacks. The absence of encryption at management and control frames exposes the medium to various types of inevitable Denial of service attacks at Data Link Layer. The attacker may spoof the unencrypted Deauthenticate/Disassociate message with the MAC address of the directed access point and continuously retransmitting it as a broadcast message to all designated clients to disrupt the connection with that particular node. Random bit approach was adapted and implemented in the proposed scheme to provide a layer of authentication in the management frames between the clients and the access point. The proposed scheme showed effectiveness in slowing the attack on both unencrypted and encrypted network by one hour and forty nine seconds without affecting the performance of the medium.

Abstract: The key stream generator is the key design issue of an encryption system. In this work presents an n-array three key stream generators (KSI, KSII and KSIII), Based on permutation of three chaotic maps (Logistic map, Kent map and tent map). This work reviews of some image encryption algorithm and finally investigate three methods for image encryption. First algorithm is encryption of original image by using KSI system. Second algorithm relies on KSII system to randomly generate two sequences of numbers by means of selecting proper factors along with seed value. Afterwards, the randomly produced numbers are employed to permute the image by means of shuffling its rows, columns and pixels sequentially in a manner by which first sequence is utilized to shuffle rows while second sequence is utilized to shuffle columns. Afterwards masking process is achieved by means of basic XOR processes between neighboring rows and columns. This technique employs the values of the two sequences together to shuffle the pixels. Third algorithm relies on KSIII system when the same procedures returned on image encryption. The results shows that the proposed algorithm has a high security, speed and gives perfect reconstruction of the decrypted image