Research On Security Ofwireless Local Area Network And Data Encryption

By analyzing the research status in wireless local area network(WLAN) security, this thesis points out that while domestic and international researches mainly consider to improve upon protocol deficiencies, issues on key replacement mechanism are seldomly involved. Most improved algorithm are consequently still deficient, and can hardly meet the demand of secure communication in WLAN.Based on the study of secure communication principles in WLAN and related theories in cryptography and mathematics, this thesis discusses on security issues and security demands in WLAN. Commencing from the relation between math problems and security communications, and by converting the research object of "3N + 1 conjecture" to binary values, some rules helpful to this problem's solution are obtained. Through these rules, an adjacent bit xor algorithm is proposed to generate random numbers for key replacement mechanism and therefore to have the communication key replaced in WLAN.The algorithm is used to replace communication key in a certain period, it guarantees the replaced key's uniqueness and high randomness, thus makes up for deficiencies in WEP proctocal that it can't replace the key or the key number is too low. The theoretical collision time of initial vector is extended to 25 years instead of the original 4 hours, this improvement can effectively prevent guess based attack and dictionary attack on specific initial vectors.Finaly, a statistical test method on random bits is carried out to test the generated binary values' randomness. Via the statistical test, experimental results on a group (totally 32) of sampled 17-bit binary values show a low randomness in adjacent bit xor algorithm generated binary values. To solve this problem, an improvement is proposed and experimental results based on the improved algorithm show expected performance and verifies the high randomness in adjacent bit xor algorithm generated binary values. Although the 3N + 1 conjecture problem is still unresolved, the proposed adjacent bit xor algorithm contains particular opinions which provides new ideas for further reasearches on this problem.