WEP数据加密协议的两种改进攻击

Two improved attacks on the WEP data encryption protocol

对于IEEE 802.11无线局域网标准中的WEP协议,利用发送数据帧探测明文数据的chop-chop攻击和利用已知明密文对恢复密钥的FMS攻击是2种重要的攻击方法。改进了chop-chop攻击,改进后的chop-chop攻击的速度和所需发送WEP数据帧的数量分别提高16倍和减少到1/16。给出了一个改进的FMS攻击——FMS+攻击,在攻击者只具备被动监听网络的能力和各种典型的已知明密文对数量的假设下,FMS+攻击将FMS攻击可以利用的WEP数据帧数量提高2倍以上,且一般情况下,FMS+将FMS攻击恢复密钥的成功率提高至少20%以上。

For the WEP protocol in the IEEE 802.11 wireless LAN standard,the chop-chop attack which sends data frames to probe plaintext information and the FMS attack which uses known plain/cipher-text pairs to recover the WEP key are two important attacks.The original chop-chop attack was improved,with both a speedup of the attack by a factor of 16 and a decrease of the amount of data frames needed to 1/16.An improved attack of FMS—FMS＋ was also pro-posed.Assuming that an attacker is only capable of passively eavesdropping the network communication and under vari-ous typical assumptions on the amount of known plain/cipher-text pairs,the number of WEP data frames that can be used by FMS＋ is more than twice of that by FMS,and in general cases,FMS＋ achieves an improvement of successful key re-covery probability of at least 20%,compared with FMS.