On the anaysis of stream cipher and its implementation

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Stream cipher is a widely-used in secured protocols. Especially, RC4 is adopted in a lot of standard protocols such as WEP, WPA and SSL/TLS as a standard encryption algorithm. We present the evaluation of these protocols based on the stream cipher. Firstly, we proposed practical plaintext recovery attacks on RC4 in SSL/TLS in the broadcast setting, independently. We give an active attack, which is a method to slide the position of a target plaintext byte into later byte of the plaintext. Our attack injects any bytes into the head of the plaintext by using malicious JavaScript. It causes improvement in probability for recovering a lot of plaintext bytes. Secondly, we propose a secure WEP operation against key recovery attacks. The proposed method requires for attackers at least 100,000 packets to recover the WEP key. At last, we propose an executable attack in a real environment without requiring the man-in-the-middle attack on WPA-TKIP.