On the anaysis of stream cipher and its implementation

流密码是一种应用广泛的安全协议。特别是，RC 4作为标准加密算法被许多标准协议采用，如WEP，WPA和SSL/TLS。我们提出了评估这些协议的基础上的流密码。 首先，我们提出了实用的明文恢复攻击RC 4在SSL/TLS的广播设置，独立。提出了一种主动攻击方法，将目标明文字节的位置滑动到明文的后面字节。我们的攻击通过使用恶意的JavaScript将任何字节注入到明文的头部。它提高了恢复大量明文字节的概率。其次，我们提出了一个安全的WEP操作，防止密钥恢复攻击。该方法需要攻击者至少100，000个数据包才能恢复WEP密钥。最后，我们提出了一种在真实的环境中的可执行攻击，而不需要对WPA-TKIP进行中间人攻击。

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.