這意味這我們需要創建兩個RC4實例，一個用於加密瀏覽器發送的消息，另一個用於解密服務器返回的消息。
The means we need to create two RC4 instances: one to encrypt what our browser sends and the other to decrypt what the server sent us.
這是由於RC4切絲機上下排鏈的進給線速度不一致，造成切絲寬度不均勻。
The first few random bytes out of the "client_write" RC4 instance are "7E 20 7A 4D FE FB 78 A7 33 ...
