"Graduate Design Diary-April" has cracked ciphertext

Today's progress is relatively fast.

In the morning to the book with Wireshark find the last grabbed package, analysis information, I have always thought that the data will be transmitted in the

In this request message, I didn't expect to actually be in the response message.

See these familiar identifiers to find the right, because the source program last sent out of the content is also msgcontent, these two ciphertext also conforms to the previous plaintext "HI" "Hey Man" (string length difference, the first character).

The main puzzle today is that this function

Do not know what his usefulness in the end is, before also conjecture is the Chinese character this special code conversion. Today asked the lab a senior, he said this is the process of converting a string into bytes, because this parameter paramstring is in 16 binary form, for example, the string "7B" into 7B, to convert the number, can be used. And a character is a byte, 8 bits 2 binary, that is, 2 bit 16, so this length must be an even number, otherwise it will throw an exception.

I was really thinking about it before ... and asked everywhere. is still too young.

Then Baidu Encyclopedia of the RC4 entry in the algorithm can be used directly, and relatively simple, the parameters in the change, the ciphertext in this form into the array:

Run or debug you can see the decrypted plaintext: (because the ciphertext is put in, encryption equivalent to decryption, call a RC4 is decrypted, and then call once encrypted, this function can also be changed to use)

At this point, the completion of the establishment has finally had some results.

The next task is to use socket programming, crawl packets that flow through the local network card, extract these fields from the HTTP response message, and decrypt them.

Again, think of the problem of the majority of days, the graduate student to give me a minute, let me think that the graduate student this road is a heavy task ...

"Graduate Design Diary-April" has cracked ciphertext