What is it? @.@

Here is the place where I record some tactics about wargame, systems, and other security issues.


Hack This Site! - Realistic 6

ToxiCo Industrial Chemicals
Decrypt a heavily encoded message from a CEO trying to bribe ecological inspectors investigating water pollution issues. Help environmentalists uncover corporations plotting to profit from the destruction of mother nature! 
Level 6
From: ToxiCo_Watch 

Message: Hello esteemed hacker, I hope you have some decent cryptography skills. I have some text I need decrypted.
I work for this company called ToxiCo Industrial Chemicals, which has recently come under fire because of the toxic chemicals we are dumping into the river nearby. Ecological inspectors have reported no problems, but it is widely speculated that they were paid off by ToxiCo management because the water pollution near the ToxiCo factory has always been a serious and widely publicized issue.
I have done some packet sniffing on my network and I have recovered this email that was sent from the CEO of the company to Chief Ecological Inspector Samuel Smith. However, it is encrypted and I cannot seem to decode it using any of my basic decryption tools. I have narrowed it down to the algorithm used to encrypt it, but it is beyond my scope. I was hoping you can take a look at it.
Please check it out, 
more details are on the page. If you can unscramble it and reply to this message with the original text, it would be much appreciated. Thank you.
  1. Save the cipher text without 'CRLF' into a file and name it "ciphertext.txt".
  2. Visit the link to figure out what is the XECryption algorithm, or maybe you could google it.
  3. Each time when you only input character 'a' without any encryption password and encrypt it, the encrypted code of character 'a' will be three individual random numbers separated by a period symbol, but the sum of the three numbers will be always 97 which is the ASCII number of character 'a'.
    input: a
    Your encrypted text is: .2.18.77
    where 2 + 18 + 77 = 97
  4. But if you input character 'a' with a encryption password, the sum will be the ASCII number of the encryption password plus 97.
  5. input: a
    encryption password: b
    Your encrypted text is: .44.46.105
    where 44 + 46 + 105 = 97 + 98 = 195
  6. So, the first thing we need to do is to find out the encryption password. Since there are always multiple spaces existed in a sentence or in the message, and the ASCII number of a space is 32, we could statistic all integers to discover the encryption password.
  7. I write a python program below to solve this challenge.

  8. Congratulations, you have successfully completed realistic 6!