Cracking an RC4 encrypted file

I. Download and install CrypTool Version 1 (A zipped file with the installer is included with this lab or find download it from the Cryptool site.

II. Download the hex file Cry-RC4-test.hex from this lab. This is a message I encrypted using RC4 encryption – the same encryption algorithm used for WEP security in WiFi systems.

III. You will use Cryptool to crack the security and retrieve the encrypted text

A. Open Cryptool (version 1.4)

B. Click File > Open

C. In the file type drop-down at the bottom of the window, click the down arrow and change the selection from text file (*.txt) to Binary file (*.hex)

D. Navigate to the Cry-RC4-text.hex file you downloaded and click Open.

E. In the menu at the top of Cryptool, click Analysis

F. Click Symmetric Encryption (Modern) > RC4

G. Since you do not know how many bits I used for the key length, leave it at 8, and click Start

H. Look through the Decryption column in the results. 

I. If any of them look like plain English text, highlight it and click Accept Selection.

J. If none of the results look like plain English, repeat the analysis using the next higher number of bits for the key.

K. Continue using higher and higher key lengths until you find the solution

L. What is the secret phrase in the message you eventually found????