Your Turn: Strengthen Previous Apps

Now that you know how to better encrypt communications, you can strengthen apps from previous activities against brute force attacks.

Update Share Something Personal – Encrypted

A scrambled alphabet substitution cipher can make the app from Share Something Personal – Encrypted activity much more difficult to crack with a brute force attack.  

You can even use cryptabet_autogenerate to generate a custom cryptabet.  If you just use the one that’s in the scrambled_alphabet_cipher script, your fellow students might have a very easy time cracking your cipher with a simple guess and test!

• Change the project names of the scripts radio_send_images_caesar and radio_receive_images_caesar
  to 
  radio_send_images_scrambled and radio_receive_images_scrambled. 
• Replace the caesar() function, and its call, with the scramble() function.  
• The cryptabet built into the function is the key, so remove the key = statement.
• Remember that to encrypt, use packet = scramble(packet, True), and to decrypt, use packet = scramble(packet, False).
• After making your updates, click Save.

Update the cyber:bot Navigation Control from a Keyboard

This cipher does not need to just have upper-case alphabet letters.  You could, for example, make alpha and crypta strings that contain the characters for the keyboard-controlled cyber:bot’s dictionary.  The alpha and crypta strings might look might look like this:

alpha = "vLR{}:,'01234 56789"
crypta = "v9L:3405'R286, 7{}1"  

With nineteen characters, there are 19! = 121,645,100,408,832,000 different ways to arrange the characters in this string.  

• Incorporate scrambled alphabet encryption into the wireless keyboard controlled cyber:bot from the Terminal Control – Go Wireless! activity. 

For an example of the steps to follow to add encryption to your data applications, try the Encrypt Your App Data activity in the Cybersecurity: Sniffing Attacks and Defenses tutorial.