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.  

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.