transpositionTest.py

# Transposition Cipher Test
# http://inventwithpython.com/hacking (BSD Licensed)

import random, sys, transpositionEncrypt, transpositionDecrypt

def main():
    random.seed(42) # set the random "seed" to a static value

    for i in range(20): # run 20 tests
        # Generate random messages to test.

        # The message will have a random length:
        message = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ' * random.randint(4, 40)

        # Convert the message string to a list to shuffle it.
        message = list(message)
        random.shuffle(message)
        message = ''.join(message) # convert list to string

        print('Test #%s: "%s..."' % (i+1, message[:50]))

        # Check all possible keys for each message.
        for key in range(1, len(message)):
            encrypted = transpositionEncrypt.encryptMessage(key, message)
            decrypted = transpositionDecrypt.decryptMessage(key, encrypted)

            # If the decryption doesn't match the original message, display
            # an error message and quit.
            if message != decrypted:
                print('Mismatch with key %s and message %s.' % (key, message))
                print(decrypted)
                sys.exit()

    print('Transposition cipher test passed.')


# If transpositionTest.py is run (instead of imported as a module) call
# the main() function.
if __name__ == '__main__':
    main()