06-transpositionTest.py

import random, sys

transpositionEncrypt = __import__('4-transpositionEncrypt')
transpositionDecrypt = __import__('5-transpositionDecrypt')

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

    for i in range(20): # run 20 tests
        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, int(len(message) / 2)):
            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 as: ' + decrypted
                sys.exit()

    print 'Transposition cipher test passed.'

if __name__ == '__main__':
    main()