atbashCipher.py

# Pyhton program to implement Atbash Cipher

# Its one of the simplest ciphers with almost no security

'''
Every character is reversed i.e. 'A' changes to 'Z'
and vice versa.
*-----------------------------------------------------*
* A B C D E F G H I J K L M N O P Q R S T U V W X Y Z *
* | | | | | | | | | | | | | | | | | | | | | | | | | | *
* | | | | | | | | | | | | | | | | | | | | | | | | | | *
* V V V V V V V V V V V V V V V V V V V V V V V V V V *
* Z Y X W V U T S R Q P O N M L K J I H G F E D C B A *
*-----------------------------------------------------*
It can be thought of as an affine cipher
with a = 25 = b

'''
# This script uses dictionaries to lookup various alphabets
lookup_table = {'A': 'Z', 'B': 'Y', 'C': 'X', 'D': 'W', 'E': 'V',
                'F': 'U', 'G': 'T', 'H': 'S', 'I': 'R', 'J': 'Q',
                'K': 'P', 'L': 'O', 'M': 'N', 'N': 'M', 'O': 'L',
                'P': 'K', 'Q': 'J', 'R': 'I', 'S': 'H', 'T': 'G',
                'U': 'F', 'V': 'E', 'W': 'D', 'X': 'C', 'Y': 'B', 'Z': 'A'}

'''
Since we are using a dictionary we don't need
separate functions for encryption and decryption
'''


def atbash(message):
    cipher = ''
    for letter in message:
        # checks for space
        if(letter != ' '):
            # adds the corresponding letter from the lookup_table
            cipher += lookup_table[letter]
        else:
            # adds space
            cipher += ' '

    return cipher

# Hard-coded driver function to run the program


def main():
    message = 'ALICE KILLED BOB'
    print(atbash(message.upper()))

    message = 'ZORXV PROOVW YLY'
    print(atbash(message.upper()))


# Executes the main function
if __name__ == '__main__':
    main()