A simple demontration on running a brute force attack on Caeser Cipher encoded text.

caeser-bruteforce.py

# Caesar Cipher

MAX_KEY_SIZE = 26

def getTranslatedMessage(mode, message, key):
    if mode[0] == 'd':
        key = -key
    translated = ''

    for symbol in message:
        if symbol.isalpha():
            num = ord(symbol)
            num += key

            if symbol.isupper():
                if num > ord('Z'):
                    num -= 26
                elif num < ord('A'):
                    num += 26
            elif symbol.islower():
                if num > ord('z'):
                    num -= 26
                elif num < ord('a'):
                    num += 26
                        
            translated += chr(num)
        else:
            translated += symbol
    return translated

print('Enter your input filename: ')
file_in = input()
fin = open(file_in, 'r')

for line in fin:
    line = line.strip()
    for i in range(MAX_KEY_SIZE + 1):
        print(getTranslatedMessage('d', line, i))
    print()