Caeser.py

MAX_KEY_SIZE = 26
def getMode():
    while True:
        print('Do you wish to Decrypt with key [D]/ Bruteforce [B] a message?')
        mode = input().lower()
        if mode in ' decrypt d brute b'.split():
            return mode
        else:
            print('Enter either "decrypt" or "D" "brute" or "B".')
def getMessage():
    print('Enter your message:')
    return input()
def getKey():
    key = 0
    while True:
        print('Enter the key number (1-%s)' % (MAX_KEY_SIZE))
        key = int(input())
        if (key >= 1 and key <= MAX_KEY_SIZE):
            return key
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
mode = getMode()
message = getMessage()
if mode[0] != 'b':
    key = getKey()
print('Your translated text is:')
if mode[0] != 'b':
    print(getTranslatedMessage(mode, message, key))
else:
    for key in range(1,MAX_KEY_SIZE + 1):
        print(key, getTranslatedMessage('decrypt',message,key))