Second post (10.04.13 - 10.08.13)

Cipher:
The program asks you to input a string and whether you want to encrypt or decrypt it. If you choose encrypt, you input your string and a key and it moves X ASCII characters up. If you decrypt it, you input a string and a key and it moves X ASCII characters down. More exciting stuff to come.

MAX_KEY_SIZE=26
def getMode():
    while True:
        print('Do you wanna encrypt or decrypt a message? '),
        mode=raw_input().lower()
        if mode in 'encrypt e decrypt d'.split():
            return mode
        else:
            print('Enter either "encrypt" or "decrypt"')
def getMessage():
    print('Enter your message:')
    return raw_input()
def getKey():
    key=0
    while True:
        print('Enter the key number (1-%s)'%(MAX_KEY_SIZE))
        key=int(raw_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
def again():
    print('Translate another message? '),
    return raw_input().lower().startswith('y')
while True:
    mode=getMode()
    message=getMessage()
    key=getKey()
    print('Your translated text is:')
    print(getTranslatedMessage(mode, message, key))
    if not again():
        break