使用凯撒密码解密

Question

我正在使用密码保护程序，并且有一个用于加密的Caesar密码：

#  The encryption key for the Caesar Cipher
encryptionKey = 16

#  Caesar Cipher Encryption
def passwordEncrypt (unencryptedMessage, key):

#  We will start with an empty string as our encryptedMessage
encryptedMessage = ''

#  For each symbol in the unencryptedMessage we will add an encrypted symbol 
into the encryptedMessage
    for symbol in unencryptedMessage:
        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

            encryptedMessage += chr(num)
        else:
            encryptedMessage += symbol

    return encryptedMessage

我有一个用于测试目的的预定义列表，其中包含两个网站及其加密密码：

passwords = [["yahoo","XqffoZeo"],["google","CoIushujSetu"]]

我给用户一系列选择，选择＃2让用户查找保存的密码，即：

if choice == '2':  # Lookup a password
    print("Which website do you want to lookup the password for?")
    for keyvalue in passwords:
        print(keyvalue[0])
    passwordToLookup = input()

密码保护程序会加密密码，但是我只需要使用passwordEncrypt（）函数来解密密码。