索引错误-适用于我的代码的一部分，而不适用于另一部分

我不断收到索引错误：

User_input is 0
Key is 0

Traceback (most recent call last):
  File "C:\Users\Theo_2\Google Drive\Computer science\Encryption and decryption work\Cipher 2\Cipher 2.5.0 alpha1.py", line 62, in <module>
    Test_algorithm(5)
  File "C:\Users\Theo_2\Google Drive\Computer science\Encryption and decryption work\Cipher 2\Cipher 2.5.0 alpha1.py", line 49, in Test_algorithm
    Encrypt(User_input)
  File "C:\Users\Theo_2\Google Drive\Computer science\Encryption and decryption work\Cipher 2\Cipher 2.5.0 alpha1.py", line 21, in Encrypt
    ref_for_output = Master_Key.index(User_input[Count]) + Master_Key.index(Key[Count])
IndexError: string index out of range

User_input为0部分正在测试

基本上，以下代码是对我编写的使用关键字加密和解密的内容的重写。这个版本还没有完成，我的所有功能都已定义，包括一个可以测试所有可能值的功能，但是我还没有启动任何接口。无论如何，我的代码如下：

import time
Master_Key = "0123456789 abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ!\"#£$%&'()*+,-./:;?@[\\]^_`{|}~\t\n\r\x0b\x0c"
global Output
Output = ""
global Key
Key = ""
def Compatibility_check(Key):
    while Key == "":  
        print("Your key cannot be blank")
        Key = input("Please input a new key: ")
    while len(Key) > len(User_input):
        Key = Key[:-1]
    while len(Key) < len(User_input): 
        Key += (Key[Temp])
        Temp += 1

def Encrypt(User_input):
    Count = 0
    Output = ""
    while Count <= len(User_input):\
        ref_for_output = Master_Key.index(User_input[Count]) + Master_Key.index(Key[Count])
        if ref_for_output > len(Master_Key):
            ref_for_output -= len(Master_Key)
        Output += Master_Key[ref_for_output]
        Count += 1
        print(Output)

def Decrypt(User_input):
    Count = 0
    Output = ""
    while Count <= len(User_input):
        ref_for_output = Master_Key.index(User_input[Count]) - Master_Key.index(Key[Count])
        if ref_for_output < 0:
            ref_for_output += len(Master_Key)
        Count += 1
        Output += Master_Key[ref_for_output]

def Test_algorithm(Null):
    fail, Input_Counter = False, 0
    while Input_Counter <= len(Master_Key):
        User_input = Master_Key[Input_Counter]
        print("User_input is " + User_input)
        Key_Counter = 0
        Input_Counter += 1
        while fail == False:
            while Key_Counter < len(Master_Key):
                Key = Master_Key[Key_Counter]
                print("Key is " + Key)
                Encrypt(User_input)
                print("The encrypted value is " + Output)
                Decrypt(Output)
                print("The decrypted value is " + Output)
                if Output == User_input:
                    print("The encryption and decryption of " + str(User_input) + " with the key " + str(Key_Counter) + " results in " + Output)
                    print("pass")
                else:
                    print("fail")
                    print("The encryption and decryption of " + str(User_input) + " with the key " + str(Key_Counter) + " results in " + Output)
                    fail = True
                Key_Counter += 1

Test_algorithm(Nothing)

##Key = "abcdefghijklmnop"
##User_input = "12345"
##Compatibility_check(Key)
##Encrypt(User_input)
##print(Output)

这是对旧脚本的改进，该脚本可以工作，但确实可以改善。我重写它的原因是我想将加密的值输出到文件，然后根据用户请求重新读取和解密它们。希望您能提供帮助-谢谢。