在这个维格纳密码中，“字符串索引超出范围”是什么意思？

Question

#Vigenere Cipher
EncryptedMessage=""
Mode=""
Keywordcount = 0 #sets everything to 0
KeywordTwocount = 0

while Mode != "encrypt" and Mode != "decrypt":
    Mode = input('Do you want to encrypt or decrypt a message?')
    Mode = Mode.lower()

if Mode == "encrypt":
    Message=input('Please eneter the message you wish to encrypt: ')
    Keyword=input('Please enter the keyword you want to use:')
    KeywordTwo = input(' Please enter second keyword you want to use:') 
    Keywordlength = len(Keyword)
    KeywordTwolength = len(KeywordTwo)

    for i in range(0, len(Message)):
        Messageencrypt = Message[i]
        Keywordencrypt = Keyword[Keywordcount]
        KeywordTwoencrypt= KeywordTwo[KeywordTwocount]
        if Messageencrypt.isalpha():
            if Messageencrypt.isupper():
                Messageencrypt = ord(Messageencrypt)
                Keywordencrypt = Keywordencrypt.upper()
                Keywordencrypt = ord(Keywordencrypt) - 64
                KeywordTwoencrypt = KeywordTwoencrypt.upper()
                KeywordTwoencrypt = ord(Keyword2encrypt) - 64
                FirstCodedMessage = Messageencrypt + Keywordencrypt
                FinalCodedMessage = FirstCodedMessage + Keyword2encrypt
                if FinalCodedMessage > 90:
                    FinalCodedMessage = FinalCodedMessage - 26
                Encryptedletter = chr(FinalCodedMessage)
            elif Messageencrypt.islower():
                Messageencrypt = ord(Messageencrypt)
                Keywordencrypt = Keywordencrypt.upper()
                Keywordencrypt = ord(Keywordencrypt) - 64
                KeywordTwoencrypt = KeywordTwoencrypt.upper()
                KeywordTwoencrypt = ord(KeywordTwoencrypt) - 64
                FinalCodedMessage = Messageencrypt + Keywordencrypt
                if FinalCodedMessage > 122:
                    FinalCodedMessage = FinalCodedMessage - 26
            Encryptedletter = chr(FinalCodedMessage)
        else:
            Encryptedletter = Messageencrypt
        EncryptedMessage = EncryptedMessage + Encryptedletter
        Keywordcount = Keywordcount + 1
        if Keywordcount >= Keywordlength:
            Keywordcount = 0
        KeywordTwocount = KeywordTwocount + 1
        if KeywordTwocount >= Keywordlength:
            KeywordTwocount = 0
    print(EncryptedMessage)

是什么

KeywordTwoencrypt= KeywordTwo[KeywordTwocount]
IndexError: string index out of range

什么意思？Error

另外，如何将此加密邮件保存为txt文件？Error

Answer 1

KeywordTwo[KeywordTwoCount] IndexError: string index out of range表示索引（KeywordTwoCount）大于要索引到KeywordTwo的字符串的长度。你知道吗

Answer 2

if KeywordTwocount >= Keywordlength:应该是if KeywordTwocount >= KeywordTwolength:

如果存在索引问题，那么应该更仔细地查看代码中处理此特定索引递增/递减的所有部分。你知道吗

在这个特定的例子中，您应该看到第二个关键字的索引不应该与第一个关键字的长度有任何关系。所以更新有问题：

if KeywordTwocount >= Keywordlength:
    KeywordTwocount = 0

---

通过定义一个用一个关键字加密消息的函数，可以很容易地避免此错误：

def vigenere(message, keyword):
    ...

然后你可以把这两个链在一起：

print(vigenere(vigenere(message, keyword1), keyword2))

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使用内置函数也可以轻松地写入文件：

with open('ciphertext.txt', 'w') as ct:
    ct.write(EncryptedMessage)