python - 有时在加密数据时我的代码返回带有奇怪符号的特定结果

Question

我正在用 python3 学习密码学

现在我正在研究凯撒密码，这是我的问题

我尝试使用 key 16 加密“hdjdyueeeje”这就是结果 "zwzt??uuzu"

你能解释一下我做错了什么以及如何解决吗

我的代码:

print("\n----------------Caesar_Cipher----------------\n")

print('  1) Crypt mode')
print("  2) Decrypt mode")

try:
    mode = int(input('\n  [#]  Enter number what you need (1,2) : '))

    if mode == 1:
        print("\n--------Crypting process is starting---------")
        key = int(input("\n  [#]  Enter here key which will be used to crypt data \n       (number from 1 to 25 including) --> "))

        if 1 >= key or key > 25:
            print("   You choosed wrong number. I will make it 1 automatically")  
            key = 1
        else:
            pass

        msg = input("\n  [#]  Now enter your message what you wanna crypt \
                \n    -->")
        print("")

        msgc = ""
        for letter in msg:
            x = ord(letter)
            y = chr(x + key)
            msgc += y

        print('\n Crypted data -->',msgc)
    elif mode == 2:
        print("\n-------Decrypting process is starting--------")

        key = int(input("\n  [#]  Enter here key which will be used to decrypt data \n       (number from 1 to 25 including) --> "))

        if 1 >= key or key > 25:
            print("   You choosed wrong number. I will make it 1 automatically")  
            key = 1
        else:
            pass

        msg = input("\n  [#]  Now enter your message what you wanna decrypt \
                \n    -->")
        print("")
        msgd = ""
        for letter in msg:
            x = ord(letter)
            y = chr(x - key)
            msgd += y

        print('\n Decrypted data -->',msgd)
    else:
        print("Number not defined")

就这样

Answer 1

你的问题在这里:

x = ord(letter)
y = chr(x + key) # <- problem
msgc += y

如果没有足够的字母留下更高的代码，字母表需要环绕。例如，当您尝试加密 y 时，您只能加 1 才能得到 z。如果 key 为 2，则需要环绕并返回到 a。这种“环绕”可以很容易地通过减去字母表的长度来完成。此版本的代码有效:

x = ord(letter)
y = x + key
if y > ord('z'):
    y -= 26
msgc += chr(y)

请注意，这仅适用于小写字母。