如何解密简单的异或加密 [英] How to decrypt simple XOR encryption

问题描述

我在网上找到了如下XOR加密函数:

I found the following XOR encryption function on the internet:

void xor_encrypt(char *key, char *string)
{
    int i, string_length = strlen(string);
    for(i=0; i<string_length; i++)
    {
        string[i]=string[i]^key[i];
        printf("%i", string[i]);
    }
}

它工作得很好，但我也想解密字符串.

It works perfect, but I would like to decrypt the string also.

例如:

void xor_decrypt(char *key, char *encrypted_string)
{
    //decrypt method goes here
}

所以基本上在我加密字符串之后，我会使用相同的加密密钥来解密之前加密的字符串.

So basically after I encrypt the string, I would use the same encryption key to decrypt the previously encrypted string.

我对编程很陌生，我只想知道如何解密以前加密的字符串.谢谢，感谢所有帮助.

I'm pretty new to programming and I would just like to know how to decrypt the previously encrypted string. Thanks, all help is appreciated.

推荐答案

关于 XOR 加密的一个很酷的事情是，当你应用它两次时，你会得到原始字符串——见 http://en.wikipedia.org/wiki/XOR_cipher.

One of the cool things about XOR encryption is that when you apply it twice, you get back the original string – see http://en.wikipedia.org/wiki/XOR_cipher.

在您的函数 xor_decrypt 中，您获取字符串和密钥并返回字符串 ^ 密钥.如果，现在，您再次使用密钥对它进行异或，您将得到 (string ^ key) ^ key = string ^ (key ^ key) = string ^ identity = string(按 XOR 运算符的属性:http://en.wikipedia.org/wiki/Exclusive_or#Properties)

In your function, xor_decrypt, you take string and key and return string ^ key. If, now, you xor that with the key again, you get (string ^ key) ^ key = string ^ (key ^ key) = string ^ identity = string (by properties of XOR operator: http://en.wikipedia.org/wiki/Exclusive_or#Properties)

因此，您可以在第一个 xor_encrypt 的输出上第二次运行您的函数 xor_encrypt.

Thus, you can just run your function, xor_encrypt, a second time on the output of the first xor_encrypt.

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