如何使用 XOR 加密字符串而不包含奇怪的字符？

Question

以下代码可以正常工作，但我不希望在加密字符串中包含奇怪的字符，例如 '\x03'。如何做到这一点？

string XOR_Encryption(string toBeEncrypted, string sKey)
{
    string sEncrypted(toBeEncrypted);
    unsigned int iKey(sKey.length()), iIn(toBeEncrypted.length()), x(0);
    for (unsigned int i = 0; i < iIn; i++)
    {
        sEncrypted[i] = toBeEncrypted[i] ^ sKey[x];
        if (++x == iKey) { x = 0; }
    }
    return sEncrypted;
}

用法：

    string message = "gbpi";
    string Key("Q4s4R4t");

    string encrypted_message = XOR_Encryption(message, Key);
    cout << "encoded: " << encrypted_message << endl;

    string decryptedMessage = XOR_Encryption(encrypted_message, Key);
    cout << "decoded: " << decryptedMessage << endl;

Answer 1

参考@kelalaka的suggestion，这里有一个使用Hex编码的解决方案：

#include "stdafx.h"

#include <stdio.h>
#include <conio.h>
#include <string>
#include <stdlib.h>
#include <iostream>

string XOR_Encryption(string toBeEncrypted, string sKey)
{
    string sEncrypted(toBeEncrypted);
    unsigned int iKey(sKey.length()), iIn(toBeEncrypted.length()), x(0);
    for (unsigned int i = 0; i < iIn; i++)
    {
        sEncrypted[i] = toBeEncrypted[i] ^ sKey[x];
        if (++x == iKey) { x = 0; }
    }
    return sEncrypted;
}

void stream2hex(const string str, string& hexstr, bool capital = false)
{
    hexstr.resize(str.size() * 2);
    const size_t a = capital ? 'A' - 1 : 'a' - 1;

    for (size_t i = 0, c = str[0] & 0xFF; i < hexstr.size(); c = str[i / 2] & 0xFF)
    {
        hexstr[i++] = c > 0x9F ? (c / 16 - 9) | a : c / 16 | '0';
        hexstr[i++] = (c & 0xF) > 9 ? (c % 16 - 9) | a : c % 16 | '0';
    }
}

void hex2stream(const string hexstr, string& str)
{
    str.resize((hexstr.size() + 1) / 2);

    for (size_t i = 0, j = 0; i < str.size(); i++, j++)
    {
        str[i] = (hexstr[j] & '@' ? hexstr[j] + 9 : hexstr[j]) << 4, j++;
        str[i] |= (hexstr[j] & '@' ? hexstr[j] + 9 : hexstr[j]) & 0xF;
    }
}

int _tmain(int argc, _TCHAR* argv[])
{
    string text = "text";
    string Key("password");

    string encrypted_message = XOR_Encryption(text, Key);
    stream2hex(encrypted_message, encrypted_message, true);
    cout << "encoded: " << encrypted_message << endl;

    hex2stream(encrypted_message, encrypted_message);
    string decryptedMessage = XOR_Encryption(encrypted_message, Key);
    cout << "decoded: " << decryptedMessage << endl;

   getch();

   return 0;
}