使用异或操作实现字符串加密与解密

异或加密是一种简单而有效的加密技术，它的特点是同一密钥可用于加密和解密，以下是一个例子：

using System;
using System.Text;

public static class Encryption
{
    /// <summary>
    /// bytes数据通过encryptCode进行异或（加密|解密）
    /// 将传入的bytes作为返回值，不再额外分配内存
    /// </summary>
    /// <param name="bytes"></param>
    /// <param name="startIndex"></param>
    /// <param name="length"></param>
    /// <param name="encrypt"></param>
    public static void GetSelfXorBytes(byte[] bytes, int startIndex, int length, byte[] encrypt)
    {
        int codeIndex = startIndex % encrypt.Length;    // 避免codeIndex超上限
        for (int i = startIndex; i < startIndex + length; i++)
        {
            bytes[i] ^= encrypt[codeIndex++];
            codeIndex %= encrypt.Length;                // 避免codeIndex超上限
        }
    }

    public static void Test()
    {
        string demo = "Hello World";
        string encrypt = "密码本";

        byte[] demoBytes = Encoding.UTF8.GetBytes(demo);
        byte[] encryptBytes = Encoding.UTF8.GetBytes(encrypt);

        GetSelfXorBytes(demoBytes, 0, demoBytes.Length, encryptBytes);
        demo = Encoding.UTF8.GetString(demoBytes);
        Console.WriteLine(demo);
        GetSelfXorBytes(demoBytes, 0, demoBytes.Length, encryptBytes);
        demo = Encoding.UTF8.GetString(demoBytes);
        Console.WriteLine(demo);
    }
}

在该代码中，我们做了点小优化，将加密|解密后数据直接存储在bytes中，避免内存浪费。以下是输出结果：