private string GetEncyptString(string inputString, int intKey)
        {
            ushort num = (ushort)intKey;
            char[] chArray = new char[4 * inputString.Length];
            for (int i = 0; i < inputString.Length; i++)
            {
                ushort num3 = (ushort)(inputString[i] + num);
                string str = new string(new char[] { this.GetNewChar((byte)(num3 & 15)), this.GetNewChar((byte)((num3 >> 4) & 15)), this.GetNewChar((byte)((num3 >> 8) & 15)), this.GetNewChar((byte)((num3 >> 12) & 15)) });
                chArray[4 * i] = str[0];
                chArray[(4 * i) + 1] = str[1];
                chArray[(4 * i) + 2] = str[2];
                chArray[(4 * i) + 3] = str[3];
                num = (ushort)(num + 0x6fd);
            }
            return new string(chArray);
        }

        private char GetNewChar(byte value)
        {
            return (char)(0x61 + value);
        }

.method public hidebysig static string 
          x9919(string x12346_1,
                int32 x12347_2) cil managed
  {
    // 代码大小       158 (0x9e)
      .maxstack  5
      .locals init (unsigned int16 V_0,
               char[] V_1,
               int32 V_2,
               unsigned int16 V_3)
        ldarg.1           //参数 1 入栈，int32 x12347_2
        conv.u2           //将位于计算堆栈顶部的值转换为 unsigned int16，然后将其扩展为 int32 
        stloc.0     //出栈到V_0 int16型
        ldarg.0     //参数 0 入栈,那个入参string x12346_1
        callvirt   instance int32 [mscorlib]System.String::get_Length() //调用求字符串儿长度函数
        ldc.i4.4    //将整数值 4 作为 int32 推送到计算堆栈上
         div        //除，上面的串儿长度除以4?
        newarr     [mscorlib]System.Char //Create a zero-base, on-dimensional array
        stloc.1    //出栈到V_1，那个char[]数组
        ldc.i4.0   //将整数值 0 作为 int32 推送到计算堆栈上
        stloc.2    //出栈到V_2,那个int32 V_2的临时变量
       IL_WHILE: ldloc.2   //V_2入栈,int32 V_2,第一次到此处时为0
     
        ldarg.0   //参数0入栈,那个string
        callvirt   instance int32 [mscorlib]System.String::get_Length() //又调用求串儿长度
        ldc.i4.4  ////将整数值 4 作为 int32 推送到计算堆栈上 //这段儿和标签IL_0061及其后的作用一样，好象，往下跑着看
        div        //除，上面的串儿长度除以4?
        blt.s      IL_IF //小于跳转

        ldloc.1
        br.s       IL_END
      
      IL_IF:  ldarg.0   ////参数0入栈,那个string
        ldc.i4.4  //将整数值 4 作为 int32 推送到计算堆栈上
        ldloc.2   //V_2入栈,int32 V_2
        mul       //乘  4*V_2入栈
         callvirt   instance char [mscorlib]System.String::get_Chars(int32) //据一个int32值取它对应的字符
        ldc.i4.s   97   //将 num 作为 int32 推送到堆栈上（短格式）。
         sub   //减97
       ldarg.0 //参数0入栈,那个string
        ldc.i4.4 //将整数值 4 作为 int32 推送到计算堆栈上
        ldloc.2 ///V_2入栈,int32 V_2
        mul     //乘  4*V_2入栈
        ldc.i4.1  //将整数值 1 作为 int32 推送到计算堆栈上
        add       //加 4*V_2+1
        callvirt   instance char [mscorlib]System.String::get_Chars(int32) //据一个int32值取它对应的字符
        ldc.i4.s   97 //将 num 作为 int32 推送到堆栈上（短格式）。
        sub          //减
        ldc.i4.4     //将整数值 4 作为 int32 推送到计算堆栈上
        shl          //左移,移上面指出的4位，后面补0
        add          //加
        ldarg.0        ////参数0入栈,那个string
        ldc.i4.4      //将整数值 4 作为 int32 推送到计算堆栈上
        ldloc.2       //V_2入栈,int32 V_2
        mul       //从栈取两值乘，结果入栈
       ldc.i4.2  //将整数值2 作为 int32 推送到计算堆栈上
        add       //从栈取两值加，结果入栈
        callvirt   instance char [mscorlib]System.String::get_Chars(int32) //据一个int32值取它对应的字符
        ldc.i4.s   97  //将 num 作为 int32 推送到堆栈上（短格式）。
        sub        //减
        ldc.i4.8   //将整数值8作为 int32 推送到计算堆栈上
        shl         //左移8位
        add         
        ldarg.0
        ldc.i4.4
        ldloc.2
        mul
        ldc.i4.3
        add
        callvirt   instance char [mscorlib]System.String::get_Chars(int32)
        ldc.i4.s   97
        sub
        ldc.i4.s   12
        shl
        add
        conv.u2
        stloc.3
       ldloc.3
       ldloc.0
       sub
        conv.u2
        stloc.3
        ldloc.1
        ldloc.2
        ldloc.3
        stelem.i2
       ldloc.0
       ldc.i4     0x6fd
        add
        conv.u2
        stloc.0
        ldloc.2
        ldc.i4.1
        add
        stloc.2
       // ldloc.2   //V_2入栈,int32 V_2,第一次到此处时为0
        br.s       IL_WHILE  ////跳到标签处
      
      IL_END:  newobj     instance void [mscorlib]System.String::.ctor(char[])
      ret
  } // end of method Form1::x9919

private static string x9919(string x12346_1, int x12347_2)
{
    ushort num = (ushort) x12347_2;
    char[] chArray = new char[x12346_1.Length / 4];
    for (int i = 0; i < (x12346_1.Length / 4); i++)
    {
        ushort num3 = (ushort) ((((x12346_1[4 * i] - 'a') + ((x12346_1[(4 * i) + 1] - 0x61) << 4)) + ((x12346_1[(4 * i) + 2] - 0x61) << 8)) + ((x12346_1[(4 * i) + 3] - 0x61) << 12));
        num3 = (ushort) (num3 - num);
        chArray[i] = (char) num3;
        num = (ushort) (num + 0x6fd);
    }
    return new string(chArray);
}