请教如何将如下VC++代码转换成C#代码，谢谢

int nKeyLen = strKey.GetLength();
if (nKeyLen == 0)
    strKey = _T("xxsswww");
srand((unsigned)time(NULL));
int nRange = 256;
int nOffset = (rand() % nRange);
CString strDest = _T("");
strDest.Format(_T("%1.2x"), nOffset);

int nSrcAsc = 0;
int nKeyPos = 0;
for (int nSrcPos = 0; nSrcPos < strSrc.GetLength(); nSrcPos++)
{
    int n = strSrc[nSrcPos];
    nSrcAsc = (strSrc[nSrcPos] + nOffset) % 255;
    if (nKeyPos < nKeyLen - 1)
        nKeyPos += 1;
    else
        nKeyPos = 1;
    nSrcAsc = nSrcAsc ^ strKey[nKeyPos];
    CString strTemp = _T("");
    strTemp.Format(_T("%1.2x"), nSrcAsc);
    strDest += strTemp;
    nOffset = nSrcAsc;
}
return strDest;

 int nKeyLen = strKey.Length;
if (nKeyLen == 0)
    strKey = "xxsswww;
Random rnd = new Random();
int nRange = 256;
int nOffset = (rnd.NextInt() % nRange);
string strDest = string.Format("{0:X2}", nOffset);
int nSrcAsc = 0;
int nKeyPos = 0;
for (int nSrcPos = 0; nSrcPos < strSrc.Length; nSrcPos++)
{
    int n = strSrc[nSrcPos];
    nSrcAsc = (strSrc[nSrcPos] + nOffset) % 255;
    if (nKeyPos < nKeyLen - 1)
        nKeyPos += 1;
    else
        nKeyPos = 1;
    nSrcAsc = nSrcAsc ^ strKey[nKeyPos];
    string strTemp = "";
    strTemp = string.Format("{0:X2}", nSrcAsc);
    strDest += strTemp;
    nOffset = nSrcAsc;
}
return strDest;

nSrcAsc = (strSrc[nSrcPos] + nOffset) % 255;
看上去应该 %256 才对，你检查下。