将PHP密码解密转换为C#

我继承了一些C#代码，其中一个PHP页面包含函数&decrypt已编译/转换为独立的Windows EXE。我想把这段PHP代码放到C#中。

function &decrypt($enc_text, $password)
{
    $iv_len = 16;
    $enc_text = base64_decode($enc_text);
    $i = $iv_len;
    $n = strlen($enc_text);
    $plain_text = '';
    $iv = substr($password ^ substr($enc_text, 0, $iv_len), 0, 512);
    while ($i < $n)
    {
        $block = substr($enc_text, $i, 16);
        $plain_text .= $block ^ pack('H*', md5($iv));
        $iv = substr($block . $iv, 0, 512) ^ $password;
        $i += 16;
        }
    return $plain_text;
}

我发现了几个涉及此代码的问题，但没有提供太多见解：只想将代码解码为纯文本以及"；MD5解密"；php函数到MySQL存储函数

有用的链接：PHP base64_decode C#等效

http://nuronconsulting.com/c-pack-h.aspx

我可以得到正确的结果，除了第二个和第三个到最后一个字符。我想我的base64解码仍然关闭。

编辑：更新为正在使用的最新代码。删除了中间编辑。

    private string decipher(string ienc_text, string ipassword)
    {
        int iv_len = 16;
        byte[] toEncryptArray = Convert.FromBase64String(ienc_text);
        string encryptedStringx = System.Text.Encoding.Default.GetString(toEncryptArray);
        string encryptedString = Encoding.GetEncoding(28591).GetString(toEncryptArray);
        string password = ipassword;
        int i = iv_len;
        int n = encryptedString.Length;
        string plain_text = "";
        string iv = phpXOR(ipassword, encryptedString.Substring(0, iv_len));
        while (i < n)
        {
            string block = encryptedString.Substring(i, iv_len);
            string md5 = getMD5(iv);
            byte[] testPack = PackH(md5);
            string testPackstring = Encoding.Default.GetString(testPack);
            string tmp = phpXOR(block, testPackstring);
            plain_text += tmp;
            string block_iv = block + iv;
            string tmp_iv = block_iv;
            if (block_iv.Length > 512)
            {
                tmp_iv = block_iv.Substring(0, 512);
            }
            iv = phpXOR(tmp_iv, password);
            i += 16;
        }
        return plain_text;
    }
    public static byte[] PackH(string hex)
    {
        if ((hex.Length % 2) == 1) hex += '0';
        byte[] bytes = new byte[hex.Length / 2];
        for (int i = 0; i < hex.Length; i += 2)
        {
            bytes[i / 2] = Convert.ToByte(hex.Substring(i, 2), 16);
        }
        return bytes;
    }
    string phpXOR(string text, string key)
    {
        byte[] result = new byte[key.Length];
        for (int c = 0; c < key.Length; c++)
            result[c] = (byte)(((byte)text[c]) ^ ((byte)key[c]));
        return Encoding.Default.GetString(result);
    }
    public static string getMD5(string iValue)
    {
        byte[] textBytes = System.Text.Encoding.Default.GetBytes(iValue);
        //byte[] textBytes = System.Text.Encoding.GetEncoding(28591).GetBytes(password);
        try
        {
            System.Security.Cryptography.MD5CryptoServiceProvider cryptHandler;
            cryptHandler = new System.Security.Cryptography.MD5CryptoServiceProvider();
            byte[] hash = cryptHandler.ComputeHash(textBytes);
            string ret = "";
            foreach (byte a in hash)
            {
                if (a < 16)
                    ret += "0" + a.ToString("x");
                else
                    ret += a.ToString("x");
            }
            return ret;
        }
        catch
        {
            throw;
        }
    }