Stream fs = FileUpload1.PostedFile.InputStream;

        MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider();
        byte[] md5byte = md5.ComputeHash(fs);
        string rr = string.Empty;

        foreach (byte b in md5byte)
        {
            rr += b.ToString("x2");
        }
        Label1.Text = rr;