how to convert encrpted code to PDF file

Hi all

i want to convert encrypted code to PDF file. i am using USPS tracking service they provide me encrpted form now i need to convert that into label. so i am passing that encrypt code so that i can get one pdf file. lables like tracking number ,barcode etc will be in that particular PDF file. 

i have tried following code

 byte[] labelBuffer = Encoding.ASCII.GetBytes("my encrpted code here");

   string fileSaveLocation = " d:/test.pdf";
            // Save label buffer to file
            FileStream LabelFile = new FileStream(fileSaveLocation, FileMode.Create);

            LabelFile.Write(labelBuffer, 0, labelBuffer.Length);
            LabelFile.Close();

here file is  PDF created but not able to open the file. 

 Please help me out.

Regards

sanjay