how to make bar-code label from encrypted text.

i am using USPS service. when i sent request for tracking label i got out put of encrypted text now i should make that encrypted text to bar code label.

I have tried following code but did not get any result. i C# (ASP.net) i am using

string str ="JVBERi0xLjINCjUgMCBvYmoNCjw8DQovVHlwZSAvWE9iamVjdA0KL1N1YnR5cGUg....";byte[] arr =System.Text.Encoding.ASCII.GetBytes(str);string strFileName =GetTempFolderName()+"yourfilename.gif";if(byteArrayIn !=null){
            using (MemoryStream stream =newMemoryStream(byteArrayIn)){
                newImage =System.Drawing.Image.FromStream(stream);

                newImage.Save(strFileName);Image11.Attributes.Add("src", strFileName);}}

Please help me if you have any solution