Thanks for your interest in our products.
I am a representative from Aspose.Pdf team. Aspose.Pdf is a component which is used to generate PDF documents from scratch. But I am afraid Aspose.Pdf does not support the conversion of Crystal Report files into PDF format because due to some legal complications, we might not be able to accomplish this feature. In order to develop this feature, we need to hack the Crystal Reports file format but SAP has some licensing restrictions: http://www.sap.com/solutions/sapbusinessobjects/sme/reporting/crystalreports/licensing/index.epx which does not permit us to do so. I hope you would understand the circumstances.
Nevertheless, we have a component named Aspose.Pdf.Kit which is used to manipulate/edit existing PDF documents. As you have stated that you are able to convert the RPT file into PDF format by yourself, then I would suggest you to please try using Aspose.Pdf.Kit. For more information on how to encrypt the existing PDF document using Aspose.Pdf.Kit, please visit Implementing Security
For your convenience, I am also moving this thread to Aspose.Pdf.Kit forum where I believe our team of experts taking care of that product would be in better position to answer this query. If you have any further query, please feel free to contact.
We apologize for your inconvenience.