I'd like to digitally sign a PDF document out of an ABAP program or class, just to ensure that the document was not modified by anyone.
In my program I hold the PDF as a binary stream in a XSTRING variable. I convert it into a binary table and use the function module 'SSF_KRN_SIGN_BY_AS' to sign this binary stream. In general, this is working fine (validating it with function module 'SSF_KRN_VERIFY' is successful).
But if I open the generated file with Acrobat Reader, no signature is found.
Obviously it does not work to sign the binary directly, as I did.
How can I create a digital signature on PDFs using ABAP? Do I have to convert it into ASCII or so before? Or: How must a signature be attached to a PDF file?
Our release is 620. Every little hint is appreciated.