Here is a Windows command line version PdfSigner with TimeStamp(TSA) support,

Usage pdfsigner InPdf OutPdf Pkcs12KeyStore Pkcs12KeyStorePassword

because It is a demo application, so the TSA server only supports http://tss.pki.gva.es:8318/tsa
If you have interest, please download it here,pdfsigner(4.9M)

I got a email with the following requirement,

I came across your post while searching for a solution to add barcode to my invoices.
I can print the invoices as a pdf file but the problem is to have my tracking number printed as a barcode.
Can you do some software customization so it can read a certain area of the pdf file, convert and insert a barcode for printing ? I usually print about 50 invoices at a time.

After many exchanges, I finally decided to use pdftohml to parser pdf and get the text with the give position, use itext to insert barcode In order to be convenient for the customer, I use gcj to compile it to native code, so it can be run without jvm.

And my customer has used this application over 3 years.