PDF conversion may require some additional jars on your classpath to handle some PDF files. As these can increase the size of download substantially but are needed on only a small number of PDF files, we do not include them all.
If they are required, the software will generate an error or tell you.
You can either add the jars into the ext directory of Java or add them to the classpath using the -cp option (in which case you can not use the -jar option and will need to specify the class you are running).
If the file is encrypted, the JCE library from The Legion Of The Bouncy Castle (http://www.bouncycastle.org).
mailbc.jar is also required along with the main jar to compile or open a PDF with a certificate.