Java itext4.x digital signature

Question

I am using itext4 and I know this method of implementation has been removed in new versions but I am able to generate pdf but its damaged. Appearance method setcrypto is used to sign. I added sign field while creating document. Later open same pdf and apply sign logic as mentioned in itext in action 2nd edition page 397.

First stamper.close give null pointer exception and next if i comment that line and generate pdf,the pdf wont open or its damaged

Please advise I am using itext 4.2.1 jar

Answer 1

I am able to create digital signature after setting visible signature with 3 param method. Adding field while generating pdf and later using visible method by passing one param singature field didn't help me.

Thanks for your support.