Alghorithm of comparing PDF/A

[Guest]

Hi there. I am looking for some algorithm of comparing PDF/A. So the task is: PDF file is created on my side signed by my certificate then it is sent to partner and signed by his certificate. So, I need to compare the content of the file (if it was not changed) so just the orginal part with first signature. Actually, I am thinking about creating  checksum (hash) of orginal part and then compare with checksum (hash) after partners' signature. So now I have two questions, Is it possible to parse the file for these parts and create the checksum after second signature to compare with the checksum I did before sending? And If the checksum wil be the same after second signature, since I see that something is written to the original part too?

Thanks

[try67]

Try the Acrobat SDK forum...