I re-post this message because I've found a way to detect that a file as been modified . I found that any modification may corrupted the cross reference table & it's easily detect with "bycepdfdata" , a software that shows metadata.... But I don't know if it do detect a file modified with acrobatpro ? Your opinion ?
There is no sure proof way to determine if a generic pdf file is modified. If you go to the document properties (control or command d), if the proper metadata is available, it will list the creation date and time and modified date and time. This can help you determine if a pdf file has been modified since creation. However, it is not foolproof. This metadata is not secured. The easiest way to detect if a file has been modified to to digitally sign the document. Reader and Acrobat will report if the document has been changed since it was signed.
I am using timestamps to track copy editors edit updates on PDF documents. As I understand from the forum my copyeditors are able to change the edit times. I would like to make it impossible for them to do so. The current process allows me to access first to the PDF document and then send it to them for copy editing work. Ideally, before sending it to them, I would block their ability to change edit times. Is that possible?
If you have signed the file, it will be changed to a read-only version. Also, if you have the file signed using a digital certificate, you can check its authenticity. More info here: Validating digital signatures, Adobe Acrobat
Hope this helps.
-Souvik
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As I understand it, if you modify (edit) a PDF with Acrobat Pro, it will create a new reference table on save that coincides with the changes made. At that point a new "created" date is applied.
If you don't want anyone to modify your PDFs, why not just lock and password protect them?
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