digital signature


I am looking for ways to get my documents into DT in a way that conforms with german laws. In Germany, we have to either keep the originals (which is waht I don’t want to do), or make sure that the PDFs we created are protected against changes or tampering.

The law says, we need to digitally sign those PDFs, and we also need to have a revision audit trail so that changes within the database and the documents can be seen (who did what with which document and when).

Are there any ways we can implement this in DT somehow? I am thinking of scripting DT so that all incoming PDFs will be sent to some online signature service, who sign the documents and return them back to DT. Or something like that. I am just playing with the idea.

Any thoughts on this?


no one here who needs to digitally sign their documents?

Some years ago I did use digital signatures on PDFs that had regulatory significance, simply because subsequent modification of them could be detected by invalidation of the digital signature.

I used Acrobat for that, and it’s the only Mac application I can think of that does digital signatures (there are several others for flavors of Windows). You might want to check out Adobe’s description to decide whether the audit trail would satisfy your governmental regulations. If so, you could open your PDFs within your database under Acrobat in order to digitally sign them.

As you noted, there are several online services that digitally sign documents. I’m not familiar with them.

Ok thanks.

What happens when I import PDFs into DT and OCR them? Will that alter the PDFs, e.g. break the signature?

DT doesn’t touch the contents of documents (PDF or otherwise) other than reading them. If DT can’t read the content (such as an encrypted PDF) then nothing changes.

What happens if you import and OCR? - Test it yourself and find out. Only way to know for sure. :confused:

I would, but I am not quite there yet :slight_smile: I am still evaluating my possibilities before I buy all the stuff (DT, Scanner, signature card etc.).

I suspect that OCR would break a digital signature, so it would be better to digitally sign the PDF after OCR.

Would there be an easy way to do that from within DT? Import, OCR, send to signature software (e.g. by means of putting the files in a special folder or something) and then have them finally stored in DT?

Maybe through scripting or something like that?

Or would it be best to scan outside of DT (ScanSnap -> Adobe Acrobat OCR -> Adobe Acrobat digital signature -> import to DT)?

The latter is easily possible, but I really would prefer to do everything from inside DT (I hear the OCR is superior to Adobe’s?).

Thanks for any suggestions or thoughts…

I would OCR into DT Pro Office (or convert to searchable PDF if the image-onky PDF is already in the database), and afterwards open (Data > Open With) it under the application (e.g., Acrobat) that will add the digital signature, then Save the signed PDF back into the database.

Certainly, it would be possible to have a group with an attached script so that the script operates automatically on all the documents in the group. If the program that does the signing can be scripted, then you can simply automate the whole procedure (if you open a document that is stored inside DT by some external program, modify and save it, DT updates its indices etc automatically; I do that all the time).

Or there are many other ways to do it, for instance, arrange for a script to run every evening at some given time (via iCal), locate all documents that you have designated as "to be signed’ (eg by replicating to a group or tagging), then use whatever program you’re going to use to sign them, and you’re done.

I have found that, as a general rule, Acrobat Pro produces smaller and better-looking pdfs. There are exceptions where the difference is small or nonexistent, but generally that’s the case. I don’t know about the quality of the recognition though, I only use OCR to be able to search so I have never actually tried to read the output myself…

You should probably experiment a bit with both (and with various quality settings in DTPO) to see how they behave in your application. At any rate, you could scan the PDF directly into DTPO, use Acrobat to perform OCR and save it. That works; I haven’t found any way to usefully script acrobat with applescript though.

Thanks for your detailed response. I am going to give it a shot then. Experiement with it.

Just one more question, just to be absolutely sure: Will DT alter my PDFs in any way once they are imported? Or are all changes like annotations, notes etc. that I enter for a PDF stored in metadata somewhere? Thing is, once the files are digitally signed, any change to the document will break the signature, and that must not happen.

So what actions exactly can I safely do with my PDFs inside DT without tampering with the file itself?

Annotations “inside” the PDF (ie, the sort of annotation that is also visible in Preview or Acrobat) are saved with the PDF, so I suppose those will affect the signature. I suppose annotations via the provided template (which creates a separate RTF with a link to the PDF you are annotating) do not affect the signature.

Having said that, I don’t really know as I know nothing about digital signing and have never used it. Better to just try it to be sure.

DT doesn’t in any way alter the actual PDF when it is imported, classified, opened or viewed.

But any edit/save of the PDF such as highlighting would break an existing digital signature.

if you convert-to-searchable an existing pdf that has internal annotations - the annotations are lost in the created searchable;

Is this expected behavior?

Yes. The original image layer is lost when OCR is performed.