Sample of the Week:
Adobe Acrobat DC makes the act of signing PDF files ridiculously simple; it’s at the point now where all you need is Adobe Reader and either your finger or a mouse. But signing PDF can be tricky. This article is not intended to dissuade you from using PDF files for signing documents, quite the opposite. The intention is to help developers to add the necessary attributes to the PDF to make the document reliable for signing and to ensure that all parties involved understand what is being agreed to. The issue is that the PDF language provides a number of capabilities that can make the rendered appearance of a PDF document vary even in the same version of Acrobat but on different machines. These capabilities could potentially be used to construct a document that misleads the recipient of a document and are relevant when considering the legal implications of a signed PDF. The most obvious of these capabilities is the layers feature but can be as esoteric as not embedding a font; remember, there are PDF files out there that were created before the invention of the Euro symbol.
When signing a document in Acrobat or Reader, you can examine the document and create an “Appearance Integrity Report” that will explain how different systems or different viewers may present the document differently.
Acrobat examines the document looking for specific features of PDF that may impact the visual appearance… and there are a lot of them… and then attaches a “Legal” dictionary in the document catalog. Scrubbing through a PDF file looking for these types of features requires quite a bit of knowledge of the PDF specification but fortunately, Acrobat does this for you automatically. The good news is, so does the Datalogics PDF Java Toolkit with the LegalScrubber class.
The LegalScrubber class provides means to scan PDF documents for elements which may affect its appearance. These elements should be considered when placing or checking digital signatures in a PDF document to ensure the validity of the signature with respect to the intent of signing the document. This is to ensure that the view approved by the signer is the same as the one displayed to the document receiver.
Like a lot of the service classes in the Datalogics PDF Java Toolkit, the LegalScrubber is incredibly easy to use and was designed so that the developer doesn’t need to either know or even understand the specific features of PDF that are can cause visual discrepancies. As a matter of fact, it only takes 3 lines of code to do some very sophisticated PDF analysis, generate the Legal Attestation and add it to the document.
The rest of the Gist referenced above will look for specific warnings that developers can then use them to create explanations of the document characteristics that may be easier to understand. You can then either Certify the document or send it out for signatures knowing that the document has all of the information to inform the viewer or signer of any issues that they may need to be aware of.