![]() For example, should they use the "text" signature? ![]() They typically will use Mac Preview or Adobe Reader.to sign. What is the recommended approach, say for our "clients" that sign the documents to use. In comments you asked follow-up questions. Obviously, though, this restricts your code to scribbled signatures added with Adobe software. Thus, in custom code to find signature images like these you only need to find images referenced inside content marked as ADBE_FillSign. To identify which bitmap was used for which cause, you can compare those coordinates with the coordinates of the 6 empty signature fields.įurthermore, the Adobe software used to add those scribbles even specially marked the added contents with a custom tag: /ADBE_FillSign BMC To do so you have to apply image extraction (with coordinates) to your PDF. Thus, there indeed may be a need to extract those scribbles even though they do not fill the official, AcroForm form fields. Nonetheless those bitmaps may count as legally binding (albeit easy to repudiate) signatures depending on your local legislation. Actually they do no represent any dynamic content at all, they are part of the static page content. Those bitmap images, therefore, do not fill any of the AcroForm form fields. It has 6 empty (unsigned) signature fields.Īnd it has two bitmaps with scribbles located approximately in the area of two of the signature form fields. In case of the example file you shared there is a mixture (as Lonzak already explained while I wrote this): You have to analyze the exact nature of the low-level data in your PDF and probably even have to ask the creator of the signature to provide sufficient information (specifications, decryption material. In either case there is no generic way to find the signature related information of them and interpret it. or your PDF is broken making iText not recognize the signature.or they are not even signatures according to spec to start with,.either not interoperable but at least signatures according to spec,.Thus, the other "signatures" you recognize when viewing your PDF are ![]() Thus, let's ignore them.Ĭertification signatures, approval signatures, and document time stamps are stored in AcroForm signature fields, and you retrieve the signature fields filled-in (signed) with interoperable signatures using your code. Usage rights signatures are merely a means to communicate to Adobe Reader that it shall enable certain usually inactive features they are not meant to be created by users or validated as user signature. The only kinds of signatures specified in the PDF specification ISO 32000-2 are certification signatures, approval signatures, document time stamps, and usage rights signatures. ![]()
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