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Digital signatures can be considered as the electronic equivalent of a physical signature with ink on paper. However an electronic signature also provides certain advantages over an ink-and-paper signature. Some of these are (but not limited to):
A PDF document allows multiple types of signatures, each serving a different purpose. The below table lists the different types of signatures supported in a PDF document.
|Signature Type||Signatures allowed in a document (up to)||Description|
|Certification signature||1||Certifies the document, similar to notarizing a paper document.|
|Usage rights signature||1||(Deprecated) Represents a 'Usage Rights' signature, which determines the types of modifications that are allowed to be performed on the document.|
|Approval signature||No limit||Represents an approval of the document, when it is used as part of an approval workflow.|
The PDFTron SDK provides the low-level API required for working with digital signatures, as laid out in the PDF specification. For the full detail of digital signatures in PDF, please refer to section 12.8 of the PDF standard ISO 32000-1, which describes the details of the support for digital signatures in a PDF document.
We support all three types of signatures in a PDF document. Working with digital signatures can be daunting, however we do have a sample for digital signatures, which provides actual examples on how the API can be used to implement digital signature support, for PDF documents, in your application.
We provide a built-in PKCS#12 parser, that enables signing using existing certificates with the '.pk12' or '.pfx' extensions. In addition to this, you may write your own certificate handler to parse other formats, and use the handler with the PDFNet library.