The main package from the @signpdf family that tries to make signing of PDFs simple in Node.js.

Usage

$ npm i -S @signpdf/signpdf node-forge. Then considering you have a well-prepared PDF that already has a signature placeholder and you have prepared a signer implementation usage should be as simple as:

``javascript
import signpdf from '@signpdf/signpdf';
...
const signedPdf = await signpdf.sign(fs.readFileSync(PATH_TO_PDF_FILE), signer);
`

If your PDF does not contain a placeholder, we have helpers:

- @signpdf/placeholder-pdfkit010
- @signpdf/placeholder-plain

We also have a single signer implementation currently:

- @signpdf/signer-p12

Notes

* The process of signing a document is described in the Digital Signatures in PDF document. As Adobe's files are deprecated, here is the standard as defined by ETSIBaselineProfile>).
* This lib:
* requires the signature placeholder to already be in the document (There are helpers included that can try to add it);
* requires the Contents descriptor in the Sig be placed after the ByteRange one;
* takes Buffer of the PDF and a Signer implementation to use when signing;
* does cover only basic scenarios of signing a PDF. If you have suggestions, ideas or anything, please CONTRIBUTE;
* Feel free to copy and paste any part of this code. See its defined Purpose.

$3

To produce PAdES compliant signatures, the ETSI Signature Dictionary SubFilter value must be ETSI.CAdES.detached` instead of the standard Adobe value. If you are using placeholder-plain or placeholder-pdfkit010 this can be done with a parameter.

Credits

* The whole signing flow is a rework of what's already in pdfsign.js so thanks go to @tbocek