verify pdf files in JS (supports both node.js & browser).

The signed PDF file has the public certificate embedded in it, so all we need to verify a PDF file is the file itself.

npm i @ninja-labs/verify-pdf

// CommonJS require
const verifyPDF = require('@ninja-labs/verify-pdf');

// ES6 imports
import verifyPDF from '@ninja-labs/verify-pdf';

Verify the digital signature of the pdf and extract the certificates details

const verifyPDF = require('@ninja-labs/verify-pdf');
const signedPdfBuffer = fs.readFileSync('yourPdf');

const {
    verified,
    authenticity,
    integrity,
    expired,
    signatures
} = verifyPDF(signedPdfBuffer);

import verifyPDF from '@ninja-labs/verify-pdf';

const readFile = (e) => {
    const file = e.target.files[0]
    let reader = new FileReader();
    reader.onload = function(e) {
        const { verified } = verifyPDF(reader.result);
    }
    reader.readAsArrayBuffer(file);
};

• signedPdfBuffer: signed PDF as buffer.
• verified: The overall status of verification process.
• authenticity: Indicates if the validity of the certificate chain and the root CA (overall in case of multiple signatures).
• integrity: Indicates if the pdf has been tampered with or not (overall in case of multiple signatures).
• expired: Indicates if any of the certificates has expired.
• signatures: Array that contains the certificate details and signatureMeta (Reason, ContactInfo, Location and Name) for each signature.

You can get the details of the certificate chain by using the following api.

const { getCertificatesInfoFromPDF } = require('@ninja-labs/verify-pdf');  // require

import { getCertificatesInfoFromPDF } from '@ninja-labs/verify-pdf';  // ES6

const certs = getCertificatesInfoFromPDF(signedPdfBuffer);

• signedPdfBuffer: signed PDF as buffer.

• certs:

  • issuedBy: The issuer of the certificate.
  • issuedTo: The owner of the certificate.
  • validityPeriod: The start and end date of the certificate.
  • pemCertificate: Certificate in pem format.
  • clientCertificate: true for the client certificate.

node-forge is used for working with signatures.

• The process of signing and verifying a document is described in the Digital Signatures in PDF document.
• This incredible Stack Overflow answer for describing the whole process of verifying PKCS7 signatures.