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Overview

Digital signatures are the best way to protect your PDF files from being forged. Syncfusion Essential PDF is a Flutter PDF library that helps users add digital signatures to their PDF files in any Flutter application. Syncfusion provides many ways to digitally sign a document: X509 certificates, such as .pfx files with private keys. It also supports hardware security modules (HSM), Online Certificate Status Protocol (OCSP), and certificate revocation lists (CRL) for authenticity and integrity.

Customize appearance

The Syncfusion Flutter PDF library provides a completely customizable appearance for its e-signatures. The content of the signature can be images, texts, graphics, and shapes.

Custom appearance

Additional features of digital signatures and timestamps

Sign existing PDFs with digital signatures.
Add multiple digital signatures to a PDF.
Externally sign a PDF document.

PDF Digital Signature Code Example

Add the digital signature to a PDF document using a few simple lines of code as demonstrated below. Also, explore our online Flutter PDF Example for various PDF functionalities.

dart
import 'dart:io';
import 'package:syncfusion_flutter_pdf/pdf.dart';

//Creates a new PDF document.
PdfDocument document = PdfDocument();

//Adds a new page.
PdfPage page = document.pages.add();

//Creates a digital signature and sets signature information.
PdfSignatureField field = PdfSignatureField(page, 'signature',
    bounds: Rect.fromLTWH(0, 0, 200, 100),
    signature: PdfSignature(
        //Creates a certificate instance from the PFX file with a private key.
        certificate:
            PdfCertificate(File('PDF.pfx').readAsBytesSync(), 'password123'),
        contactInfo: '[email protected]',
        locationInfo: 'Honolulu, Hawaii',
        reason: 'I am author of this document.',
        digestAlgorithm: DigestAlgorithm.sha256,
        cryptographicStandard: CryptographicStandard.cms));

//Add a signature field to the form.
document.form.fields.add(field);

//Save and dispose the PDF document.
File('Output.pdf').writeAsBytes(document.save());
document.dispose();