PDF Digital Signature Library: Prebuilt Signature Tools

.NET PDF Digital Signature Library

Use the pdf digital signature library and certificates to ensure the authenticity and integrity of your PDF documents.

Add advanced signing support with a high level of security to all your applications with the GdPicture.NET PDF Signature SDK, including — PDF/A compliance, digital certificates, timestamps, multiple signatures, and more.

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Illustration GdPicture.NET PDF Signature SDK

Digital signatures

Each country has laws regarding the use of digital or electronic signatures.
In the European Union, the eIDAS regulation allows three types of electronic signatures:

the simple electronic signature suitable for everyday acts or those with low legal or financial consequences for the signatory.
the advanced electronic signature, which includes the use of a digital certificate.
the qualified electronic signature, generally used for authentic acts of notaries, lawyers, bailiffs, courts, and the like. Its security criteria are comparable to those of the advanced digital signature.

Still, its procedure cannot be entirely carried out remotely: a certification authority approved by the government must verify and validate the identity of the signatory.

You can use the GdPicture.NET PDF Signature SDK in all cases, thanks to the high level of security and the ability to import a digital certificate.

Main Features of the PDF Digital Signature Library

PDF/A conformant signatures
Support for European Signature Standards
Add an optional visual appearance of the signature (page, size, color, position, text, image, etc.)

Support for Multiple Signatures
Remove digital signatures

Digital certificates

A digital signature certificate (DSC) contains information about the user’s name, pin code, country, email address, date of issuance of the certificate, and name of the certifying authority. It also makes it possible to prove that the document has not been modified since the signature. The digital certificate is an electronic file, as well as a private key allowing cryptographic signature operations. Only a Certification Authority, whose role is to verify the identity and make the link between the private signature key and the identity of the signatory, can issue a certificate.

Main features

Certify documents using Modification detection & prevention (MDP)
Apply signatures using:
- Public Key Cryptography Standard #12 containers (pfx, p12)
- Windows certificate store
- Smart Cards

Security of the digital signing process

The digital signature process is based on an encryption system with a private key (which is used to sign) and a public key (to verify the signature). It is this encryption system that allows authentication of the document sender. To ensure the highest security level, GdPicture.NET uses the SHA-256 hash algorithm.
Read more about the safety of the signing process.

Main features

Digital signatures validation
RFC3161 compliant Timestamp support
Use of the SHA-256 hash algorithm

Illustration of Security of the digital signing process

Digital signing on the Web

Get all the GdPicture.NET signing features in your web applications with our HTML5 Viewer and Document Management Kit DocuVieware.
The digital signature features are conveniently bundled in a snap-in.

Test the DocuVieware demo

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Unified API to sign a PDF

Thanks to our PassportPDF API, you can integrate PDF signing features in any application.

Try with your document

How to use

Download and install GdPicture.NET package from here.

You will be able to find some compiled demo applications in
[Install directory]\Samples\Bin\

You will be able to find C# and VB.NET demo applications including source code in
[Install directory]\Samples\WinForm\

You will find other code snippets within the online reference guide found here

https://www.gdpicture.com/guides/gdpicture/

You can find some discussions about PDF in the dedicated section of our community forums located here

PDF dedicated forum

Example of usage

How to digitally sign or certify PDF documents

FAQs

The SDK supports various digital certificates, including those stored in Public Key Cryptography Standard #12 (PFX, P12) containers, Windows certificate stores, and smart cards. This flexibility allows users to utilize certificates from multiple sources for signing PDF documents.

Yes, the GdPicture.NET PDF Signature SDK allows for the application of multiple digital signatures to a single PDF document. Users can add several signatures sequentially without invalidating previously applied ones, facilitating collaborative workflows and multi-party approvals.

Absolutely. The SDK includes RFC3161-compliant timestamp support, enabling users to add trusted timestamps to their digital signatures. This feature provides verifiable proof of the time at which a document was signed, enhancing the credibility and legal standing of the signature.

Yes, the GdPicture.NET PDF Signature SDK offers functionalities to validate existing digital signatures. It can retrieve information about applied signatures and their corresponding certificates, checking for any alterations to the document since signing and ensuring the certificate’s validity.

The SDK employs robust security measures, including the use of the SHA-256 hash algorithm during the signing process. This ensures a high level of encryption and data integrity, safeguarding the document against unauthorized modifications and ensuring the authenticity of the signer.