How to digitally sign a PDF document

From paper to digital document: what changes?

The digital revolution and the adoption of new technologies in every area of ​​life have spread those innovative tools that allow people to digitally sign a digital document, giving it the same legal validity as a paper document with handwritten signature.

What is an electronic document? The Italian Digital Administration Code (CAD) defines it as a “computer representation of legally relevant deeds, facts or data” (Art.1, letter p). On the contrary, an analogue document is a “non-IT representation of legally relevant deeds, facts or data” (Art. 1, letter p-bis).

Similarly, the eIDAS Regulation (electronic IDentification Authentication and Signature) defines the electronic document as “any content stored in electronic form, in particular text or sound, visual or audiovisual recording” (Art.3, n.35). In addition, the EU Regulation 910/2014 on digital identity establishes the non-discrimination of electronic documents compared to paper documents.

Art. 20 of the Italian CAD concerns the validity and probative value of an IT document. In particular, par. 1-bis establishes that such documents have the same effectiveness as a “private agreement” (Art. 2702 of the Italian Civil Code) when they are in written form, have a digital signature or a qualified/advanced electronic signature, or are created following the requirements of the Agency for Digital Italy (AgID) that guarantee the security, integrity and immutability of the document and the traceability to the author.

If an electronic document does not meet these requirements, the written form and its probative value can be evaluated in court, in relation to the security, integrity and immutability criteria.

Signing an electronic document: the different types of signature

To give legal validity to an electronic document it is necessary to use an advanced electronic signature (AdES) or a qualified electronic signature (QES). The elDAS Regulation regulates both and defines the electronic signature as a “data in electronic form which is attached to or logically associated with other data in electronic form and which is used by the signatory to sign“.

To better understand the differences between the two types of signature, let’s see the features of the AdES and QES:

Advanced Electronic Signature (AdES)

It is more secure than a generic electronic signature as it must meet the following requirements:

  • It refers only to the signatory;
  • It must be suitable for identifying the signatory;
  • It is created from data that the signatory can use under his own exclusive control, with high levels of security;
  • It must be linked to the data in order to allow the identification of any their subsequent modification;

A classic example of AdEs is the graphometric signature using a tablet and a special stylus.

Qualified electronic signature (QES)

It is a particular type of FEA which, in addition to the characteristics of the advanced electronic signature, also:

  • Is created using a specific device for creating electronic signatures;
  • Is based on a qualified electronic certificate;
  • Has the same legal value as a handwritten signature.

As already said, art. 20 of the CAD specifies that a computer document has the same effectiveness as a private writing when there is an AdES, a QES or a digital signature.

What is a digital signature? A digital signature is a type of qualified electronic signature, provided only in Italy and regulated by the Italian CAD regulation. It has the same validity as a handwritten signature on paper and guarantees the authenticity, non-repudiation and integrity of the message to the recipient.

To digitally sign a document with this type of QES it is necessary to have a kit consisting of a physical tool, such as a business key or a smart card with a special reader, containing the signature certificates. The kit can only be issued by one of the certification bodies accredited by the Agency for Digital Italy (AgID). However, business owners can also refers the local Chamber of Commerce.

It is also possible to use a simple and immediate tool that does not require the installation of specific hardware. It is the remote digital signature. This type of signature allows people to sign digital documents in a simple, fast and secure way using a device (smartphone, tablet or PC) connected to the internet, a signature software and a One Time Password generated by a token or an app that guarantees safety.

How to digitally sign the Portable Document Format?

One of the most popular formats for exchanging documents via web is PDF, Portable Document Format.

Adobe Inc. created this format in the 1990s to make text and image documents usable independently of the hardware and software that generated or displayed them.

A Portable Document Format can contain any combination of text, multimedia (audio and video), hypertext (links and bookmarks) and page thumbnails. Additionally, a PDF never loses formatting when sent to another user and is also accepted by businesses and governments.

To digitally sign a PDF document you need to have:

  • A smart card or USB device containing a digital signature certificate issued by one of the certification bodies accredited by the Agency for Digital Italy (AgID);
  • A smart card reader;
  • A digital signature software;

Signing a PDF document: Namirial’s FirmaCerta

Namirial S.p.A. is a certification body accredited by the Italian AgID. Therefore, it is authorized to issue qualified certificates compliant with European Regulation 910/2014.

The signature software FirmaCerta Client by Namirial S.p.A. allows to:

  • Integrate the digital signature into the file to which it refers;
  • Integrate the timestamp into the signed file to which it refers;
  • Verify signature and timestamp;
  • Counter-sign the file (validation).

Furthermore, FirmaCerta also allows to:

  • Simultaneously sign a large number of digital documents (invoices, policies, payment receipts, wire transfers, etc.);
  • Sign PDF documents keeping the original format;
  • Choose the device with which to sign (Smartcard-Token);
  • Associate a timestamp to a document;
  • Drag and drop one or more files into the same signature window;
  • Sign password protected pdf documents.

FirmaCerta software is compatible with the following operating systems:

  • Windows 10
  • Windows 8 32-bit – 64-bit
  • Windows 7 32-bit – 64-bit
  • Mac OS 10.13 (High Sierra)
  • Mac OS 10.14 (Mojave)
  • Mac OS 10.15 (Catalina)
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