How to sign a digital document: signature types and procedure

In a context where companies are increasingly moving towards dematerialisation, the question of electronic signatures becomes unavoidable. Indeed, it is not simply a matter of digitally signing a document or scanning a handwritten signature, but rather of setting up a process that ensures total compliance with the legal regulations in force.

To do this, how to sign a digital document? Indeed, the objective is to guarantee the integrity of your documents and the authentication of the signatory, whether a legal entity or a natural person.

But how to implement the electronic signature in practice? Find out how it works, its legal context and how to affix a certified electronic signature thanks to dedicated tools.

See all software Electronic Signature

Types of digital signature

Before going on to analyse the procedure for signing a digital document, it is necessary to differentiate between the different types of digital signatures that can be affixed to electronic documents.

Simple' electronic signature

This type of signature consists of affixing one's signature by 'drawing' it on the screen or by scanning it from a previously hand-signed paper document.

This type of signature has no legal validity because the signature affixed in this way cannot be certified by special evaluation tools.

The only way to confirm the validity of the signature would be through the judgement of a judge who would use the expertise of a handwriting expert.

Advanced electronic signature

This type of signature is valid for legal purposes because it is created through the use of computer software capable of proving the authenticity and integrity of documents. The signatory has unique and exclusive control over the signature affixed.

Qualified electronic signature

This type of signature has the highest level of security and authenticity, because the signature is affixed through the use of special kits issued by accredited certification bodies. For this reason, the signature is valid for legal purposes for all types of documents and contracts.

Digital electronic signature

A special type of signature is the digital electronic signature, which is a 'version of the advanced electronic signature in which there is a system of encrypted keys that enable the holder by means of the private key and the recipient by means of the public key respectively to make manifest and verify the origin of an electronic document' Source (CAD)

How to sign a digital document: procedure

To create the signature of a digital document in compliance with the law, you use a provider of electronic signature and archiving services with evidentiary value. In the secure space they provide, transactions are tracked, recorded, sealed, stamped and archived in an integrated and secure manner.

Software for digital signatures

To be able to perform the digital signature procedure, you need software or hardware that is legally certified:

• a smart card or USB device equipped with a digital signature certificate. This device must be issued by an accredited certifier, which you can find on the DigitPA list.
• smart card reader, which you can buy on the Chamber of Commerce website).
• digital signature software. Open source and free software that can be downloaded online are Dike or File Protector, which you can find at www.card.infocamere.it.

If the person signing the digital signature has a USB token, he is not obliged to install the reader and signature software.

Once you have the system that allows you to digitally sign the document, you follow the steps below:

How to sign a document with an electronic signature

• you click on the access link received by e-mail
• you consult the electronic document
• you sign after receiving a security code via SMS that guarantees the unique connection.

How to request to have a document signed electronically

• you import the document (in the chosen format) into the software;
• you select the settings;
• you request the recipient to sign.

All you have to do is monitor the status of the document in real time to ensure that deadlines are met, then receive the signed document and store it in a digital safe if necessary.

The characteristics of the digital document to be signed

Technically, all file formats can be signed electronically (Word, XML, PDF, JPG, etc.). However, good practice favours the PDF format as it offers better preservation and protection of content.

To be more precise, the document must be in PDF-A LOGO II, written in static format, i.e. PDF/A, the best format for archiving electronic documents over a long period of time.

Why are other formats not suitable? All files that contain within them 'macro-instructions' or 'executable codes' that allow the modification of information, data, and documents are not suitable, as changes can be made even after digital signature.

Therefore, files in .doc (Word), .xls (Excel), .odt, .ods (Open Office), i.e. all files with the extension .p7m are editable after signing and must therefore be converted to the standard PDF/A format.

See all software Electronic Signature

How to sign a digital document: step by step procedure

Document valid for legal purposes

1. Equip yourself with one of the digital signature kits we have mentioned in the previous paragraphs.
2. Launch the signature software contained in the kit
3. Select the file on which you wish to affix the digital signature
4. Enter the PIN of the smart card with which the digital signature certificate is associated
5. Select the type of file to be generated after signing:
   1. P7M cryptographic envelope (CAdES), to generate a P7M-format file enclosing the original document together with the digital signature files;
   2. PDF, to generate a PDF file that has the digital signature included (whether visible or not);
   3. XML (XAdES) to again create a P7M format file.
6. Choose between the two options provided by the software:
   1. a certification to verify the date and time when the digital signature was inserted on the document;
   2. the addition of a password to encrypt the file. In this the document is protected and only the selected recipients, who can have a decryption key, can have access to the selected file.

Document without legal validity

As we saw at the beginning, you can affix a simple digital signature to the digital document, which, however, will have no legal validity.

In this case, you do not need a certified digital signature kit: you can affix your signature by hand and then scan the document. Alternatively, there are programmes that allow you to put your signature directly on the document, or if you have a touch screen, you can draw it directly by hand.

So are you ready to sign your first digital document?