In Portugal there are three main types of digital signature, each with different levels of legal validity:
Simple Electronic Signature
This is the most basic type of digital signature. It can be something as simple as typing a name at the end of an email or scanning a handwritten signature. Although it is legally accepted in some cases, it has limited probative value, as it is difficult to guarantee the identity of the signatory or their intention to sign.
Advanced Electronic Signature
This type offers more guarantees than the simple signature. It must be exclusively linked to the signatory and allow their identification. Although it has greater probative value than the simple signature, it is still evaluated case by case by the courts.
Qualified Electronic Signature
This is the most secure and legally robust form of digital signature in Portugal. Main characteristics:
- Has the same legal value as a handwritten signature.
- Creates a presumption of authenticity, integrity, and non-repudiation of the signed document.
- Requires a qualified digital certificate issued by a recognized certification authority.
- Can be performed with the Citizen Card or Digital Mobile Key.
The qualified electronic signature is the only one that has legal effect equivalent to a handwritten signature, providing full proof of the provisions contained in the document.
It is important to note that the legal validity of digital signatures in Portugal is regulated by Decree-Law 290-D/99 and the European Union eIDAS Regulation. These laws ensure that digital signatures, especially qualified ones, have full legal validity when used correctly.