If we look at eIDAS regulation, based on the level of security of each three types of electronic signatures are defined:
Even with different security levels, all three types of signatures are perfectly legal. Choosing one or the other will depend on each particular case, as well as the type of document you want to sign.
Simple electronic signature
Simple electronic signature means 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. It has legal effect and can hold up in a court of law, although it may have to be backed with other type of evidence.
Advanced electronic signature
A signature that is uniquely linked to the signatory. It allows to uniquely identify the signatory. Created using signature creation data that only the signatory can use, with a high level of confidence, under his exclusive control and linked to the data signed by him so that any possible further changes are detected.
This type of signature certifies the identity of the signatory, integrity of data, providing more legal guarantees.
Qualified electronic signature
It’s an advanced electronic signature created using a qualified electronic signature creation device and is based on a qualified e-signature certificate. A qualified electronic signature will have a legal effect similar to the handwritten signature.