European law (directive n.93/1999, hereinafter referred to as "dir.") provides three kinds of electronic signatures, each with different juridical value:
1. electronic signature (also called a weak electronic signature or light electronic signature): "means data in electronic form which are attached to or logically associated with other electronic data and which serve as a method of authentication" (art. 2.1 dir.)
2. advanced electronic signature: "means an electronic signature which meets the following requirements:
[a] it is uniquely linked to the signatory;
[b] it is capable of identifying the signatory;
[c] it is created using means that the signatory can maintain under his sole control; and
[d] it is linked to the data to which it relates that any subsequent change of the data is detectable" (art. 2.2 dir.).
3. advanced electronic signature which is based on a qualified certificate and which is created by a secure-signature-creation device (also called a secure digital signature, strong digital signature, or qualified digital signature). The secure-signature-creation device (also called a Certification Authority or CA) must have the technical standards needed to ensure the key can neither be forced nor reproduced in a reasonable time, one that is longer than the validity period for the signature.