Digital signatures

Definitions

Spanish Law 59/2003 dated December 19, 2003, for digital signatures offers three types of digital signature:

• Ordinary signatures: The law does not include the term "ordinary" but is often used to indicate that we are talking about a particular type of digital signatures. An ordinary digital signature is linked to "data in electronic form which is attached to or logically associated with other electronic data and which serves as a method of authentication."

• Advanced digital signature: “Digital signatures that can identify the signer and detect any subsequent change in the signed data, linked only to the signatory and to the data that is created by means that the signatory can maintain under his exclusive control”

• Qualified digital signature: “Advanced digital signature based on a qualified certificate and generated by a secure signature creation device." This definition has no equivalent in the European directive

Thus, each definition contains the previous and adds one more requirement.

From the above definitions it can be deduced that an appropriate system of user and password can generate ordinary digital signatures, while for the other two types more complex systems are needed based on message authentication code or public key cryptography.