An electronic signature made with a system as secure as Closd’s is more reliable than a handwritten signature. The entry into force of the eIDAS regulation has been a giant step in its generalization: The certification of an electronic signature provider is a trust factor and a guarantee of compliance with the rules established by European and national laws. The validity of an electronic signature made on Closd is therefore proved by:
Regarding the verification of an electronic signature by PDF readers, it is based on a “chain of trust” principle. The encryption certificate is validated by the Certification Authority that issued it (i.e., the electronic signature service provider), itself validated by an authority with a higher level of trust and so on, until a Root Certification Authority is reached, the last link in the chain (generally private companies acting as trusted third party for numerous uses). The PDF reader is able to verify the reliability of each level: if one of the links in the chain is missing, it will not validate the electronic signature.