In digital signing, the level of security is heavily dependent on the medium on which the digital certificate holder stores their private key. Smart cards are currently considered the highest-security medium since the user’s private signature key never leaves the card and all encryption and digital signing actually take place on the card itself.
Another key ingredient of the security of digital signing is the size of public and private signature keys. Only keys of sufficient size can protect public keys, and their corresponding private keys, from being compromised.
The primary condition for the use of digital signature security features is the authentication of public keys, which is carried out by a Certification Authority – CA. The CA issues a digital certificate for the owner, and with this certificate the holder can prove ownership of the key and, by means of a digital signature, their identity in the world of e-business.