The level of security depends on the storage media on which the digital certificate holder stores their private key. At the moment, the highest security is provided by smart cards, whose main advantage is that the private key never leaves the card and the encryption and digital signing are done on the card itself.
The security of electronic signing is also based on the length of public and private keys, considering that only keys that are large enough prevent the breaking of the public key and the discovery of the corresponding private key.
The main precondition for using electronic commerce security methods is public key certification, which is carried out by Certification Authorities or CAs. The CA issues to the holder a digital certificate proving the holder has a key and, with a digital signature, their identity in the world of electronic business.