A digital certificate is a data record that confirms certain properties of persons or objects and whose authenticity can be verified by encryption methods. The most common format for certificates is x.509. A certificate is digitally signed by a trusted authority (certification authority). This certifies that the key belongs to a specific person, for example, and has not been altered. The digital signature of the certification authority is an integral part of the certificate. This means that any subscriber who knows the public key of this certification authority can verify its certificates. A multi-level application of this method creates a public key infrastructure (PKI). The advantage of this is that only the public key of the so-called root instance of the PKI (and not from each participant) is needed later for complete verification.
