Secure relations between people as well as human to computer and computer to computer mean that you can rely on the information exchanged between the parties.
When we send an electronic letter / message from one person to another person (or a computer system), it is important that the recipient trusts the content.
This means that the information exchanged must have some important information qualities: it must be able to be deduced to a particular sender, it must not be corrupted and in case the information needs to be kept secret, it also needs to be confidential.
With the help of digital signatures, exchanged information such as orders, agreements, contracts, assurances etc. can be deduced to a particular sender and the content can be made legally binding for the sender. If the information exchanged needs to be kept secret, the information and/or communication between the parties is encrypted. To ensure that the information exchanged between the parties has not been changed, so-called encrypted checksums are used.
The use of electronic identifications (EID), i.e. certificates, is a prerequisite for secure relations and secure logging (traceability). In case of a dispute or an incident, the log information must be protected from manipulation so that you can verify who did what. Manipulating logs is a common way of concealing intrusion and fraud, that's why the logs have to be signed and timed to be reliable.