Electronic transactions, which cover transactions in both the business sector and government services in e-government, including transactions for citizens or consumers, are becoming increasingly important, especially in creating added economic value and improving the quality of life of citizens. However, communicating online to conduct transactions also involves the issue of trust that a person, website, service provider (server), or any device, or any information system, or any entity is a person or thing. This is the origin of the development of Public Key Infrastructure (PKI) technology.