Analysis of Security of PKI Operation with Multiple CP/CPS Based on Level of Assurance

The ICT environment has been rapidly developed by ubiquitization and cloud computing and has become far more convenient to use. On the other hand, the negative side also exists, such as threats of viruses and unlawful access, in which the use of the safe and secure ICT environment is threatened. Public key infrastructure (PKI) construction is desired as a structure to achieve the safe and secure use of the ICT environment at universities. However, PKI has not been widely constructed in universities because of the cost. In this paper, we introduce the concept of the level of assurance (LoA) on the cost structure at a campus PKI based on the university PKI (UPKI) specifications of the National Institute of Informatics. Moreover, we clarify the relationship between the cost structure of PKI and the security guarantee level so that campus PKI can be constructed at an appropriate cost and used more widely.