Calculating and Evaluating Trustworthiness of Certification Authority

In a public key infrastructure trust model, a trust is transferred along a set of certificates, issued by certificate authorities (CAs) considered as trustfully third parties, providing a trust chain among its entities. In order to deserve this trustworthiness, a CA should to apply the rigorous procedures for generating keys, checking the identities, and following reliable security practices. Any deficiency in these procedures may influence its trustworthiness. In this context, some authorities could be weaker than others. Then, relying parties (RPs) need a mechanism to evaluate CA trustworthiness. In this paper, we provide them this mechanism to have information about its trustworthiness. In fact, we propose a trust level calculation algorithm that is based on three parameters which are the CA reputation, the quality of procedures described in the certificate policy and its security maturity level.