How to incorporate revocation status information into the trust metrics for public-key certification

In a traditional PKI, the trust associated with a public key is expressed in binary either by 0 or 1. Alternatively, several authors have proposed trust metrics to evaluate the confidence afforded by a public key. However their work has a static point of view and does not take into account the issue of public key revocation. In this paper, we make the first attempt to incorporate the revocation status information into the trust metrics for public key certification. To achieve our goal, we use a tailored form of a vector of trust model recently proposed. This would allow us to reason formally about when there is a need to check revocation status and how reliable the revocation mechanism should be in a given security application.