Key Update Mechanism in PKI: Study and a New Approach

Public-Key Infrastructure (PKI) provides robust and scalable security services like authentication and non-repudiation using digital certificates. An efficient key management is necessary for a long term implementation of PKI. As a part of key management, key pair of all the entities within the PKI system is updated regularly to minimize overuse of keys and to comply with the organization's policies. In a hierarchical PKI system, root Certificate Authority (CA) is the highest trust anchor and hence updating its key pair is a challenging task. It requires proper authentication of certificate issuing entities to its subordinates and storage of keys for future reference. This paper discusses the various mechanisms available for updating root CA key pairs and brings out pros and cons in each. Considering the shortcomings of these methods, a new method for key pair update has been proposed, which is less complex and easy to implement. In addition, some of the open-source tools available to implement these techniques and open challenges which need to be addressed to have been highlighted.