Today, PKIs have come of age and they support the security of several large networked systems, such as company-wide document management systems, - governmentapplicationsandsecureVPN.However, despitethissuccess, the?eld has not yet reachedits full scienti?c maturity and there is still room for research in this area. For example, open issues exist in the e?cient management of large PKI (especially with respect to certi?cate validation), better performance could be attained by improved cryptographic techniques and innovative applications are continuously proposed. To discuss progress in the PKI...