1. A method of providing a Certificate Status Service (“CSS”) for checking validities of certificates issued by respective issuing Certification Authorities (“CAs”), comprising the steps of: receiving status queries for one or more certificates from requesting entities; if the issuing CAs are not found on a CSS's list of approved CAs or the certificates have expired, returning invalid statuses for those certificates; if current certificate statuses are found in a CSS cache memory, returning the found certificates' statuses; if any certificate statuses have not yet been determined, fetching, from a CSS configuration store, all certificate status reporting methods and communications information that are needed for retrieving, from the respective issuing CAs, a certificate status of each certificate whose status has not yet been determined; configuring connectors based on the identified information for communicating with the issuing CAs; communicating with the issuing CAs according to the configured connectors; retrieving the certificate statuses of all queried certificates; processing the certificate statuses according to certificate status reporting methods implemented by the CSS including, but not limited to, a real-time certificate status retrieval protocol including LDAP, OCSP, and any other certificate status retrieval protocol for retrieving certificate statuses in real-time, and one of Certificate Revocation Lists (CRLs) that are retrieved at specified publication intervals and Delta Certificate Revocation Lists (ΔCRLs) that are retrieved upon notification; recording retrieved certificate statuses in the CSS cache memory; and returning the retrieved certificate statuses to the requesting entities; wherein the issuing CAs and connector parameters, which enable the CSS to interwork with any CAs and CA domains even though the CSS and issuing CAs may operate using dissimilar certificate practices and policies, are designated on a list of approved CAs in the CSS configuration store.