An improved certificate issuing system may comprise a certificate translation engine for translating incoming certificates and certificate requests from a first format into a second format. A certificate issuing engine may then operate on incoming requests in the common format. The issuing engine can issue certificates to clients according to its certificate issuing policy. The policy may be expressed as data in a policy expression language that can be consumed at runtime, which provides for flexible and efficient changing of issuing policy. Issued certificates can be translated back into a format that is consumed by the requesting client. Such translation can be performed by the translation engine prior to delivery of certificates to requesting clients.