We present the logical design of a trust engine for Information-Centric Networking (ICN) that is capable of efficiently and correctly verifying content integrity and authenticity. Our primary contribution is the synthesis and unified treatment of four different and popular trust models. We show in which operational aspects they vary and emphasize which parts of the verification mechanics are invariant. The verifier logic is expressed in Prolog to show its simplicity (abstracting away, e.g., procedural certification chain verification steps) and to highlight subtle errors that can occur in the use and enforcement of trust models. The details of an implementation of our trust engine in the CCNx network stack are presented to demonstrate its viability and general modularity. A simplistic interface enables the trust engine to be easily ported to any ICN-style network software. Finally, we demonstrate how application instantiations of various trust models are natively supported by the trust engine to illustrate its flexibility.