A digital logic circuit comprises a programmable logic device and a programmable security circuit. The programmable security circuit stores a set of authorized configuration security keys. The programmable security circuit compares the authorized configuration security keys with an incoming configuration request, and selectively enables a new configuration for the programmable logic device in response to the configuration request. In another exemplary embodiment, a programmable security circuit also stores a set of authorized operation security keys. The programmable security circuit compares the authorized operation security keys with an incoming operation request from the programmable logic device, and selectively enables an operation within the programmable logic device in response to the operation request.