Patent ID: 8549633

Claim:
A security controller comprising: first and second read request paths configured to perform security checking of read requests received from at least one master device and to control issuing of said read requests to at least one slave device; and a selector configured to select which of said first read request path and said second read request path to use for controlling issuing of an incoming read request; wherein: if said first read request path is selected for said incoming read request, then said first read request path controls issuing of said read request to a target slave device in dependence on a result of said security checking; if said second read request path is selected for said incoming read request, then said second read request path issues said incoming read request to said target slave device without waiting for a result of said security checking, and stores to a tracking data store tracking data indicating said result of said security checking; said security controller comprises a response path configured to receive a response to an issued read request from said target slave device and to forward said response to a source master device which initiated said issued read request; and if said tracking data indicates that said security checking identified a security violation for an issued read request issued using said second read request path, then said response path modifies the response to said issued read request to mask read data read by said target slave device in accordance with said issued read request, and forwards the modified response to said source master device.