Whilst working on a proof of concept WCF service I ran into an interesting security “zone” issue which caused me a few headaches for an afternoon. I was moving some code out of a prototype WinForm application into a WCF service to prove and demonstrate the next phase of the infrastructure. The functionality in question reference some custom ‘C’ libraries which had already been proven to run when referenced locally within the Windows application. However moving the same the code and therefore the reference to the ‘C’ libraries into a WCF service resulted in most calls to the library throwing a “Security Exception”. Stepping through the debugger, the issue was clear enough, calling “unsafe” code requires Full Trust but even though everything was running locally the WCF service was showing as “Internet” zone and triggering the security exception. This had me confused for quite a while, I wasn’t hosting the WCF service within IIS (see previous post, no admin rights!), so my only opt…