The Name 'SpSecurity' Does Not Exist In the current context in Sharepoint 2013

   In some cases the SPSecurity name does not  exist in the current context either in Event Handler  r webpart. That is because of  SPSecurity class is not available in sandboxed solutions. It is available in farm solutions.

When you deployed a event handler as sandboxed solution you will see an error that " The name SPsecurity doesnot exist in the current context."

                   So if you deploy the event handler as a farm solution SHAREPOINT you will see that SPSecurity class is available in the current context.