Required Header Files

You will note in the initial code segments that, apart from the standard header files, we include the ProtectToolkit-C set of required library files. 

#include "cryptoki.h"
#include "ctextra.h" 
#include "ctlutil.h" 
#include "chkret.h" 

Whereas cryptoki.h is the required PKCS#11 header, the remainder implement some of the advanced or extended features of the ProtectToolkit-C implementation, such as error feedback.

Next, see Runtime Switches.