This class represents a callback object for certificate decryption. If user wants to use their own certificate security callback, user should inherit this callback class and implement the pure virtual functions (as callback functions), and then register their own certificate security callback object to Foxit PDF SDK by function FSLibrary::registerSecurityCallback:callback: with filter "Adobe.PubSec". Function FSLibrary::unregisterSecurityCallback: can be called to unregister the security callback object with the registered filter name.