A modular security control device for controlling an apparatus or an installation includes a basic control apparatus which is configured such that an apparatus or an installation which is at least connectable to the basic control apparatus is at least controllable via a sequence of a control program in the basic control apparatus, and includes a security module which is configured to provide or perform a cryptographic functionality for the basic control apparatus, where the security module is connected to the basic control apparatus by a data connection via a data interface, the basic control apparatus is configured to interact with the security module to achieve a security function of the security control device, and where the basic control apparatus is configured to query an identity and/or authenticity of the security module.