Methods and devices for transferring data from a non-volatile memory to a working memory of an electronic data processing device are provided. Security data is copied from the non-volatile memory to the working memory. The security data is to be write-protected. A blocking function is activated for the security data in the working memory. The activation is triggered by the copying being made to the working memory. All communication with the working memory is monitored. All write attempts to the copied security data stored in the working memory are blocked according to the blocking function. At least activating a blocking function, monitoring communication and blocking write attempts are performed independently of a central processing unit of the electronic data processing device, such that the central processing unit cannot manipulate the security data.