VERFAHREN UND SCHALTKREIS UM EIN SYSTEM IN EINEM SICHEREN UMFELD SELEKTIV ZU BETREIBEN

摘要

A method for selective secure operation of a system on a chip includes the step of disabling debug circuitry forming a part of the system on a chip at power on reset to prevent access by an unauthorized party to security resources. A determination is made as to whether a security procedure is called for during system initialization from boot memory. When a security procedure is called for, an attempt is made to execute a selected security procedure. A vector is mapped to the selected location in boot memory storing security code corresponding to the selected security procedure. The security code in boot memory is executed to determine whether the called security procedure is valid, and if the called security procedure is valid, the system operates in a secure environment in response to the called security procedure.