Systems, methods, and other embodiments associated with implementing security functions in a read-only memory (ROM) are described. According to one embodiment, an device includes a read-only memory (ROM) that stores (i) a plurality of security functions and (ii) a mapping of locations of the plurality of security functions in the ROM. The device also includes a processing unit configured to, in response to a request by a process being executed by the processing unit, determine a location in the ROM of a security function using the mapping, and execute the security function for the process from the ROM.