Designing secure systems is challenging because threats are constantly changing. It is very difficult, if not impossible, to guarantee that a system has absolute security. Off-the-shelf microprocessors have security features built in, such as accelerators for common cryptographic routines and secure boot. However, this can be a limitation as they only have access to the specific accelerator blocks they were designed with. If a new security vulnerability becomes apparent after a product has shipped, then it is feasible that a cryptographic standard may need to be designed, this would lead the developer having a challenge when creating an update. New algorithms would need to be implemented in software, and these algorithms would burden the CPU. This could potentially lead to product features needing to be disabled if the designer does not have enough capacity to cope with the new software based routines.