Enhancing an Embedded Processor Core with a Cryptographic Unit for Speed and Security

We implement a set of relatively low-cost enhancement techniques to accelerate certain arithmetic operations common in cryptographic applications on an extensible, embedded processor core. The enhancements are generic in the sense that they can be applied in many RISC processors beneficially. We organize these enhancements into a cryptographic unit (CU) that offers an extended ISA to the programmer. We then present the speedup values obtained for various arithmetic and public key cryptography operations through these enhancements. We also give the hardware overhead of integrating the CU to the embedded processor in terms of chip area. Our experimental results show that the proposed architectural enhancements provide significant amount of speedup values in elliptic curve cryptography and RSA with a conservative increase in hardware. We also demonstrate that the proposed enhancements facilitate protection of cryptographic algorithms against certain side-channel attacks by reporting our case study of AES implementation hardened against cache-based attacks.