Destructive and constructive aspects of efficient algorithms and implementation of cryptographic hardware

In an ever-increasing digital world, the need for secure communications over unsecured channels like Internet has exploded. To meet the different security requirements, communication devices have to perform computationally-intensive cryptographic operations. Hardware processor or co-processor are therefore often needed to meet goals such as speed, ubiquity or cost-effectiveness. For such devices, the size of security parameters are chosen as small as possible to save resources and time. It is therefore necessary to know the effective security of given sets of parameters in order to achieve the best trade-off between efficiency and security. The best way to address this problem is by means of accurate estimations of dedicated hardware attacks. In this thesis, we investigate two aspects of cryptographic hardware: constructive applications that deal with general purpose secure devices and destructive applications that handle dedicated hardware attacks against cryptosystems. Their set of constraints is clearly different but they both need efficient algorithms and hardware architectures. First, we deal with efficient and novel modular inversion and division algorithms on Field-Programmable Gate Array (FPGA) hardware platform. Such algorithms are an important building block for both constructive and destructive use of elliptic curve cryptography. Then, we provide new or highly improved architectures for attacks against RC5 cipher, GF(2m) elliptic curves and RSA by means of efficient elliptic curve-based factorization engines (ECM). We prove that FPGA-based solutions are much more cost-effective and low power than software-based solutions. Our resulting cost assessments should serve as a basis for improving the accuracy of current hardware or software-based security evaluations. Finally, we handle the efficiency-flexibility trade-off problem for highspeed hardware implementations of elliptic curve. Then, we present efficient elliptic curve digital signature algorithm coprocessors for smart cards. We also show that, surprisingly, affine coordinates can be an attractive solution for such an application.