Abstract. This paper revisits a model for elliptic curves over Q introduced by Huff in 1948 to study a diophantine problem. Huff’s model readily extends over fields of odd characteristic. Every elliptic curve over such a field and containing a copy of Z/4Z × Z/2Z is birationally equivalent to a Huff curve over the original field. This paper extends and generalizes Huff’s model. It presents fast explicit formulæ for point addition and doubling on Huff curves. It also addresses the problem of the efficient evaluation of pairings over Huff curves. Remarkably, the so-obtained formulæ feature some useful properties, including completeness and independence of the curve parameters.

Abstract. In this work, we analyze and present experimental data evaluating the efficiency of several techniques for speeding up the computation of elliptic curve point multiplication on emerging x86-64 processor architectures. In particular, we study the efficient combination of such techniques as elimination of conditional branches and incomplete reduction to achieve fast field arithmetic over F p. Furthermore, we study the impact of (true) data dependencies on these processors and propose several generic techniques to reduce the number of pipeline stalls, memory reads/writes and function calls. We also extend these techniques to field arithmetic over F p2, which is utilized as underlying field by the recently proposed Galbraith-Lin-Scott (GLS) method to achieve higher performance in the point multiplication. By efficiently combining all these methods with state-of-the-art elliptic curve algorithms we obtain high-speed implementations of point multiplication that are up to 31 % faster than the best previous published results on similar platforms. This research is crucial for advancing high-speed cryptography on new emerging processor architectures.

Abstract. We give two parametrizations of points on Edwards curves that omit the X coordinate. The first parametrization leads to a differential addition formula that has the cost 5M + 4S, a doubling formula that has the cost 5S and a tripling formula that costs 4M+7S. The second one yields a differential addition formula with cost 5M + 2S and a doubling formula with cost 5S both even on generalized Edwards curves. The price to pay for this representation is the extraction of two square roots in the ground field. For both parametrizations the formula for recovering the missing coordinate is also provided. In addition, we give an addition chain for computing the scalar multiple of a point on the Edwards curve.

In this paper, we consider the Frobenius endomorphism on twisted Edwards curve and give the characteristic polynomial of the map. Applying the Frobenius endomorphism on twisted Edwards curve, we construct a skew-Frobenius map defined on the quadratic twist of an twisted Edwards curve. Our results show that the Frobenius endomorphism on twisted Edwards curve and the skew-Frobenius endomorphism on quadratic twist of an twisted Edwards curve can be exploited to devise fast point multiplication algorithm that do not use any point doubling. As an application, the GLV method can be used for speeding up point multiplication on twisted Edwards curve.

In this paper, the twisted Jacobi intersections which contains Jacobi intersections as a special case is introduced. We show that every elliptic curve over the prime field with three points of order 2 is isomorphic to a twisted Jacobi intersections curve. Some fast explicit formulae for twisted Jacobi intersections curves in projective coordinates are presented. These explicit formulae for addition and doubling are almost as fast as the Jacobi intersections. In addition, the scalar multiplication can be more effective in twisted Jacobi intersections than in Jacobi intersections. Moreover, we propose new addition formulae which are independent of parameters of curves and more effective in reality than the previous formulae in the literature.

Abstract. In this paper, we propose an elaborate geometry approach to explain the group law on twisted Edwards curves which are seen as the intersection of quadric surfaces in place. Using the geometric interpretation of the group law we obtain the Miller function for Tate pairing computation on twisted Edwards curves. Then we present the explicit formulae for pairing computation on twisted Edwards curves. Our formulae for the doubling step are a littler faster than that proposed by Arène et.al.. Finally, to improve the efficiency of pairing computation we present twists of degree 4 and 6 on twisted Edwards curves.