2009/09/01 by Dunand, Clement, Lercier, Reynald
#Cryptography and Security (cs.CR) #FOS: Computer and information sciences
paper · doi:10.48550/arxiv.0909.0236
We consider representations of algebraic tori Tn(Fq) over finite fields. We make use of normal elliptic bases to show that, for infinitely many squarefree integers n and infinitely many values of q, we can encode m torus elements, to a small fixed overhead and to m ϕ(n)-tuples of Fq elements, in quasi-linear time in log q. This improves upon previously known algorithms, which all have a quasi-quadratic complexity. As a result, the cost of the encoding phase is now negligible in Diffie-Hellman cryptographic schemes.