On 7/8/15, Marcel <tiepelt@dev-nu11.de> wrote:

... So my question is, why do i need to random values m_A and n_A to compute the torsiongroup E[l_A] and respectively the kernel K_A ?

Why does is not suffice to use only 1 point to generate E[l_A] and Kernel K_A ?

it is late, and i may mis understand, yet the two are requisite for peers arriving at a shared secret by way of these constructed isogeny; and the random values necessary to not give too much (confirm secret values, without exposing secret values) i found this paper a helpful expansion on the subject: http://cacr.uwaterloo.ca/techreports/2014/cacr2014-20.pdf "In this paper, we mainly explore the efficiency of implementing recently proposed isogeny-based post-quantum public key cryptography..." specifically the graph on page 5. note that the key exchange relies on finding a path connecting vertices in a graph of supersingular isogenies - thus a pair on both ends, not just a pair arrived at among both participants. if this is clear as mud, i will try tomorrow on a fresh brain :) best regards,