(*ctxt)->cx = (element_t*)calloc(mpk->dimension, sizeof(element_t));
for (size_t i = 0; i < mpk->dimension; ++i){
element_pow_zn(x1, param->g1, x[i]);
element_pow_zn(x1, x1, r);
element_pow_zn(k1, mpk->k[i], s);
(*ctxt)->cx = (element_t*)calloc(mpk->dimension, sizeof(element_t));
for (size_t i = 0; i < mpk->dimension; ++i){
element_pow_zn(x1, param->g1, x[i]);
element_pow_zn(x1, x1, r);
element_pow_zn(k1, mpk->k[i], s);