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/*
* ecgen, tool for generating Elliptic curve domain parameters
* Copyright (C) 2017-2018 J08nY
*/
#include "gens.h"
#include "exhaustive/arg.h"
#include "math/subgroup.h"
#include "obj/point.h"
#include "obj/subgroup.h"
static subgroup_t *gens_point(GEN point, const curve_t *curve) {
subgroup_t *sub = subgroup_new();
point_t *p = point_new();
sub->generator = p;
p->point = gcopy(point);
p->order = ellorder(curve->curve, p->point, NULL);
p->cofactor = divii(curve->order, p->order);
return sub;
}
static int gens_put(curve_t *curve, GEN generators, long len) {
curve->generators = subgroups_new((size_t)len);
curve->ngens = (size_t)len;
for (long i = 1; i <= len; ++i) {
curve->generators[i - 1] = gens_point(gel(generators, i), curve);
}
return 1;
}
GENERATOR(gens_gen_any) {
GEN generators = ellff_get_gens(curve->curve);
long len = glength(generators);
return gens_put(curve, generators, len);
}
GENERATOR(gens_gen_one) {
pari_sp ltop = avma;
GEN generators = ellff_get_gens(curve->curve);
long len = glength(generators);
if (len == 2) {
avma = ltop;
return -5;
}
return gens_put(curve, generators, len);
}
GENERATOR(gens_gen_cofactor) {
HAS_ARG(args);
pari_ulong cofactor = *(pari_ulong *)args->args;
pari_sp ltop = avma;
GEN order = diviuexact(curve->order, cofactor);
GEN generators = ellff_get_gens(curve->curve);
long len = glength(generators);
point_t *p = NULL;
for (long i = 1; i <= len; ++i) {
GEN gen = gel(generators, i);
GEN gen_order = ellorder(curve->curve, gen, NULL);
if (equalii(order, gen_order)) {
p = point_new();
p->point = gcopy(gen);
p->order = gen_order;
p->cofactor = utoi(cofactor);
break;
}
if (dvdiu(gen_order, cofactor)) {
GEN res = diviuexact(gen_order, cofactor);
p = point_new();
p->point = gcopy(ellmul(curve->curve, gen, utoi(cofactor)));
p->order = res;
p->cofactor = utoi(cofactor);
break;
}
}
if (p) {
curve->ngens = (size_t)(len + 1);
curve->generators = subgroups_new(curve->ngens);
for (long i = 1; i <= len; ++i) {
curve->generators[i] = gens_point(gel(generators, i), curve);
}
subgroup_t *sub = subgroup_new();
sub->generator = p;
curve->generators[0] = sub;
return 1;
} else {
avma = ltop;
return -5;
}
}
CHECK(gens_check_anomalous) {
if (cfg->field == FIELD_BINARY) return 1;
for (size_t i = 0; i < curve->ngens; ++i) {
if (mpcmp(curve->field, curve->generators[i]->generator->order) == 0) {
return -5;
}
}
return 1;
}
GEN gens_get_embedding(GEN prime, GEN generator_order) {
return order(mkintmod(prime, generator_order));
}
CHECK(gens_check_embedding) {
HAS_ARG(args);
if (cfg->field == FIELD_BINARY) return 1;
pari_sp ltop = avma;
const char *min_degree = args->args;
GEN mind = strtoi(min_degree);
for (size_t i = 0; i < curve->ngens; ++i) {
GEN power = gens_get_embedding(curve->field,
curve->generators[i]->generator->order);
if (mpcmp(power, mind) <= 0) {
avma = ltop;
return -5;
}
}
avma = ltop;
return 1;
}
UNROLL(gens_unroll) {
if (curve->generators) {
subgroups_free_deep(&curve->generators, curve->ngens);
}
return -1;
}
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