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/*
* ecgen, tool for generating Elliptic curve domain parameters
* Copyright (C) 2023 J08nY
*/
#include "nums.h"
#include "math/subgroup.h"
#include "obj/point.h"
#include "obj/subgroup.h"
GENERATOR(nums_gen_field) {
pari_sp ltop = avma;
GEN base = int2u(cfg->bits);
GEN c = stoi(1);
GEN p = subii(base, c);
while (!isprime(p)) {
c = addiu(c, 4);
p = subii(base, c);
}
curve->field = gerepilecopy(ltop, p);
return 1;
}
GENERATOR(nums_gen_a) {
curve-> a = gmodulo(stoi(-3), curve->field);
return 1;
}
static GEN b = NULL;
static curve_t *curve_b = NULL;
GENERATOR(nums_gen_b) {
pari_sp ltop = avma;
if (!b) {
b = gclone(gen_1);
curve->b = gmodulo(gen_1, curve->field);
curve_b = curve;
return 1;
} else {
if (curve_b == curve) {
// use b, add 1 to it, store it back modified,
GEN bn;
if (equaliu(b, 1)) {
bn = addiu(b, 2);
} else {
bn = addiu(b, 1);
}
gunclone(b);
b = gclone(bn);
curve->b = gerepilecopy(ltop, gmodulo(bn, curve->field));
return 1;
} else {
// dont use b, regenerate it,
gunclone(b);
b = gclone(gen_1);
curve->b = gerepilecopy(ltop, gmodulo(gen_1, curve->field));
curve_b = curve;
return 1;
}
}
}
GENERATOR(nums_gen_order) {
pari_sp ltop = avma;
GEN order = ellsea(curve->curve, 1);
GEN frobenius = subii(addis(curve->field, 1), order);
GEN twist_order = addii(order, muliu(frobenius, 2));
if (gequal0(order) || !(isprime(order)) || !(isprime(twist_order))) {
avma = ltop;
return -2; // Just go one step back and regenerate the b.
} else {
curve->order = gerepilecopy(ltop, order);
obj_insert_shallow(curve->curve, 1, curve->order);
return 1;
}
}
GENERATOR(nums_gen_gens) {
pari_sp ltop = avma;
GEN x = stoi(1);
GEN Qy = ellordinate(curve->curve, x, 0);
while (glength(Qy) == 0) {
x = addiu(x, 1);
Qy = ellordinate(curve->curve, x, 0);
}
GEN P = NULL;
if (cmpii(lift(gel(Qy, 1)), lift(gel(Qy, 2))) < 0) {
P = mkvec2(gmodulo(x, curve->field), gel(Qy, 1));
} else {
P = mkvec2(gmodulo(x, curve->field), gel(Qy, 2));
}
curve->generators = subgroups_new(1);
curve->ngens = 1;
subgroup_t *sub = subgroup_new();
curve->generators[0] = sub;
point_t *G = point_new();
sub->generator = G;
G->point = P;
G->order = ellorder(curve->curve, G->point, NULL);
G->cofactor = divii(curve->order, G->order);
gerepileall(ltop, 3, &G->point, &G->order, &G->cofactor);
return 1;
}
void nums_quit(void) {
if (b && isclone(b)) {
gunclone(b);
}
}
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