diff options
| -rw-r--r-- | src/math/twists.c | 11 | ||||
| -rw-r--r-- | src/math/twists.h | 4 | ||||
| -rw-r--r-- | test/src/math/test_twists.c | 9 |
3 files changed, 18 insertions, 6 deletions
diff --git a/src/math/twists.c b/src/math/twists.c index 3f1296d..043594f 100644 --- a/src/math/twists.c +++ b/src/math/twists.c @@ -13,16 +13,25 @@ void twist_rand_to(curve_t *to, const curve_t *of) { if (typ(of->field) == t_INT) { to->a = ell_get_a4(to->curve); to->b = ell_get_a6(to->curve); + if (of->order != NULL) { + GEN q = addis(mulis(of->field, 2), 2); + to->order = subii(q, of->order); + obj_insert_shallow(to->curve, 1, to->order); + } } else if (typ(of->field) == t_FFELT) { to->a = ell_get_a2(to->curve); to->b = ell_get_a6(to->curve); + if (of->order != NULL) { + GEN q = addis(mulis(int2n(degree(FF_mod(of->field))), 2), 2); + to->order = subii(q, of->order); + obj_insert_shallow(to->curve, 1, to->order); + } } } void twist_rand(curve_t *what) { twist_rand_to(what, what); seed_free(&what->seed); - what->order = NULL; points_free_deep(&what->points, what->npoints); points_free_deep(&what->generators, what->ngens); }
\ No newline at end of file diff --git a/src/math/twists.h b/src/math/twists.h index dcbdb31..d68bb27 100644 --- a/src/math/twists.h +++ b/src/math/twists.h @@ -15,8 +15,8 @@ void twist_rand_to(curve_t *to, const curve_t *of); /** - * @brief - * @param what + * @brief Twists the <code>what</code> curve randomly, inplae. + * @param what The curve to be twisted, also the result. */ void twist_rand(curve_t *what); diff --git a/test/src/math/test_twists.c b/test/src/math/test_twists.c index 8a869bf..cc39369 100644 --- a/test/src/math/test_twists.c +++ b/test/src/math/test_twists.c @@ -4,7 +4,6 @@ */ #include <criterion/criterion.h> #include "gen/field.h" -#include "gen/point.h" #include "math/poly.h" #include "math/twists.h" #include "test/default.h" @@ -19,7 +18,8 @@ Test(twists, test_twist_rand_to_fp) { curve_t curve = {.a = a, .b = b, .field = stoi(23), - .curve = ellinit(mkvec2(a, b), stoi(23), -1)}; + .curve = ellinit(mkvec2(a, b), stoi(23), -1), + .order = stoi(24)}; curve_t to = {0}; twist_rand_to(&to, &curve); @@ -27,6 +27,7 @@ Test(twists, test_twist_rand_to_fp) { cr_assert_not_null(to.b, ); cr_assert_not_null(to.field, ); cr_assert_not_null(to.curve, ); + cr_assert(equalii(to.order, stoi(24)), ); } Test(twists, test_twist_rand_to_f2m) { @@ -38,7 +39,8 @@ Test(twists, test_twist_rand_to_f2m) { .a = a, .b = b, .field = field, - .curve = ellinit(mkvecn(5, gen_1, a, gen_0, gen_0, b), NULL, -1)}; + .curve = ellinit(mkvecn(5, gen_1, a, gen_0, gen_0, b), NULL, -1), + .order = stoi(8140)}; curve_t to = {0}; twist_rand_to(&to, &curve); @@ -46,4 +48,5 @@ Test(twists, test_twist_rand_to_f2m) { cr_assert_not_null(to.b, ); cr_assert_not_null(to.field, ); cr_assert_not_null(to.curve, ); + cr_assert(equalii(to.order, stoi(8246)), ); }
\ No newline at end of file |