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secp256k1_gej_double_nonzero supports infinity

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This commit is contained in:
Pieter Wuille 2020-07-28 18:12:14 -07:00
parent 214cb3c321
commit 18d36327fd
5 changed files with 11 additions and 11 deletions
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2
src/ecmult_const_impl.h
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@ -208,7 +208,7 @@ static void secp256k1_ecmult_const(secp256k1_gej *r, const secp256k1_ge *a, cons
int n;
int j;
for (j = 0; j < WINDOW_A - 1; ++j) {
secp256k1_gej_double_nonzero(r, r);
secp256k1_gej_double(r, r);
}
n = wnaf_1[i];

4
src/group.h
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@ -95,8 +95,8 @@ static int secp256k1_gej_is_infinity(const secp256k1_gej *a);
/** Check whether a group element's y coordinate is a quadratic residue. */
static int secp256k1_gej_has_quad_y_var(const secp256k1_gej *a);
/** Set r equal to the double of a, a cannot be infinity. Constant time. */
static void secp256k1_gej_double_nonzero(secp256k1_gej *r, const secp256k1_gej *a);
/** Set r equal to the double of a. Constant time. */
static void secp256k1_gej_double(secp256k1_gej *r, const secp256k1_gej *a);
/** Set r equal to the double of a. If rzr is not-NULL this sets *rzr such that r->z == a->z * *rzr (where infinity means an implicit z = 0). */
static void secp256k1_gej_double_var(secp256k1_gej *r, const secp256k1_gej *a, secp256k1_fe *rzr);

7
src/group_impl.h
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@ -303,7 +303,7 @@ static int secp256k1_ge_is_valid_var(const secp256k1_ge *a) {
return secp256k1_fe_equal_var(&y2, &x3);
}
static SECP256K1_INLINE void secp256k1_gej_double_nonzero(secp256k1_gej *r, const secp256k1_gej *a) {
static SECP256K1_INLINE void secp256k1_gej_double(secp256k1_gej *r, const secp256k1_gej *a) {
/* Operations: 3 mul, 4 sqr, 0 normalize, 12 mul_int/add/negate.
*
* Note that there is an implementation described at
@ -313,8 +313,7 @@ static SECP256K1_INLINE void secp256k1_gej_double_nonzero(secp256k1_gej *r, cons
*/
secp256k1_fe t1,t2,t3,t4;
VERIFY_CHECK(!secp256k1_gej_is_infinity(a));
r->infinity = 0;
r->infinity = a->infinity;
secp256k1_fe_mul(&r->z, &a->z, &a->y);
secp256k1_fe_mul_int(&r->z, 2); /* Z' = 2*Y*Z (2) */
@ -363,7 +362,7 @@ static void secp256k1_gej_double_var(secp256k1_gej *r, const secp256k1_gej *a, s
secp256k1_fe_mul_int(rzr, 2);
}
secp256k1_gej_double_nonzero(r, a);
secp256k1_gej_double(r, a);
}
static void secp256k1_gej_add_var(secp256k1_gej *r, const secp256k1_gej *a, const secp256k1_gej *b, secp256k1_fe *rzr) {

3
src/tests.c
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@ -2218,6 +2218,9 @@ void test_ge(void) {
/* Normal doubling. */
secp256k1_gej_double_var(&resj, &gej[i2], NULL);
ge_equals_gej(&ref, &resj);
/* Constant-time doubling. */
secp256k1_gej_double(&resj, &gej[i2]);
ge_equals_gej(&ref, &resj);
}
/* Test adding opposites. */

6
src/tests_exhaustive.c
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@ -141,10 +141,8 @@ void test_exhaustive_addition(const secp256k1_ge *group, const secp256k1_gej *gr
/* Check doubling */
for (i = 0; i < order; i++) {
secp256k1_gej tmp;
if (i > 0) {
secp256k1_gej_double_nonzero(&tmp, &groupj[i]);
ge_equals_gej(&group[(2 * i) % order], &tmp);
}
secp256k1_gej_double(&tmp, &groupj[i]);
ge_equals_gej(&group[(2 * i) % order], &tmp);
secp256k1_gej_double_var(&tmp, &groupj[i], NULL);
ge_equals_gej(&group[(2 * i) % order], &tmp);
}