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Fix in fast math version of ecc_projective_dbl_point to use a local for x,y,z since ecc_point fp_int's are reduced size and cause math issues with ALT_ECC_SIZE enabled. Added local stack variable cleanups for ecc_projective_add_point.

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This commit is contained in:
David Garske
2016-05-04 23:22:14 -07:00
parent 0ddbe0e60e
commit a4782fcf01
1 changed files with 69 additions and 43 deletions
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112
wolfcrypt/src/ecc.c
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@@ -298,7 +298,14 @@ int ecc_projective_add_point(ecc_point *P, ecc_point *Q, ecc_point *R,
fp_sub(modulus, Q->y, &t1); fp_sub(modulus, Q->y, &t1);
if ( (fp_cmp(P->x, Q->x) == FP_EQ) && if ( (fp_cmp(P->x, Q->x) == FP_EQ) &&
(get_digit_count(Q->z) && fp_cmp(P->z, Q->z) == FP_EQ) && (get_digit_count(Q->z) && fp_cmp(P->z, Q->z) == FP_EQ) &&
(fp_cmp(P->y, Q->y) == FP_EQ || fp_cmp(P->y, &t1) == FP_EQ)) { (fp_cmp(P->y, Q->y) == FP_EQ || fp_cmp(P->y, &t1) == FP_EQ))
{
fp_clear(&x);
fp_clear(&y);
fp_clear(&z);
fp_clear(&t1);
fp_clear(&t2);
return ecc_projective_dbl_point(P, R, modulus, mp); return ecc_projective_dbl_point(P, R, modulus, mp);
} }
@@ -423,10 +430,18 @@ int ecc_projective_add_point(ecc_point *P, ecc_point *Q, ecc_point *R,
} }
fp_div_2(&y, &y); fp_div_2(&y, &y);
/* return result */
fp_copy(&x, R->x); fp_copy(&x, R->x);
fp_copy(&y, R->y); fp_copy(&y, R->y);
fp_copy(&z, R->z); fp_copy(&z, R->z);
/* clear stack variables */
fp_clear(&x);
fp_clear(&y);
fp_clear(&z);
fp_clear(&t1);
fp_clear(&t2);
return MP_OKAY; return MP_OKAY;
} }
@@ -442,41 +457,40 @@ int ecc_projective_add_point(ecc_point *P, ecc_point *Q, ecc_point *R,
int ecc_projective_dbl_point(ecc_point *P, ecc_point *R, mp_int* modulus, int ecc_projective_dbl_point(ecc_point *P, ecc_point *R, mp_int* modulus,
mp_digit* mp) mp_digit* mp)
{ {
fp_int t1, t2; fp_int x, y, z, t1, t2;
int err; int err;
if (P == NULL || R == NULL || modulus == NULL || mp == NULL) if (P == NULL || R == NULL || modulus == NULL || mp == NULL)
return ECC_BAD_ARG_E; return ECC_BAD_ARG_E;
if (P != R) { if ((err = mp_init_multi(&x, &y, &z, &t1, &t2, NULL)) != MP_OKAY) {
fp_copy(P->x, R->x);
fp_copy(P->y, R->y);
fp_copy(P->z, R->z);
}
if ((err = mp_init_multi(&t1, &t2, NULL, NULL, NULL, NULL)) != MP_OKAY) {
return err; return err;
} }
/* t1 = Z * Z */ /* Use local due to possible insufficient size of alt_ecc_size in ecc_point x,y,z */
fp_sqr(R->z, &t1); fp_copy(P->x, &x);
fp_copy(P->y, &y);
fp_copy(P->z, &z);
/* T1 = Z * Z */
fp_sqr(&z, &t1);
fp_montgomery_reduce(&t1, modulus, *mp); fp_montgomery_reduce(&t1, modulus, *mp);
/* Z = Y * Z */ /* Z = Y * Z */
fp_mul(R->z, R->y, R->z); fp_mul(&z, &y, &z);
fp_montgomery_reduce(R->z, modulus, *mp); fp_montgomery_reduce(&z, modulus, *mp);
/* Z = 2Z */ /* Z = 2Z */
fp_add(R->z, R->z, R->z); fp_add(&z, &z, &z);
if (fp_cmp(R->z, modulus) != FP_LT) { if (fp_cmp(&z, modulus) != FP_LT) {
fp_sub(R->z, modulus, R->z); fp_sub(&z, modulus, &z);
} }
/* &t2 = X - T1 */ /* T2 = X - T1 */
fp_sub(R->x, &t1, &t2); fp_sub(&x, &t1, &t2);
if (fp_cmp_d(&t2, 0) == FP_LT) { if (fp_cmp_d(&t2, 0) == FP_LT) {
fp_add(&t2, modulus, &t2); fp_add(&t2, modulus, &t2);
} }
/* T1 = X + T1 */ /* T1 = X + T1 */
fp_add(&t1, R->x, &t1); fp_add(&t1, &x, &t1);
if (fp_cmp(&t1, modulus) != FP_LT) { if (fp_cmp(&t1, modulus) != FP_LT) {
fp_sub(&t1, modulus, &t1); fp_sub(&t1, modulus, &t1);
} }
@@ -495,15 +509,15 @@ int ecc_projective_dbl_point(ecc_point *P, ecc_point *R, mp_int* modulus,
} }
/* Y = 2Y */ /* Y = 2Y */
fp_add(R->y, R->y, R->y); fp_add(&y, &y, &y);
if (fp_cmp(R->y, modulus) != FP_LT) { if (fp_cmp(&y, modulus) != FP_LT) {
fp_sub(R->y, modulus, R->y); fp_sub(&y, modulus, &y);
} }
/* Y = Y * Y */ /* Y = Y * Y */
fp_sqr(R->y, R->y); fp_sqr(&y, &y);
fp_montgomery_reduce(R->y, modulus, *mp); fp_montgomery_reduce(&y, modulus, *mp);
/* T2 = Y * Y */ /* T2 = Y * Y */
fp_sqr(R->y, &t2); fp_sqr(&y, &t2);
fp_montgomery_reduce(&t2, modulus, *mp); fp_montgomery_reduce(&t2, modulus, *mp);
/* T2 = T2/2 */ /* T2 = T2/2 */
if (fp_isodd(&t2)) { if (fp_isodd(&t2)) {
@@ -511,37 +525,49 @@ int ecc_projective_dbl_point(ecc_point *P, ecc_point *R, mp_int* modulus,
} }
fp_div_2(&t2, &t2); fp_div_2(&t2, &t2);
/* Y = Y * X */ /* Y = Y * X */
fp_mul(R->y, R->x, R->y); fp_mul(&y, &x, &y);
fp_montgomery_reduce(R->y, modulus, *mp); fp_montgomery_reduce(&y, modulus, *mp);
/* X = T1 * T1 */ /* X = T1 * T1 */
fp_sqr(&t1, R->x); fp_sqr(&t1, &x);
fp_montgomery_reduce(R->x, modulus, *mp); fp_montgomery_reduce(&x, modulus, *mp);
/* X = X - Y */ /* X = X - Y */
fp_sub(R->x, R->y, R->x); fp_sub(&x, &y, &x);
if (fp_cmp_d(R->x, 0) == FP_LT) { if (fp_cmp_d(&x, 0) == FP_LT) {
fp_add(R->x, modulus, R->x); fp_add(&x, modulus, &x);
} }
/* X = X - Y */ /* X = X - Y */
fp_sub(R->x, R->y, R->x); fp_sub(&x, &y, &x);
if (fp_cmp_d(R->x, 0) == FP_LT) { if (fp_cmp_d(&x, 0) == FP_LT) {
fp_add(R->x, modulus, R->x); fp_add(&x, modulus, &x);
} }
/* Y = Y - X */ /* Y = Y - X */
fp_sub(R->y, R->x, R->y); fp_sub(&y, &x, &y);
if (fp_cmp_d(R->y, 0) == FP_LT) { if (fp_cmp_d(&y, 0) == FP_LT) {
fp_add(R->y, modulus, R->y); fp_add(&y, modulus, &y);
} }
/* Y = Y * T1 */ /* Y = Y * T1 */
fp_mul(R->y, &t1, R->y); fp_mul(&y, &t1, &y);
fp_montgomery_reduce(R->y, modulus, *mp); fp_montgomery_reduce(&y, modulus, *mp);
/* Y = Y - T2 */ /* Y = Y - T2 */
fp_sub(R->y, &t2, R->y); fp_sub(&y, &t2, &y);
if (fp_cmp_d(R->y, 0) == FP_LT) { if (fp_cmp_d(&y, 0) == FP_LT) {
fp_add(R->y, modulus, R->y); fp_add(&y, modulus, &y);
} }
/* Return x, y, and z */
fp_copy(&x, R->x);
fp_copy(&y, R->y);
fp_copy(&z, R->z);
/* Clear used locals */
fp_clear(&x);
fp_clear(&y);
fp_clear(&z);
fp_clear(&t1);
fp_clear(&t2);
return MP_OKAY; return MP_OKAY;
} }