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Fixed bug with "ecc_projective_add_point" that was not protecting the case where Q == R and using the R variable directly for the result. Now if Q == R then swap P and Q and using a local x,y,z, is only required when used with ALT_ECC_SIZE.

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This commit is contained in:
David Garske
2016-05-22 17:31:36 -07:00
parent eb6153f028
commit 15cd06b7ca
1 changed files with 16 additions and 8 deletions
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24
wolfcrypt/src/ecc.c
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@ -281,14 +281,22 @@ int ecc_projective_add_point(ecc_point* P, ecc_point* Q, ecc_point* R,
mp_int* modulus, mp_digit* mp)
{
mp_int t1, t2;
#if (defined(USE_FAST_MATH) && defined(ALT_ECC_SIZE)) || !defined(USE_FAST_MATH)
#ifdef ALT_ECC_SIZE
mp_int rx, ry, rz;
#endif
mp_int *x, *y, *z;
int err;
if (P == NULL || Q == NULL || R == NULL || modulus == NULL || mp == NULL)
if (P == NULL || Q == NULL || R == NULL || modulus == NULL || mp == NULL) {
return ECC_BAD_ARG_E;
}
/* if Q == R then swap P and Q, so we don't require a local x,y,z */
if (Q == R) {
ecc_point* tPt = P;
P = Q;
Q = tPt;
}
if ((err = mp_init_multi(&t1, &t2, NULL, NULL, NULL, NULL)) != MP_OKAY) {
return err;
@ -313,7 +321,9 @@ int ecc_projective_add_point(ecc_point* P, ecc_point* Q, ecc_point* R,
return err;
}
#if (defined(USE_FAST_MATH) && defined(ALT_ECC_SIZE)) || !defined(USE_FAST_MATH)
/* If use ALT_ECC_SIZE we need to use local stack variable since
ecc_point x,y,z is reduced size */
#ifdef ALT_ECC_SIZE
/* Use local stack variable */
x = ℞
y = &ry;
@ -520,17 +530,13 @@ int ecc_projective_add_point(ecc_point* P, ecc_point* Q, ecc_point* R,
if (err == MP_OKAY)
err = mp_div_2(y, y);
#if (defined(USE_FAST_MATH) && defined(ALT_ECC_SIZE)) || !defined(USE_FAST_MATH)
#ifdef ALT_ECC_SIZE
if (err == MP_OKAY)
err = mp_copy(x, R->x);
if (err == MP_OKAY)
err = mp_copy(y, R->y);
if (err == MP_OKAY)
err = mp_copy(z, R->z);
mp_clear(x);
mp_clear(y);
mp_clear(z);
#endif
#ifndef USE_FAST_MATH
@ -568,6 +574,8 @@ int ecc_projective_dbl_point(ecc_point *P, ecc_point *R, mp_int* modulus,
return err;
}
/* If use ALT_ECC_SIZE we need to use local stack variable since
ecc_point x,y,z is reduced size */
#ifdef ALT_ECC_SIZE
/* Use local stack variable */
x = ℞