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Map the Jacobian point back to affine space in wolfSSL_EC_POINT_get_affine_coordinates_GFp

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This commit is contained in:
Juliusz Sosinowicz
2019-11-28 13:05:36 +01:00
parent aea95232d1
commit 84a2ca7a4e
3 changed files with 29 additions and 2 deletions
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24
src/ssl.c
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@@ -34413,12 +34413,14 @@ int wolfSSL_EC_POINT_get_affine_coordinates_GFp(const WOLFSSL_EC_GROUP *group,
WOLFSSL_BIGNUM *y, WOLFSSL_BIGNUM *y,
WOLFSSL_BN_CTX *ctx) WOLFSSL_BN_CTX *ctx)
{ {
mp_digit mp;
mp_int modulus;
(void)ctx; (void)ctx;
WOLFSSL_ENTER("wolfSSL_EC_POINT_get_affine_coordinates_GFp"); WOLFSSL_ENTER("wolfSSL_EC_POINT_get_affine_coordinates_GFp");
if (group == NULL || point == NULL || point->internal == NULL || if (group == NULL || point == NULL || point->internal == NULL ||
x == NULL || y == NULL) { x == NULL || y == NULL || wolfSSL_EC_POINT_is_at_infinity(group, point)) {
WOLFSSL_MSG("wolfSSL_EC_POINT_get_affine_coordinates_GFp NULL error"); WOLFSSL_MSG("wolfSSL_EC_POINT_get_affine_coordinates_GFp NULL error");
return WOLFSSL_FAILURE; return WOLFSSL_FAILURE;
} }
@@ -34432,6 +34434,26 @@ int wolfSSL_EC_POINT_get_affine_coordinates_GFp(const WOLFSSL_EC_GROUP *group,
} }
} }
if (!wolfSSL_BN_is_one(point->Z)) {
/* Map the Jacobian point back to affine space */
if (mp_read_radix(&modulus, ecc_sets[group->curve_idx].prime, MP_RADIX_HEX) != MP_OKAY) {
WOLFSSL_MSG("mp_read_radix failed");
return WOLFSSL_FAILURE;
}
if (mp_montgomery_setup(&modulus, &mp) != MP_OKAY) {
WOLFSSL_MSG("mp_montgomery_setup failed");
return WOLFSSL_FAILURE;
}
if (ecc_map((ecc_point*)point->internal, &modulus, mp) != MP_OKAY) {
WOLFSSL_MSG("ecc_map failed");
return WOLFSSL_FAILURE;
}
if (SetECPointExternal((WOLFSSL_EC_POINT *)point) != WOLFSSL_SUCCESS) {
WOLFSSL_MSG("SetECPointExternal failed");
return WOLFSSL_FAILURE;
}
}
BN_copy(x, point->X); BN_copy(x, point->X);
BN_copy(y, point->Y); BN_copy(y, point->Y);

5
tests/api.c
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@@ -1825,6 +1825,11 @@ static void test_wolfSSL_EC(void)
/* check if point X coordinate is zero */ /* check if point X coordinate is zero */
AssertIntEQ(BN_is_zero(new_point->X), WOLFSSL_FAILURE); AssertIntEQ(BN_is_zero(new_point->X), WOLFSSL_FAILURE);
/* Force non-affine coordinates */
AssertIntEQ(wolfSSL_BN_add(new_point->Z, (WOLFSSL_BIGNUM*)BN_value_one(),
(WOLFSSL_BIGNUM*)BN_value_one()), 1);
new_point->inSet = 0;
/* extract the coordinates from point */ /* extract the coordinates from point */
AssertIntEQ(EC_POINT_get_affine_coordinates_GFp(group, new_point, X, Y, ctx), WOLFSSL_SUCCESS); AssertIntEQ(EC_POINT_get_affine_coordinates_GFp(group, new_point, X, Y, ctx), WOLFSSL_SUCCESS);

2
wolfcrypt/src/ecc.c
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@@ -2281,7 +2281,7 @@ int ecc_projective_dbl_point(ecc_point *P, ecc_point *R, mp_int* a,
/** /**
Map a projective jacbobian point back to affine space Map a projective Jacobian point back to affine space
P [in/out] The point to map P [in/out] The point to map
modulus The modulus of the field the ECC curve is in modulus The modulus of the field the ECC curve is in
mp The "b" value from montgomery_setup() mp The "b" value from montgomery_setup()