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Reject projective points in SP math only FP_ECC wc_ecc_mulmod_ex() #11971

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Reject projective points in SP math only FP_ECC wc_ecc_mulmod_ex() #11971

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527be8c
Reject projective points in SP math only FP_ECC wc_ecc_mulmod_ex()
LinuxJedi Nov 3, 2026
56387a1
Skip curves below ECC_MIN_KEY_SZ in test_wc_ecc_mulmod_projective
LinuxJedi Nov 3, 2026
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139 changes: 139 additions & 0 deletions tests/api/test_ecc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4316,6 +4316,145 @@ int test_wc_ecc_mulmod_curves(void)
return EXPECT_RESULT();
} /* END test_wc_ecc_mulmod_curves */

/*
* Testing wc_ecc_mulmod() and wc_ecc_mulmod_ex2() with a base point that is
* not affine.
*
* With FP_ECC, the SP code caches a table for a point keyed on its x and y
* ordinates only. (Gx, Gy, p - 1) is -G but has the same x and y as G, so with
* SP math only a table built from one was used for the other. That build now
* rejects a point whose z is not 1; other builds return the right point.
*/
int test_wc_ecc_mulmod_projective(void)
{
EXPECT_DECLS;
#if defined(HAVE_ECC) && defined(WOLFSSL_PUBLIC_MP) && \
!defined(NO_ECC_SECP) && \
!(defined(WOLFSSL_ATECC508A) || defined(WOLFSSL_ATECC608A) || \
defined(WOLFSSL_MICROCHIP_TA100) || \
defined(WOLFSSL_VALIDATE_ECC_IMPORT)) && \
!defined(WOLF_CRYPTO_CB_ONLY_ECC) && !defined(HAVE_SELFTEST) && \
!defined(WOLFSSL_KCAPI_ECC) && !defined(WOLFSSL_STM32_PKA) && \
!defined(FREESCALE_LTC_ECC) && !defined(HAVE_FIPS) && \
!defined(WOLFSSL_NO_ECC_SW)
static const int curves[] = {
#if (!defined(NO_ECC256) || defined(HAVE_ALL_CURVES)) && \
(ECC_MIN_KEY_SZ <= 256) && \
(!defined(WOLFSSL_SP_MATH) || !defined(WOLFSSL_SP_NO_256))
ECC_SECP256R1,
#endif
#if (defined(HAVE_ECC384) || defined(HAVE_ALL_CURVES)) && \
(ECC_MIN_KEY_SZ <= 384) && \
(!defined(WOLFSSL_SP_MATH) || defined(WOLFSSL_SP_384))
ECC_SECP384R1,
#endif
#if (defined(HAVE_ECC521) || defined(HAVE_ALL_CURVES)) && \
(ECC_MIN_KEY_SZ <= 521) && \
(!defined(WOLFSSL_SP_MATH) || defined(WOLFSSL_SP_521))
ECC_SECP521R1,
#endif
ECC_CURVE_INVALID
};
#if defined(WOLFSSL_SP_MATH) && defined(FP_ECC)
const int projRet = WC_NO_ERR_TRACE(ECC_BAD_ARG_E);
#else
const int projRet = 0;
#endif
const ecc_set_type* dp = NULL;
ecc_point* g = NULL;
ecc_point* r = NULL;
ecc_point* kG = NULL;
ecc_point* negKG = NULL;
mp_int k;
mp_int a;
mp_int prime;
mp_int order;
int c;
int i;
int cnt = 1;

XMEMSET(&k, 0, sizeof(mp_int));
XMEMSET(&a, 0, sizeof(mp_int));
XMEMSET(&prime, 0, sizeof(mp_int));
XMEMSET(&order, 0, sizeof(mp_int));

ExpectIntEQ(mp_init_multi(&k, &a, &prime, &order, NULL, NULL), 0);
ExpectIntEQ(mp_read_radix(&k,
"1A2B3C4D5E6F708192A3B4C5D6E7F8091A2B3C4D5E6F708192A3B4C5D6E7F80",
MP_RADIX_HEX), 0);
ExpectNotNull(g = wc_ecc_new_point());
ExpectNotNull(r = wc_ecc_new_point());
ExpectNotNull(kG = wc_ecc_new_point());
ExpectNotNull(negKG = wc_ecc_new_point());

#ifdef WOLFSSL_PUBLIC_ECC_ADD_DBL
/* Also test wc_ecc_mulmod_ex2(). */
cnt = 2;
#endif

for (c = 0; curves[c] != ECC_CURVE_INVALID; c++) {
ExpectNotNull(dp = wc_ecc_get_curve_params(
wc_ecc_get_curve_idx(curves[c])));
if (dp != NULL) {
ExpectIntEQ(mp_read_radix(&a, dp->Af, MP_RADIX_HEX), 0);
ExpectIntEQ(mp_read_radix(&prime, dp->prime, MP_RADIX_HEX), 0);
ExpectIntEQ(mp_read_radix(&order, dp->order, MP_RADIX_HEX), 0);
ExpectIntEQ(mp_read_radix(g->x, dp->Gx, MP_RADIX_HEX), 0);
ExpectIntEQ(mp_read_radix(g->y, dp->Gy, MP_RADIX_HEX), 0);
}
ExpectIntEQ(mp_set(g->z, 1), 0);

/* kG from the affine base point, and -kG. */
ExpectIntEQ(wc_ecc_mulmod(&k, g, kG, &a, &prime, 1), 0);
ExpectIntEQ(wc_ecc_copy_point(kG, negKG), 0);
ExpectIntEQ(mp_sub(&prime, kG->y, negKG->y), 0);

for (i = 0; i < cnt; i++) {
/* (Gx, Gy, p - 1) is -G. */
ExpectIntEQ(mp_sub_d(&prime, 1, g->z), 0);
#ifdef FP_ECC
/* Don't let a table in the generic cache hide the SP code. */
wc_ecc_fp_free();
#endif
if (i == 0) {
ExpectIntEQ(wc_ecc_mulmod(&k, g, r, &a, &prime, 1), projRet);
}
#ifdef WOLFSSL_PUBLIC_ECC_ADD_DBL
else {
ExpectIntEQ(wc_ecc_mulmod_ex2(&k, g, r, &a, &prime, &order,
NULL, 1, NULL), projRet);
}
#endif
#if !defined(WOLFSSL_SP_MATH) || !defined(FP_ECC)
ExpectIntEQ(wc_ecc_cmp_point(r, negKG), MP_EQ);
#endif

/* G again: a table of -G must not be used. */
ExpectIntEQ(mp_set(g->z, 1), 0);
#ifdef FP_ECC
wc_ecc_fp_free();
#endif
ExpectIntEQ(wc_ecc_mulmod(&k, g, r, &a, &prime, 1), 0);
ExpectIntEQ(wc_ecc_cmp_point(r, kG), MP_EQ);
}
}

wc_ecc_del_point(negKG);
wc_ecc_del_point(kG);
wc_ecc_del_point(r);
wc_ecc_del_point(g);
mp_free(&order);
mp_free(&prime);
mp_free(&a);
mp_free(&k);

#ifdef FP_ECC
wc_ecc_fp_free();
#endif
#endif
return EXPECT_RESULT();
} /* END test_wc_ecc_mulmod_projective */

/*
* Testing wc_ecc_is_valid_idx()
*/
Expand Down
2 changes: 2 additions & 0 deletions tests/api/test_ecc.h
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Original file line number Diff line number Diff line change
Expand Up @@ -76,6 +76,7 @@ int test_wc_ecc_mulmod(void);
int test_wc_ecc_mulmod_unreduced(void);
int test_wc_ecc_mulmod_zero(void);
int test_wc_ecc_mulmod_curves(void);
int test_wc_ecc_mulmod_projective(void);
int test_wc_ecc_is_valid_idx(void);
int test_wc_ecc_get_curve_id_from_oid(void);
int test_wc_ecc_sig_size_calc(void);
Expand Down Expand Up @@ -141,6 +142,7 @@ int test_wc_ecc_make_key_id_dev(void);
TEST_DECL_GROUP("ecc", test_wc_ecc_mulmod_unreduced), \
TEST_DECL_GROUP("ecc", test_wc_ecc_mulmod_zero), \
TEST_DECL_GROUP("ecc", test_wc_ecc_mulmod_curves), \
TEST_DECL_GROUP("ecc", test_wc_ecc_mulmod_projective), \
TEST_DECL_GROUP("ecc", test_wc_ecc_is_valid_idx), \
TEST_DECL_GROUP("ecc", test_wc_ecc_get_curve_id_from_oid), \
TEST_DECL_GROUP("ecc", test_wc_ecc_sig_size_calc), \
Expand Down
10 changes: 10 additions & 0 deletions wolfcrypt/src/ecc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -14983,6 +14983,12 @@ int wc_ecc_mulmod_ex(const mp_int* k, ecc_point *G, ecc_point *R, mp_int* a,
mp_count_bits(G->z) > mp_count_bits(modulus)) {
return IS_POINT_E;
}
/* The SP code caches tables for points keyed on x and y only, so a point
* with z other than 1 could be multiplied using the table of another
* point. Only affine points are supported. */
if (!mp_isone(G->z)) {
return ECC_BAD_ARG_E;
}

#if defined(WOLFSSL_SM2) && defined(WOLFSSL_SP_SM2)
if ((mp_count_bits(modulus) == 256) && (!mp_is_bit_set(modulus, 224))) {
Expand Down Expand Up @@ -15150,6 +15156,10 @@ int wc_ecc_mulmod_ex2(const mp_int* k, ecc_point *G, ecc_point *R, mp_int* a,
mp_count_bits(G->z) > mp_count_bits(modulus)) {
return IS_POINT_E;
}
/* Only affine points are supported - see wc_ecc_mulmod_ex(). */
if (!mp_isone(G->z)) {
return ECC_BAD_ARG_E;
}

#if defined(WOLFSSL_SM2) && defined(WOLFSSL_SP_SM2)
if ((mp_count_bits(modulus) == 256) && (!mp_is_bit_set(modulus, 224))) {
Expand Down
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