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ecc: extract software public-key derivation into ecc_make_pub_sw

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Move the software private-scalar range checkout of ecc_make_pub_ex into
a dedicated helper. Pure code motion, no functional change.
This commit is contained in:
Marco Oliverio
2026-06-11 15:02:05 +02:00
parent 6ff1f8f2b8
commit 2f38b856c2
1 changed files with 74 additions and 48 deletions
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wolfcrypt/src/ecc.c
+74 -48
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@@ -5433,66 +5433,30 @@ static WC_INLINE void wc_ecc_reset(ecc_key* key)
}
/* create the public ECC key from a private key
#ifdef HAVE_ECC_MAKE_PUB
/* compute the public key Q = d*G in software
*
* key an initialized private key to generate public part from
* curve [in]curve for key, cannot be NULL
* pubOut [out]ecc_point holding the public key, if NULL then public key part
* is cached in key instead.
*
* Note this function is local to the file because of the argument type
* ecc_curve_spec. Having this argument allows for not having to load the
* curve type multiple times when generating a key with wc_ecc_make_key().
* For async the results are placed directly into pubOut, so this function
* does not need to be called again
* key private key holding the scalar d, must be present and in range
* curve [in]curve for key, cannot be NULL
* pub [out]initialized ecc_point receiving the public key
* rng optional RNG for a timing-resistant point multiply, may be NULL
*
* returns MP_OKAY on success
*/
static int ecc_make_pub_ex(ecc_key* key, ecc_curve_spec* curve,
ecc_point* pubOut, WC_RNG* rng)
static int ecc_make_pub_sw(ecc_key* key, ecc_curve_spec* curve,
ecc_point* pub, WC_RNG* rng)
{
int err = MP_OKAY;
#ifdef HAVE_ECC_MAKE_PUB
ecc_point* pub;
#endif /* HAVE_ECC_MAKE_PUB */
(void)rng;
if (key == NULL) {
return BAD_FUNC_ARG;
}
#ifdef HAVE_ECC_MAKE_PUB
/* if ecc_point passed in then use it as output for public key point */
if (pubOut != NULL) {
pub = pubOut;
}
else {
/* caching public key making it a ECC_PRIVATEKEY instead of
ECC_PRIVATEKEY_ONLY */
pub = &key->pubkey;
key->type = ECC_PRIVATEKEY_ONLY;
}
if ((err == MP_OKAY) && (mp_iszero(ecc_get_k(key)) ||
mp_isneg(ecc_get_k(key)) ||
(mp_cmp(ecc_get_k(key), curve->order) != MP_LT))) {
/* The private scalar must be in range for the base-point multiply
* below. */
if (mp_iszero(ecc_get_k(key)) || mp_isneg(ecc_get_k(key)) ||
(mp_cmp(ecc_get_k(key), curve->order) != MP_LT)) {
err = ECC_PRIV_KEY_E;
}
if (err == MP_OKAY) {
#ifndef ALT_ECC_SIZE
err = mp_init_multi(pub->x, pub->y, pub->z, NULL, NULL, NULL);
#else
pub->x = (mp_int*)&pub->xyz[0];
pub->y = (mp_int*)&pub->xyz[1];
pub->z = (mp_int*)&pub->xyz[2];
alt_fp_init(pub->x);
alt_fp_init(pub->y);
alt_fp_init(pub->z);
#endif
}
#if defined(WOLFSSL_ASYNC_CRYPT) && defined(WC_ASYNC_ENABLE_ECC_KEYGEN) && \
defined(HAVE_INTEL_QA)
if (err == MP_OKAY && key->asyncDev.marker == WOLFSSL_ASYNC_MARKER_ECC) {
@@ -5583,6 +5547,68 @@ static int ecc_make_pub_ex(ecc_key* key, ecc_curve_spec* curve,
#endif /* WOLFSSL_SP_MATH */
} /* END: Software Crypto */
return err;
}
#endif /* HAVE_ECC_MAKE_PUB */
/* create the public ECC key from a private key
*
* key an initialized private key to generate public part from
* curve [in]curve for key, cannot be NULL
* pubOut [out]ecc_point holding the public key, if NULL then public key part
* is cached in key instead.
*
* Note this function is local to the file because of the argument type
* ecc_curve_spec. Having this argument allows for not having to load the
* curve type multiple times when generating a key with wc_ecc_make_key().
* For async the results are placed directly into pubOut, so this function
* does not need to be called again
*
* returns MP_OKAY on success
*/
static int ecc_make_pub_ex(ecc_key* key, ecc_curve_spec* curve,
ecc_point* pubOut, WC_RNG* rng)
{
int err = MP_OKAY;
#ifdef HAVE_ECC_MAKE_PUB
ecc_point* pub;
#endif /* HAVE_ECC_MAKE_PUB */
(void)rng;
if (key == NULL) {
return BAD_FUNC_ARG;
}
#ifdef HAVE_ECC_MAKE_PUB
/* if ecc_point passed in then use it as output for public key point */
if (pubOut != NULL) {
pub = pubOut;
}
else {
/* caching public key making it a ECC_PRIVATEKEY instead of
ECC_PRIVATEKEY_ONLY */
pub = &key->pubkey;
key->type = ECC_PRIVATEKEY_ONLY;
}
if (err == MP_OKAY) {
#ifndef ALT_ECC_SIZE
err = mp_init_multi(pub->x, pub->y, pub->z, NULL, NULL, NULL);
#else
pub->x = (mp_int*)&pub->xyz[0];
pub->y = (mp_int*)&pub->xyz[1];
pub->z = (mp_int*)&pub->xyz[2];
alt_fp_init(pub->x);
alt_fp_init(pub->y);
alt_fp_init(pub->z);
#endif
}
if (err == MP_OKAY) {
err = ecc_make_pub_sw(key, curve, pub, rng);
}
if (err != MP_OKAY
#ifdef WOLFSSL_ASYNC_CRYPT
&& err != WC_NO_ERR_TRACE(WC_PENDING_E)