int err_reason = DH_R_BN_ERROR;
BIGNUM *pubkey = NULL;
const BIGNUM *p;
- size_t p_size;
+ int ret;
if ((pubkey = BN_bin2bn(buf, len, NULL)) == NULL)
goto err;
DH_get0_pqg(dh, &p, NULL, NULL);
- if (p == NULL || (p_size = BN_num_bytes(p)) == 0) {
+ if (p == NULL || BN_num_bytes(p) == 0) {
err_reason = DH_R_NO_PARAMETERS_SET;
goto err;
}
- /*
- * As per Section 4.2.8.1 of RFC 8446 fail if DHE's
- * public key is of size not equal to size of p
- */
- if (BN_is_zero(pubkey) || p_size != len) {
+ /* Prevent small subgroup attacks per RFC 8446 Section 4.2.8.1 */
+ if (!ossl_dh_check_pub_key_partial(dh, pubkey, &ret)) {
err_reason = DH_R_INVALID_PUBKEY;
goto err;
}