Add EC public key auto derivation from private key

src/wp_ecc_kmgmt.c

@@ -1149,6 +1149,31 @@ static int wp_ecc_import_keypair(wp_Ecc* ecc, const OSSL_PARAM params[],
         ) {
         ecc->key.type = ECC_PRIVATEKEY;
         ecc->hasPriv = 1;
+
+        /* Auto-derive public key if not already present and curve is 
+         * set with OpenSSL version newer than 3.6.0 */
+#if OPENSSL_VERSION_NUMBER > 0x30600000L
+        if (!ecc->hasPub && ecc->curveId != 0) {
+            int rc;
+
+            rc = wc_ecc_set_curve(&ecc->key, 0, ecc->curveId);
+            if (rc == 0) {
+#ifdef ECC_TIMING_RESISTANT
+                rc = wc_ecc_make_pub_ex(&ecc->key, NULL, &ecc->rng);
+#else
+                rc = wc_ecc_make_pub_ex(&ecc->key, NULL, NULL);
+#endif
+                /* Indicate public key is available if derivation succeeds */
+                if (rc == 0) {
+                    ecc->key.type = ECC_PRIVATEKEY;
+                    ecc->hasPub = 1;
+                }
+                /* If derivation fails, continue.
+                 * The key is still valid for private key operations.
+                 * We will fail later if public key is accessed. */
+            }
+        }
+#endif /* OPENSSL_VERSION_NUMBER > 0x30600000L 3.6.0+ */
     }
 
     WOLFPROV_LEAVE(WP_LOG_COMP_ECC, __FILE__ ":" WOLFPROV_STRINGIZE(__LINE__), ok);

test/test_ecc.c

@@ -1877,7 +1877,51 @@ static int test_ec_import_priv(void)
         err = EVP_PKEY_fromdata(ctx2, &pkey2, EVP_PKEY_KEYPAIR, params) != 1;
     }
 
-    /* For imported private only keys, get bn params should fail */
+    /* For imported private only keys, public key params behavior depends on OpenSSL version */
+#if OPENSSL_VERSION_NUMBER > 0x30600000L
+    /* OpenSSL 3.6.0+ auto-derives public keys from private keys */
+    if (err == 0) {
+        err = EVP_PKEY_get_bn_param(pkey1, OSSL_PKEY_PARAM_EC_PUB_X, &x1) != 1;
+    }
+    if (err == 0) {
+        err = EVP_PKEY_get_bn_param(pkey2, OSSL_PKEY_PARAM_EC_PUB_X, &x2) != 1;
+    }
+    if (err == 0) {
+        err = EVP_PKEY_get_bn_param(pkey1, OSSL_PKEY_PARAM_EC_PUB_Y, &y1) != 1;
+    }
+    if (err == 0) {
+        err = EVP_PKEY_get_bn_param(pkey2, OSSL_PKEY_PARAM_EC_PUB_Y, &y2) != 1;
+    }
+
+    /* Verify public key is available */
+    if (err == 0) {
+        if (EVP_PKEY_get_octet_string_param(pkey1,
+                OSSL_PKEY_PARAM_PUB_KEY, NULL, 0, (size_t *)&len) != 1) {
+            err = 1;
+        }
+    }
+    if (err == 0) {
+        if (EVP_PKEY_get_octet_string_param(pkey2,
+                OSSL_PKEY_PARAM_PUB_KEY, NULL, 0, (size_t *)&len) != 1) {
+            err = 1;
+        }
+    }
+
+    /* Verify encoded public key is available */
+    if (err == 0) {
+        if (EVP_PKEY_get_octet_string_param(pkey1,
+            OSSL_PKEY_PARAM_ENCODED_PUBLIC_KEY, NULL, 0, (size_t *)&len) != 1) {
+            err = 1;
+        }
+    }
+    if (err == 0) {
+        if (EVP_PKEY_get_octet_string_param(pkey2,
+            OSSL_PKEY_PARAM_ENCODED_PUBLIC_KEY, NULL, 0, (size_t *)&len) != 1) {
+            err = 1;
+        }
+    }
+#else
+    /* OpenSSL < 3.6.0: private-only keys should not have public components */
     if (err == 0) {
         err = EVP_PKEY_get_bn_param(pkey1, OSSL_PKEY_PARAM_EC_PUB_X, &x1) == 1;
     }
@@ -1918,7 +1962,8 @@ static int test_ec_import_priv(void)
             err = 1;
         }
     }
-#endif
+#endif /* OPENSSL_VERSION_NUMBER >= 0x30006000L 3.0.6+ */
+#endif /* OPENSSL_VERSION_NUMBER > 0x30600000L 3.6.0+ */
 
     EVP_PKEY_free(pkey1);
     EVP_PKEY_free(pkey2);
@@ -2060,4 +2105,105 @@ int test_ec_null_init(void* data)
     return err;
 }
 
+#if OPENSSL_VERSION_NUMBER > 0x30600000L
+static int test_ec_auto_derive_pub(void)
+{
+    int err = 0;
+    EVP_PKEY_CTX *ctx = NULL;
+    EVP_PKEY* pkey = NULL;
+    OSSL_PARAM *params = NULL;
+    OSSL_PARAM_BLD *bld = NULL;
+    BIGNUM* priv = NULL;
+    BIGNUM* pub_x = NULL;
+    BIGNUM* pub_y = NULL;
+    unsigned char pub_key[65] = {0};
+    size_t pub_key_len = sizeof(pub_key);
+
+    /* Build params with private key only (no public key) */
+    err = (bld = OSSL_PARAM_BLD_new()) == NULL;
+    if (err == 0) {
+        err = OSSL_PARAM_BLD_push_utf8_string(bld, OSSL_PKEY_PARAM_GROUP_NAME,
+                ecc_p256_group_str, 0) != 1;
+    }
+    if (err == 0) {
+        err = (priv = BN_bin2bn(ecc_p256_priv, sizeof(ecc_p256_priv), NULL)) == NULL;
+    }
+    if (err == 0) {
+        err = OSSL_PARAM_BLD_push_BN(bld, OSSL_PKEY_PARAM_PRIV_KEY, priv) != 1;
+    }
+    if (err == 0) {
+        err = (params = OSSL_PARAM_BLD_to_param(bld)) == NULL;
+    }
+    /* Import key using wolfProvider */
+    if (err == 0) {
+        err = (ctx = EVP_PKEY_CTX_new_from_name(wpLibCtx, "EC", NULL)) == NULL;
+    }
+    if (err == 0) {
+        err = EVP_PKEY_fromdata_init(ctx) != 1;
+    }
+    if (err == 0) {
+        err = EVP_PKEY_fromdata(ctx, &pkey, EVP_PKEY_KEYPAIR, params) != 1;
+    }
+    /* Verify public X coordinate is available (auto-derived) */
+    if (err == 0) {
+        err = EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_EC_PUB_X, &pub_x) != 1;
+    }
+    /* Verify public Y coordinate is available (auto-derived) */
+    if (err == 0) {
+        err = EVP_PKEY_get_bn_param(pkey, OSSL_PKEY_PARAM_EC_PUB_Y, &pub_y) != 1;
+    }
+    /* Verify public key octet string is available */
+    if (err == 0) {
+        err = EVP_PKEY_get_octet_string_param(pkey, OSSL_PKEY_PARAM_PUB_KEY,
+                pub_key, pub_key_len, &pub_key_len) != 1;
+    }
+    if (err == 0) {
+        if (pub_key_len == 0 || pub_key_len > sizeof(pub_key)) {
+            err = 1;
+        }
+    }
+    /* Verify encoded public key is available */
+    if (err == 0) {
+        pub_key_len = sizeof(pub_key);
+        err = EVP_PKEY_get_octet_string_param(pkey, OSSL_PKEY_PARAM_ENCODED_PUBLIC_KEY,
+                pub_key, pub_key_len, &pub_key_len) != 1;
+    }
+    if (err == 0) {
+        if (pub_key_len == 0 || pub_key_len > sizeof(pub_key)) {
+            err = 1;
+        }
+    }
+    /* Verify the derived public key is valid (non-zero coordinates) */
+    if (err == 0) {
+        if (BN_is_zero(pub_x) || BN_is_zero(pub_y)) {
+            err = 1;
+        }
+    }
+
+    EVP_PKEY_free(pkey);
+    EVP_PKEY_CTX_free(ctx);
+    OSSL_PARAM_free(params);
+    OSSL_PARAM_BLD_free(bld);
+    BN_clear_free(priv);
+    BN_free(pub_x);
+    BN_free(pub_y);
+
+    return err;
+}
+#endif /* OPENSSL_VERSION_NUMBER > 0x30600000L */
+
+int test_ec_auto_derive_pubkey(void* data)
+{
+    int err = 0;
+    (void)data;
+
+#if OPENSSL_VERSION_NUMBER > 0x30600000L
+    err = test_ec_auto_derive_pub();
+#else
+    err = 0;
+#endif
+
+    return err;
+}
+
 #endif /* WP_HAVE_ECC */

test/unit.c

@@ -355,6 +355,7 @@ TEST_CASE test_case[] = {
     #endif
     TEST_DECL(test_ec_decode, NULL),
     TEST_DECL(test_ec_import, NULL),
+    TEST_DECL(test_ec_auto_derive_pubkey, NULL),
     TEST_DECL(test_ec_null_init, NULL),
 #endif
 #ifdef WP_HAVE_EC_P384

test/unit.h

@@ -396,6 +396,7 @@ int test_ec_load_cert(void* data);
 
 int test_ec_decode(void* data);
 int test_ec_import(void* data);
+int test_ec_auto_derive_pubkey(void* data);
 int test_ec_null_init(void* data);
 
 #endif /* WP_HAVE_ECC */