allow ECC private key only import

wolfcrypt/src/ecc.c

@@ -4790,10 +4790,38 @@ int wc_ecc_export_private_raw(ecc_key* key, byte* qx, word32* qxLen,
 #endif /* HAVE_ECC_KEY_EXPORT */
 
 #ifdef HAVE_ECC_KEY_IMPORT
-int wc_ecc_import_private_key_ex(const byte* priv, word32 privSz, const byte* pub,
+/* import private key, public part optional if (pub) passed as NULL */
-                           word32 pubSz, ecc_key* key, int curve_id)
+int wc_ecc_import_private_key_ex(const byte* priv, word32 privSz,
+                                 const byte* pub, word32 pubSz, ecc_key* key,
+                                 int curve_id)
 {
-    int ret = wc_ecc_import_x963_ex(pub, pubSz, key, curve_id);
+    int ret;
+    void* heap;
+
+    /* public optional, NULL if only importing private */
+    if (pub != NULL) {
+
+        ret = wc_ecc_import_x963_ex(pub, pubSz, key, curve_id);
+
+    } else {
+
+        if (key == NULL || priv == NULL)
+            return BAD_FUNC_ARG;
+
+        /* init key */
+        heap = key->heap;
+        ret = wc_ecc_init_ex(key, NULL, INVALID_DEVID);
+        key->heap = heap;
+
+        key->state = ECC_STATE_NONE;
+
+        if (ret != 0)
+            return ret;
+
+        /* set key size */
+        ret = wc_ecc_set_curve(key, privSz-1, curve_id);
+    }
+
     if (ret != 0)
         return ret;
 

wolfcrypt/test/test.c

@@ -10261,6 +10261,7 @@ static int ecc_sig_test(WC_RNG* rng, ecc_key* key)
 static int ecc_exp_imp_test(ecc_key* key)
 {
     int        ret;
+    int        curve_id;
     ecc_key    keyImp;
     byte       priv[32];
     word32     privLen;
@@ -10302,6 +10303,19 @@ static int ecc_exp_imp_test(ecc_key* key)
         goto done;
     }
 
+    wc_ecc_free(&keyImp);
+    wc_ecc_init(&keyImp);
+
+    curve_id = wc_ecc_get_curve_id(key->idx);
+    if (curve_id < 0)
+        return -1074;
+
+    /* test import private only */
+    ret = wc_ecc_import_private_key_ex(priv, privLen, NULL, 0, &keyImp,
+                                       curve_id);
+    if (ret != 0)
+        return -1075;
+
 done:
     wc_ecc_free(&keyImp);
     return ret;